Investigating FDA-Approved Anti-Tumor Drugs For Effects On Template-Switch Mutagenesis (TSM) In E. coli

Abstract

Quasipalindromes (QPs) are imperfect inverted repeats of DNA that are known to form secondary structures (such as hairpins and cruciforms). QPs sites have also been associated with a specific class of mutation known as template-switch mutations (TSM). It is known that TSM can be caused by the addition of drugs such as 5-azaC, AZT, and ciprofloxacin. This study aims to analyze the effects of two FDA approved antitumor drugs, CPT-11 and Doxorubicin hydrochloride for their ability to promote or prevent template-switch mutagenesis and, if there is an increase in mutation rates, we aim to clarify by what mechanism that effect is induced. To do this, we use a previously published TSM reporter in the lacZ gene that provides both a qualitative and quantitative measure of TSM frequencies. Using this established system, we study mutation frequencies and rates in both the leading and lagging strand of DNA to provide possible pathways that lead to TSM. Our data proposes mechanisms of mutations that are correlated to each drug mode of action.