Overexpression Of Prostate-specific Antigen Promoter-Driven Pro-Caspase-7 For The Induction Of Therapeutic Apoptosis In Prostate Cancer

We have achieved increasing prostate cancer check rate in recenct years with the raising quantity of examination method. The increasing rate of prostate cancer is the highest one compared with other malignancy in the urinary in our country. Therefor, people have tried many ways to treat prostate cancer and gene therapy is one of the promising methods.The aim of this study is to construct the eukaryotic expression vector that driven pro-Caspase-7 by prostate-specific antigen promoter(PSAP) especially and investigated whether PSAP-driven pro-Caspase-7 could induce death of prostate cancer cells, and whether the cytotoxicity is restricted to cells of prostate origin. We extracted genomic DNA from benign prostate tissues and obtained prostate specific antigen promoter (PSAP) fragment by polymerase-chain-reaction (PCR).Using gene technology, we replace the pCMV on pcDNA3 by PSAP and obtained PSAP-pcDNA3 vector. We obtained PSAP-pIRES2-EGFP and PSAP-Casp7-pIRES2-EGFP eukaryotic expression vectors respectively after the replacement of pCMV on pIRES2-EGFP and Casp7-pIRES2-EGFP by PSAP.Lipofection-mediated gene transfers were performed with these two vectors and a control plasmid, pIRES2-EGFP, in human prostate cancer cell line PC-3m and 2 other cell lines (Hep2 [human cancer of larynx] and MC3T3 [mice fibroblast]). Light and electron microscopy were used to observe the proliferation and apoptosis of all cell lines. Immunohistochemistry methods were used to evaluate the expression of Caspase-7 protein. The results indicate all vectors were successfully constructed. All cells showed green fluorescence after transfected with pIRES2-EGFP. When transfected with PSAP-pIRES2-EGFP, only PC-3m showed green fluorescence and there were no apoptosis cells appeared in all three transfected groups. After transfected with PSAP-Casp7-pIRES2-EGFP, PC-3m cells showed the strong growth inhibition and the other two cell lines showed no changes after transfection. There was no Caspase-7 protein detected in the Hep2 and MC3T3 cell lines after transfection. Morphologically some of the PC-3m transfected cells manifested apoptotic features. Our results showed that PSAP-driven pro-Caspase-7 gene therapy inhibits the growth of human prostate cancer cells and the cytotoxic effect is restricted to the cells of prostate origin.