Littérature scientifique sur le sujet « NEUROBLASTOMA, HIF-2α »

Neuroblastoma is a biologically very heterogeneous tumor with its clinical manifestation ranging from spontaneous regression to highly aggressive metastatic disease. Several adverse factors have been linked to oncogenesis, tumor progression and metastases of neuroblastoma including NMYC amplification, the neural adhesion molecule NCAM, as well as CXCR4 as a promoter of metastases. In this study, we investigate to what extent the expression of AQP1 in neuroblastoma correlates with changing cellular factors such as the hypoxic status, differentiation, expression of known adverse factors such as NMYC and NCAM, and CXCR4-related metastatic spread. Our results show that while AQP1 expression leads to an increased migratory behavior of neuroblastoma cells under hypoxic conditions, we find that hypoxia is associated with a reduction of NMYC in the same cells. A similar effect can be observed when using the tetracycline driven mechanism of SH-EP/Tet cells. When NMYC is not expressed, the expression of AQP1 is increased together with an increased expression of HIF-1α and HIF-2α. We furthermore show that when growing cells in different cell densities, they express AQP1, HIF-1α, HIF-2α, NMYC and NCAM to different degrees. AQP1 expression correlates with a hypoxic profile of these cells with increased HIF-1α and HIF-2α expression, as well as with NMYC and NCAM expression in two out of three neuroblastoma cell lines. When investigating cell properties of the cells that actually migrate, we find that the increased APQ1 expression in the migrated cells correlates with an increased NMYC and NCAM expression again in two out of three cell lines. Expression of the tumor cell homing marker CXCR4 varies between different tumor areas and between cell lines. While some migrated tumor cells highly express CXCR4, cells of other origin do not. In the initial phase of migration, we determined a dominant role of AQP1 expression of migrating cells in the scratch assay.

Abstract Introduction CO2 pneumoperitoneum can influence the biological behavior of neuroblastoma (NB). Angiogenesis and genetic features are responsible for malignant phenotype of this tumor. We examined the CO2 effects on N-Myc, vascular endothelial growth factor (VEGF), and matrix metalloproteinase-2 (MMP-2) expression as critical biomarkers of tumor invasiveness, in NB cells without N-Myc amplification. Materials and Methods SH-SY5Y cells were exposed to CO2 (100%) at 15 mm Hg pressure for 4 hours and then moved to normal condition for 24 hours. Control cells were incubated with 5% CO2 for the same time. In control and CO2-exposed cells, the messenger ribonucleic acid (mRNA) levels of hypoxia-inducible factor (HIF)-1α, HIF-2α, VEGF-A, and MMP-2 were quantified by real-time polymerase chain reaction. N-Myc expression was evaluated by Western blot analysis. Results The exposure to 15 mm Hg CO2 (100%) for 4 hours induced an increase in HIF-1α, but not in HIF-2α, mRNA levels. No differences were observed in N-Myc expression between exposed and control cells at each incubation time. Similarly, no significant differences were found for VEGF-A and MMP-2 transcript levels. In CO2 exposed cells, we observed only a slight increase in both VEGF-A and MMP-2 mRNA levels after 4 and 24 hours in comparison to controls. Conclusion In our study, the hypoxic environment induced by CO2 exposure does not affect the expression of critical biomarkers of NB aggressiveness, such as N-Myc, VEGF, and MMP-2, in human SH-SY5Y NB cells without N-Myc amplification. These data suggest that CO2 pneumoperitoneum might not adversely impact NB cell invasiveness; however, it is necessary to evaluate these effects in others in vitro and in vivo models.

Erythropoietin (Epo) is the critical hormone for erythropoiesis. In adults, Epo is mainly produced by a subset of interstitial fibroblasts in the kidney, with minor amounts being produced in the liver and the brain. In this study, we used the immortalized renal interstitial fibroblast cell line FAIK F3-5 to investigate the ability of the bioactive sphingolipid sphingosine 1-phosphate (S1P) to stimulate Epo production and to reveal the mechanism involved. Stimulation of cells with exogenous S1P under normoxic conditions (21% O2) led to a dose-dependent increase in Epo mRNA and protein levels and subsequent release of Epo into the medium. S1P also enhanced the stabilization of HIF-2α, a key transcription factor for Epo expression. S1P-stimulated Epo mRNA and protein expression was abolished by HIF-2α mRNA knockdown or by the HIF-2 inhibitor compound 2. Furthermore, the approved S1P receptor modulator FTY720, and its active form FTY720-phosphate, both exerted a similar effect on Epo expression as S1P. The effect of S1P on Epo was antagonized by the selective S1P1 and S1P3 antagonists NIBR-0213 and TY-52156, but not by the S1P2 antagonist JTE-013. Moreover, inhibitors of the classical MAPK/ERK, the p38-MAPK, and inhibitors of protein kinase (PK) C and D all blocked the effect of S1P on Epo expression. Finally, the S1P and FTY720 effects were recapitulated in the Epo-producing human neuroblastoma cell line Kelly, suggesting that S1P receptor-dependent Epo synthesis is of general relevance and not species-specific. In summary, these data suggest that, in renal interstitial fibroblasts, which are the primary source of plasma Epo, S1P1 and 3 receptor activation upregulates Epo under normoxic conditions. This may have a therapeutic impact on disease situations such as chronic kidney disease, where Epo production is impaired, causing anemia, but it may also have therapeutic value as Epo can mediate additional tissue-protective effects in various organs.

Il neuroblastoma (NB) è un tumore embrionale del sistema nervoso simpatico, che deriva da cellule della cresta neurale. È il tumore extracranico più diffuso tra i bambini di età inferiore a un anno e rappresenta circa il 7% di tutti i tumori infantili. L'ipossia si sviluppa comunemente durante la crescita tumorale ed è associata ad una prognosi infausta con resistenza ai trattamenti terapeutici. Molte evidenze suggeriscono una correlazione tra i fattori ipossia-inducibile (HIF), HIF-1α e HIF-2α, con il grado di differenziamento e quindi l’aggressività tumorale. In particolare, nel Neuroblastoma HIF-2α è stabile anche in condizioni di normossiche e continua ad essere attivo anche dopo 48-72 ore dall’ipossia. In NB HIF-2α, localizzato principalmente nelle nicchie peri-vascolare del tumore ed è correlato ad una prognosi infausta. Studi recenti hanno dimostrato il coinvolgimento di HIF-2α nella proliferazione e nell’aumento della aggressività tumorale. Lo scopo del progetto è quello di acquisire ulteriori informazioni sui meccanismi molecolari indotti dall’over-espressione di HIF-2α che sono alla base della resistenza ai convenzionali trattamenti terapeutici. Il nostro progetto, quindi, propone un approccio proteomico, basato sull’analisi DIGE e sull’identificazione di antigeni di membrana (FACS), per identificare nuovi bersagli prognostici e terapeutici per il trattamento clinico di forme di NB più aggressive e resistenti ai protocolli terapeutici convenzionali. Attraverso l’indagine DIGE e studi funzionali sono stati identificati nel nostro sistema sperimentale diverse proteine coinvolte nel metabolismo cellulare e nei processi di regolazione dell’mRNA. Inoltre sono stati identificati nuovi antigeni di membrana differenzialmente espressi soffermandoci sulle proprietà antiadesive e proinvasive di CD55, marker specifico di HIF-2α.Quindi, CD55 potrebbe essere usato nella diagnosi e per la stratificazione di pazienti affetti da forme più aggressive di Neuroblastoma.
Neuroblastoma (NB) is an embryonal tumor of neuroectodermal cells derived from precursor or immature cells of the sympathetic nervous system (SNS). This disease rappresents the most common extracranial tumor in infants, accounting for 8% to 10% of all childhood cancer and for approximately 15% of cancer deaths in children. The deep knowledge of NB biology is imperative toward the development of novel therapy. Hypoxia is a typical feature of several solid tumors microenvironment and is associated with a poor prognosis and resistance to therapy. The relationship among hypoxia, tumor phenotypes and clinical parameters in NB is not well characterized. Tumor adaptation to hypoxia is mainly mediated by two transcription factors: the hypoxia-inducible factors (HIFs) HIF-1α and HIF-2α. HIF-2α is stable also in normoxia condition and continues to be active even after 48–72 h of hypoxia in some neuroblastoma cell lines thus indicate that HIF-2α plays a critical role in driving the hypoxic response. Interesting, HIF-2α is correlated with poor patient prognosis in NB and is localizated in tumor peri-vascular niches. These findings indicate that HIF-2α protein expression in NB samples at normoxic levels might affect the aggressive tumor phenotype. The main aim of my phD program has been to get new insights into the molecular mechanism of tumor aggressiveness mediated by HIF-2α protein overexpression in NB cells. Interesting, HIF-2α overexpressing cells acquire an undifferentiated phenotype and the ability to grow as neurospheres in soft agar. Then I applied two different proteomic approaches, DIGE analysis and FACS detection of membrane antigens to identify new putative prognostic and therapeutic hypoxia-related targets to be used in clinical treatment of aggressive NB forms. The identified proteins have important roles in a variety of pathways such as “citrate cycle”, “glycolysis” and “splicesoma” thus indicating that HIF-2α over-expression affects the cellular metabolic balance and increases the processes of mRNA regulation. These findings might provide an innovative therapeutic strategy by combining anti-metabolic drugs and pathways inhibitors.Among the cell surface antigens which were differentialy HIF-2α regulated CD55 was the most significantly expressed marker in our cellular system. I assessed CD55 has anti-adhesive and pro-invading functions that might provide the basis for NB solid tumors to survive as microscopic residual disease. Furthermore, the use of CD55 antibody-based visualization as in PET (Positron Emission Tomography) imaging will have implications for the development of more accurate diagnosis and prognosis in challenging cases and for driving personalized treatment. In conclusion, the HIF-2α novel markers identified in this study might improve patients risk stratification and could be also used as putative drug targets being immunotherapy is one of the most promising anticancer treatment.