The Study Of Hypoxia Promotes Proliferation Of The Cd133-Positive Pancreatic Cancer Stem Cells Through Activation Of HIF-1α

Objective:In this study, we investigate the relationship between HIF-1αand the proliferation of the CD133-positive cancer stem cells of pancreatic cancer PANC-1 cell line under hypoxia, and discuss the regulating effects of HIF-1αon pancreatic cancer stem cells.Methods:1. PANC-1 cells are divided into four groups: normoxic control group; hypoxic group (12h), hypoxic group(24h) and hypoxic group(48h). The mRNA expressions of HIF-1αand VEGF were shown by the semi-quantitative reverse transcription PCR (RT-PCR). The HIF-1αand VEGF proteins were tested using western blot analysis. CD133 was detected by flow cytometry on the control group and hypoxic group(48h). Therefore, sphere-forming assays show the self-renewal capacity of cancer stem cells in the cells line. The control and the hypoxic group PANC-1 cells were plated in serum-free DMEM/F12 under normoxic and hypoxic conditions respectively for 5 days. Then the number of tumor spheres was counted.2. HIF-1α-siRNA confirmed by the preceding study was transfected into pancreatic cancer cell line PANCA-1 cells by using cationic liposomes Lipofectamine? 2000. Then, as mentioned above, the expression of the HIF-1α, VEGF, CD133 and the sphere-forming capacity under normoxic and hypoxic conditions were detected.Result:1. Under the hypoxic conditions, compared with the normoxic group, the mRNA and protein expression of HIF-1αand VEGF increased significantly (P<0.01) in hypoxic groups. The expression of CD133 is remarkably up-regulated (P<0.05) in the hypoxic groups.2. The siRNA abrogates the induction of HIF-1αin response to hypoxia and decreases VEGF expression. And the expression of CD133 was down-regulated as well. HIF-1αdepletion also led to a significant reduction in the sphere-forming capacity.Conclusion:Hypoxia can increase the expression of the CD133-positive pancreatic cancer stem cells in PANC-1 cell line. This effect can be abrogated by HIF-1α-siRNA .Thus, we can conclude that HIF-1αcan promote the expansion of the CD133-positive pancreatic cancer stem cells in the pancreatic cancer PANC-1 cell line under hypoxic conditions., and knockdown of HIF-1αabrogated the hypoxia-mediated CD133-positive cancer stem cells expansion. This study laid the foundation for further study of incidence and therapy of pancreatic cancer stem cells.