Boyne DJ et al. -The effects of sex hormones on epigenetic markers related to cancer risk have not been well-described. The current study described the association between endogenous sex hormone exposure and levels of LINE-1 and Alu methylation in healthy postmenopausal women. Thus, LINE-1 and Alu methylation may be epigenetic mechanisms through which estrogen exposure impacts cancer risk.

Methods

• Study participants consisted of healthy postmenopausal women who had never been diagnosed with cancer (n = 289).
• Sex hormone exposures included serum concentrations of estradiol, estrone, testosterone, androstenedione, and sex hormone-binding globulin.
• Buffy coat samples were assessed for DNA methylation.

Results

• Both estradiol and estrone had a significant positive dose–response association with LINE-1 methylation.
• Lifetime number of menstrual cycles was associated with both LINE-1 and Alu methylation.
• LNMC had a non-linear association with LINE-1 methylation regardless of folate intake and a negative linear association with Alu methylation, but only amongst low folate consumers.
• Androgen exposure was not associated with either outcome.