Nucleoside analog cytotoxicity and bystander cell killing of cancer cells expressing Drosophila melanogaster deoxyribonucleoside kinase in the nucleus or cytosol

We have recently shown that the overexpression of Drosophila melanogaster m ultisubstrate deoxyribonucleoside kinase (Dm-dNK) in cancer cell lines incr eases the cells' sensitivity to several cytotoxic nucleoside analogs and th e enzyme may accordingly be used as a suicide gene in combined gene/chemoth erapy treatment of cancer. To further characterize the enzyme for possible use as a suicide gene, we constructed a replication-deficient retroviral ve ctor that expressed either the wild-type enzyme that localizes to the cell nucleus or a mutant (arg247-ser) that localizes to the cytosol. A thymidine kinase-deficient osteosarcoma cell line was transduced with the recombinan t virus and we compared the sensitivity and bystander cell killing when the cell lines were incubated with the pyrimidine nucleoside analogs (E)-5-(2- bromovinyl)-2'-deoxyuridine and 1-beta -D-arabinofurano-sylthymine. In summ ary, we showed that the cells' sensitivity and the efficiency of bystander cell killing were not dependent on whether Dm-dNK was located in the nucleu s or cytosol. (C) 2001 Academic Press.