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1
Manier, Salomon, Antonio Sacco, Patricia Maiso, Yong Zhang, Yang Liu, Yosra Aljawai, Weixin Wang, et al. "Let-7 Microrna Family Members Regulate Cell Proliferation in Multiple Myeloma." Blood 120, no. 21 (November 16, 2012): 570. http://dx.doi.org/10.1182/blood.v120.21.570.570.
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Abstract Abstract 570 Background. MicroRNAs (miRNAs) play a pivotal role in tumorigenesis, due to their ability to target mRNAs involved in the regulation of cell proliferation, survival and differentiation. In particular, the Let-7 miRNA family members have been described to act as tumor suppressors, as demonstrated both in solid cancer and hematologic malignancies. However, the role of Let-7 in multiple myeloma (MM) has not been studied. Method. Circulating miRNA profiling has been performed in MM patients compared to healthy individuals using TaqMan human miRNA profiling, and validated by qRT-PCR. Exosomes were collected from both normal and MM peripheral blood, using ultracentrifugation; and further studied by using electron microscopy and immunogold labeling for the detection of CD63 and CD81. Exosomes were then evaluated for their miRNA content, by qRT-PCR. Gain- and loss-of functions studies were performed on MM cell lines (MM.1S; U266), using Let-7-mimic and Lin28B siRNA, respectively. Scramble probe-transfected cells were used as control. Cell proliferation and cell survival have been evaluated by using BrdU assay and MTT assay, respectively. Effects of Let-7 and Lin28B on signaling cascades have been evaluated by western blot. Results. We identified a MM specific signature characterized by down-regulation of miRNA-15a, −19b, −21, let-7b, let-7c and over-expression of miR-720 (P < 0.001). Circulating exosomes were studied at ultrastructural level showing positivity for CD81 and CD63, as demonstrated by immunogold labeling and electron microscopy. The same miRNA signature was found in the circulating exosomes, suggesting that circulating miRNAs may be transported by exosomes. The Let-7 family members were significantly decreased in peripheral blood of MM patient compared to healthy individuals, suggesting that Let-7 family could be down-regulated in MM cells. We then performed qRT-PCR in MM primary cells; and found that the Let-7 family is significantly down-regulated in MM primary cells, especially for Let-7b and c (5 fold change, P< 0.05). Over-expression of Let-7b and Let-7c in MM cells (U266; MM1S) transfected decreased cell proliferation. The RNA binding protein Lin28B is known to regulate the Let-7 family: we therefore performed Lin28-loss of function studies which led to up-regulation of the Let-7 family members, in MM transfected cells; and found that Lin28B-knockdown cells presented with reduced cell proliferation, supported by down-regulation of c-Myc and K-Ras, known to be Let-7-related targets. Conclusion. This data indicate that Let-7 miRNA family members play an important role in modulating MM biology, thus providing the basis for the development of new miRNA-based target therapies and biomarker in this disease. Disclosures: Ghobrial: Novartis: advisory board, advisory board Other; Millennium: Membership on an entity's Board of Directors or advisory committees; Onyx: Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: advisory board, advisory board Other.
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Fang, W.-J., C.-Z. Lin, H.-H. Zhang, J. Qian, L. Zhong, and N. Xu. "Detection of let-7a MicroRNA by Real-time PCR in Colorectal Cancer: a Single-centre Experience from China." Journal of International Medical Research 35, no. 5 (September 2007): 716–23. http://dx.doi.org/10.1177/147323000703500518.
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Colorectal cancer, a heterogeneous disease arising from a complex series of molecular changes, is one of the world's leading causes of cancer deaths. MicroRNAs (miRNAs), an extensive class of small non-coding RNAs, have been implicated in cancer development and progression. One of the first miRNAs to be identified was let-7 miRNA, which has recently been found to be expressed at reduced levels in human lung cancer cells. We used a rapid stem-loop reverse transcription polymerase chain reaction method to quantify human let-7a miRNA expression in samples of human colorectal cancer. This method was able to detect let-7a miRNA in as little as 0.05 ng of total RNA from colorectal mucosa and its specificity was high (100%). Our results showed that the expression of let-7a miRNA was considerably reduced in two of eight patients. To our knowledge, this is the first study of Chinese patients to show reduced expression of endogenous let-7 miRNA in colorectal cancer.
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Campbell, Ashley M., Carlos F. De La Cruz-Herrera, Edyta Marcon, Jack Greenblatt, and Lori Frappier. "Epstein-Barr Virus BGLF2 commandeers RISC to interfere with cellular miRNA function." PLOS Pathogens 18, no. 1 (January 10, 2022): e1010235. http://dx.doi.org/10.1371/journal.ppat.1010235.
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The Epstein-Barr virus (EBV) BGLF2 protein is a tegument protein with multiple effects on the cellular environment, including induction of SUMOylation of cellular proteins. Using affinity-purification coupled to mass-spectrometry, we identified the miRNA-Induced Silencing Complex (RISC), essential for miRNA function, as a top interactor of BGLF2. We confirmed BGLF2 interaction with the Ago2 and TNRC6 components of RISC in multiple cell lines and their co-localization in cytoplasmic bodies that also contain the stress granule marker G3BP1. In addition, BGLF2 expression led to the loss of processing bodies in multiple cell types, suggesting disruption of RISC function in mRNA regulation. Consistent with this observation, BGLF2 disrupted Ago2 association with multiple miRNAs. Using let-7 miRNAs as a model, we tested the hypothesis that BGLF2 interfered with the function of RISC in miRNA-mediated mRNA silencing. Using multiple reporter constructs with 3’UTRs containing let-7a regulated sites, we showed that BGLF2 inhibited let-7a miRNA activity dependent on these 3’UTRs, including those from SUMO transcripts which are known to be regulated by let-7 miRNAs. In keeping with these results, we showed that BGLF2 increased the cellular level of unconjugated SUMO proteins without affecting the level of SUMO transcripts. Such an increase in free SUMO is known to drive SUMOylation and would account for the effect of BGLF2 in inducing SUMOylation. We further showed that BGLF2 expression inhibited the loading of let-7 miRNAs into Ago2 proteins, and conversely, that lytic infection with EBV lacking BGLF2 resulted in increased interaction of let-7a and SUMO transcripts with Ago2, relative to WT EBV infection. Therefore, we have identified a novel role for BGLF2 as a miRNA regulator and shown that one outcome of this activity is the dysregulation of SUMO transcripts that leads to increased levels of free SUMO proteins and SUMOylation.
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Pasquinelli, Amy E. "The primary target of let-7 microRNA." Biochemical Society Transactions 41, no. 4 (July 18, 2013): 821–24. http://dx.doi.org/10.1042/bst20130020.
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The let-7 miRNA (microRNA) is an essential regulator of development from nematode worms to humans. Altered expression of let-7 results in larval arrest or lethality in Caenorhabditis elegans. Likewise, under- or over-expression of let-7 in human cells can result in cellular overproliferation or halted cell division respectively. Thus the biogenesis of this critical miRNA is controlled at multiple levels. An unexpected mechanism for regulating the initial processing of let-7 was recently found to involve the let-7 miRNA itself. The mature let-7 miRNA along with its effector protein, Argonaute, were shown to bind to a site in the primary transcripts produced by the let-7 gene. This interaction enhances processing through a novel auto-regulatory feedback loop. This discovery highlights a new role for the miRNA complex in regulating miRNA biogenesis and enriches the classes of RNAs targeted by Argonaute.
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Ren, Zhiji, and Victor R. Ambros. "Caenorhabditis elegans microRNAs of the let-7 family act in innate immune response circuits and confer robust developmental timing against pathogen stress." Proceedings of the National Academy of Sciences 112, no. 18 (April 20, 2015): E2366—E2375. http://dx.doi.org/10.1073/pnas.1422858112.
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Animals maintain their developmental robustness against natural stresses through numerous regulatory mechanisms, including the posttranscriptional regulation of gene expression by microRNAs (miRNAs). Caenorhabditis elegans miRNAs of the let-7 family (let-7-Fam) function semiredundantly to confer robust stage specificity of cell fates in the hypodermal seam cell lineages. Here, we show reciprocal regulatory interactions between let-7-Fam miRNAs and the innate immune response pathway in C. elegans. Upon infection of C. elegans larvae with the opportunistic human pathogen Pseudomonas aeruginosa, the developmental timing defects of certain let-7-Fam miRNA mutants are enhanced. This enhancement is mediated by the p38 MAPK innate immune pathway acting in opposition to let-7-Fam miRNA activity, possibly via the downstream Activating Transcription Factor-7 (ATF-7). Furthermore, let-7-Fam miRNAs appear to exert negative regulation on the worm’s resistance to P. aeruginosa infection. Our results show that the inhibition of pathogen resistance by let-7 involves downstream heterochronic genes and the p38 MAPK pathway. These findings suggest that let-7-Fam miRNAs are integrated into innate immunity gene regulatory networks, such that this family of miRNAs modulates immune responses while also ensuring robust timing of developmental events under pathogen stress.
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Liu, Jun, Madeline A. Sauer, Shaza G. Hussein, Junyu Yang, Daniel G. Tenen, and Li Chai. "SALL4 and microRNA: The Role of Let-7." Genes 12, no. 9 (August 24, 2021): 1301. http://dx.doi.org/10.3390/genes12091301.
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SALL4 is a zinc finger transcription factor that belongs to the spalt-like (SALL) gene family. It plays important roles in the maintenance of self-renewal and pluripotency of embryonic stem cells, and its expression is repressed in most adult organs. SALL4 re-expression has been observed in different types of human cancers, and dysregulation of SALL4 contributes to the pathogenesis, metastasis, and even drug resistance of multiple cancer types. Surprisingly, little is known regarding how SALL4 expression is controlled, but recently microRNAs (miRNAs) have emerged as important regulators of SALL4. Due to the ability of regulating targets differentially in specific tissues, and recent advances in systemic and organ specific miRNA delivery mechanisms, miRNAs have emerged as promising therapeutic targets for cancer treatment. In this review, we summarize current knowledge of the interaction between SALL4 and miRNAs in mammalian development and cancer, paying particular attention to the emerging roles of the Let-7/Lin28 axis. In addition, we discuss the therapeutic prospects of targeting SALL4 using miRNA-based strategies, with a focus on the Let-7/LIN28 axis.
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Zhang, Pengcheng, Mallory I. Frederick, and Ilka U. Heinemann. "Terminal Uridylyltransferases TUT4/7 Regulate microRNA and mRNA Homeostasis." Cells 11, no. 23 (November 23, 2022): 3742. http://dx.doi.org/10.3390/cells11233742.
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The terminal nucleotidyltransferases TUT4 and TUT7 (TUT4/7) regulate miRNA and mRNA stability by 3′ end uridylation. In humans, TUT4/7 polyuridylates both mRNA and pre-miRNA, leading to degradation by the U-specific exonuclease DIS3L2. We investigate the role of uridylation-dependent decay in maintaining the transcriptome by transcriptionally profiling TUT4/7 deleted cells. We found that while the disruption of TUT4/7 expression increases the abundance of a variety of miRNAs, the let-7 family of miRNAs is the most impacted. Eight let-7 family miRNAs were increased in abundance in TUT4/7 deleted cells, and many let-7 mRNA targets are decreased in abundance. The mRNAs with increased abundance in the deletion strain are potential direct targets of TUT4/7, with transcripts coding for proteins involved in cellular stress response, rRNA processing, ribonucleoprotein complex biogenesis, cell–cell signaling, and regulation of metabolic processes most affected in the TUT4/7 knockout cells. We found that TUT4/7 indirectly control oncogenic signaling via the miRNA let-7a, which regulates AKT phosphorylation status. Finally, we find that, similar to fission yeast, the disruption of uridylation-dependent decay leads to major rearrangements of the transcriptome and reduces cell proliferation and adhesion.
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Medhi, Ragini, Jonathan Price, Giulia Furlan, Beronia Gorges, Alexandra Sapetschnig, and Eric A. Miska. "RNA uridyl transferases TUT4/7 differentially regulate miRNA variants depending on the cancer cell type." RNA 28, no. 3 (December 23, 2021): 353–70. http://dx.doi.org/10.1261/rna.078976.121.
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The human terminal uridyl transferases TUT4 and TUT7 (TUT4/7) catalyze the additions of uridines at the 3′ end of RNAs, including the precursors of the tumor suppressor miRNA let-7 upon recruitment by the oncoprotein LIN28A. As a consequence, let-7 family miRNAs are down-regulated. Disruption of this TUT4/7 activity inhibits tumorigenesis. Hence, targeting TUT4/7 could be a potential anticancer therapy. In this study, we investigate TUT4/7-mediated RNA regulation in two cancer cell lines by establishing catalytic knockout models. Upon TUT4/7 mutation, we observe a significant reduction in miRNA uridylation, which results in defects in cancer cell properties such as cell proliferation and migration. With the loss of TUT4/7-mediated miRNA uridylation, the uridylated miRNA variants are replaced by adenylated isomiRs. Changes in miRNA modification profiles are accompanied by deregulation of expression levels in specific cases. Unlike let-7s, most miRNAs do not depend on LIN28A for TUT4/7-mediated regulation. Additionally, we identify TUT4/7-regulated cell-type-specific miRNA clusters and deregulation in their corresponding mRNA targets. Expression levels of miR-200c-3p and miR-141-3p are regulated by TUT4/7 in a cancer cell-type-specific manner. Subsequently, BCL2, which is a well-established target of miR-200c is up-regulated. Therefore, TUT4/7 loss causes deregulation of miRNA–mRNA networks in a cell-type-specific manner. Understanding of the underlying biology of such cell-type-specific deregulation will be an important aspect of targeting TUT4/7 for potential cancer therapies.
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Emmrich, Stephan, Sarva Keihani, Dirk Reinhardt, and Jan-Henning Klusmann. "Members of the Mir-99/100~125 Tricistrons Cooperatively Induce a Pre-Leukemic Myeloproliferative Disorder." Blood 126, no. 23 (December 3, 2015): 3579. http://dx.doi.org/10.1182/blood.v126.23.3579.3579.
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Abstract MicroRNAs (miRNAs) reflect the best studied class of regulatory non-coding RNAs (ncRNAs), which control genetic networks with key cellular functions. In vertebrate genomes, a significant number of miRNA genes are located closely adjacent to each other in miRNA polycistrons. The mature miRNAs of the three human miR-99/100~125 clusters, each containing one miR-99/100, let-7 and miR-125 family member in identical polycistronic configuration, are processed from one single transcript and are highly expressed in acute promyelocytic leukemia (APL). Expression profiling by qPCR in sorted murine hematopoietic stem cells (HSCs), common myeloid progenitors (CMPs), megakaryocytic erythroid progenitors (MEPs) and granulocytic monocytic progenitors (GMPs) revealed high expression levels of miR-99/100 and miR-125 family members in HSCs and CMPs. However, the consequences of the coordinated expression of the miRNAs belonging to different seed families on self-renewal and proliferation of HSCs and myeloid progenitors and their contribution to the pathogenesis of APL are not well understood. To elucidate the genetic interactive network of miR-99/100~125 miRNAs and the role of each individual miRNA within this network, we generated a set of eight different constructs covering any permutation of miRNA family members from the two miR-99/100~125 clusters on hsa11 and hsa21 (miR-99a, miR-125b-2, let-7c, miR-99a/let-7c, miR-100/miR-125b-1, let-7a-2/miR-125b-1, miR-100/let-7a-2/miR-125b-1 and miR-99a/let-7c/miR-125b-2). Lentiviral overexpression of these constructs in human hematopoietic stem and progenitor cells (HSPCs) resulted in a significant reduction of monocytic/macrophage colony-forming units (CFU-M; 2.2-2.8-fold, p≤0.05) and granulocytic CFU-Gs (2-4.3-fold, p≤0.05) in methylcellulose-based CFU assays exclusively for miR-125-containing bi-/tricistronic constructs (miR-100/miR-125b-1, let-7a-2/miR-125b-1, miR-100/let-7a-2/miR-125b-1 and miR-99a/let-7c/miR-125b-2), but not for the single miRNA expression constructs. Accordingly, during myelomonocytic differentiation HSPCs transduced with those miR-125-containing bi-/tricistronic constructs gave rise to a major population of monomorphic, non-adherent cells devoid of granulocytic and monocytic markers, which was not present in single miRNA-transduced cells. In murine isogenic transplantation experiments (N=105), only the combined miRNA expression of miR-125b with let-7 and/or miR-99/100 led to the expansion and retention of immature Gr-1(low)/Mac-1(+)/B220(-) cells in the bone marrow (1.6-1.8fold; p≤0.01). Accordingly, either the CMP or GMP compartment of transplanted mice was expanded in miR-125-containing bi-/tricistronic constructs (CMPs 1.6-fold in let-7a-2/miR-125b-1, GMPs 1.8-1.9-fold in miR-100/miR-125b-1 and tricistrons; p≤0.01;), but not upon single miRNA overexpression (1.1-1.3-fold; p≥0.1). Global gene expression profiling of human HSPCs transduced with the eight miRNA constructs revealed a core expression signature commonly regulated by the four miR-125b-containing bi-/ tricistronic constructs (367 genes upregulated [>1.5-fold]; 417 genes downregulated). Strikingly, this core signature is enriched for genes with concordant expression in leukemic stem cells (LSCs) and HSCs (FDR q≤1.8x10-14). The genes of the core signature were not or only modestly affected in the context of the single miRNAs. Thus, the miR-99/100~125 tricistron miRNAs form an interaction network, wherein the combined activity of miR-125b with let-7 and/or miR-99/100 family members converged to induce a stem cell signature creating a synthetic phenotype. The synthetic phenotype can only be observed in the combination of two or all three miRNAs but not for each miRNA alone, and is generated by miR-99/100 and/or let-7 altering the hematologically dominant miR-125 phenotype. This interactive network might explain the genomic miR-99/100~125 clustering and reveals a novel cooperative mode to induce self-renewal and a differentiation block in myeloid progenitor cells, predisposing them to leukemic transformation in APL. Disclosures No relevant conflicts of interest to declare.
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de Vasconcellos, Jaira F., Colleen Byrnes, Y. Terry Lee, Megha Kaushal, Joshua M. Allwardt, Antoinette Rabel, and Jeffery L. Miller. "Targeted Reduction of Let-7a miRNA Increases Fetal Hemoglobin in Human Adult Erythroblasts." Blood 124, no. 21 (December 6, 2014): 451. http://dx.doi.org/10.1182/blood.v124.21.451.451.
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Abstract MicroRNAs (miRNAs) are a class of small, noncoding RNAs that bind and regulate target messenger RNAs (mRNAs). The let-7 family consists of twelve genes encoding nine highly conserved miRNAs that are involved in developmental timing events in multicellular organisms. Previous studies showed regulation during the fetal-to-adult transition in the erythroid lineage with significant increases in let-7 miRNAs from adult compared to umbilical cord blood reticulocytes (1). Further studies indicated that reduced expression of let-7 in adult CD34+ cells by “sponge” targeting the miRNA family seed region caused increased fetal hemoglobin (HbF), but the mean level of HbF remained less than 20% of the total hemoglobin (2). Increased expression of LIN28A (a major regulator of all let-7 miRNAs) caused greater increases in HbF (greater than 30% of the total) in cultured erythrocytes from pediatric patients with HbSS genotype (3). However, these studies did not address the potential for targeting an individual let-7 miRNA family member to regulate HbF expression. For this purpose, we initially determined the expression levels of mature let-7 family members in purified cell populations sorted from peripheral blood. The total levels of let-7 miRNAs in peripheral blood cells were as follows: reticulocytes: 1.7E+08 ± 1.0E+08 copies/ng; neutrophils: 2.0E+07 ± 1.1E+07 copies/ng; lymphocytes: 1.1E+07 ± 6.2E+06 copies/ng and monocytes: 3.5E+06 ± 2.7E+06 copies/ng. Among the individual species, let-7a was identified as a predominantly expressed let-7 family member in reticulocytes. As such, we hypothesized that specifically targeting let-7a may be sufficient to regulate HbF levels. To study the effects of let-7a miRNAs upon erythropoiesis and globin expression, a lentiviral construct that incorporated the tough decoy (TuD) design to target let-7a was compared with empty vector controls. Transductions were performed in CD34+ cells from five adult healthy volunteers cultivated ex vivo in erythropoietin-supplemented serum-free media for 21 days. Down-regulation of let-7a was confirmed by Q-RT-PCR at day 14 (control: 1.4E+07 ± 2.4E+06 copies/ng; let-7a-TuD: 1.6E+06 ± 4.6E+05 copies/ng; p=0.0003). Cell proliferation and differentiation were comparable in let-7a-TuD versus control transductions. Expression levels of globin genes were evaluated upon let-7a-TuD by Q-RT-PCR. Let-7a-TuD transductions caused significantly increased gamma-globin mRNA expression levels compared to control transductions (control: 1.2E+06 ± 6.8E+05 copies/ng; let-7a-TuD: 1.1E+07 ± 4.5E+06 copies/ng; p=0.004). HPLC analyses at the end of the culture period demonstrated robust increases in HbF levels after let-7a-TuD transduction (HbF control: 4.7 ± 0.6%; let-7a-TuD: 38.2 ± 3.8%; p=0.00003). In addition, the expression patterns of the erythroid transcription factors BCL11A, KLF1 and SOX6 were investigated. Let-7a-TuD decreased BCL11A mRNA expression levels (control: 1.7E+03 ± 4.5E+02 copies/ng; let-7a-TuD: 4.3E+02 ± 1.8E+02 copies/ng; p=0.003), but major changes in KLF1 or SOX6 were not detected. In summary, we report here that the let-7 miRNA family is differentially expressed in purified cell populations from adult human blood, and that let-7a is a predominantly expressed species in reticulocytes. Further, targeted reduction of let-7a in erythroblasts is sufficient to cause robust increases in gamma-globin mRNA expression and HbF to mean levels around 35-40% of the total hemoglobin produced. Targeting of individual let-7 genes or RNA transcripts may be useful for therapeutic induction of HbF expression in patients with sickle cell disease or other beta-hemoglobinopathies. 1) Noh SJ et al. J Transl Med. 7:98 (2009). 2) Lee YT et al. Blood. 122:1034-41 (2013). 3) Vasconcellos JF et al. Blood. 122: Abstract 313 (2013). Disclosures No relevant conflicts of interest to declare.
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Takemoto, Clifford, Christopher Gamper, Youl-Nam Lee, Joshua Mendell, Stephanie Brandal, Jonathan Powell, and Michael McDevitt. "Regulation of IL-13 in mast cells by the Let-7 miRNA family (86.15)." Journal of Immunology 184, no. 1_Supplement (April 1, 2010): 86.15. http://dx.doi.org/10.4049/jimmunol.184.supp.86.15.
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Abstract In mast cells, IL-13 protein is robustly expressed with IgE activation; IL-13 mRNA transcript also increases, but rapidly returns to baseline levels within several hours. Based on these observations, we postulated that miRNAs may regulate IL-13 protein expression at the post-transcriptional level. miRNAs play roles in a number of biologic processes but little is known about their function in mediating allergic disease. To explore if miRNAs contribute to IL-13 regulation and other IgE responses, we performed a microarray screen for miRNAs regulated by IgE in both mouse and human mast cells. We found that IgE stimulation resulted in widespread depression of miRNAs, including downregulation of the Let-7 miRNA family. We looked for proteins expressed in IgE activated mast cells that were potentially targeted by Let-7. We found a highly conserved Let-7 binding site in the 3’UTR of the IL-13 gene. We further demonstrate that the IL-13 UTR is regulated by Let-7; forced expression of Let-7 represses expression of a reporter gene with the IL-13 UTR, and repression is abrogated by mutation of the Let-7 binding site. Conversely, we show that Let-7 inhibition results in increased expression of a reporter gene with the IL-13 UTR, either by transfection of “antagomirs”, or by overexpression of the Let-7 family inhibitor, LIN28B. These results suggest that in mast cells, IL-13 protein expression is regulated by Let-7 miRNAs and support a role for miRNAs mediating IgE responses.
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Bayani, Jane, Uros Kuzmanov, Punit Saraon, William A. Fung, Antoninus Soosaipillai, Jeremy A. Squire, and Eleftherios P. Diamandis. "Copy Number and Expression Alterations of miRNAs in the Ovarian Cancer Cell Line OVCAR-3: Impact on Kallikrein 6 Protein Expression." Clinical Chemistry 59, no. 1 (January 1, 2013): 296–305. http://dx.doi.org/10.1373/clinchem.2012.193060.
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BACKGROUND Kallikrein-related peptidase 6 (KLK6), a member of the serine protease family of kallikrein (KLK) genes, is dysregulated in ovarian carcinomas (OCa) and its overexpression is associated with poor prognosis. Regulation of its expression is poorly understood and is likely to be influenced by multiple mechanisms. The KLK locus is subject to copy number changes and heterogeneity in serous OCas. These copy number imbalances generally correlate with KLK6 protein expression; however, this is not always the case. In this study we explored the role of miRNAs in the posttranscriptional control of KLK6 expression and the contributions of copy numbers, not only of the KLK locus, but also of the miRNAs predicted to regulate it. METHODS AND RESULTS By miRNA profiling of the KLK6-overexpressing OCa cell line, OVCAR-3, we identified overexpressed and underexpressed miRNAs. Publically available miRNA databases identified the human miRNA lethal 7 (hsa-let-7) family members as putative regulating miRNAs, from which hsa-let-7a was chosen for functional analysis. The transient transfection of hsa-let-7a to OVCAR-3 resulted in a decrease of KLK6 secreted protein. Moreover, such transfection was also able to weakly affect the expression of another member of the KLK gene family, KLK10 (kallikrein-related peptidase 10). Cytogenomic analysis, including array comparative genomic hybridization, fluorescence in situ hybridization, and spectral karyotyping revealed the overall net copy number losses of hsa-let-7a and other miRNAs predicted to target KLK6. CONCLUSIONS The hsa-let-7 family member hsa-let-7a is a modulator of KLK6 protein expression that is independent of the KLK6 copy number status.
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Kokkonos, Konstantinos G., Nicolas Fossat, Louise Nielsen, Christina Holm, Wytske M. Hepkema, Jens Bukh, and Troels K. H. Scheel. "Evolutionary selection of pestivirus variants with altered or no microRNA dependency." Nucleic Acids Research 48, no. 10 (May 6, 2020): 5555–71. http://dx.doi.org/10.1093/nar/gkaa300.
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Abstract Host microRNA (miRNA) dependency is a hallmark of the human pathogen hepatitis C virus (HCV) and was also described for the related pestiviruses, which are important livestock pathogens. The liver-specific miR-122 binds within the HCV 5′ untranslated region (UTR), whereas the broadly expressed let-7 and miR-17 families bind two sites (S1 and S2, respectively) in the pestiviral 3′ UTR. Here, we dissected the mechanism of miRNA dependency of the pestivirus bovine viral diarrhea virus (BVDV). Argonaute 2 (AGO2) and miR-17 binding were essential for viral replication, whereas let-7 binding was mainly required for full translational efficiency. Furthermore, using seed site randomized genomes and evolutionary selection experiments, we found that tropism could be redirected to different miRNAs. AGO cross-linking and immunoprecipitation (CLIP) experiments and miRNA antagonism demonstrated that these alternative variants bound and depended on the corresponding miRNAs. Interestingly, we also identified miRNA-independent variants that were obtained through acquisition of compensatory mutations near the genomic 3′ terminus. Rescue experiments demonstrated that miRNA binding and 3′ mutagenesis contribute to replication through mutually exclusive mechanisms. Altogether, our findings suggest that pestiviruses, although capable of miRNA-independent replication, took advantage of miRNAs as essential host factors, suggesting a favorable path during evolutionary adaptation.
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Bakre, Abhijeet, Patricia Mitchell, Jonathan K. Coleman, Les P. Jones, Geraldine Saavedra, Michael Teng, S. Mark Tompkins, and Ralph A. Tripp. "Respiratory syncytial virus modifies microRNAs regulating host genes that affect virus replication." Journal of General Virology 93, no. 11 (November 1, 2012): 2346–56. http://dx.doi.org/10.1099/vir.0.044255-0.
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Respiratory syncytial virus (RSV) causes substantial morbidity and life-threatening lower respiratory tract disease in infants, young children and the elderly. Understanding the host response to RSV infection is critical for developing disease-intervention approaches. The role of microRNAs (miRNAs) in post-transcriptional regulation of host genes responding to RSV infection is not well understood. In this study, it was shown that RSV infection of a human alveolar epithelial cell line (A549) induced five miRNAs (let-7f, miR-24, miR-337-3p, miR-26b and miR-520a-5p) and repressed two miRNAs (miR-198 and miR-595), and showed that RSV G protein triggered let-7f expression. Luciferase–untranslated region reporters and miRNA mimics and inhibitors validated the predicted targets, which included cell-cycle genes (CCND1, DYRK2 and ELF4), a chemokine gene (CCL7) and the suppressor of cytokine signalling 3 gene (SOCS3). Modulating let-7 family miRNA levels with miRNA mimics and inhibitors affected RSV replication, indicating that RSV modulates host miRNA expression to affect the outcome of the antiviral host response, and this was mediated in part through RSV G protein expression.
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Miles, J. R., T. G. McDaneld, R. T. Wiedmann, R. A. Cushman, S. E. Echternkamp, J. L. Vallet, and T. P. L. Smith. "174 MicroRNA EXPRESSION PROFILE IN BOVINE CUMULUS-OOCYTE COMPLEXES DURING LATE OOGENESIS." Reproduction, Fertility and Development 21, no. 1 (2009): 186. http://dx.doi.org/10.1071/rdv21n1ab174.
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During late oogenesis, the mammalian oocyte synthesizes and stores mRNA necessary to guide the early stages of embryo development before the activation of embryonic transcription. The oocyte also contains many post-transcriptional regulatory mechanisms that coordinate mRNA stability and translation before specific activation. MicroRNAs (miRNAs) are short noncoding RNAs (17–25 nucleotides) that repress translation of target genes through sequence complementation and have recently been identified in murine oocytes. The objective of the current study was to identify and characterize the expression of miRNAs in bovine cumulus–oocyte complexes (COC) during late oogenesis as a potential mechanism for post-transcriptional regulation of mRNA in developing bovine oocytes. Ovaries from beef cattle (mixed populations) were obtained at a local abattoir. The COC were aspirated from 2- to 10-mm follicles and were pooled from each of 5 replicate collections for RNA extraction (n = 2241 total COC). Small RNA in the 16- to 27-bp range was isolated and used to construct cDNA libraries for sequencing, producing 2529 successful sequences that were clustered based on matching 14 consecutive bases to the most common member of the cluster. The consensus sequences of the clusters were screened for mitochondrial RNA, rRNA, tRNA, and snoRNA contaminants, leading to removal of 774 (31%) sequences from consideration. The remaining 1755 putative miRNA sequences were compared with known miRNA in miRBase, revealing 62 bovine COC miRNA clusters matching previously known sequences and 4 with no match. The cluster with the largest number of sequences identified in bovine COC matched the sequence of the let-7 miRNA family (657 sequences or 37% of putative miRNA). Within the let-7 family, let-7b (459 sequences or 26%) was the most abundant followed by let-7i (135 sequences or 8%). The four clusters that did not match sequences in miRBase represent putative novel miRNA. One of these four clusters had relatively high expression in bovine COCs (308 sequences or 18%), whereas the other 3 clusters had relatively low expression (total of 55 combined sequences or 3%). Expression of several putative miRNAs (let-7b, let-7i, miR-106a, and the abundant novel miRNA) in bovine COC were confirmed using TaqMan miRNA assays. These results demonstrate the presence of miRNA within bovine COC during late oogenesis, which suggests that these post-transcriptional regulatory elements may play a role in coordinating mRNA stability and translation in bovine oocytes.
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Tasena, Hataitip, Alen Faiz, Wim Timens, Jacobien Noordhoek, Machteld N. Hylkema, Reinoud Gosens, Pieter S. Hiemstra, et al. "microRNA–mRNA regulatory networks underlying chronic mucus hypersecretion in COPD." European Respiratory Journal 52, no. 3 (August 2, 2018): 1701556. http://dx.doi.org/10.1183/13993003.01556-2017.
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Chronic mucus hypersecretion (CMH) is a common feature in chronic obstructive pulmonary disease (COPD) and is associated with worse prognosis and quality of life. This study aimed to identify microRNA (miRNA)–mRNA regulatory networks underlying CMH.The expression profiles of miRNA and mRNA in bronchial biopsies from 63 COPD patients were associated with CMH using linear regression. Potential mRNA targets of each CMH-associated miRNA were identified using Pearson correlations. Gene set enrichment analysis (GSEA) and STRING (search tool for the retrieval of interacting genes/proteins) analysis were used to identify key genes and pathways.20 miRNAs and 539 mRNAs were differentially expressed with CMH in COPD. The expression of 10 miRNAs was significantly correlated with the expression of one or more mRNAs. Of these, miR-134-5p, miR-146a-5p and the let-7 family had the highest representation of CMH-associated mRNAs among their negatively correlated predicted targets. KRAS and EDN1 were identified as key regulators of CMH and were negatively correlated predicted targets of miR-134-5p and let-7a-5p, let-7d-5p, and let-7f-5p, respectively. GSEA suggested involvement of MUC5AC-related genes and several other relevant gene sets in CMH. The lower expression of miR-134-5p was confirmed in primary airway fibroblasts from COPD patients with CMH.We identified miR-134-5p, miR-146a-5p and let-7 family, along with their potential target genes including KRAS and EDN1, as potential key miRNA–mRNA networks regulating CMH in COPD.
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Ali, Asghar, Gerrit J. Bouma, Russell V. Anthony, and Quinton A. Winger. "The Role of LIN28-let-7-ARID3B Pathway in Placental Development." International Journal of Molecular Sciences 21, no. 10 (May 21, 2020): 3637. http://dx.doi.org/10.3390/ijms21103637.
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Placental disorders are a major cause of pregnancy loss in humans, and 40–60% of embryos are lost between fertilization and birth. Successful embryo implantation and placental development requires rapid proliferation, invasion, and migration of trophoblast cells. In recent years, microRNAs (miRNAs) have emerged as key regulators of molecular pathways involved in trophoblast function. A miRNA binds its target mRNA in the 3ʹ-untranslated region (3ʹ-UTR), causing its degradation or translational repression. Lethal-7 (let-7) miRNAs induce cell differentiation and reduce cell proliferation by targeting proliferation-associated genes. The oncoprotein LIN28 represses the biogenesis of mature let-7 miRNAs. Proliferating cells have high LIN28 and low let-7 miRNAs, whereas differentiating cells have low LIN28 and high let-7 miRNAs. In placenta, low LIN28 and high let-7 miRNAs can lead to reduced proliferation of trophoblast cells, resulting in abnormal placental development. In trophoblast cells, let-7 miRNAs reduce the expression of proliferation factors either directly by binding their mRNA in 3ʹ-UTR or indirectly by targeting the AT-rich interaction domain (ARID)3B complex, a transcription-activating complex comprised of ARID3A, ARID3B, and histone demethylase 4C (KDM4C). In this review, we discuss regulation of trophoblast function by miRNAs, focusing on the role of LIN28-let-7-ARID3B pathway in placental development.
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Weissman, Ran, Eli L. Diamond, Julien Haroche, Nir Pillar, Guy Shapira, Benjamin H. Durham, Justin Buthorn, et al. "The Contribution of MicroRNAs to the Inflammatory and Neoplastic Characteristics of Erdheim–Chester Disease." Cancers 12, no. 11 (November 3, 2020): 3240. http://dx.doi.org/10.3390/cancers12113240.
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The pathogenesis of histiocytic neoplasms is driven by mutations activating the MAPK/ERK pathway, but little is known about the transcriptional and post-transcriptional alterations involved in these neoplasms. We analyzed microRNA (miRNA) expression in plasma samples and tissue biopsies of Erdheim–Chester disease (ECD) and Langerhans cell histiocytosis (LCH) patients. In silico analysis revealed a potential role of miRNAs in regulating gene expression in these neoplasms as compared with healthy controls (HC). NanoString analysis revealed 101 differentially expressed plasma miRNAs in 16 ECD patients as compared with 11 HC, 95% of which were downregulated. MiRNAs-15a-5p, -15b-5p, -21-5p, -107, -221-3p, -320e, -630, and let-7 family miRNAs were further evaluated by qRT-PCR in an extended cohort of 32 ECD patients, seven LCH and 15 HC. Six miRNAs (let-7a, let-7c, miR-15a-5p, miR-15b-5p, miR-107 and miR-630) were highly expressed in LCH plasma and tissue samples as compared with ECD. Pathway enrichment analysis indicated the miRNA contribution to inflammatory and pro-survival signaling pathways. Moreover, the let-7 family members were downregulated in untreated ECD patients as compared with HC, while treatment with MAPK/ERK signaling inhibitors for 16 weeks resulted in their upregulation, which was in parallel with the radiologic response seen by PET-CT. The study highlights the potential contribution of miRNA to the inflammatory and neoplastic characteristics of ECD and LCH.
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Gamper, Christopher, Youl-Nam Lee, Stephanie Brandal, Joshua Mendell, Clifford Takemoto, Michael McDevitt, and Jonathan Powell. "Regulation of IL-13 expression in lymphocytes by the Let-7 miRNA family (51.11)." Journal of Immunology 184, no. 1_Supplement (April 1, 2010): 51.11. http://dx.doi.org/10.4049/jimmunol.184.supp.51.11.
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Abstract IL-13 is a Th2 cytokine that plays a critical role in antibody production, parasite immunity, allergic disorders, and as a negative regulator of anti-tumor immunity. Curiously, microarray screens of activated Th1 clones demonstrated high levels of IL-13 RNA in spite of essentially no IL-13 protein production. Such findings were subsequently confirmed in primary cells cultured in Th1 conditions. We hypothesized that these observations might be due to regulation by miRNAs. Indeed, a highly conserved Let-7 site is predicted in the 3’ UTR of IL-13. Furthermore, several Let-7 family members are more highly expressed in activated Th1 cells when compared with activated Th2 cells. To test our hypothesis, we generated luciferase reporter constructs containing the native 3’ UTR of IL-13 (WT) or a 3’ UTR with the Let-7 site mutated (Mut). Overexpression of Let-7 mimetics inhibited the IL-13 WT but not the IL-13 Mut construct. In addition, the transfection of the mimetics or infection with Let-7g expressing retrovirus led to the inhibition of native IL-13 protein production. Alternatively, inhibitors of Let-7 family members or infection with a retrovirus encoding the Let-7 antagonist LIN28B led to enhanced IL-13 production. Overall our data suggest Let-7 miRNA plays a critical role in the regulation of IL-13 and that such molecules might be exploited to inhibit IL-13 in allergic diseases and to enhance anti-tumor immunity.
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Drummond, Micah J., John J. McCarthy, Mala Sinha, Heidi M. Spratt, Elena Volpi, Karyn A. Esser, and Blake B. Rasmussen. "Aging and microRNA expression in human skeletal muscle: a microarray and bioinformatics analysis." Physiological Genomics 43, no. 10 (May 2011): 595–603. http://dx.doi.org/10.1152/physiolgenomics.00148.2010.
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A common characteristic of aging is loss of skeletal muscle (sarcopenia), which can lead to falls and fractures. MicroRNAs (miRNAs) are novel posttranscriptional modulators of gene expression with potential roles as regulators of skeletal muscle mass and function. The purpose of this study was to profile miRNA expression patterns in aging human skeletal muscle with a miRNA array followed by in-depth functional and network analysis. Muscle biopsy samples from 36 men [young: 31 ± 2 ( n = 19); older: 73 ± 3 ( n = 17)] were 1) analyzed for expression of miRNAs with a miRNA array, 2) validated with TaqMan quantitative real-time PCR assays, and 3) identified (and later validated) for potential gene targets with the bioinformatics knowledge base software Ingenuity Pathways Analysis. Eighteen miRNAs were differentially expressed in older humans ( P < 0.05 and >500 expression level). Let-7 family members Let-7b and Let-7e were significantly elevated and further validated in older subjects ( P < 0.05). Functional and network analysis from Ingenuity determined that gene targets of the Let-7s were associated with molecular networks involved in cell cycle control such as cellular proliferation and differentiation. We confirmed with real-time PCR that mRNA expression of cell cycle regulators CDK6, CDC25A, and CDC34 were downregulated in older compared with young subjects ( P < 0.05). In addition, PAX7 mRNA expression was lower in older subjects ( P < 0.05). These data suggest that aging is characterized by a higher expression of Let-7 family members that may downregulate genes related to cellular proliferation. We propose that higher Let-7 expression may be an indicator of impaired cell cycle function possibly contributing to reduced muscle cell renewal and regeneration in older human muscle.
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Angelou, Constance C., Alexandria C. Wells, Jyothi Vijayarhagavan, Carey E. Dougan, Rebecca Lawlor, Elizabeth Iverson, Vanja Lazarevic, et al. "Pathogenic Th17 cell differentiation is negatively regulated by let-7 microRNAs in a mouse model of multiple sclerosis." Journal of Immunology 204, no. 1_Supplement (May 1, 2020): 76.11. http://dx.doi.org/10.4049/jimmunol.204.supp.76.11.
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Abstract Autoimmune disorders such as multiple sclerosis (MS) are caused by proinflammatory events mediated by pathogenic Th17 cells. In MS, these cells arise in response to autoantigen recognition and exposure to the cytokines IL-1β and IL-23, migrate to the central nervous system (CNS) by following gradients of CCR2- and CCR5-cognate chemokines, and secrete GM-CSF. GM-CSF is essential for disease development, as it promotes the activation, differentiation, and recruitment of peripheral inflammatory myeloid cells to the CNS that directly demyelinate neurons and damage axons. Th17 cell pathogenicity in MS has been correlated with microRNA (miRNA) dysregulation, which leads to aberrant post-transcriptional regulation of gene expression and enhanced autoreactive phenotype. We found that the lethal-7 (let-7) miRNA family is abundantly expressed in naive CD4+ T cells, but gets dramatically downregulated over time following antigen encounter, indicating that let-7 may control the differentiation of pathogenic Th17 cells. To investigate a potential regulatory role for let-7 in Th17 cell autoreactivity, we used experimental autoimmune encephalomyelitis (EAE), the animal model of MS. Specifically, we demonstrated that let-7 confers protection from EAE by negatively regulating the proliferation, IL-1β/IL-23-dependent differentiation, and CCR2/CCR5-dependent migration of pathogenic Th17 cells to the CNS. Conversely, absence of let-7 led to enhanced Th17 cell autoreactivity and aggravated disease. Therefore, our results identify a novel regulatory role for let-7 miRNAs in pathogenic Th17 differentiation during EAE development, suggesting a promising therapeutic application for the treatment of MS-related autoimmune diseases.
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Niculae, Andrei Marian, Maria Dobre, Vlad Herlea, Teodora Ecaterina Manuc, Bogdan Trandafir, Elena Milanesi, and Mihail Eugen Hinescu. "Let-7 microRNAs Are Possibly Associated with Perineural Invasion in Colorectal Cancer by Targeting IGF Axis." Life 12, no. 10 (October 19, 2022): 1638. http://dx.doi.org/10.3390/life12101638.
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Increased insulin-like growth factor (IGF) axis activity is associated with the development and progression of different types of malignancies, including colorectal cancer (CRC). MicroRNAs (miRNAs) belonging to the let-7 family have been reported to target genes involved in this axis and are known as tumor suppressors. In this study, in silico bioinformatic analysis was performed to assess miRNA–mRNA interactions between eight miRNAs belonging to the let-7 family and genes involved in the IGF signaling pathway, coding for receptors and substrates. miRNAs’ expression analysis revealed that hsa-let-7a-5p, hsa-let-7b-5p, hsa-let-7c-5p, hsa-let- 97 7d-5p, hsa-let-7e-5p, hsa-let-7f-5p, and hsa-let-7g-5p were significantly down-regulated in 25 CRC tumoral tissues (T) compared to the corresponding adjacent peritumoral tissues (PT). Moreover, our results showed an upregulation of miR-let-7e-5p in CRC tissues with mutations in KRAS codon 12 or 13, and, for the first time, found a specific dysregulation of let-7a-5p, let-7b-5p, let-7c-5p, let-7d-5p, and let-7i-5p in CRC with perineural invasion. Our results sustain the relationship between the IGF axis, let-7 miRNAs, and CRC and suggest an association between the expression of these miRNAs and perineural invasion.
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You, Xiangbin, Min Liu, Qian Liu, Huijuan Li, Yilin Qu, Xiaoxiao Gao, Chengyu Huang, Gan Luo, Gang Cao, and Dequan Xu. "miRNA let-7 family regulated by NEAT1 and ARID3A/NF-κB inhibits PRRSV-2 replication in vitro and in vivo." PLOS Pathogens 18, no. 10 (October 10, 2022): e1010820. http://dx.doi.org/10.1371/journal.ppat.1010820.
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Porcine reproductive and respiratory syndrome (PRRS) is one of the most economically devastating diseases affecting the swine industry worldwide. To investigate the role of miRNAs in the infection and susceptibility of PRRS virus (PRRSV), twenty-four miRNA libraries were constructed and sequenced from PRRSV-infected and mock-infected Porcine alveolar macrophages (PAMs) of Meishan, Landrace, Pietrain and Qingping pigs at 9 hours post infection (hpi), 36 hpi, and 60 hpi. The let-7 family miRNAs were significantly differentially expressed between PRRSV-infected and mock-infected PAMs from 4 pig breeds. The let-7 family miRNAs could significantly inhibit PRRSV-2 replication by directly targeting the 3’UTR of the PRRSV-2 genome and porcine IL6, which plays an important role in PRRSV replication and lung injury. NEAT1 acts as a competing endogenous lncRNA (ceRNA) to upregulate IL6 by attaching let-7 in PAMs. EMSA and ChIP results confirmed that ARID3A could bind to the promoter region of pri-let-7a/let-7f/let-7d gene cluster and inhibit the expression of the let-7 family. Moreover, the NF-κB signaling pathway inhibits the expression of the let-7 family by affecting the nuclear import of ARID3A. The pEGFP-N1-let-7 significantly reduced viral infections and pathological changes in PRRSV-infected piglets. Taken together, NEAT1/ARID3A/let-7/IL6 play significant roles in PRRSV-2 infection and may be promising therapeutic targets for PRRS.
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Gray, Clint, Minglan Li, Rachna Patel, Clare M. Reynolds, and Mark H. Vickers. "Let-7 miRNA Profiles Are Associated With the Reversal of Left Ventricular Hypertrophy and Hypertension in Adult Male Offspring From Mothers Undernourished During Pregnancy After Preweaning Growth Hormone Treatment." Endocrinology 155, no. 12 (December 1, 2014): 4808–17. http://dx.doi.org/10.1210/en.2014-1567.
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Maternal undernutrition (UN) is known to cause cardiac hypertrophy, elevated blood pressure, and endothelial dysfunction in adult offspring. Maternal UN may also lead to disturbances in GH regulation in offspring. Because GH plays a key role in cardiac development, we used a model of maternal UN to examine the effects of neonatal GH treatment on cardiac hypertrophy, cardiac micro RNA (miRNA) profiles, and associated gene regulation in adult offspring. Female Sprague-Dawley rats were fed either a standard control diet (CON) or 50% of CON intake throughout pregnancy (UN). From neonatal day 3 until weaning (d 21), CON and UN pups received either saline (S) (CON-S, UN-S) or GH (2.5 μg/g·d) (CON-GH, UN-GH). Heart structure was determined by hematoxylin and eosin staining, and miRNA was isolated from cardiac tissue and miRNA expression analyzed using Cardiovascular miRNA gene Arrays (SABiosciences Ltd). Maternal UN caused marked increases in cardiac hypertrophy and left ventricular cardiomyocyte area, which were reversed by preweaning GH treatment. Systolic blood pressure was increased in UN-S groups and normalized in UN-GH groups (CON-S 121 ± 2 mmHg, CON-GH 115 ± 3 mm Hg, UN-S 146 ± 3 mmHg, and UN-GH 127 ± 2 mmHg). GH treatment during early development facilitated a reversal of pathological changes in offspring hearts caused by UN during pregnancy. Specific cardiac miRNA profiles were exhibited in response to maternal UN, accompanied by up-regulation of the lethal-7 (LET-7) miRNA family in GH-treated offspring. miRNA target analysis revealed a number of genes associated with inflammation and cardiovascular development, which may be involved in the altered cardiac function of these offspring. Up-regulation of the LET-7 family of miRNAs observed in GH groups may mediate the reversal of cardiac hypertrophy observed in adult offspring males of UN mothers.
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Zipeto, Maria Anna, Angela Court Recart, Nathaniel Delos Santos, Qingfei Jiang, Leslie A. Crews, and Catriona HM Jamieson. "Inflammatory Cytokine-Responsive ADAR1 Impairs Let-7 Biogenesis and Promotes Leukemia Stem Cell Generation." Blood 126, no. 23 (December 3, 2015): 4014. http://dx.doi.org/10.1182/blood.v126.23.4014.4014.
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Abstract Background In advanced human malignancies, RNA sequencing (RNA-seq) has uncovered deregulation of adenosine deaminase acting on RNA (ADAR) editases that promote therapeutic resistance and leukemia stem cell (LSC) generation. Chronic myeloid leukemia (CML), an important paradigm for understanding LSC evolution, is initiated by BCR-ABL1 oncogene expression in hematopoietic stem cells (HSCs) but undergoes blast crisis (BC) transformation following aberrant self-renewal acquisition by myeloid progenitors harboring cytokine-responsive ADAR1 p150 overexpression. Emerging evidence suggests that adenosine to inosine editing at the level of primary (pri) or precursor (pre)-microRNA (miRNA), alters miRNA biogenesis and impairs biogenesis. However, relatively little is known about the role of inflammatory niche-driven ADAR1 miRNA editing in malignant reprogramming of progenitors into self-renewing LSCs. Methods Primary normal and CML progenitors were FACS-purified and RNA-Seq analysis as well as qRT-PCR validation were performed according to published methods (Jiang, 2013). MiRNAs were extracted from purified CD34+ cells derived from CP, BC CML and cord blood by RNeasy microKit (QIAGEN) and let-7 expression was evaluated by qRT-PCR using miScript Primer assay (QIAGEN). CD34+ cord blood (n=3) were transduced with lentiviral human JAK2, let-7a, wt-ADAR1 and mutant ADAR1, which lacks a functional deaminase domain. Because STAT signaling triggers ADAR1 transcriptional activation and both BCR-ABL1 and JAK2 activate STAT5a, nanoproteomics analysis of STAT5a levels was performed. Engrafted immunocompromised RAG2-/-γc-/- mice were treated with a JAK2 inhibitor, SAR302503, alone or in combination with a potent BCR-ABL1 TKI Dasatinib, for two weeks followed by FACS analysis of human progenitor engraftment in hematopoietic tissues and serial transplantation. Results RNA-seq and qRT-PCR analysis in FACS purified BC CML progenitors revealed an over-representation of inflammatory pathway activation and higher levels of JAK2-dependent inflammatory cytokine receptors, when compared to normal and chronic phase (CP) progenitors. Moreover, RNA-seq and qRT-PCR analysis showed decreased levels of mature let-7 family of stem cell regulatory miRNA in BC compared to normal and CP progenitors. Lentiviral human JAK2 transduction of CD34+ progenitors led to an increase of ADAR1 transcript levels and to a reduction in let-7 family members. Interestingly, lentiviral human JAK2 transduction of normal progenitors enhanced ADAR1 activity, as revealed by RNA editing-specific qRT-PCR and RNA-seq analysis. Moreover, qRT-PCR analysis of CD34+ progenitors transduced with wt-ADAR1, but not mutant ADAR1 lacking functional deaminase activity, reduced let-7 miRNA levels. These data suggested that ADAR1 impairs let-7 family biogenesis in a RNA editing dependent manner. Interestingly, RNA-seq analysis confirmed higher frequency of A-to-I editing events in pri- and pre-let-7 family members in CD34+ BC compared to CP progenitors, as well as normal progenitors transduced with human JAK2 and ADAR1-wt, but not mutant ADAR1. Lentiviral ADAR1 overexpression enhanced CP CML progenitor self-renewal and decreased levels of some members of the let-7 family. In contrast, lentiviral transduction of human let-7a significantly reduced self-renewal of progenitors. In vivo treatments with Dasatinib in combination with a JAK2 inhibitor, significantly reduced self-renewal of BCR-ABL1 expressing BC progenitors in the bone marrow thereby prolonging survival of serially transplanted mice. Finally, a reduction in ADAR1 p150 transcripts was also noted following combination treatment only suggesting a role for ADAR1 in CSC propagation. Conclusion This is the first demonstration that intrinsic BCR-ABL oncogenic signaling and extrinsic cytokines signaling through JAK2 converge on activation of ADAR1 that drives LSC generation by impairing let-7 miRNA biogenesis. Targeted reversal of ADAR1-mediated miRNA editing may enhance eradication of inflammatory niche resident cancer stem cells in a broad array of malignancies, including JAK2-driven myeloproliferative neoplasms. Disclosures Jamieson: J&J: Research Funding; GSK: Research Funding.
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He, Qijun, Fenix W. Huang, Christopher Barrett, and Christian M. Reidys. "Genetic robustness of let-7 miRNA sequence–structure pairs." RNA 25, no. 12 (September 23, 2019): 1592–603. http://dx.doi.org/10.1261/rna.065763.118.
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Ali, Asghar, Mark Stenglein, Thomas Spencer, Gerrit Bouma, Russell Anthony, and Quinton Winger. "Trophectoderm-Specific Knockdown of LIN28 Decreases Expression of Genes Necessary for Cell Proliferation and Reduces Elongation of Sheep Conceptus." International Journal of Molecular Sciences 21, no. 7 (April 6, 2020): 2549. http://dx.doi.org/10.3390/ijms21072549.
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LIN28 inhibits let-7 miRNA maturation which prevents cell differentiation and promotes proliferation. We hypothesized that the LIN28-let-7 axis regulates proliferation-associated genes in sheep trophectoderm in vivo. Day 9-hatched sheep blastocysts were incubated with lentiviral particles to deliver shRNA targeting LIN28 specifically to trophectoderm cells. At day 16, conceptus elongation was significantly reduced in LIN28A and LIN28B knockdowns. Let-7 miRNAs were significantly increased and IGF2BP1-3, HMGA1, ARID3B, and c-MYC were decreased in trophectoderm from knockdown conceptuses. Ovine trophoblast (OTR) cells derived from day 16 trophectoderm are a useful tool for in vitro experiments. Surprisingly, LIN28 was significantly reduced and let-7 miRNAs increased after only a few passages of OTR cells, suggesting these passaged cells represent a more differentiated phenotype. To create an OTR cell line more similar to day 16 trophectoderm we overexpressed LIN28A and LIN28B, which significantly decreased let-7 miRNAs and increased IGF2BP1-3, HMGA1, ARID3B, and c-MYC compared to control. This is the first study showing the role of the LIN28-let-7 axis in trophoblast proliferation and conceptus elongation in vivo. These results suggest that reduced LIN28 during early placental development can lead to reduced trophoblast proliferation and sheep conceptus elongation at a critical period for successful establishment of pregnancy.
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Frederick, Mallory I., Tarana Siddika, Pengcheng Zhang, Nileeka Balasuriya, Matthew A. Turk, Patrick O’Donoghue, and Ilka U. Heinemann. "miRNA-Dependent Regulation of AKT1 Phosphorylation." Cells 11, no. 5 (February 26, 2022): 821. http://dx.doi.org/10.3390/cells11050821.
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The phosphoinositide-3-kinase (PI3K)/AKT pathway regulates cell survival and is over-activated in most human cancers, including ovarian cancer. Following growth factor stimulation, AKT1 is activated by phosphorylation at T308 and S473. Disruption of the AKT1 signaling pathway is sufficient to inhibit the epithelial-mesenchymal transition in epithelial ovarian cancer (EOC) cells. In metastatic disease, adherent EOC cells transition to a dormant spheroid state, characterized previously by low S473 phosphorylation in AKT1. We confirmed this finding and observed that T308 phosphorylation was yet further reduced in EOC spheroids and that the transition from adherent to spheroid growth is accompanied by significantly increased levels of let-7 miRNAs. We then used mechanistic studies to investigate the impact of let-7 miRNAs on AKT1 phosphorylation status and activity in cells. In growth factor-stimulated HEK 293T cells supplemented with let-7a, we found increased phosphorylation of AKT1 at T308, decreased phosphorylation at S473, and enhanced downstream AKT1 substrate GSK-3β phosphorylation. Let-7b and let-7g also deregulated AKT signaling by rendering AKT1 insensitive to growth factor simulation. We uncovered let-7a-dependent deregulation of PI3K pathway components, including PI3KC2A, PDK1, and RICTOR, that govern AKT1 phosphorylation and activity. Together, our data show a new role for miRNAs in regulating AKT signaling.
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Lightfoot, Helen L., Eric A. Miska, and Shankar Balasubramanian. "Identification of small molecule inhibitors of the Lin28-mediated blockage of pre-let-7g processing." Organic & Biomolecular Chemistry 14, no. 43 (2016): 10208–16. http://dx.doi.org/10.1039/c6ob01945e.
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Copley, Michael R., David G. Kent, Claudia Benz, Stefan Wohrer, Keegan M. Rowe, Chris W. Day, and Connie J. Eaves. "Inhibition of Let-7 Processing in Adult Murine Hematopoietic Stem Cells Induces a Fetal-Like High Self-Renewal Pattern in Their Progeny." Blood 118, no. 21 (November 18, 2011): 45. http://dx.doi.org/10.1182/blood.v118.21.45.45.
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Abstract Abstract 45 Fetal hematopoietic stem cells (HSCs) in mice differ from their adult counterparts in a number of key properties. These include a higher cycling activity, an ability to more rapidly reconstitute the HSC compartment of irradiated recipient mice, a higher output of myeloid as compared to lymphoid progeny, and a greater sensitivity to the self-renewal promoting activity of Steel factor. We have previously shown that most of these features of fetal HSCs are sustained until 3 weeks after birth at which time they are rapidly (within 1 week), completely and permanently replaced with the corresponding properties of adult HSCs. A candidate regulator of this transition, Hmga2, was identified based on its greater expression in highly purified fetal versus adult HSCs (CD45+EPCR+CD48−CD150+; E-SLAM cells) with persistence of this difference in the matching lineage-negative (lin−) compartments. Experiments in which Hmga2 was overexpressed by lentiviral transduction of purified adult HSCs which were then transplanted into irradiated mice provided evidence that this chromatin remodeling factor can activate a fetal-like HSC program in these cells; i.e., more rapidly reconstitute the HSC compartment (increased self-renewal response) and produce clones with a higher proportion of myeloid cells. Based on the known ability of the let-7 family of microRNAs (miRNAs) to target Hmga2 transcripts resulting in their degradation and/or translational repression, we next hypothesized that let-7 miRNAs might be involved in controlling HSC developmental programs. A comparison of the levels of expression of 6 members of the let-7 family in purified fetal and adult HSCs, as well as in lin− hematopoietic cells, showed that transcripts for all of these are higher in the adult subsets, although this difference was significant only for let-7b (p<0.05). Since Lin28 is a natural inhibitor of let-7 miRNA biogenesis we proposed that overexpression of this protein might be used to simultaneously inhibit all let-7 miRNA species and therefore modulate let-7-mediated effects in HSCs. Transduction of BA/F3 cells with a Lin28-YFP lentiviral vector led to an elevated expression of Lin28 and a significant decrease in multiple let-7 miRNAs. To investigate the influence of Lin28 overexpression on adult HSC self-renewal activity in vivo, we used the same Lin28 lentiviral vector (or a control YFP vector) to transduce highly purified HSCs (40 E-SLAM cells, i.e. ∼20 HSCs/group/experiment, 3 experiments) in a 3–4-hour exposure protocol and then transplanted all of the cells directly into irradiated mice (total of 3–4 mice/group). The number of HSCs regenerated 6 weeks later was subsequently measured by performing limiting-dilution transplants in secondary mice (total of 12–16 secondary mice/group/experiment). Interestingly, analysis of the secondary recipients showed that the Lin28-overexpressing adult HSCs had expanded in the primary recipients ∼6-fold more than the control-virus transduced HSCs (p<0.001). These findings support our thesis that alterations in let-7 miRNA levels play a key role in regulating the developmental switch from fetal to adult HSCs programs that occurs between 3 and 4 weeks after birth in mice. Disclosures: No relevant conflicts of interest to declare.
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Mehta, Ritu, Pratibha Ghosh, and Sibin MK. "Role of liquid biopsy in non small cell lung cancer." IP Journal of Diagnostic Pathology and Oncology 8, no. 4 (December 15, 2023): 204–8. http://dx.doi.org/10.18231/j.jdpo.2023.048.
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Lung cancer is the leading cause of morbidity and mortality worldwide. It is usually diagnosed in advance stage. miRNA present in serum and pleural fluid can be studied for early diagnosis of lung cancer. Present study was carried out to evaluate whether miRNA can be used as biomarkers in diagnosis of non small cell lung cancer. The study was intended to find the non-invasive tumour biomarkers for presence of lung malignancy with the intent of instituting early diagnosis to reduce lung cancer related mortality. The aim of the study was to evaluate circulating microRNA expression in adenocarcinoma and squamous cell carcinoma lung in comparison with age and sex matched healthy controls. The expression of these miRNA was correlated with histopathology and/or immunohistochemistry. The circulating miRNA expression in age and sex matched non-smoking healthy controls was also noted. It was a Prospective observational study in which 50 cases of non small cell lung cancer was included. 50 healthy non smoker volunteers (control group, well adjusted to the patients according to the age and sex) were also included in the study. About 5 ml of serum and wherever possible pleural fluid was collected in the sterile container. The sample was allowed to stand at room temperature for one hour, and then samples were centrifuged at 1300g for ten minutes at room temperature.RNA was extracted using miRNeasy mini kit (Cat no. 217004) and quantative PCR was done. The patients age, sex, histopathological results, clinical staging, immunohistochemistry, presence of pleural effusion. Expression of mi RNA (miRNA 21, miRNA 17-92 cluster, miRNA 221/222, miRNA Let- 7, miRNA 34 and miRNA 200) were studied. Out of 50 patients of suspected lung cancer 17 were females (34%) and 33 (66%) were males. Mean age of presentation was 63.26 years. 37 patients gave history of smoking (74%) while 13 patients were non Smokers (26%). 29 patients (58%) showed histomorphological features suggestive of adenocarcinoma whereas 21 patients (42%) showed histomorphological features of squamous cell carcinoma. EGFR mutation was seen in 10 patients (34%). Pleural effusion was present in 20 cases.Statistically significant correlation was found between the expression of miRNA in healthy controls and in lung cancer patients. All the tested miRNAs were significantly correlated with the corresponding expression in the healthy control. As compared to healthy controls that let-7, miR-34 and miR-200 were downregulated in lung cancer patients whereas miRNA-221, miRNA 17-92, miRNA-21 were upregulated in lung cancer patients. miR 34, miR 200 and let 7 was detected in healthy controls also. No statically significant correlation of miRNA with age, sex, smoking, histopathological type, grade of tumor, stage of disease, EGFR mutation and IHC was found. Stastically significant correlation was found between miRNA 200 and pleural effusion patients. Present study concludes that miRNA can be a potential biomarker for diagnosing lung cancer. To date, there is convincing evidence supporting the potential role of miRNAs as biomarkers for lung cancer diagnosis and prognosis. However, further research is required in this aspect.
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Winkler, Ivana, Catrin Bitter, Sebastian Winkler, Dieter Weichenhan, Abhishek Thavamani, Jan G. Hengstler, Erawan Borkham-Kamphorst, et al. "Identification of Pparγ-modulated miRNA hubs that target the fibrotic tumor microenvironment." Proceedings of the National Academy of Sciences 117, no. 1 (December 23, 2019): 454–63. http://dx.doi.org/10.1073/pnas.1909145117.
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Liver fibrosis interferes with normal liver function and facilitates hepatocellular carcinoma (HCC) development, representing a major threat to human health. Here, we present a comprehensive perspective of microRNA (miRNA) function on targeting the fibrotic microenvironment. Starting from a murine HCC model, we identify a miRNA network composed of 8 miRNA hubs and 54 target genes. We show that let-7, miR-30, miR-29c, miR-335, and miR-338 (collectively termed antifibrotic microRNAs [AF-miRNAs]) down-regulate key structural, signaling, and remodeling components of the extracellular matrix. During fibrogenic transition, these miRNAs are transcriptionally regulated by the transcription factor Pparγ and thus we identify a role of Pparγ as regulator of a functionally related class of AF-miRNAs. The miRNA network is active in human HCC, breast, and lung carcinomas, as well as in 2 independent mouse liver fibrosis models. Therefore, we identify a miRNA:mRNA network that contributes to formation of fibrosis in tumorous and nontumorous organs of mice and humans.
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Manier, Salomon, John T. Powers, Antonio Sacco, Michaela R. Reagan, Michele Moschetta, Siobhan Glavey, Patricia Maiso, et al. "Lin28B/Let-7 Axis Regulates Multiple Myeloma Proliferation By Enhancing c-Myc and Ras Survival Pathways." Blood 122, no. 21 (November 15, 2013): 273. http://dx.doi.org/10.1182/blood.v122.21.273.273.
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Abstract Background MicroRNAs (miRNAs) play a pivotal role in tumorigenesis, due to their ability to target mRNAs involved in the regulation of cell proliferation, survival and differentiation. Lin28B is an RNA binding protein that regulates Let-7 miRNA maturation. Lin28B and Let-7 have been described to act as oncogenes or tumor suppressor genes, respectively, as demonstrated both in solid cancer and hematologic malignancies. However, the role of the Lin28B/Let-7 axis in Multiple Myeloma (MM) has not been studied. Method Lin28B level expression in MM patients was studied using previously published gene expression profiling (GEP) datasets. Let-7 expression levels were assessed in CD138+ primary MM cells and bone marrow stromal cells (BMSCs) by using PCR, as well as in circulating exosomes using miRNA array (Nanostring® Technology). Exosomes were collected from both normal and MM peripheral blood, using ultracentrifugation; and further studied by using electron microscopy and immunogold labeling for the detection of CD63 and CD81. The knockdown of Lin28B was performed on MM cell lines (U266, MM.1S, MOLP-8) by using a lentiviral Lin28B shRNA. Gain- and loss-of function studies for Let-7 were performed using Let-7 mimic and anti-Let-7 transfection in MM cell lines (MM1S, U266) and primary BMSCs. Cell proliferation has been evaluated by using thymidine assays. Effects of Let-7 and Lin28B on signaling cascades have been evaluated by western blot. Results Two independent GEP datasets (GSE16558; GSE2658) were analyzed for Lin28B expression, showing a significantly higher level in MM patients compared to healthy controls. In addition, high Lin28B levels correlated with a shorter overall survival (p = 0.0226). We next found that the Let-7 family members are significantly down-regulated in MM primary cells, particularly Let-7a and b (5 fold change, p < 0.05), as demonstrated by using qRT-PCR. Similarly, miRNA arrays showed a lower expression of Let-7-related miRNAs in circulating exosomes obtained from MM patients compared to healthy individuals. We further dissected the functional relevance of Lin28B in MM cells, by performing Lin28 knockdown (KD) in MM cell lines (U266, MOLP-8). This led to a significant decrease in MM cell proliferation associated with G1 phase cell cycle arrest. This was supported by up-regulation of Let-7 and down-regulation of c-Myc, Ras and Cyclin D1 in Lin28 KD MM cells. To further prove that Lin28B-dependent effects on MM cells are mediated by Let7, we next showed that let-7 gain- and loss-of-function studies regulate MM cell proliferation and Myc expression. Lin28B regulation in MM cells is dependent on Let-7, as demonstrated by an increase of both cell proliferation and c-Myc expression after anti-Let-7 transfection in the Lin28B KD cells. We therefore studied the regulation of Let-7 in MM cells through the interaction with BMSCs. Let-7 expression levels were significantly lower in BMSCs obtained from MM patients compared to healthy donors. Interestingly, the Let-7 expression level in MM cells was increased after co-culture with Let-7 over-expressing BMSCs, associated with a decrease of both cell proliferation and c-Myc expression. This suggests a potential transfer of Let-7 from BMSCs to MM cells. Conclusion This work describes a new signaling pathway involving Lin28B, Let-7, Myc and Ras in MM. Let-7 expression in MM cells is also regulated through the interaction of MM cells with BMSCs, leading to cell proliferation and Myc regulation in MM. Interference with this pathway might offer therapeutic perspectives. Disclosures: Leleu: CELGENE: Honoraria; JANSSEN: Honoraria. Daley:Johnson and Johnson: Consultancy, Membership on an entity’s Board of Directors or advisory committees; MPM Capital: Consultancy, Membership on an entity’s Board of Directors or advisory committees; Verastem: Consultancy, Membership on an entity’s Board of Directors or advisory committees; Epizyme: Consultancy, Membership on an entity’s Board of Directors or advisory committees; iPierian: Consultancy, Membership on an entity’s Board of Directors or advisory committees; Solasia, KK: Consultancy, Membership on an entity’s Board of Directors or advisory committees. Ghobrial:Onyx: Advisoryboard Other; BMS: Advisory board, Advisory board Other, Research Funding; Noxxon: Research Funding; Sanofi: Research Funding.
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Anelli, Luisa, Antonella Zagaria, Giorgina Specchia, Pellegrino Musto, and Francesco Albano. "Dysregulation of miRNA in Leukemia: Exploiting miRNA Expression Profiles as Biomarkers." International Journal of Molecular Sciences 22, no. 13 (July 2, 2021): 7156. http://dx.doi.org/10.3390/ijms22137156.
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Micro RNAs (miRNAs) are a class of small non-coding RNAs that have a crucial role in cellular processes such as differentiation, proliferation, migration, and apoptosis. miRNAs may act as oncogenes or tumor suppressors; therefore, they prevent or promote tumorigenesis, and abnormal expression has been reported in many malignancies. The role of miRNA in leukemia pathogenesis is still emerging, but several studies have suggested using miRNA expression profiles as biomarkers for diagnosis, prognosis, and response to therapy in leukemia. In this review, the role of miRNAs most frequently involved in leukemia pathogenesis is discussed, focusing on the class of circulating miRNAs, consisting of cell-free RNA molecules detected in several body fluids. Circulating miRNAs could represent new potential non-invasive diagnostic and prognostic biomarkers of leukemia that are easy to isolate and characterize. The dysregulation of some miRNAs involved in both myeloid and lymphoid leukemia, such as miR-155, miR-29, let-7, and miR-15a/miR-16-1 clusters is discussed, showing their possible employment as therapeutic targets.
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Ramanjaneya, Manjunath, Ilham Bettahi, Krunal Pawar, Najeeb M. Halabi, Abu Saleh Md Moin, Thozhukat Sathyapalan, Abdul Badi Abou-Samra, Stephen L. Atkin, and Alexandra E. Butler. "MicroRNA Changes Up to 24 h following Induced Hypoglycemia in Type 2 Diabetes." International Journal of Molecular Sciences 23, no. 23 (November 24, 2022): 14696. http://dx.doi.org/10.3390/ijms232314696.
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Hypoglycemia, as a complication of type 2 diabetes (T2D), causes increased morbidity and mortality but the physiological response underlying hypoglycemia has not been fully elucidated. Small noncoding microRNA (miRNA) have multiple downstream biological effects. This pilot exploratory study was undertaken to determine if induced miRNA changes would persist and contribute to effects seen 24 h post-hypoglycemia. A parallel, prospective study design was employed, involving T2D (n = 23) and control (n = 23) subjects. The subjects underwent insulin-induced hypoglycemia (2 mmol/L; 36 mg/dL); blood samples were drawn at baseline, upon the induction of hypoglycemia, and 4 h and 24 h post-hypoglycemia, with a quantitative polymerase chain reaction analysis of miRNA undertaken. The baseline miRNAs did not differ. In the controls, 15 miRNAs were downregulated and one was upregulated (FDR < 0.05) from the induction of hypoglycemia to 4 h later while, in T2D, only four miRNAs were altered (downregulated), and these were common to both cohorts (miR-191-5p; miR-143-3p; let-7b-5p; let-7g-5p), correlated with elevated glucagon levels, and all were associated with energy balance. From the induction of hypoglycemia to 24 h, 14 miRNAs were downregulated and 5 were upregulated (FDR < 0.05) in the controls; 7 miRNAs were downregulated and 7 upregulated (FDR < 0.05) in T2D; a total of 6 miRNAs were common between cohorts, 5 were downregulated (miR-93-5p, let-7b-5p, miR-191-5p, miR-185-5p, and miR-652-3p), and 1 was upregulated (miR-369-3p). An ingenuity pathway analysis indicated that many of the altered miRNAs were associated with metabolic and coagulation pathways; however, of the inflammatory proteins expressed, only miR-143-3p at 24 h correlated positively with tumor necrosis factor-α (TNFa; p < 0.05 and r = 0.46) and negatively with toll-like receptor-4 (TLR4; p < 0.05 and r = 0.43). The MiRNA levels altered by hypoglycemia reflected changes in counter-regulatory glucagon and differed between cohorts, and their expression at 24 h suggests miRNAs may potentiate and prolong the physiological response. Trial registration: ClinicalTrials.gov NCT03102801.
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Delaidelli, Alberto, Gian Luca Negri, Que Xi Wang, Albert Huang, Simran Sidhu, Joyce Zhang, Yue Zhou Huang, et al. "EMBR-20. ELONGATION CONTROL OF MRNA TRANSLATION DRIVES GROUP 3 MEDULLOBLASTOMA." Neuro-Oncology 23, Supplement_1 (June 1, 2021): i10. http://dx.doi.org/10.1093/neuonc/noab090.038.
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Abstract Medulloblastoma (MB) is the most common pediatric intracranial tumor and leading cause of childhood related cancer deaths. Group 3 affiliation and genetic amplifications of the MYC oncogene are predictors of adverse outcome in MB, underscoring a dire need for novel and more effective therapeutic approaches. The let-7 family of small non-coding RNAs (miRNAs) is known to inhibit tumor progression and regulate metabolism by targeting and degrading several cellular mRNAs, including MYC. Indeed, let-7 miRNAs are frequently repressed in several cancer types, including in MYC-driven MB. We previously reported that the mRNA translation elongation regulator eukaryotic Elongation Factor-2 Kinase (eEF2K) is a pivotal mediator of cancer cell adaptation to nutrient deprivation. In the current work, we identified a potential binding site for let-7 miRNAs on the eEF2K 3’ untranslated region (UTR). In addition, eEF2K mRNA and let-7 miRNA expressions negatively correlate in MB, suggesting a potential regulation of the former by the latter. Let-7 miRNAs transfection decreases eEF2K mRNA and protein levels (by ~40–50%). Down-regulation of luciferase activity by let-7 miRNAs is impaired upon mutation of the let-7 binding site on the eEF2K 3’UTR. Inhibition of eEF2K significantly reduces survival of MYC-amplified MB cell lines under nutrient deprivation, altering their mRNA translation rates. Knockout of eEF2K increases survival of MYC-amplified MB xenografts when mice are kept under calorie restricted diets. We conclude that let-7 miRNAs degrade the eEF2K mRNA by binding to its 3’UTR, indicating that let-7 repression in MYC-driven MB is partially responsible for increased eEF2K levels. Moreover, the let-7-eEF2K axis constitutes a critical mechanism for MYC-driven MB adaptation to acute metabolic stress, representing a promising therapeutic target. Future therapeutic studies will aim to combine eEF2K inhibition with caloric restriction mimetic drugs, as eEF2K activity appears critical under metabolic stress conditions.
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Liu, Lei, Hailing Wang, Chaohui Yan, and Shudong Tao. "An Integrated Analysis of mRNAs and miRNAs Microarray Profiles to Screen miRNA Signatures Involved in Nasopharyngeal Carcinoma." Technology in Cancer Research & Treatment 19 (January 1, 2020): 153303382095699. http://dx.doi.org/10.1177/1533033820956998.
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Objective: We aim to identify several microRNAs (miRNAs/miRs)-messenger RNAs (mRNAs) biomarkers correlated to nasopharyngeal carcinoma (NPC) based on an integrated analysis of miRNA and mRNAs microarray expression profiles. Methods: The available mRNA and miRNA microarray datasets were retrieved from Gene Expression Omnibus (GEO) database according to pre-determined screening criteria. Differentially expressed miRNA and mRNAs (DEmiRNAs and DEmRNAs) were extracted between NPC and noncancerous nasopharyngeal tissues. The target genes of DEmiRNAs were predicted with miRTarBase followed by the construction of DEmiRNAs-target DEmRNAs network, and functional analyses were performed. The DEmiRNAs expressions were validated and the performance of these DEmiRNAs was assessed by the area under the curve (AUC) values. Finally, the correlations between DEmiRNAs and specific clinical factors were analyzed. Results: There were 1140 interaction pairs (including let-7d/f- MYC/ HMGA2 and miR-452- ITGA9) in DEmiRNAs-target DEmRNAs network. The GO annotation analysis showed that several genes such as MYC, HMGA2 and ITGA9 primarily participated in cellular process. KEGG analysis showed that these targets were associated with cell cycle and cancer-related pathways. Down-regulated let-7(-d and –f) and up-regulated miR-452 were verified in datasets. The AUC values of these 3 DEmiRNAs (let-7d, let-7-f and miR-452) was 0.803, 0.835 and 0.735, respectively. Besides, miR-452 was significantly related to survival rate of NPC patients. Conclusion: The findings implied let-7d/f- MYC/ HMGA2 and miR-452- ITGA9 might be promising targets for the detection and treatment of NPC.
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TRIANTAFYLLOU, ALEXANDRA, NIKOLAOS DOVROLIS, ELENI ZOGRAFOS, CHARALAMPOS THEODOROPOULOS, GEORGE C. ZOGRAFOS, NIKOLAOS V. MICHALOPOULOS, and MARIA GAZOULI. "Circulating miRNA Expression Profiling in Breast Cancer Molecular Subtypes: Applying Machine Learning Analysis in Bioinformatics." Cancer Diagnosis & Prognosis 2, no. 6 (November 3, 2022): 739–49. http://dx.doi.org/10.21873/cdp.10169.
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Background/Aim: Breast cancer is a leading worldwide cause of female cancer-related morbidity and mortality. Since molecular characteristics increasingly guide disease management, demystifying breast tumor miRNA signature emerges as an essential step toward personalized care. This study aimed to investigate the variations in circulating miRNA expression profiles between breast cancer subtypes and healthy controls and to identify relevant target genes and molecular functions. Materials and Methods: MiRNA expression was tested by miScript™ miRNA PCR Array Human Cancer Pathway Finder kit, and subsequently, a machine learning approach was applied for miRNA profiling of the various breast cancer molecular subtypes. Results: Serum samples from patients with primary breast cancer (n=66) and healthy controls (n=16) were analyzed. MiR-21 was the single common molecule among all breast cancer subtypes. Furthermore, several miRNAs were found to be differentially expressed explicitly in the different subtypes; luminal A (miR-23b, miR-142, miR-29a, miR-181d, miR-16, miR-29b, miR-155, miR-181c), luminal B (miR-148a, let-7d, miR-92a, miR-34c, let-7b, miR-15a), HER2+ (miR-125b, miR-134, miR-98, miR-143, miR-138, miR-135b) and triple negative breast cancer (miR-17, miR-150, miR-210, miR-372, let-7f, miR-191, miR-133b, miR-146b, miR-7). Finally, miRNA-associated target genes and molecular functions were identified. Conclusion: Applying a machine learning approach to delineate miRNA signatures of various breast cancer molecular subtypes allows further understanding of molecular disease characteristics that can prove clinically relevant.
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Wang, Yan, Chunlai Cui, Guandong Wang, Yifei Li, and Sibao Wang. "Insects defend against fungal infection by employing microRNAs to silence virulence-related genes." Proceedings of the National Academy of Sciences 118, no. 19 (May 3, 2021): e2023802118. http://dx.doi.org/10.1073/pnas.2023802118.
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Chemical insecticides remain the main strategy to combat mosquito-borne diseases, but the growing threat of insecticide resistance prompts the urgent need to develop alternative, ecofriendly, and sustainable vector control tools. Entomopathogenic fungi can overcome insecticide resistance and represent promising biocontrol tools for the control of mosquitoes. However, insects have evolved robust defense mechanisms against infection. Better understanding of mosquito defenses against fungal infection is critical for improvement of fungal efficacy. Here, we show that as the pathogenic fungus Beauveria bassiana penetrates into the host hemocoel, mosquitoes increase expression of the let-7 and miR-100 microRNAs (miRNAs). Both miRNAs translocate into fungal hyphae to specifically silence the virulence-related genes sec2p and C6TF, encoding a Rab guanine nucleotide exchange factor and a Zn(II)2Cys6 transcription factor, respectively. Inversely, expression of a let-7 sponge (anti–let-7) or a miR-100 sponge (anti–miR-100) in the fungus efficiently sequesters the corresponding translocated host miRNA. Notably, B. bassiana strains expressing anti–let-7 and anti–miR-100 are markedly more virulent to mosquitoes. Our findings reveal an insect defense strategy that employs miRNAs to induce cross-kingdom silencing of pathogen virulence-related genes, conferring resistance to infection.
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Shi, Fei, Wenbao Yu, and Xia Wang. "Bistable Switch in let-7 miRNA Biogenesis Pathway Involving Lin28." International Journal of Molecular Sciences 15, no. 10 (October 21, 2014): 19119–33. http://dx.doi.org/10.3390/ijms151019119.
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He, Yuxuan, Yong Zhang, Hongyan Li, Hong Zhang, Zongshuai Li, Longfei Xiao, Junjie Hu, Youji Ma, Quanwei Zhang, and Xingxu Zhao. "Comparative Profiling of MicroRNAs Reveals the Underlying Toxicological Mechanism in Mice Testis Following Carbon Ion Radiation." Dose-Response 16, no. 2 (April 1, 2018): 155932581877863. http://dx.doi.org/10.1177/1559325818778633.
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This study investigated the toxicity of heavy ion radiation to mice testis by microRNA (miRNA) sequencing and bioinformatics analyses. Testicular indices and histology were measured following enterocoelia irradiation with a 2 Gy carbon ion beam, with the testes exhibiting the most serious injuries at 4 weeks after carbon ion radiation (CIR) exposure. Illumina sequencing technology was used to sequence small RNA libraries of the control and irradiated groups at 4 weeks after CIR. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses implicated differential miRNAs in the regulation of target genes involved in metabolism, development, and reproduction. Here, 8 miRNAs, including miR-34c-5p, miR-138, and 6 let-7 miRNA family members previously reported in testis after radiation, were analyzed by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) to validate miRNA sequencing data. The differentially expressed miRNAs described here provided a novel perspective for the role of miRNAs in testis toxicity following CIR.
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Jiang, Jiquan, Bin Zhang, Chi Zhang, and Yifu Guan. "A Novel Design Combining Isothermal Exponential Amplification and Gold-Nanoparticles Visualization for Rapid Detection of miRNAs." International Journal of Molecular Sciences 19, no. 11 (October 28, 2018): 3374. http://dx.doi.org/10.3390/ijms19113374.
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MicroRNAs (miRNAs) play important roles in a wide range of biological processes, and their aberrant expressions are associated with various diseases. The levels of miRNAs can be useful biomarkers for cellular events or disease diagnosis; thus, sensitive and selective detection of microRNAs is of great significance in understanding biological functions of miRNAs, early-phase diagnosis of cancers, and discovery of new targets for drugs. However, traditional approaches for the detection of miRNAs are usually laborious and time-consuming, with a low sensitivity. Here, we develop a simple, rapid, ultrasensitive colorimetric assay based on the combination of isothermal Exponential Amplification Reaction (EXPAR) and AuNP-labeled DNA probes for the detection of miRNAs (taking let-7a as a model analyte). In this assay, the presence of let-7a is converted to the reporter Y through EXPAR under isothermal conditions. The subsequent sandwich hybridization of the reporter Y with the AuNP-labeled DNA probes generates a red-to-purple color change. In other words, if the reporter Y is complementary to the AuNP-labeled DNA probes, the DNA-functionalized AuNPs will be aggregated, resulting in the change of solution color from red to purple/blue, while when the AuNP-labeled DNA probes are mismatched to the reporter Y, the solution remains red. This assay represents a simple, time-saving technique, and its results can be visually detected with the naked eye due to the colorimetric change. The method provides superior sensitivity, with a detection limit of 4.176 aM over a wide range from 1 nM to 1 aM under optimal conditions. The method also shows high selectivity for discriminating even single-nucleotide differences between let-7 miRNA family members. Notably, it is comparable to the most sensitive method reported to date, thus providing a promising alternative to standard approaches for the direct detection of let-7a miRNA. Importantly, through combination with specific templates, different miRNAs can be converted to the same reporter Y, which can hybridize with the same set of AuNP-labeled DNA probes to form sandwich hybrids. The color change of the solution can be observed in the presence of the target miRNA. This technique has potential as a routine method for assessing the levels of miRNAs, not only for let-7, but also for various miRNAs in the early phase of cancers. In addition, it can be a useful tool in biomedical research and clinical diagnosis, as well as diagnosis or surveillance programs in field conditions.
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Hashimoto, Kazuya, Satoshi Matsuura, Yoshihiko Fujita, Karin Hayashi, Naoshi Sugimoto, Takuya Yamamoto, Hirohide Saito, and Koji Eto. "Synthetic miRNA Switch Technology Elucidates Heterogeneity in Regulation of Immortalized Megakaryocyte Cell Lines, Associated with Improvement of Platelet Generation Efficiency for Clinical Use." Blood 128, no. 22 (December 2, 2016): 3867. http://dx.doi.org/10.1182/blood.v128.22.3867.3867.
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Abstract We have developed a robust in vitro platelet generation system using a self-renewing megakaryocyte (MK) cell line, imMKCL, which was established by introducing three doxycycline (DOX)-inducible transgenes, c-MYC, BMI1, and BCL-XL into human induced pluripotent stem cells (iPSCs)-derived megakaryocyte-erythroid progenitor (MEP) cells for immortalization (Nakamura et al. Cell Stem Cell 2014). This system is suitable for clinical application since imMKCLs proliferate from 106 to over 1010 cells in only 20 days in the presence of DOX (self-renewing stage), and when DOX is removed, imMKCLs enlarge, form proplatelets and release platelets (maturation stage). However, although imMKCLs display homogenous appearance at their self-renewing stage, only a minor population eventually produces platelets at a level comparable to MKs in vivo. Therefore, it is critical to resolve this heterogeneity in terms of maturation to improve the efficiency of platelet production for their practical use. In that regard, we herein apply microRNA (miRNA) switch technology to identify a subpopulation of imMKCLs with high capacity to produce platelets upon maturation. The synthetic miRNA responsive switches could be used for detecting and efficiently purifying cell populations based on endogenous miRNA activity (Miki et al. Cell Stem Cell 2015). First we performed a screening of miRNA switches to investigate the miRNA activities in imMKCLs at the self-renewing stage. Twenty-six miRNA candidates turned out to have some activities in imMKCLs in the presence of DOX. Among those miRNAs, we noticed that Let-7a-5p showed a clear distinguishable pattern with about 10% of the cells in the lower Let-7a-5p activity group (Group L), while other large majority in the higher activity group (Group H). When we sorted the two groups by flow cytometer even in the presence of DOX (self-renewing stage), Group L population in imMKCL revealed to produce significantly more platelets than Group H population (average of 9.9 vs 6.0 platelets per each MK, p<0.01) after DOX depletion. Transfecting Let-7a-5p inhibitor into Group H cells increased platelet production equivalent to the level of Group L, suggesting that Let-7a-5p suppresses the maturation of imMKCLs. Next, we found that the expression level of LIN28A but not LIN28B, a putative downstream target of c-MYC for self-renewal in imMKCL, in Group L was 8.3 times higher than that in Group H (p<0.01), where LIN28A is reported to downregulate the expression of Let-7a-5p by inhibiting the processing of Let-7 miRNA precursors by DICER (Piskounova et al. Cell 2011). This difference was not affected by Let-7a-5p inhibitor, in line with the role of LIN28A as the upstream regulator of Let-7. Finally, to address the targets of Let-7a-5p, we then performed RNA-seq analysis to compare gene expression profiles between Group L and Group H. We found that 691 genes were upregulated more than twice in Group L than in Group H. Among these, 48 genes were predicted to be the targets of Let-7a-5p according to three miRNA target prediction databases, miRSystem, miRDB, and miRSearch. Validation of 48 genes by qPCR confirmed the upregulation of several genes selectively in platelet-producing imMKCLs. Accordingly, transfecting Let-7a-5p inhibitor into Group H cells upregulated the expressions of these confirmed genes, strongly suggesting that they are the candidate targets of Let-7a-5p regulating maturation of imMKCLs. In conclusion, miRNA switch technology enabled us to purify an imMKCL population with high platelet production capability based on the activity of Let-7a-5p. Furthermore, this study revealed the heterogeneity of miRNA expressions in imMKCLs at their self-renewal stage, and suggests that miRNA-mediated gene regulation at this stage affect their maturation afterwards. Disclosures No relevant conflicts of interest to declare.
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Hou, Jin, Lei Zhao, Jing Yan, Xiaoyong Ren, Kang Zhu, Tianxi Gao, Xiaoying Du, Huanan Luo, Zhihui Li, and Min Xu. "MicroRNA expression profile is altered in the upper airway skeletal muscle tissue of patients with obstructive sleep apnea-hypopnea syndrome." Journal of International Medical Research 47, no. 9 (July 12, 2019): 4163–82. http://dx.doi.org/10.1177/0300060519858900.
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Objective To investigate the involvement of microRNAs (miRNAs) in the pathogenesis of obstructive sleep apnea-hypopnea syndrome (OSAHS). Methods In this study, we investigated miRNA profiles in the upper airway (UA) skeletal muscles of four patients with OSAHS and four matched controls using the miRCURY miRNA array. In another cohort of 12 OSAHS cases and 7 controls, the mRNA expression levels of interleukin (IL)-6 and Lin-28 homolog A (Lin28A), targets of the downregulated let-7 family members, were measured by real-time quantitative-PCR. The potential targets of the miRNAs were predicted by miRNA target prediction databases miRanda, Microcosm, and Targetscan. Results The array identified 370 differentially expressed miRNAs, of which 181 were upregulated and 189 were downregulated in OSAHS patients (based on a fold-change >2.0 and p < 0.05). Upregulation of IL-6 and Lin28A was validated by quantitative reverse transcription PCR. The 612 targets predicted by all three algorithms were subjected to gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses. The results revealed perturbations in signaling pathways and cellular functions. Conclusion This study demonstrated profoundly altered miRNA expression profiles in upper airway muscular tissues of patients with OSAHS, which might contribute to the formation and development of OSAHS.
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Philip, Philip Agop, Husain Saleh, Shadan Ali, Wei Chen, Paulette Palazzolo, Seema Sethi, and Fazlul H. Sarkar. "MicroRNA analysis of fine-needle aspirates from pancreatic cancer." Journal of Clinical Oncology 30, no. 4_suppl (February 1, 2012): 200. http://dx.doi.org/10.1200/jco.2012.30.4_suppl.200.
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200 Background: Tissue-based research is a major challenge in localized pancreatic cancer (PC) especially those with locally advanced unresectable or borderline resectable disease. Approximately half of the patients are diagnosed by a fine needle aspirate (FNA) /biopsy of the pancreatic primary tumor with limited tissue available for correlative assays. Micro-RNAs (miRNAs) are biomarkers with the potential to be developed for prognostic and predictive purposes. Moreover, these molecules can facilitate the development of targeted therapies in PC. Methods: miRNA expression profiling and quantitative real-time PCR (qRT-PCR) were performed from RNA (25-100 ng per patient) extracted from formalin-embedded cell blocks (FFPE) obtained from diagnostic FNA of the pancreas. Expression profiles of miRNAs were compared to those from patients undergoing pancreatic biopsy for non-malignant conditions. Results: Cell blocks from FNAs from twenty-nine and 15 patients with pancreatic adenocarcinoma and non-malignant conditions were studied, respectively. miRNA profiling demonstrated deregulation of over 228 miRNA. The top 7 were validated by qRT-PCR. The expression of let-7c, let-7f, and miR-200c were significantly reduced in most patients. Conversely, the expression levels of miR-486-5p and miR-451 were significantly elevated. Significant interindividual variations were also noted in expression of certain miRNAs. Conclusions: FFPE obtained from diagnostic FNA of pancreatic tumor can be a valuable resource to study miRNA expression profiles of multiple miRNAs and undertake qRT-PCR in patients with localized PC and further supports the use of diagnostic FNA in RNA-based translational research. miRNA expression can be developed for use as prognostic and predictive biomarkers in future clinical trials in patients with PC.
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Zhang, Zhang, Maki Hosoki, Masamitsu Oshima, Toyoko Tajima, Mayu Miyagi, Swarnalakshmi Raman, Resmi Raju, and Yoshizo Matsuka. "Identification of microRNA Signatures in Peripheral Blood of Young Women as Potential Biomarkers for Metal Allergy." Biomedicines 11, no. 2 (January 19, 2023): 277. http://dx.doi.org/10.3390/biomedicines11020277.
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MicroRNA (miRNA) is a short (19–24 nucleotide) endogenous non-protein RNA that exists in the body and controls the translation process from genes to proteins. It has become useful as a diagnostic tool and a potential treatment target in cancer research. To explore the function of miRNA in contact dermatitis, female participants with a positive metal allergy diagnosis (n = 3) were enrolled along with additional female participants with no medical history of metal allergy (n = 3). A patch test was performed on each participant. Peripheral blood was collected from all the participants before the patch test and at days 3 and 7 after starting the patch test. After total RNA was obtained from peripheral blood leukocytes and cDNA was generated, microarray analysis was performed to analyze the large-scale circulating miRNA profile. Real-time polymerase chain reaction (RT-PCR) was then used to clarify the overall target miRNA expression. Downregulation of hsa-let-7d-5p, hsa-miR-24-3p, hsa-miR-23b-3p, hsa-miR-26b-5p, and hsa-miR-150-5p was found on day 7. Certain miRNAs were confirmed using RT-PCR. These peripheral blood miRNAs could be diagnostic biomarkers for metal allergies.
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Marzi, Matteo J., Eleonora M. R. Puggioni, Valentina Dall'Olio, Gabriele Bucci, Loris Bernard, Fabrizio Bianchi, Marco Crescenzi, Pier Paolo Di Fiore, and Francesco Nicassio. "Differentiation-associated microRNAs antagonize the Rb–E2F pathway to restrict proliferation." Journal of Cell Biology 199, no. 1 (October 1, 2012): 77–95. http://dx.doi.org/10.1083/jcb.201206033.
Full textAbstract:
The cancer-associated loss of microRNA (miRNA) expression leads to a proliferative advantage and aggressive behavior through largely unknown mechanisms. Here, we exploit a model system that recapitulates physiological terminal differentiation and its reversal upon oncogene expression to analyze coordinated mRNA/miRNA responses. The cell cycle reentry of myotubes, forced by the E1A oncogene, was associated with a pattern of mRNA/miRNA modulation that was largely reciprocal to that induced during the differentiation of myoblasts into myotubes. The E1A-induced mRNA response was preponderantly Retinoblastoma protein (Rb)-dependent. Conversely, the miRNA response was mostly Rb-independent and exerted through tissue-specific factors and Myc. A subset of these miRNAs (miR-1, miR-34, miR-22, miR-365, miR-29, miR-145, and Let-7) was shown to coordinately target Rb-dependent cell cycle and DNA replication mRNAs. Thus, a dual level of regulation—transcriptional regulation via Rb–E2F and posttranscriptional regulation via miRNAs—confers robustness to cell cycle control and provides a molecular basis to understand the role of miRNA subversion in cancer.
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Sokol, Lubomir, Myka Estes, Ann H. Williams, Yukiyasu Ozawa, Stefano Volinia, Chang-Gong Liu, Carlo M. Croce, and Alan F. List. "Myelodysplastic Syndromes (MDS) Display a Risk and Senescence-Dependent MicroRNA (miRNA) Signature." Blood 108, no. 11 (November 16, 2006): 2630. http://dx.doi.org/10.1182/blood.v108.11.2630.2630.
Full textAbstract:
Abstract MDS comprise a spectrum of senescence-dependent stem cell malignancies with cytogenetic abnormalities characterized by segmental or numerical chromosome deletion or duplication. Accumulation of genetic events with age has been implicated in MDS pathogenesis. MiRNAs are short non-coding double-stranded RNAs that regulate the posttranscriptional gene expression. Expression profiling has shown that miRNA signatures are tumor specific and may have a role in leukemia pathogenesis. We hypothesized that altered regulation of miRNA expression in hematopoietic progenitors plays a critical role in the physiology of hematopoietic senescence and in MDS pathogenesis. To this end, we compared the miRNA microarray profile of MDS BM-MNC with normal controls, and validated differences by Northern blot and real-time RT-PCR. Twenty MDS patients (10 IPSS Low or Int-1 risk [LR], 10 Int-2 and high risk [HR]) and 20 normal controls (NC) (10 younger, ages 18–35 years [YC] and 10 older >70 years [OC]) were investigated. Total RNA was extracted and 5 mg were labeled with biotin and used for microarray analysis on a miRNA chip (OSUCC 3rd generation). Arrays were normalized with Cyclic Loess (Bioconductor). Statistical comparisons were made using the Significance Analysis of Microarray (SAM) Excel plugin. MiRNA predictors and 10-fold cross-validation were computed with use of Prediction Analysis of Microarray (PAM). Fifty-six miRNAs were up-regulated and 8 down-regulated in HR MDS vs. LR MDS with a >2 fold change and q value <0.01 (false positive rate) indicating that miRNA over-expression is a common event in MDS and possibly implicated in disease progression. Results of PAM (predictor analysis of microarray) revealed that HR MDS and LR MDS could be segregated by miRNA profile. A signature consisting of seven up-regulated miRNAs correctly discriminated between HR and LR groups with a misclassification error of 0 (10-fold CV). All seven miRNAs in this signature belong to the miR-181 family, which play key roles in hematopoiesis. Furthermore, our studies show divergent miRNA profiles between HR MDS and normal controls (NC), with 117 up-regulated miRNAs and 12 downregulated in HR MDS (>2-fold change, q<0.01). A miRNA signature consisting of 15 up-regulated miRNAs correctly discriminates these two groups with a misclassification error of 0 (threshold of 4.6). LR MDS and NC samples had greater similarity and a larger number of miRNAs was needed for discrimination with misclassification error of 11.4%. Similar data were obtained in comparisons of OC with YC; however, several members of let-7 miRNA family implicated in the down-regulation of RAS were consistently down-regulated in OC. We conclude that miRNA up-regulation is a frequent event in MDS. Up-regulation of miR-181 is sufficient to discriminate between HR and LR disease. Down-regulation of let-7 miRNA with age suggests a possible role in age-related predisposition to myeloid malignancy.
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de Almeida, dos Anjos, Uno, Cunha, Soares, Baiocchi, Baracat, and Carvalho. "Let-7 miRNA’s Expression Profile and Its Potential Prognostic Role in Uterine Leiomyosarcoma." Cells 8, no. 11 (November 17, 2019): 1452. http://dx.doi.org/10.3390/cells8111452.
Full textAbstract:
The lethal-7 (let-7) family is an important microRNA (miRNA) group that usually exerts functions as a tumor suppressor. We aimed to evaluate the expression profile of let-7a, let-7b, let-7c, let-7d, let-7e, let-7f, let-7g, and let-7i and to assess their value as prognostic markers in uterine leiomyosarcoma (LMS) patients. The miRNAs expression profile was assessed in 34 LMS and 13 normal myometrium (MM) paraffin-embedded samples. All let-7 family members showed downregulation in LMS. Our findings showed that patients with let-7e downregulation had worse overall survival (OS) and is an independent prognostic factor (hazard ratio [HR] = 2.24). In addition, almost half the patients had distant metastasis. LMS patients with downregulated let-7b and let-7d had worse disease-free survival (DFS); they are not independent prognostic factors (HR = 2.65). Patients’ ages were associated with let-7d, let-7e and let-7f (p = 0.0160) downregulation. In conclusion, all the let-7 family members were downregulated in LMS patients, and the greater the loss of expression of these molecules, the greater their relationship with worse prognosis of patients. Let-7e expression might influence the OS, while let-7b and le-7d might influence the DFS. The lowest expression levels of let-7d, let-7e, and let-7f were associated with the oldest patients. Our findings indicate strong evidence of let-7′s role as a potential prognostic biomarker in LMS.
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Katayama, Mutsumi, Rasmus J. O. Sjögren, Brendan Egan, and Anna Krook. "miRNA let-7 expression is regulated by glucose and TNF-α by a remote upstream promoter." Biochemical Journal 472, no. 2 (November 13, 2015): 147–56. http://dx.doi.org/10.1042/bj20150224.
Full textAbstract:
We investigated the putative promoter region of miRNA let-7a-1/f-1/d cluster, determined promoter activity and identified a novel promoter area for these three let-7 family members expressed. We provide evidence that let-7 expression is regulated by insulin and tumour necrosis factor (TNF)-α.