Role of mismatch repair proteins in the processing of cisplatin interstrand cross-links

Abstract

Mismatch repair (MMR) deficiency gives rise to cisplatin resistance and can lead to poor prognosis in cancers. Various models have been proposed to explain this low level of resistance caused due to loss of MMR proteins. We have shown that MMR proteins are required to maintain cisplatin interstrand cross-links (ICLs) on the DNA leading to increased cellular sensitivity. In our previous studies, we have shown that BER processing of the cisplatin ICLs is mutagenic. Polymerase β (Polβ) can generate mismatches which leads to the activation and the recruitment of mismatch repair proteins. In this paper, we distinguished between the requirement of different downstream MMR proteins for maintaining cisplatin sensitivity. We show that the MutSα (MSH2-MSH6) heterocomplex is required to maintain cisplatin sensitivity, whereas the Mutsβ complex has no effect. These results can be correlated with the increased repair of cisplatin ICLs and ICL induced DNA double strand breaks (DSBs) in the resistant cells. Moreover, we show that MLH1 proficient cells displayed a cisplatin sensitive phenotype when compared with the MLH1 deficient cells and the ATPase activity of MLH1 is essential to mediate this effect. Based on these results, we propose that MutSα as well as the downstream MMR pathway proteins are essential to maintain a cisplatin sensitive phenotype as a consequence of processing Polβ induced mismatches at sites flanking cisplatin ICLs.

Clinical and Genome-Wide Analysis of Cisplatin-Induced Peripheral Neuropathy in Survivors of Adult-Onset Cancer

“…Emerging data indicate that RPRD1B plays an important role in several DNA repair mechanisms, including double-strand breaks (DSB) repair through the association with core non-homologous end joining (NHEJ) proteins (45) and mismatch repair (46). Defects in RPRD1B expression or knockdown cause a deficiency in DNA repair mechanisms known to be critical in resolving cisplatin-induced lesions (47). Consistent with our data indicating low levels of RPRD1B being associated with CisIPN, knockdown of this gene in a breast cancer cell line, MDA-123 results in increased sensitivity to cisplatin (45).…”

Cisplatin resistance in cell models: evaluation of metallomic and biological predictive biomarkers to address early therapy failure

“…Nevertheless, the fact that cell viability was similar for GM04312 and A2780 cells following cisplatin treatment suggests that other repair pathways (different from NER) could be contributing to the cisplatininduced DNA damage response, at least at low doses. 10,22 Despite similarities in cell viability with the GM04312 cells, the sensitivity of the A2780 cells to cisplatin cannot be linked to a deficiency of DNA repair. However, it might be related to their higher Pt influx, as described, 27,37,42,43 even for other platinum chemicals, 44 which could be related to high levels of the copper transport protein CTR1, 23 although recently the influence of this type of protein was considered controversial.…”

“…34 However, detection of DNA strand breaks after cisplatin treatment is not a straightforward result; some authors reported them in different cells and organisms, 20,26 and others reported their absence. 20,51,52 Although some authors have used the Comet assay to detect and quantitate cisplatin-induced DNA adducts, 15,22,51 we have used it to study which DNA adduct levels would induce detectable genomic instability. Our results show that cisplatin induced DNA strand breaks only in GM04312 cells at AT-1 time.…”

“…17 Furthermore, cisplatin can also induce genomic instability, which is generally measured as the presence of DNA strand breaks. [19][20][21][22] Nevertheless, studies combining these two parameters with cisplatin-induced adduct levels are scarce, and most of them make use of rather high and/or different cisplatin concentrations to evaluate each parameter, 13,21,23 thus preventing their comparison. Moreover, significant correlations among parameters have rarely been detected, probably due to difficulties in quantitating DNA adducts accurately.…”

Differential role of base excision repair proteins in mediating cisplatin cytotoxicity

“…Our results showed that Polβ misincorporates dATP at ~1.6 fold higher frequency as compared to the correct nucleotide base dCTP opposite guanine near the ICL site [5]. The generation of these mismatches leads to increased recruitment of MMR proteins and a subsequent role of MMR in blocking productive cisplatin specific ICL repair [12, 20]. The binding of BER and MMR proteins results in a futile cycle at the ICLs by blocking the productive ICL DNA repair pathways, resulting in the persistence of DNA ICLs which give rise to enhanced cisplatin cytotoxicity.…”