Strategic down-regulation of DNA polymerase p by antisense RNA sensitizes mammalian cells to specific DNA damaging agents

摘要

Previously, mouse NIH 3T3 cells were stably transfected with human DNA polymerase (3 (beta-pol) cDNA in the antisense orientation and under the control of a metallothionein promoter [2mudzka,B.Z. and Wil-son.S.H. (1990) Som. Cell Mol. Gen., 16, 311-320]. To assess the feasibility of enhancing the efficacy of chemotherapy by an antisense approach and to confirm a role for beta-pol in cellular DNA repair, we looked for increased sensitivity to DNA damaging agents under conditions where p-pol is down-regulated in the antisense cell line. Such a sensitization is anticipated only where beta-pol is rate-limiting in a DNA repair pathway. A number of agents were tested: cis-diamminedichloroplatinum II (cisplatin); 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU); ionizing radiation and the radio-mimetic drug bfeomycin; the bifunctional alkylating agents nitrogen mustard and u-prtenylaianine mustard (melphalan); the monofunctional alkylating agent methyl methane sulfonate (MMS) and ultraviolet (UV) radiation. Inthe cases of cisplatin and UV radiation, a significant enhancement of cytotoxicity was observed. Damage as a result of both of these agents is thought to be repaired by the nucleotide excision repair (NER) pathway. The results suggest that, in this cell line, beta-pol is involved in and is rate-limiting in NER. We propose that down-regulation of p-pol by antisense approaches might be used to enhance the cytotoxic effects of cisplatin and other DNA damaging chemotherapeutic agents.