Hypoxia inducible factor (HIF)-1α directly activates leptin receptor (Ob-R) in pancreatic cancer cells

The aim of this study is to investigate the regulatory mechanism of leptin receptors (Ob-R) in pancreatic cancer. We found that the over-expression of hypoxia inducible factor (HIF-1)α and hypoxia up-regulated the expression of Ob-R in pancreatic cancer cells. When HIF-1α gene was silenced in vitro, the expression of Ob-R was significantly decreased. Xenograft mouse models showed that the inhibition of HIF-1α resulted in the concomitant decrease of Ob-R in vivo. In addition, HIF-1α expression was correlated with Ob-R in pancreatic cancer tissues by immunohistochemical staining. Clinical data showed that over-expression of HIF-1 was associated with pathological tumor node metastasis stage, lymph node metastasis and overall survival. HIF-1α directly bound to the hypoxia-responsive element (HRE) located in Ob-R gene promoter (−828/−832) and activated the transcription. Finally, we demonstrated that the silence of HIF-1α gene reversed the inhibitory effect of leptin/Ob-R in pancreatic cancer cells. Taken together, our results indicate that HIF-1α directly regulated Ob-R expression in pancreatic cancer, which might be a valuable therapeutic target for pancreatic cancer.