DNA excision‐repair synthesis is enhanced in a murine leukemia L1210 cell line resistant to cisplatin

Abstract

Among various molecular mechanisms of cel resistance to antitumor agents such as cisplatin, it has recently been suggested that enhanced DNA‐repair activity might be involved in the resistant phenotype of cell lines. Mouse leukemia‐cisplatin‐resistant cell lines L1210/10 (adapted in vitro) and L1210/DDP (adapted in vivo) have been reported to exhibit an increase DNA‐ repair activity, as determined by host‐cell reactivation after transformation with damaged plasmids. In this paper, excision‐repair activity was monitored by an in‐votro assay allowing quantification of DNA‐repair synthesis in cell extracts from resistant and sensitive parental cells (L1210/10 versus L1210/0 and L1210/DDP versus L1210/S). Experimental conditions for optimal repair‐synthesis activity were found to be different from these reported with human cell‐line extracts. L1210/S sensitive cell line, grown in vivo by a weekly intraperitoneal graft in mice, sdisplayed a repair activity about fourfold lower than the same cell line maintained in vitro or than L1210/0 cell grown in votro. The repair activity was found similar in a L1210/10 and L1210/0 cell lines, but it was enhanced in L1210/DDP resistant cell line when compared with its parental line.