Inhibition of RhoA expression by adenovirus-mediated siRNA combined with TNF-α induced apoptosis of hepatocarcinoma cells

Tumor necrosis factor-alpha (TNF-alpha) has been used as an effective treatment for Hepatocellular Carcinoma, however, inducing tumor cell apoptosis by TNF-alpha alone is still unsatisfactory. RhoA is highly expressed in hepatocarcinoma cells and can be activated by TNF-alpha. The activation of RhoA directly leads to a poor prognosis of HCC. Therefore, we propose to investigate the therapeutic effect of TNF-alpha together with RhoA siRNA. RhoA inhibition was accomplished by constructing a recombinant adenovirus that can efficiently express RhoA siRNA in HepG2 cells. The recombinant adenovirus AdshRNA-RhoA and AdU6-control were generated by adenovirus-mediated siRNA expression system. The inhibition effects were detected by RT-PCR in addition to immunoblot to quantify the decreased levels of RhoA expression, and the therapeutic effect for HCC was demonstrated by the proliferation and apoptosis ratios of HepG2 cells. The inhibition effects of RhoA by AdshRNA-RhoA were significant at both mRNA and protein levels: the transcription of RhoA mRNA decreased by 74.46%, and the expression of protein decreased by 76.48%. The proliferation rate of HepG2 cells detected by MTT showed that a treatment of AdshRNA-RhoA and TNF-alpha together could strengthen the suppression ability of TNF-alpha to HepG2 cells, resulting in approximately 14.2% more than those treated with only TNF-alpha. FCA and TUNEL assays results revealed that the combined treatment can induce apoptosis in approximately 52.14%-65% of the HepG2 cells, whereas this ratio in the TNF-alpha-alone group was only 21.91%-32%. Our results showed that AdshRNA-RhoA can efficiently enhance the TNF-alpha-induced apoptosis of hepatocarcinoma cells. This method might be a useful therapeutic route in HCC and other tumors.