SMALL MOLECULE INHIBITORS OF DNA GLYCOSYLASES AS POTENTIAL DRUGS IN CHEMO- AND RADIOTHERAPIES

Published

March 19, 2016

Author(s)

M Miral Dizdar, Aaron C. Jacobs, Nathan Donley, Marcus J. Calkins, Ajit Jadhav, Dorjbal Dorjsuren, David Maloney, Anton Simeonov, Amanda K. McCullough, R S. Lloyd, Erdem Coskun, Pawel Jaruga

Abstract

Introduction: Ionizing radiation and most chemotherapeutic agents kill tumor cells by damag-ing DNA. The efficacy of DNA-damaging agents may be influenced by increased DNA repair capacity in tumors that results from overexpression of DNA repair proteins. Inhibition of activities of these pro-teins in tumors is a promising approach to enhance the efficacy of DNA damage-based therapy. Of these proteins, DNA glycosylases are involved in the first step of base excision repair mechanism by removing modified DNA bases. Despite the successes with other proteins of this repair pathway, the develop-ment of inhibitors has been lagging for DNA glyco-sylases. Recently, several DNA glycosylases includ-ing NEIL1, OGG1 and NTH1 were identified as po-tential targets in combination therapeutic strategies. Here, we designed experiments to discover small molecule inhibitors of NEIL1, OGG1 and NTH1. Materials and Methods: A fluorescence-based assay was developed to detect both glycosylase and AP lyase activities of DNA glycosylases. The screening collection consisted of the LOPAC1280 collection from Sigma–Aldrich (1280 compounds) and cherry-picked purine analogs from the ≈400,000-member Molecular Libraries Small Mole-cule Repository collection. For the fluorescence-based assay, double-stranded oligodeoxynucleotides were used, consisting of a quencher strand and a fluorescent reporter strand (Figure 1). The substrates incorporated in the fluorescent strand were 8-oxoguanine (8-oxo-Gua), thymine glycol (Tg), ura-cil (U), spirodihydantoin (Sp) or guanidinohydanto-in (Gh). Gas chromatography/isotope-dilution tan-dem mass spectrometry (GC-MS/MS) was also used to measure the glycosylase activities of NEIL1, OGG1 and NTH1 using damaged DNA containing multiple lesions. Results: Four purine analogs were found to be potent inhibitors of NEIL1 with the inhibitor poten-cies (IC50) varying from 4 µmol/L to 10 µmol/L. These compounds efficiently inhibited the excision of the main substrates of NEI

Conference Dates

March 19-24, 2016

Conference Location

Melbourne

Conference Title

Radiation Damage to DNA

Pub Type

Conferences

Keywords

DNA glycosylases, small molecule inhibitors, cancer therapy, GC-MS/MS

Citation

, M. , Jacobs, A. , Donley, N. , Calkins, M. , Jadhav, A. , Dorjsuren, D. , Maloney, D. , Simeonov, A. , McCullough, A. , Lloyd, R. , Coskun, E. and Jaruga, P. (2016), SMALL MOLECULE INHIBITORS OF DNA GLYCOSYLASES AS POTENTIAL DRUGS IN CHEMO- AND RADIOTHERAPIES, Radiation Damage to DNA, Melbourne, -1 (Accessed November 13, 2024)