Cytotoxic effects of adenovirus- and lentivirus-mediated expression of Drosophila melanogaster deoxyribonucleoside kinase on Bcap37 breast cancer cells.

Gene transfer using different viral vectors has demonstrated different antitumor effects in suicide gene therapy. In the present study, in order to optimize the efficacy of replication-defective adenoviral and lentiviral vectors for gene therapy, RT-PCR was used to evaluate the expression of Drosophila melanogaster deoxyribonucleoside kinase (Dm-dNK) in the Bcap37 human breast cancer cell line, dThd was used to determine the activity of Dm-dNK, cell cytotoxicity was evaluated by MTT assay and cell proliferation was assessed using a hemocytometer. Moreover, apoptosis induction was evaluated by the Annexin V-FITC-labeled FACS method. Furthermore, BALB/C nude mice bearing tumors were treated with Dm-dNK mediated with the pyrimidine nucleoside analog, brivudine [BVDU, (E)-5-(2-bromovinyl)-2'-deoxyuridine]. Our results indicated that the gene expression of Dm-dNK transfected by adenoviral and lentiviral vectors may be detected and that its long-term activity may be retained. Both vectors containing the Dm-dNK gene revealed high cytotoxicity and sensitized cell apoptosis from the BVDU prodrug. In tumor models, lentivirus-mediated gene therapy significantly inhibited the growth of tumors compared with adenovirus-mediated gene therapy. Although adenovirus- and lentivirus-transduced Dm-dNK reveal strong treatment efficacy in vitro, the latter has great potential due to the long-term expression of the therapeutic gene in vivo.