DNA mismatch repair (MMR)‐dependent 5‐fluorouracil cytotoxicity and the potential for new therapeutic targets

Abstract

The metabolism and efficacy of 5-fluorouracil (FUra) and other fluorinated pyrimidine (FP) derivatives have been intensively investigated for over fifty years. FUra and its antimetabolites can be incorporated at RNA-and DNA-levels, with RNA level incorporation provoking toxic responses in human normal tissue, and DNA-level antimetabolite formation and incorporation believed primarily responsible for tumour-selective responses. Attempts to direct FUra into DNA-level antimetabolites, based on mechanism-of-action studies, have led to gradual improvements in tumour therapy. These include the use of leukovorin to stabilize the inhibitory thymidylate synthase-5-fluoro-2′-deoxyuridine 5′ monophoshate (FdUMP)-5,10-methylene tetrahydrofolate (5,10-CH2FH4) trimeric complex. FUra incorporated into DNA also contributes to antitumour activity in preclinical and clinical studies. This review examines our current state of knowledge regarding the mechanistic aspects of FUra:Gua lesion detection by DNA mismatch repair (MMR) machinery that ultimately results in lethality. MMR-dependent direct cell death signalling or futile cycle responses will be discussed. As 10-30% of sporadic colon and endometrial tumours display MMR defects as a result of human MutL homologue-1 (hMLH1) promoter hypermethylation, we discuss the use and manipulation of the hypomethylating agent, 5-fluorodeoxycytidine (FdCyd), and our ability to manipulate its metabolism using the cytidine or deoxycytidylate (dCMP) deaminase inhibitors, tetrahydrouridine or deoxytetrahydrouridine, respectively, as a method for re-expression of hMLH1 and re-sensitization of tumours to FP therapy. (2009) Keywords: 5-fluorouracil; DNA mismatch repair; thymidylate synthase; hypermethylation; hMLH1; MMR/c-Abl/p73a/ GADD45a signalling Abbreviations: 5,10-CH2FH4, 5,10-methylene tetrahydrofolate; 5′-dRP, 5′-deoxyribose phosphate; AM, adaptors/mediators; AP, apyrimidinic/apurinic site; APE, apurinic/apyrimidinic endonuclease; ATM, ataxia telangiectasia mutated; ATR, ataxia telangiectasia-and-rad3-related; BER, base excision repair; CD, cytosine deaminase; dCMP, deoxycytidylate; dCMPD, deoxycytidylate deaminase; dH4Urd, deoxytetrahydrouridine; DS, damage sensors; DSBs, DNA double-strand breaks; dThyd, thymidine; ES, embryonic stem; FdCyd, 5-fluoro-2′-deoxycyticine; FdUDP, 5-fluoro-2′-deoxyuridine 5′-diphosphate; FdUMP, 5-fluoro-2′-deoxyuridine 5′-monophosphate; FdUTP, 5-fluoro-2′-deoxyuridine-5′-triphosphate; FdUrd, 5-fluoro-2′-deoxyuridine; FEN1, flap-endonuclease 1; FPs, fluorinated pyrimidines; FUDP, 5-fluorouridine 5′-diphosphate; FUra (or 5-FU), 5-fluorouracil; FUrd, fluorouridine; FUTP, 5-fluorouridine-5′-triphosphate; GADD45, growth arrest and DNA damage-inducible-45 gene/ protein; H4Urd, 3,4,5,6-tetrahydrouridine; hMLH1, human MutL homologue-1; hMSH2, human MutS homologue-2; hMSH3, human MutS homologue-3; hMSH6, human MutS homologue-6; hPMS2, postmeiotic segregation increased 2; IDL, insertion/deletion loop-type; MBD4, methyl-CpG binding domain protein 4; British Journal of Phar...

Defective Mismatch Repair Status as a Prognostic Biomarker of Disease-Free Survival in Stage III Colon Cancer Patients Treated with Adjuvant FOLFOX Chemotherapy

“…Various preclinical data suggested that the effect of 5-FU chemotherapy was dependent on the MMR status (29,30). Several studies have shown that 5-FU induces G 2 arrest less efficiently in MMR-deficient cells than in their MMR-proficient counterparts (31)(32)(33).…”

Microsatellite instability in sporadic gastric cancer: its prognostic role and guidance for 5‐FU based chemotherapy after R0 resection

“…Defective DNA MMR might be one mechanism for tumor resistance to 5-FU and a reason that MMR deficient colon cancer cells are not readily killed by 5-FU. [12][13][14][15] However, in vitro studies and clinical data do not accord well together. Some authors found that fluorouracil-based adjuvant chemotherapy benefited patients with stage II or stage III colon cancer with MSS and MSI-L phenotype but not those with tumors exhibiting MSI-H. 2,3 They suggested that adjuvant 5-FU-based chemotherapy may not be useful in stage II and III MMR deficient colorectal cancer.…”

Predictive markers for the response to 5-fluorouracil therapy in cancer cells: Constant-field gel electrophoresis as a tool for prediction of response to 5-fluorouracil-based chemotherapy

“…A similar finding was reported by Adamsen et al (34) who suggested that BER (or NER) is sufficient to repair the bolus-5FU-induced DNA damage (FdUTP/dUTP mis-incorporation) in the absence of functional MMR in the TP53-proficient HCT116 cell line. In addition, Li et al (35) have shown that MMR-deficient cells incorporate higher levels of fluoropyrimidine metabolites than MMR-proficient cells.…”

“…Differences between the four cell lines in the conversion of 5FU to its active metabolites and/or its catabolism by dihydropyrimidine dehydrogenase to inactive metabolites is another possible explanation for the different number of 5FU-induced DSBs in the four cell lines at the same drug concentration [reviewed by Koopman et al (27) and Li et al (35)]. …”