Roles of translesion synthesis DNA polymerases in the potent mutagenicity of tobacco-specific nitrosamine-derived O2-alkylthymidines in human cells.

Autor: Weerasooriya S; Department of Chemistry, University of Connecticut, Storrs, CT 06269, United States., Jasti VP; Department of Chemistry, University of Connecticut, Storrs, CT 06269, United States., Bose A; Department of Chemistry, University of Connecticut, Storrs, CT 06269, United States., Spratt TE; Department of Biochemistry and Molecular Biology, Penn State College of Medicine, Hershey, PA 17033, United States., Basu AK; Department of Chemistry, University of Connecticut, Storrs, CT 06269, United States. Electronic address: ashis.basu@uconn.edu.
Jazyk: angličtina
Zdroj: DNA repair [DNA Repair (Amst)] 2015 Nov; Vol. 35, pp. 63-70. Date of Electronic Publication: 2015 Sep 21.
DOI: 10.1016/j.dnarep.2015.09.023
Abstrakt: The tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is a potent human carcinogen. Metabolic activation of NNK generates a number of DNA adducts including O(2)-methylthymidine (O(2)-Me-dT) and O(2)-[4-(3-pyridyl)-4-oxobut-1-yl]thymidine (O(2)-POB-dT). To investigate the biological effects of these O(2)-alkylthymidines in humans, we have replicated plasmids containing a site-specifically incorporated O(2)-Me-dT or O(2)-POB-dT in human embryonic kidney 293T (HEK293T) cells. The bulkier O(2)-POB-dT exhibited high genotoxicity and only 26% translesion synthesis (TLS) occurred, while O(2)-Me-dT was less genotoxic and allowed 55% TLS. However, O(2)-Me-dT was 20% more mutagenic (mutation frequency (MF) 64%) compared to O(2)-POB-dT (MF 53%) in HEK293T cells. The major type of mutations in each case was targeted T → A transversions (56% and 47%, respectively, for O(2)-Me-dT and O(2)-POB-dT). Both lesions induced a much lower frequency of T → G, the dominant mutation in bacteria. siRNA knockdown of the TLS polymerases (pols) indicated that pol η, pol ζ, and Rev1 are involved in the lesion bypass of O(2)-Me-dT and O(2)-POB-dT as the TLS efficiency decreased with knockdown of each pol. In contrast, MF of O(2)-Me-dT was decreased in pol ζ and Rev1 knockdown cells by 24% and 25%, respectively, while for O(2)-POB-dT, it was decreased by 44% in pol ζ knockdown cells, indicating that these TLS pols are critical for mutagenesis. Additional decrease in both TLS efficiency and MF was observed in cells deficient in pol ζ plus other Y-family pols. This study provided important mechanistic details on how these lesions are bypassed in human cells in both error-free and error-prone manner.
(Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.)
Databáze: MEDLINE
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