Up-regulation of p21 ^WAF1/CIP1 by small activating RNA inhibits the in vitro and in vivo growth of pancreatic cancer cells

Abstract

Aims and background To study the inhibitory effect of p21 WAF1/CIP1 activation by saRNA on the growth of human pancreatic cancer cells PANC-1 in vitro and in vivo. Methods and study design A dsRNA (dsP21) targeting the p21 WAF1/CIP1 gene promoter at position-322 relative to the transcription start site was transfected into PANC-1 cells. Expression of mRNA and protein was evaluated by semiquantitative RT-PCR and Western blotting. Proliferation of PANC-1 cells was measured by the MTT method, and the apoptosis rate was detected by flow cytometry. PANC-1 cells were transplanted subcutaneously in nude mice, and the inhibitory effect of dsP21 on tumor growth was observed. Results The introduction of dsP21 was shown to efficiently up-regulate expression of the p21 WAF1/CIP1 gene in PANC-1 cells according to the results of RT-PCR and Western blotting (P <0.01, compared with controls). The inhibitory effect on cell proliferation was confirmed by the MTT test (P <0.05, compared with controls). The apoptosis rate of PANC-1 cells treated with dsP21 was significantly higher than that of the control cells (P <0.01). Our experimental data showed that dsP21-mediated up-regulation of p21 expression exerted an apparent growth inhibitory effect on PANC-1 cells in vivo. Conclusions dsP21 targeting the p21 WAF1/CIP1 gene promoter can specifically up-regulate expression of the p21 WAF1/CIP1 gene in PANC-1 cells. It therefore has a substantially inhibitory effect on cell proliferation in vitro and in vivo and can be used as a new method and material for the gene therapy of pancreatic cancer.