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

作者：Zafar Maroof K; Maddukuri Leena; Ketkar Amit; Penthala Narsimha R; Reed Megan R; Eddy Sarah; Crooks Peter A; Eoff Robert L^*

来源：Biochemistry, 2018, 57(7): 1262-1273.

DOI：10.1021/acs.biochem.7b01176

Translesion DNA synthesis (TLS) performed by human DNA polymerase eta (hpol eta) allows tolerance of damage from cis-diamminedichloroplatinum(II) (CDDP or cisplatin). We have developed hpol eta 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 eta activity with an IC50 value of 8 mu M and exhibited 5-10-fold specificity for hpol eta 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 eta. A synergistic increase in CDDP toxicity was observed in hpol eta-proficient cells co-treated with PNR-7-02 (combination index values = 0.4-0.6). Increased gamma H2AX formation accompanied treatment of hpol eta-proficient cells with CDDP and PNR-7-02. Importantly, PNR-7-02 did not impact the effect of CDDP on cell viability or gamma H2AX in hpol eta-deficient cells. In summary, we observed hpol eta-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 eta to improve the cytotoxic effect of CDDP may aid in the development of more effective chemotherapeutic strategies.

• 出版日期2018-2-20