Loss of DNA mismatch repair facilitates reactivation of a reporter plasmid damaged by cisplatin

• Published in: British Journal of Cancer 1999-05, Vol.80 (5-6), p.699-704
• Main Authors: Cenni, B, Kim, H-K, Bubley, G J, Aebi, S, Fink, D, Teicher, B A, Howell, S B, Christen, R D
• Format: Article
• Language: English
• Subjects: Adenocarcinoma - drug therapy; Adenocarcinoma - genetics; Antineoplastic agents; Antineoplastic Agents - metabolism; Antineoplastic Agents - pharmacology; Base Pair Mismatch - drug effects; Base Pair Mismatch - genetics; Biological and medical sciences; Biomedical and Life Sciences; Biomedicine; Cancer Research; Chemotherapy; Cisplatin - metabolism; Cisplatin - pharmacology; Colorectal Neoplasms - drug therapy; Colorectal Neoplasms - genetics; DNA Adducts - metabolism; DNA Damage; DNA Repair - drug effects; DNA, Neoplasm - drug effects; DNA, Neoplasm - genetics; Drug Resistance; Endometrial Neoplasms - drug therapy; Endometrial Neoplasms - genetics; Epidemiology; Female; Gene Expression Regulation, Neoplastic - drug effects; Genes, Reporter - drug effects; Humans; Luciferases - genetics; Medical sciences; Molecular Medicine; Oncology; Pharmacology. Drug treatments; Plasmids - drug effects; Plasmids - genetics; Regular; regular-article; Spectrophotometry, Atomic; Transfection; Tumor Cells, Cultured
• ISSN: 0007-0920; 1476-5381; 1532-1827
• DOI: 10.1038/sj.bjc.6690412

Summary In addition to recognizing and repairing mismatched bases in DNA, the mismatch repair (MMR) system also detects cisplatin DNA adducts and loss of MMR results in resistance to cisplatin. A comparison was made of the ability of MMR-proficient and -deficient cells to remove cisplatin adducts from their genome and to reactivate a transiently transfected plasmid that had previously been inactivated by cisplatin to express the firefly luciferase enzyme. MMR deficiency due to loss of hMLH1 function did not change the extent of platinum (Pt) accumulation or kinetics of removal from total cellular DNA. However, MMR-deficient cells, lacking either hMLH1 or hMSH2, generated twofold more luciferase activity from a cisplatin-damaged reporter plasmid than their MMR-proficient counterparts. Thus, detection of the cisplatin adducts by the MMR system reduced the efficiency of reactivation of the damaged luciferase gene compared to cells lacking this detector. The twofold reduction in reactivation efficiency was of the same order of magnitude as the difference in cisplatin sensitivity between the MMR-proficient and -deficient cells. We conclude that although MMR-proficient and -deficient cells remove Pt from their genome at equal rates, the loss of a functional MMR system facilitates the reactivation of a cisplatin-damaged reporter gene.