Characterization of the ARHI tumor-suppressor as a target for gene therapy in ovarian cancer

Objective: Identification and characterization of relevant tumorsuppressor genes (ARHI) that are downregulated in ovarian cancer should identify targets for gene therapy. The tumor-suppressor function of ARHI was evaluated analyzing the impact of adenoviral ARHI transduction (in-vitro gene therapy) on ovarian cancer cell growth and induction of apoptosis was analyzed. Material and Methods: To study in-vitro gene therapy, ovarian cancer cells were transduced with a recombinant adenovirus (Ad5CMV-ARHI). Transduction efficiency was assessed using a β-gal-containing adenovirus (Ad5CMV-LacZ). Cell-counting assays were used to evaluate the effect of transduction on the growth of cells. P26ARHI expression was evaluated using Western blot analysis. Cell cycle and apoptosis were analyzed using fluorescent activated cell sorting (FACS) and TUNEL staining. Results: Adenoviral ARHI transduction efficiencies varied between the analyzed cell lines. P26ARHI reexpression was detected 8 hours after infection, with a peak at 48 hours. More than 90% growth inhibition occurred in seven of eight cell lines after infection with Ad5CMV-ARHI if a viral dose leading to at least 50% of cells infected was used. ARHI transduction leads to apoptosis but no G1 arrest was determined. Conclusion: ARHI appears to be a putative tumor-suppressor gene whose function is abrogated in ovarian cancers. Adenoviral transduction (in-vitro gene therapy) is a method to induce ARHI reexpression with consecutive induction of apoptosis in ovarian cancer cells. Further evaluation of ARHI should elucidate its potential prognostic significance and its possible value for gene therapy in human ovarian cancer.