Objective: To investigate the effect and mechanism of NF-kappaB P65 gene silencing by small interference RNA on the apoptosis of human pancreatic cancer cells induced by gemcitabine in vitro and in vivo.
Methods: Human pancreatic cancer cells (BxPC-3 and PANC-1) were cultured and respectively divided into five groups: blank control group, negative control siRNA group, gemcitabine group, NF-kappaB P65 siRNA group and gemcitabine + P65 siRNA group. The ability of cell proliferation was analyzed by MTT; the expression of NF-kappaB P65 and the apoptosis related proteins were examined by Western blot assay; the apoptosis was evaluated by the flow cytometry and laser scanning confocal microscopy analysis stained with Annexin V-FITC/PI; the DNA binding activity of NF-kappaB was examined by electrophoretic mobility shift assay. BxPC-3 cells were injected subcutaneously into nude mice to establish pancreatic xenograft tumors. The tumor volume was monitored and TUNEL assay was used to assess the apoptosis index in tumor tissue after treatment.
Results: At 72 h after transfection, the combination with gemcitabine and p65 siRNA significantly decreased the cell viability index (P < 0.05), and down-regulated the expression of Bcl-2 and procaspase-3 and up-regulated the expression of Bax compared with other groups. The combined treatment significantly increased the rate of apoptosis compared with other groups (P < 0.05). EMSA assay indicated that the DNA binding activity of NF-kappaB significantly decreased in NF-kappaB P65 siRNA group and gemcitabine+P65 siRNA group compared with Control group. The combined therapy inhibited the growth of pancreatic xenograft tumors by apoptosis induction in nude mice (P < 0.01).
Conclusions: The effect of gemcitabine inducing cell apoptosis may be potentiated through inhibiting the DNA binding activity of NF-kappaB and regulating the expression of apoptosis related proteins by NF-kappaB P65 siRNA, which can activate the mitochondria apoptosis pathway in pancreatic cancer in vitro and in vivo.