Reduced global genomic repair of ultraviolet light-induced cyclobutane pyrimidine dimers in simian virus 40-transformed human cells

Abstract

The p53 tumor‐suppressor gene has been implicated in the inducible activation of excision repair of ultraviolet (UV)‐induced cyclobutane pyrimidine dimers (CPDs) in human cells. Because the large T antigen (LTAg) of the simian virus 40 (SV40) binds p53 protein and can interfere with its function, it was of interest to study DNA repair in normal human fibroblasts that had been transformed by SV40 compared with that in their nontransformed parental counterparts and to determine whether such transformation attenuated global genomic repair (GGR) of CPDs. Three methods were used to measure GGR in UV‐irradiated cells: (i) an immunoassay using monoclonal antibodies specific for CPDs or 6‐4 photoproducts (6‐4PPs), (ii) zone sedimentation in alkaline sucrose gradients to measure the average DNA strand size after specific nicking at CPD sites in duplex DNA with T4 endonuclease V (TEV), and (iii) Southern hybridization of TEV‐treated DNA with strand‐specific mRNA probes to assess removal of CPDs from either strand of a defined genetic sequence in an expressed gene. Whereas repair of 6‐4PPs was very similar in paired SV40‐transformed and primary fibroblasts, GGR of CPDs was significantly reduced in the SV40‐transformed cells. In contrast, SV40 transformation did not appreciably affect the efficiency of transcription‐coupled repair. These data support the hypothesis that SV40 transformation can result in reduced levels of GGR, most likely because of the inhibition of normal p53 function by LTAg. Mol. Carcinog. 29:17–24, 2000. © 2000 Wiley‐Liss, Inc.

Elevation of Cellular BPDE Uptake by Human Cells: A Possible Factor Contributing to Co-Carcinogenicity by Arsenite

“…NER is responsible for removing bulky lesions such as BPDE–DNA adducts from the genome. Abrogation of the p53 function by SV40 transformation could further diminish DNA repair (Bowman et al 2000). In the present study BPDE was used to generate BPDE–DNA adducts.…”

Modulation of Homology-Directed Repair in T98G Glioblastoma Cells Due to Interactions between Wildtype p53, Rad51 and HCMV IE1-72

“…Existing studies have examined a variety of different repair pathways in the context of expression of a single viral protein and have assessed that protein’s capability to influence the repair of exogenously introduced damage in the cellular DNA [35,36,37,38,39,40,41,42,43,44,45,46]. The effects on repair during a complete infection have also been examined [12,47,48,49,50,51,52,53,54,55,56]. A handful of these studies have looked specifically at HDR [12,35,37,45,49].…”

Lesion Sensing and Decision Points in the DNA Damage Response

“…That deficiency was documented by three different assays and in several different SV40 transformed cell lines, and was in striking contrast to the proficient GGR in nontransformed parental cells. 58 A third example is the hepatitis B virus X gene (HBx). The HBx protein physically interacts with and sequesters p53 in the cytoplasm.…”