Reproductive history and obesity are among the well-recognized risk factors in the development of breast cancer, which are partially mediated by the increased exposure of breast tissues to estrogens. However, only a few studies have investigated the link between these risk factors and the pattern of methylation signatures in the breast tissue of healthy women. The role of estrogen receptor 1 (ESR1) gene hypermethylation is reportedly important in the development of breast cancer. Thus, it is speculated that such ESR1 epigenetic changes may be influenced or shaped by obesity and the reproductive history-related factors before and during breast carcinogenesis.
MATERIALS AND METHODS:
Breast samples were collected from 120 cancer-free women who had undergone cosmetic mammoplasty. DNA was extracted from the breast tissues and, then, the methylation levels at the promoter and exon 1 regions of the ESR1 gene CpG island were determined by using the methylated DNA immunoprecipitation-quantitative PCR assay.
Methylation level of the ESR1 promoter observed in women with body mass index (BMI) ≥30 kg/m2 (p ≤ 0.001) was high compared with that in the subgroup of women of BMI <25 kg/m2 (p < 0.001) and BMI 25-29 kg/m2 (p < 0.001) and also was high in posdata; name="publish_language" 10