Replication Protein A Availability during DNA Replication Stress Is a Major Determinant of Cisplatin Resistance in Ovarian Cancer Cells

Abstract

Intrinsic and acquired resistance to cisplatin remains a primary hurdle to treatment of high-grade serous ovarian cancer (HGSOC). Cisplatin selectively kills tumor cells by inducing DNA crosslinks that block replicative DNA polymerases. Single-stranded DNA (ssDNA) generated at resulting stalled replication forks (RF) is bound and protected by heterotrimeric replication protein A (RPA), which then serves as a platform for recruitment and activation of replication stress response factors. Cells deficient in this response are characterized by extensive ssDNA formation and excessive RPA recruitment that exhausts the available pool of RPA, which (i) inhibits RPA-dependent processes such as nucleotide excision repair (NER) and (ii) causes catastrophic failure of blocked RF. Here, we investigated the influence of RPA availability on chemosensitivity using a panel of human HGSOC cell lines. Our data revealed a striking correlation among these cell lines between cisplatin sensitivity and the inability to efficiently repair DNA via NER, specifically during S phase. Such defects in NER were attributable to RPA exhaustion arising from aberrant activation of DNA replication origins during replication stress. Reduced RPA availability promoted Mre11-dependent degradation of nascent DNA at stalled RF in cell lines exhibiting elevated sensitivity to cisplatin. Strikingly, defective S-phase NER, RF instability, and cisplatin sensitivity could all be rescued by ectopic overexpression of RPA. Taken together, our findings indicate that RPA exhaustion represents a major determinant of cisplatin sensitivity in HGSOC cell lines. The influence of replication protein A exhaustion on cisplatin sensitivity harbors important implications toward improving therapy of various cancers that initially respond to platinum-based agents but later relapse due to intrinsic or acquired drug resistance. .

Combined elevation of TRIB2 and MAP3K1 indicates poor prognosis and chemoresistance to temozolomide in glioblastoma

“…Hierarchical bi‐clustering analysis indicated significant gene signatures in TRIB2 High /MAP3K1High GBM compared withTRIB2 Low /MAP3K1Low GBM (Figure A). Additionally, KEGG pathway analysis demonstrated multiple molecular pathways that were related to malignant cancer and therapeutic resistance, including cell cycle pathways and the NOTCH, DNA replication, and p53 pathways. Similar results were observed by gene set enrichment analysis (GSEA) (Figure C,D, and E).…”

“…Increasing evidence has suggested that rapid acquired therapeutic resistance is the major cause of the failure of standard comprehensive treatments, leading to the recurrence and high mortality of glioma . Various molecular pathways have been shown to be responsible for the acquisition of therapeutic resistance in glioma . Therefore, it is essential to identify the mechanisms, especially prognostic biomarkers, underlying therapeutic resistance in glioma.…”

“…29,30 Various molecular pathways have been shown to be responsible for the acquisition of therapeutic resistance in glioma. 26,[31][32][33] Therefore, it is essential to identify the mechanisms, especially prognostic biomarkers, underlying therapeutic resistance in glioma. In this study, we analyzed the transcriptome expression profiles of 3 published GEO databases related to pathological classification, radioresistance, and TMZ resistance and identified TRIB2…”

Platinum-Induced Ubiquitination of Phosphorylated H2AX by RING1A is Mediated by Replication Protein A in Ovarian Cancer

“…replication stress is demonstrated to be a vital determinant of cisplatin resistance in HGSOC cells (52). We demonstrate that RPA mediates RING1A localization to damage sites connecting NER and HRR pathways to RING1A mediated gH2AXub1 (Supplementary Figure S6C).…”

Replication Protein A (RPA) Mediates Radio-Resistance of Glioblastoma Cancer Stem-Like Cells

“…Bélanger et al (2018) reported that RPA exhaustion represents a major determinant of cisplatin sensitivity in ovarian cancer cell lines, a finding that harbors an important implication toward improving therapy of various cancers that initially respond to platinum-based agents but later relapse due to intrinsic or acquired drug resistance [26]. Wang et al (2018) showed that RPA70 promotes tumor proliferation via CDK4/Cyclin-D pathway [27].…”