A site-selective, irreversible inhibitor of the DNA replication auxiliary factor proliferating cell nuclear antigen (PCNA).

摘要: Proliferating cell nuclear antigen (PCNA) assumes an indispensable role in supporting cellular DNA replication and repair by organizing numerous protein components of these pathways via a common PCNA-interacting sequence motif called PIP-box. Given the multifunctional nature PCNA, selective inhibition PIP-box-mediated interactions may represent new strategy for chemosensitization cancer cells to existing DNA-directed therapies; however, promiscuous blockage also be universally deleterious. To address possibilities, we utilized chemical irreversibly block interactions. Initially, identified validated PCNA methionine 40 (M40) histidine 44 (H44) as essential residues PCNA/PIP-box general and, more specifically, efficient loading onto chromatin within cells. Next, created novel small molecule incorporating electrophilic di-chloro platinum moiety that preferentially alkylated M40 H44 residues. The compound, designated T2Pt, covalently cross-linked wild-type but not M40A/H44A inhibited interactions, mildly plasmid vitro. In cells, T2Pt persistently induced cycle arrest, activated ATR-Chk1 signaling modestly strand breaks, features typical stress. Despite sustained activation stress response compound its genotoxic nature, demonstrated little activity clonogenic survival assays single agent, yet sensitized cisplatin. discovery represents original effort directed at development irreversible inhibitors sets stage analogues over other nucleophiles.