Acetylcholine enhances HIF-1α signaling in pancreatic cancer cells under hypoxia through the nAChR-α7/ PDPK1/YAP pathway

초록

Recent studies have extensively addressed the potential role of the autonomic nervous system, which extensively innervates the pancreas, in the development of pancreatic ductal adenocarcinoma (PDAC). Targeting hypoxia-inducible factor-1 (HIF-1) for cancer management has attracted significant research interest, in view of the finding that HIF-1 regulates the expression of various genes involved in tumor angiogenesis, metastasis, proliferation, chemoresistance, and radioresistance. In this study, we investigated the molecular mechanisms by which the neurotransmitter acetylcholine enhances the expression of HIF-1 alpha in pancreatic cancer cells in hypoxia. Under hypoxic conditions, acetylcholine induced a concentration-dependent increase in nAChR-alpha 7-mediated HIF-1 alpha expression in pancreatic cancer cells in vitro, leading to enhanced expression of HIF-1 alpha target genes. It also increased HIF-1 alpha protein stability in pancreatic cancer cells under hypoxic conditions. The acetylcholine-induced elevation of HIF-1 alpha expression was blocked by siRNA-mediated knockdown of PDPK1/YAP signaling, indicating a role for this pathway in mediating these effects. A bioinformatics analysis of publicly available clinical datasets revealed that overall survival was significantly poorer in patients with CHRNA7 copy number amplification, whereas those with high CHRNA7 mRNA expression showed a non-significant trend toward reduced survival, suggesting that copy number alterations have stronger clinical relevance than mRNA levels. Functionally, alpha-bungarotoxin, a nAChR-alpha 7-specific inhibitor, markedly blunted the acetylcholine-induced increase in the viability of pancreatic cancer organoids under hypoxic conditions. In a mouse xenograft model, acetylcholine administration accelerated tumor growth in animals bearing control pancreatic cancer cells but not in those implanted with nAChR-alpha 7-knockdown cells. Collectively, our findings reveal a novel mechanism of acetylcholine-induced enhancement of HIF-1 alpha expression involving PDPK1/YAP signaling and highlight the utility of HIF-1 alpha as a therapeutic target in acetylcholine-potentiated pancreatic cancer.

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