Abstract

REV1 interacts with Y-type DNA polymerases (Pol) and Pol ζ to bypass many types of adducts that block the replicative DNA polymerases. This pathway accounts for many of the mutations induced by cisplatin (cis-diamminedichloroplatinium II, DDP). This study sought to determine how increasing human REV1 (hREV1) affects the cytotoxicity and mutagenicity of DDP. Human ovarian carcinoma 2008 cells were transfected with an hREV1 expression vector and 4 sublines developed in which the hREV1 mRNA level was increased by 6.3- to 23.4-fold and hREV1 protein by 2.7- to 6.2-fold. The sublines were 1.3- to 1.7-fold resistant to the cytotoxic effect of DDP and 2.3- to 5.1-fold hypersensitive to the mutagenic effect of DDP. The hREV1-transfected sublines were 1.5- to 1.8-fold better than the parental 2008 cells at managing DDP adducts as assessed by their ability to express Renilla reniformis luciferase from a vector that had been extensively loaded with DDP adducts before transfection. Increased hREV1 expression was associated with a 1.5-fold increase in the rate at which the whole population acquired resistance to DDP during sequential cycles of drug exposure. Increasing the abundance of hREV1 thus resulted in both resistance to DDP and a significant elevation in DDP-induced mutagenicity. This was accompanied by an enhanced capacity to synthesize a functional protein from a DDP-damaged gene and, most importantly, by more rapid development of resistance during sequential cycles of DDP exposure that mimic clinical schedules of DDP administration. We conclude that hREV1-dependent processes are important determinants of DDP-induced genomic instability and the development of resistance.