Objectives: Apoptotic effect of apoptin has been demonstrated in numerous studies. However, its tumor specificity has been questioned by some reports. The aim of this study was to confine the expression of apoptin in the prostate tumor cells by inducing its gene expression under the control of a chimeric enhancer composing of prostate-specific membrane antigen (PSMA) and prostate-specific antigen (PSA) regulatory elements (PSES). Furthermore, we investigated the effects of apoptin expression on LNCaP prostate carcinoma cell survival and apoptosis using MTT assay and annexin V/7-AAD flow cytometry assay.
Materials and methods: Recombinant plasmids containing apoptin gene under the control of PSES/PSA promoter or Cytomegalovirus (CMV) promoter were constructed. Tumor cell lines including LNCaP cells and HeLa cells, and LX-2 cells (as a normal control) were transfected with the plasmids and the expression of apoptin was evaluated by real time-PCR and western blot analyses. The effects of apoptin expression on cell survival and apoptosis were then investigated using MTT and annexinV/7-AAD flow cytometry assay, respectively.
Results: Western blot and real time PCR analyses confirmed the specific expression of apoptin under the control of PSES/PSA regulatory element in the LNCaP cells, while CMV promoter caused apoptin expression in both tumor and normal cell lines. Apoptin expression significantly increased cell death and apoptosis in tumor cells when compared with the normal cells (P<0.001).
Conclusion: These results suggest that PSES/PSA regulatory element may be considered as an efficient approach for specific expression of apoptin gene in prostate tumor cells and treatment of prostate cancer.
Keywords: Apoptin protein; Apoptosis; Prostate-specific antigen; Prostate-specific-membrane antigen Prostate cancer.