A Small-Molecule Inhibitor of Human DNA Polymerase ? Potentiates the Effects of Cisplatin in Tumor Cells.

ABSTRACT: Translesion DNA synthesis (TLS) performed by human DNA polymerase eta (hpol ?) allows tolerance of damage from cis-diamminedichloroplatinum(II) (CDDP or cisplatin). We have developed hpol ? inhibitors derived from N-aryl-substituted indole barbituric acid (IBA), indole thiobarbituric acid (ITBA), and indole quinuclidine scaffolds and identified 5-((5-chloro-1-(naphthalen-2-ylmethyl)-1H-indol-3-yl)methylene)-2-thioxodihydropyrimidine-4,6(1H,5H)-dione (PNR-7-02), an ITBA derivative that inhibited hpol ? activity with an IC50 value of 8 ?M and exhibited 5-10-fold specificity for hpol ? over replicative pols. We conclude from kinetic analyses, chemical footprinting assays, and molecular docking that PNR-7-02 binds to a site on the little finger domain and interferes with the proper orientation of template DNA to inhibit hpol ?. A synergistic increase in CDDP toxicity was observed in hpol ?-proficient cells co-treated with PNR-7-02 (combination index values = 0.4-0.6). Increased ?H2AX formation accompanied treatment of hpol ?-proficient cells with CDDP and PNR-7-02. Importantly, PNR-7-02 did not impact the effect of CDDP on cell viability or ?H2AX in hpol ?-deficient cells. In summary, we observed hpol ?-dependent effects on DNA damage/replication stress and sensitivity to CDDP in cells treated with PNR-7-02. The ability to employ a small-molecule inhibitor of hpol ? to improve the cytotoxic effect of CDDP may aid in the development of more effective chemotherapeutic strategies.

SUBMITTER: Zafar MK 

PROVIDER: S-EPMC7312786 | biostudies-literature | 2018 Feb

REPOSITORIES: biostudies-literature