siRNA Targeting HIF-1α Induces Apoptosis of Pancreatic Cancer Cells through NF-κB-independent and -dependent Pathways under Hypoxic Conditions

Abstract

Objective: The primary objective was to explore the molecular mechanism of small interference RNA (siRNA) targeting hypoxic inducible factor-1α (HIF-1α) for inducing apoptosis of pancreatic cancer cells through a nuclear factor-kappaB (NF-κB)-independent or -dependent pathway under hypoxic conditions. Materials and Methods: A cassette encoding siRNA targeting HIF-1α mediated by recombinant adeno-associated virus (rAAV) was constructed, giving rAAV-siHIF. rAAV-siHIF or rAAV-hrGFP were transfected into exponentially growing MiaPaCa2 cells under hypoxic conditions. The expression of HIF-1α mRNA and protein and the activity of NF-κB were observed by real-time PCR, Western blot and electromobility shift assay (EMSA). The proliferation and apoptosis of MiaPaCa2 cells with or without PDTC, as an inhibitor of NF-κB, were investigated by MTT and TUNEL. Results: rAAV-siHIF inhibited the expression of HIF-1α mRNA and protein and the activity of NF-κB in MiaPaCa2 cells under hypoxic conditions. At the same time, rAAV-siHIF decreased MiaPaCa2 cell proliferation and induced apoptosis, but these effects were not abrogated by PDTC. Moreover, PDTC also inhibited MiaPaCa2 cell proliferation and induced apoptosis while rAAV-hrGFP did not have these effects. Conclusion: Under hypoxic conditions, HIF-1α plays a key role in the proliferation of MiaPaCa2 cells and inhibition of HIF-1α expression may lead to MiaPaCa2 cell apoptosis through NF-κB-independent and -dependent pathways.