Effects of Estrogenic Agents 17.BETA.-Estradiol (E2) and Bisphenol A on the Expression of RecQ DNA Helicases in Mammary Tumor MCF-7 Cells

Abstract

17β-Estradiol (E2) and bisphenol A (BPA) damage DNA in estrogen receptor (ER)-positive human mammary tumor MCF-7 cells. The effect of E2and BPA is associated with increased expression of Bloom helicase (BLM) and formation of nuclear foci consisting of BLM and γH2AX at double stranded break regions. BLM is one of five human RecQ helicases that participate in the maintenance of genomic stability. This study investigated if the expressions of RecQ helicases Werner syndrome helicase (WRN), Rothmund-Thomson syndrome helicase (RTS), RecQ5 helicase (RecQ5), RecQ protein-like 1 helicase (RecQL1, also known as RecQ1) and BLM helicase are affected in MCF-7 cells by treatment with estrogenic agents. The expression of RTS mRNA significantly increased although the expression in RTS protein only slightly increased. The expressions of WRN, RecQ5 and RecQL1 were almost unaffected both at mRNA and protein levels. These data suggest that the expression of human RecQ helicases is differentially regulated depending on the tissues and cells. We showed that some helicase expressions are regulated depending on the DNA damage.