Background and objective: Adenovirus vector has been widely used in tumor gene therapy. ING4 is a member of growth inhibiting factors and a potent anti-tumor gene which could induce apoptosis of many tumor cells. This study was to investigate the inhibitory effects of adenovirus-mediated ING4 (Ad-ING4) gene on the proliferation of human prostate cancer PC-3 cells in vitro and in vivo, and to explore its mechanisms.
Methods: Ad-ING4 was obtained by virus-amplification technique. After transfection of purified Ad-ING4 into PC-3 cells, the expression of ING4 was detected by reverse transcription-polymerase chain reaction(RT-PCR); the influence of Ad-ING4 transfection on cell proliferation was evaluated using MTT assay. Cell apoptosis was assessed using Hoechst33258 staining and flow cytometry. RT-PCR was performed to detect the mRNA levels of the transcription of apoptosis-related genes such as bcl-2, bax, p53, and caspase-3. Athymic nude mice bearing PC-3 tumors were intratumorally injected with Ad-ING4 (100 microL, 1x10(9) pfu/mL). Tumor growth was recorded. All nude mice were killed at the end of the experiment to observe the growth of xenografts. The expressions of Bcl-2, Bax, Caspase-3, and CD34 proteins in tumor tissues were detected by immunohistochemistry.
Results: Human ING4 gene was successfully transcribed in PC-3 cells and induced apoptosis by up-regulating p53, bax, caspase-3 expression and down-regulating bcl-2 expression. Inhibition of cell proliferation was significant in PC-3 cells. Tumor growth was significantly inhibited in the Ad-ING4 group as compared with that in the Ad-GFP group and the PBS group (P<0.05). The weight inhibitory rate was 37.0% in the Ad-ING4 group. The expressions of Bax and Caspase-3 were up-regulated, and the expressions of Bcl-2 and CD34 were down-regulated in the Ad-GFP group.
Conclusions: Adenovirus-mediated ING4 gene exhibits anti-tumor ability in human prostate cancer PC-3 cells in vitro and in vivo, and induces apoptosis. This may be related to the up-regulations of p53, bax, Caspase-3 and down-regulation of bcl-2.