title: Strategic down-regulation of DNA polymerase beta by antisense RNA sensitizes mammalian cells to specific DNA damaging agents.
abstract: Previously, mouse NIH 3T3 cells were stably transfected with human DNA polymerase beta (beta-pol) cDNA in the antisense orientation and under the control of a metallothionein promoter [Zmudzka, B.Z. and Wilson, 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 beta-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 bleomycin; the bifunctional alkylating agents nitrogen mustard and L-phenylalanine mustard (melphalan); the monofunctional alkylating agent methyl methane sulfonate (MMS) and ultraviolet (UV) radiation. In the 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 beta-pol by antisense approaches might be used to enhance the cytotoxic effects of cisplatin and other DNA damaging chemotherapeutic agents.
mesh_terms: D016475:3T3 Cells; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D001761:Bleomycin / Q000494:pharmacology; D002330:Carmustine / Q000494:pharmacology; D016923:Cell Death / Q000187:drug effects; D002945:Cisplatin / Q000494:pharmacology; D004247:DNA / Q000187:drug effects / Q000528:radiation effects; D004249:DNA Damage / Q000187:drug effects*; D004256:DNA Polymerase I / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D008466:Mechlorethamine / Q000494:pharmacology; D008558:Melphalan / Q000494:pharmacology; D008741:Methyl Methanesulfonate / Q000494:pharmacology; D051379:Mice; D016372:RNA, Antisense / Q000494:pharmacology*; D014162:Transfection; D014466:Ultraviolet Rays; D015032:Zinc / Q000494:pharmacology
chemical_list: D000970:Antineoplastic Agents; D016372:RNA, Antisense; D001761:Bleomycin; D008466:Mechlorethamine; D004247:DNA; D008741:Methyl Methanesulfonate; D004256:DNA Polymerase I; D015032:Zinc; D002945:Cisplatin; D008558:Melphalan; D002330:Carmustine