Investigation of MTH1 activity via mismatch-based DNA chain elongation.

Accumulation and misincorporation of oxidative damaged 8-oxo-7,8-dihydroguanine triphosphates (8-oxo-dGTP) in genomic DNA may cause serious cellular function disorders. MutT Homolog 1 (MTH1), a protein enzyme that can help to prevent 8-oxo-dGTP misincorporation, plays critical roles in oxidative stress neutralization, oncogene-associated tumor malignancy, and anticancer therapies. So, in this work, a simple and function-oriented method is developed for the assay of MTH1 activity. Specifically, a mismatch-based ("8-oxoG: A" mismatch) DNA chain elongation strategy (MB-DCE) is firstly proposed to reveal the misincorporation efficiency of 8-oxo-dGTP. Then, further coupled with the inherent activity of MTH1 to prevent 8-oxo-dGTP misincorporation, a relationship can be established to reveal the activity of MTH1 through MB-DCE. As the method is designed directly towards the cellular function of MTH1, activity of MTH1 in different breast cancer cell lines has been detected, implying the potential application of this assay method for biomedical research and clinical diagnose in the future.