Academic literature on the topic 'CCNE2'

Abstract Using a similar strategy that successfully identified PR1 as a leukemia-associated antigen (LAA), we identified two homologous HLA-A2-restricted peptides from cyclin E1 (CCNE1) and cyclin E2 (CCNE2) that could be used to elicit peptide-specific CTL from healthy donors in vitro. Two homologous nonameric peptides from CCNE1 (CCNE1144–152) and CCNE2 (CCNE2144–152), which differ by a single amino acid at position 7, have equal binding affinity for HLA-A2 and each elicited peptide-specific CTL with equal efficiency, as measured by specific lysis of T2 cells pulsed with either peptide (CCNE1 59.7% vs CCNE2 72.6% specific lysis, respectively, at E: T 10:1). TCR-Vβ spectratype analysis showed CCNE1-CTL clones to be derived from 3 Vβ families, while CCNE2-CTL clones were derived from a single Vβ family. The CCNE1-CTL and the CCNE2-CTL bound to each of the CCNE1/A2 and CCNE2/A2 tetramers, but staining intensity was greater for the CCNE1-CTL, suggesting greater TCR avidity of the CCNE1-CTL for both peptides. Because each clone cross-recognized the other homologous peptide, we hypothesized that each clone would efficiently kill leukemia that over-expressed either or both CCNE1 and CCNE2 proteins. FACsorted high avidity CTL showed higher specific lysis of peptide-pulsed T2 than did low avidity CTL (38.8% vs 31.9% specific lysis, respectively, at E: T 10:1, p = 0.02). The fluorescence decay of tetramer dissociation (ln (peptide/HLA-A2 tetramer)) over time was linear for each clone, suggesting that avidity was proportional to TCR affinity and tetramer dissociation t1/2 was determined based on first order kinetics. CCNE1-CTL had higher affinity for CCNE1144–152/HLA-A2 (CCNE1/A2, t1/2=84.5min; CCNE2/A2, t1/2=25.3min) and preferentially killed CCNE1144–152-pulsed T2 cells (CCNE1, 56.9% vs CCNE2, 38%, respectively, at E: T 10:1, p = 0.004). Interestingly, CCNE2-CTL also had higher TCR affinity for CCNE1144–152/HLA-A2 (CCNE1/A2, t1/2=29.5min; CCNE2/A2, t1/2=10.7min), but showed only slightly higher specific lysis of CCNE1144–152-pulsed T2 cells (CCNE1 = 49.3% vs CCNE2 = 44.2% specific lysis, respectively, at E: T 10:1, p = 0.33). Each clone specifically lysed HLA-A2+ T-ALL leukemia cells in proportion to both CCNE1 and CCNE2 protein overexpression assessed by Western blot (CCNE1-CTL, R2=0.89; CCNE2-CTL, R2=0.88). In contrast, healthy HLA-A2+ BM cells, which do not overexpress CCNE1 or CCNE2, and control HLA-A2− CML cells that overexpress both proteins, were not lysed. Both the high and low affinity clones showed equal lysis of T-ALL cells that expressed large amounts of each protein (specific lysis = 24.3% by CCNE1-CTL, vs lysis = 23.8% by CCNE2-CTL, at E: T 10:1). However, high affinity CCNE1-CTL killed T-ALL cells significantly better than low affinity CCNE2-CTL (16.8% vs 6.6% lysis, respectively, at E: T 10:1, p =0.02) when the T-ALL expressed a 2.5-fold lower amount of both CCNE1 and CCNE2 proteins. We conclude that the CCNE1 and CCNE2 homologous self-peptides are lymphoid leukemia-associated antigens. Furthermore, while the higher TCR affinity of CCNE1-CTL suggests that the CCNE1 peptide is the more dominant epitope, ultimate target susceptibility is enhanced due to degeneracy of the resulting CTL clones against homologous peptide epitopes.

E-type cyclins E1 (CcnE1) and E2 (CcnE2) are regulatory subunits of cyclin-dependent kinase 2 (Cdk2) and thought to control the transition of quiescent cells into the cell cycle. Initial findings indicated that CcnE1 and CcnE2 have largely overlapping functions for cancer development in several tumor entities including hepatocellular carcinoma (HCC). In the present study, we dissected the differential contributions of CcnE1, CcnE2, and Cdk2 for initiation and progression of HCC in mice and patients. To this end, we tested the HCC susceptibility in mice with constitutive deficiency for CcnE1 or CcnE2 as well as in mice lacking Cdk2 in hepatocytes. Genetic inactivation of CcnE1 largely prevented development of liver cancer in mice in two established HCC models, while ablation of CcnE2 had no effect on hepatocarcinogenesis. Importantly, CcnE1-driven HCC initiation was dependent on Cdk2. However, isolated primary hepatoma cells typically acquired independence on CcnE1 and Cdk2 with increasing progression in vitro, which was associated with a gene signature involving secondary induction of CcnE2 and up-regulation of cell cycle and DNA repair pathways. Importantly, a similar expression profile was also found in HCC patients with elevated CcnE2 expression and poor survival. In general, overall survival in HCC patients was synergistically affected by expression of CcnE1 and CcnE2, but not through Cdk2. Our study suggests that HCC initiation specifically depends on CcnE1 and Cdk2, while HCC progression requires expression of any E-cyclin, but no Cdk2.

Abstract Cyclin E1 (CCNE1) and cyclin E2 (CCNE2) are cell cycle genes that are overexpressed in AML, ALL, and CML, and in solid tumors such as breast cancer, lung cancer, and gastric cancer. We reported that two homologous nonameric peptides from CCNE1 (CCNE1144-152, ILLDWLMEV) and CCNE2 (CCNE2144-152, ILLDWLLEV), which differ by a single amino acid at position 7, have equal binding affinity for HLA-A2 and that CCNE1- and CCNE2- specific CTL elicited from healthy donors kill ALL and CML cells that overexpress CCNE1 and CCNE2. Interestingly, CCNE1/A2 and CCNE2/A2 tetramers bind to both T-cell receptors (TCR), but the longer tetramer dissociation t1/2 of CCNE1/A2 compared with CCNE2/A2 tetramer suggests CCNE1 is the more dominant epitope. To determine the clinical significance of CTL immunity to these self-epitopes, we studied peripheral blood mononuclear cells from 18 patients before and after allogeneic stem cell transplantation (SCT) using CCNE1/A2 and CCNE2/A2 tetramers. An increase in the absolute number of circulating CCNE1- or CCNE2-CTL after SCT was considered evidence of an immune response (IR). Of the18 patients, there were 10 with CML and 8 with ALL, and all were HLA-A2+ and had sufficient blood samples cryopreserved from various time points before SCT and 3–12 months after SCT for analysis. Ten patients, including all 8 ALL patients, were in complete remission (CR) prior to SCT and 5 patients achieved CR after SCT. An IR to CCNE1 was found in 12 of 18 (67%) patients and an IR to CCNE2 was found in 14 of 18 (78%) patients. All 12 patients who had an IR to CCNE1 also had an IR to CCNE2, reflecting possible cross-recognition of both peptides by the same CTL clones. By Chi-square analysis, IR to either CCNE1 or CCNE2 did not correlate with diagnosis (CML vs. ALL), source of the graft (matched related donors vs. mismatched donors), or disease status prior to SCT (remission vs. no remission). Six patients developed acute graft-versus-host disease (aGVHD) and 12 developed chronic graft-versus-host disease (cGVHD). IR to either CCNE1 or CCNE2 occurred more frequently in patients without aGVHD than in the patients with aGVHD (92% vs. 50%, p<0.05), although no significant difference in the IR frequency was observed amongst those who developed cGVHD versus those that did not. Of 8 CML patients who were not in CR prior to SCT, IR to either CCNE1 or CCNE2 occurred more frequently in patients that achieved CR compared to those that did not achieve CR after SCT (100% vs. 33%, respectively; p<0.04). These results provide clinical evidence that both CCNE1 and CCNE2 peptides are novel leukemia-associated antigens, and they justify future clinical trials to determine whether CTL immunity can be enhanced against these antigens in patients with ALL and CML.

Abstract Abstract 686 Cyclin E1 (CCNE1) and cyclin E2 (CCNE2) are tightly regulated cell cycle genes in normal cells but are over-expressed and constitutively active in breast cancer and in the majority of hematological malignances. To validate CCNE as a potential target antigen for T-cells in leukemia, we first confirmed aberrant CCNE1 and CCNE2 protein in PBMC from 26 (93%) of 28 patients (CML = 16; AML = 7; ALL =2; NHL = 3) by Western Blot compared to 4 (33%) of 12 healthy controls (p < 0.0005). Next, we screened the sequences of CCNE1 and CCNE2 for HLA-A*0201 binding motifs and identified a pair of homologous nonameric peptides with highest predicted binding to HLA-A*0201 using an NCBI algorithm. The peptides, denoted CCNE1M (144ILLDWLMEV152) and CCNE2L (144ILLDWLLEV152), differed at P7 (M or L), and both differed from mouse sequence at P1 (V). Synthetic mouse and human peptides were used to confirm high affinity HLA-A2 binding on T2 cells by FACS analysis and peptide-pulsed T2 were used to elicit peptide-specific CTLs from healthy HLA-A2+ PBMC in vitro. CCNE1M-CTL lines specifically lysed both CCNE1M-loaded and CCNE2L-loaded T2 cells, while no CTL could be elicited with mouse peptide. Similarly, CCNE2L-stimulated CTL lines killed CCNE1M-loaded and CCNE2L-loaded T2 cells but not non-loaded T2 cells. Using CCNE1M and CCNE2L HLA-A2 tetramers, we found that either tetramer could bind equally to either the CCNE1M- or CCE2L-derived CTL lines, suggesting that both peptides could be cross-recognized by CTL lines elicited with either peptide. To further study the cross-recognition and potential immune dominance of both peptides and to determine their potential anti-leukemia activity, CCNE1M- and CCNE2L-CTL clones were derived by limiting dilution assay. Two peptide-specific CTL clones from each of the lines showed 25% and 26% specific lysis, respectively, of leukemia cells at E:T 10:1. Neither CCNE-specific CTLs showed lysis of BM cells that were obtained from the same patient during remission, nor HLA-A2+ BM cells from a healthy donor. Next, we compared the T-cell antigen receptor (TCR) avidity of these CCNE1M- and the CCNE2L-CTL clones by measuring tetramer dissociation half-times (t1/2) at 25°C using CCNE1M/HLA-A2 and CCNE2L/HLA-A2 (and control pp65/HLA-A2) tetramers analyzed by flow cytometry. The decay of normalized (to time = 0) tetramer-bound fluorescence versus time was linear for each clone with either tetramer (R2 = 0.85 to 0.91), showing that tetramer binding avidity could be used to proportionally determine TCR affinity. Furthermore, first order kinetics could be used to determine the t1/2 of each of the clones. The t1/2 of CCNE1M/HLA-A2 tetramer was 85 min and 25 min, respectively, while the t1/2of CCNE1L/HLA-A2 was 30 min and 11 min, respectively, for the CCNE1M-CTL and the CCNE2L-CTL. This suggests that while both peptides were cross recognized by unique T-cell clones (with unique TCR, determined by TCR-Vβ sequence comparisons), CCNE1M appeared to be immunodominant. To determine whether immune response (IR) to either peptide occurred in leukemia patients, we studied PBMC from 18 patients (10 CML; 8 ALL) before and 3–6 mo after SCT with CCNE1M/HLA-A2- and CCNE2L/HLA-A2-tetramer assay. The mean number of CCNE1M-CTL and CCNE2L-CTL cells increased after SCT (p< 0.002 in CCNE1M-CTL and CCNE2L-CTL) compared to no change in mean number of pp65-CTL before/after SCT. IR (defined as ≥ 20% increase of specific CTL after SCT) to either CCNE1M or CCNE2L did not correlate with type of leukemia, donor-recipient HLA disparity (matched or mismatched), or disease status prior to SCT by Fisher's exact test. However, in 8 CML patients not in remission prior to SCT, IR to either CCNE1 or CCNE2 occurred more frequently in patients who achieved CR compared to those that did not achieve CR after SCT (100% vs. 33%, respectively; p < 0.04). These findings were confirmed in an additional 25 AML patients with active disease at SCT. To study whether the peptide-specific CTL were functional, we measured IFN-γ and TNF-αa production after peptide stimulation by Luminex bead assay and by intracellular cytokine flow cytometry (CFC). The assays showed production of IFN-γ and TNF-αa cytokines by T-cells after stimulation with CCNE1M or CCNE2Lpeptides. Taken together, these results show that CCNE1M and CCNE2Lself-peptides from constitutively active cell cycle proteins are novel leukemia-associated antigens that could be studied in immunotherapy strategies. Disclosures: No relevant conflicts of interest to declare.

Abstract Mantle cell lymphoma (MCL) is characterized by the t(11;14)(q13;q32) translocation resulting in overexpression of cyclin D1. However, a small subset of cyclin D1− MCL has been recognized, and approximately one-half of them harbor CCND2 translocations while the primary event in cyclin D1−/D2− MCL remains elusive. To identify other potential mechanisms driving MCL pathogenesis, we investigated 56 cyclin D1−/SOX11+ MCL by fluorescence in situ hybridization (FISH), whole-genome/exome sequencing, and gene-expression and copy-number arrays. FISH with break-apart probes identified CCND2 rearrangements in 39 cases (70%) but not CCND3 rearrangements. We analyzed 3 of these negative cases by whole-genome/exome sequencing and identified IGK (n = 2) and IGL (n = 1) enhancer hijackings near CCND3 that were associated with cyclin D3 overexpression. By specific FISH probes, including the IGK enhancer region, we detected 10 additional cryptic IGK juxtapositions to CCND3 (6 cases) and CCND2 (4 cases) in MCL that overexpressed, respectively, these cyclins. A minor subset of 4 cyclin D1− MCL cases lacked cyclin D rearrangements and showed upregulation of CCNE1 and CCNE2. These cases had blastoid morphology, high genomic complexity, and CDKN2A and RB1 deletions. Both genomic and gene-expression profiles of cyclin D1− MCL cases were indistinguishable from cyclin D1+ MCL. In conclusion, virtually all cyclin D1− MCLs carry CCND2/CCND3 rearrangements with immunoglobulin genes, including a novel IGK/L enhancer hijacking mechanism. A subset of cyclin D1−/D2−/D3− MCL with aggressive features has cyclin E dysregulation. Specific FISH probes may allow the molecular identification and diagnosis of cyclin D1− MCL.

The consumption of nicotine via smoking tobacco has been reported to stimulate the occurrence and progression of periodontitis. Many studies have demonstrated that nicotine prevents the regeneration of periodontal tissues primarily by inhibiting the proliferation of human periodontal ligament (PDL) cells. However, the mechanisms underlying this process are still unclear. Therefore, we investigated whether nicotine-upregulated miR-30a inhibited the proliferation of human PDL cells by downregulating cyclin E2 (CCNE2), in vitro. Quantitative real-time PCR analysis revealed that nicotine upregulated the expression of miR-30a in human PDL cells. In addition, nicotine inhibited the proliferation of human PDL cells by inducing cell cycle arrest. To support this hypothesis, we showed that nicotine downregulated the expression of CCNE2 in human PDL cells, whereas inhibition of miR-30a restored CCNE2 expression that had been downregulated by nicotine. Furthermore, using luciferase reporter assays, we found that miR-30a directly interacts with the CCNE2 3′UTR. In conclusion, these findings indicate that nicotine-upregulated miR-30a inhibits the proliferation of human PDL cells by downregulating the expression of CCNE2.

Abstract This study tried to explore the molecular mechanism underlying progression of lung adenocarcinoma (LUAD) and discuss the extracellular communication between cancer cells and vascular endothelial cells. Roughly, differential analysis was carried out to note that miR-30a-5p was lowly expressed in LUAD, whereas CCNE2 was highly expressed. Cell functional experiments demonstrated that overexpressed miR-30a-5p led to suppressed cell abilities in proliferation, migration and invasion. Dual-luciferase reporter gene assay and RNA immunoprecipitation verified the binding of miR-30a-5p and CCNE2, as well as decreased mRNA and protein expression of CCNE2 with miR-30a-5p overexpression. Simultaneous up-regulation of miR-30a-5p and CCNE2 reversed the promotion of CCNE2 on malignant behaviors of LUAD cells. In vivo mice experiments exhibited that high miR-30a-5p expression hindered tumor growth. Additionally, miR-30a-5p was localized on the Extracellular Vesicles microRNA (EVmiRNA) database. MiR-30a-5p was abundant in exosomes derived from vascular endothelial cells. To validate that miR-30a-5p could be delivered to LUAD cells via exosomes and then make an effect, exosomes from vascular endothelial cells were first extracted and identified by transmission electron microscopy and detection of exosomal marker proteins (Alix, CD63, TSG101). Sequentially, the extracted exosomes were labeled with DIO to note that exosomes could be internalized by cancer cells. Further experiments indicated that miR-30a-5p was increased in cancer cells co-cultured with exosomes, which in turn suppressed cell malignant behaviors and made cell cycle arrest. In all, our findings clarified that exosomes derived from vascular endothelial cells delivered miR-30a-5p to LUAD cells to affect tumor malignant progression via the miR-30a-5p/CCNE2 axis.

3569 Background: Previous studies have shown that CCNE2 expression is higher in patients’ cancers resistant to CDK4/6 inhibitors. Increased expression of CCNE2, MTDH, or TSPYL5, genes contained within the 70-gene risk of distant recurrence signature (70GS), has also been implicated in breast oncogenesis, poor prognosis, and chemoresistance. These genes are located on chromosome region 8q22.1, one of the most recurrently amplified regions out of all 70GS genes in breast tumors (Fatima et al. 2017). MYC, located on 8q24, is overexpressed in 40% of all breast cancers (BC). Here we examined the expression of CCNE2, MTDH, and TSPYL5 in relation to 70GS risk and the 80-gene molecular subtype signature (80GS), and their correlation with MYC expression in early stage BC patients. Methods: CCNE2, MTDH, TSPYL5, and MYC mRNA expression was measured in 5022 BC samples sent to Agendia (Irvine, CA) for 70GS and 80GS testing, which included FFPE microarray full-transcriptome data. 70GS was used to stratify patients into Ultra Low Risk (UL), Low Risk (LR), High Risk (HR), and Ultra High Risk (UH). Both 70GS and 80GS were used to classify patient samples into Luminal A, Luminal B, HER2, or Basal type. Wilcoxon rank sum test was used to assess expression differences. Results: The expression of CCNE2, MTDH, and TSPYL5 significantly correlated with each other and was higher in HR patients compared to LR patients (p < 0.001) and higher in UH patients compared to HR patients (p < 0.001). Expression of these genes was highest in Basal type tumors, 83% of which were UH, followed by Luminal B type tumors, and lowest in Luminal A type tumors. CCNE2 and MYC expression was elevated in LR compared to UL patients (p < 0.001 and p = 0.0043). There was no difference in MYC expression between HR vs. LR or UH vs. HR. Lastly, there was no association between the expression of 8q22.1 genes and MYC in any 70GS subgroup. Conclusions: Within the 70GS, CCNE2, MTDH, and TSPYL5 have similar expression patterns and when overexpressed may identify an UH cohort of BC. This observation, in addition to their physical proximity at 8q22.1 suggests a possible amplicon in this region. The highest expression of CCNE2, MTDH, and TSPYL5 associated with UH patients and is concordant with previous studies that support the role of these genes in BC metastasis. Furthermore, this analysis suggests MYC may not stratify patients based on metastatic potential. These data may be clinically relevant for stratifying patients in ongoing clinical trials evaluating response and resistance to targeted therapies in early stage BC.

Genome doubling is an underlying cause of cancer cell aneuploidy and genomic instability, but few drivers have been identified for this process. Due to their physiological roles in the genome reduplication of normal cells, we hypothesised that the oncogenes cyclins E1 and E2 may be drivers of genome doubling in cancer. We show that both cyclin E1 (CCNE1) and cyclin E2 (CCNE2) mRNA are significantly associated with high genome ploidy in breast cancers. By live cell imaging and flow cytometry, we show that cyclin E2 overexpression promotes aberrant mitosis without causing mitotic slippage, and it increases ploidy with negative feedback on the replication licensing protein, Cdt1. We demonstrate that cyclin E2 localises with core preRC (pre-replication complex) proteins (MCM2, MCM7) on the chromatin of cancer cells. Low CCNE2 is associated with improved overall survival in breast cancers, and we demonstrate that low cyclin E2 protects from excess genome rereplication. This occurs regardless of p53 status, consistent with the association of high cyclin E2 with genome doubling in both p53 null/mutant and p53 wildtype cancers. In contrast, while cyclin E1 can localise to the preRC, its downregulation does not prevent rereplication, and overexpression promotes polyploidy via mitotic slippage. Thus, in breast cancer, cyclin E2 has a strong association with genome doubling, and likely contributes to highly proliferative and genomically unstable breast cancers.

The potent splicing inhibitor spliceostatin A (SSA) inhibits cell cycle progression at the G1 and G2/M phases. We previously reported that upregulation of the p27 cyclin-dependent kinase inhibitor encoded by CDKN1B and its C-terminal truncated form, namely p27*, which is translated from CDKN1B pre-mRNA, is one of the causes of G1 phase arrest caused by SSA treatment. However, the detailed molecular mechanism underlying G1 phase arrest caused by SSA treatment remains to be elucidated. In this study, we found that SSA treatment caused the downregulation of cell cycle regulators, including CCNE1, CCNE2, and E2F1, at both the mRNA and protein levels. We also found that transcription elongation of the genes was deficient in SSA-treated cells. The overexpression of CCNE1 and E2F1 in combination with CDKN1B knockout partially suppressed G1 phase arrest caused by SSA treatment. These results suggest that the downregulation of CCNE1 and E2F1 contribute to the G1 phase arrest induced by SSA treatment, although they do not exclude the involvement of other factors in SSA-induced G1 phase arrest.