Role of endocrine disrupting chemicals on the tissue levels of AhR and sex steroid receptors in breast tumours

Abstract

Breast cancer affects Iranian women at least one decade younger than their counterparts in other<br />countries and the incidence of breast fibroadenoma is growing in the last two decades in Tehran. This<br />study aimed to compare the AhR levels in premenopausal breast cancer and breast fibroadnemo with<br />appropriate normal groups. Possible associations of AhR with lifestyle and reproductive risk factors<br />and other fundamental genes of breast cancer and reproductive disorders were the other major goals<br />of present study. To conduct the comparisons all possible reproductive, environmental and lifestyle<br />risk factors of mentioned diseases were recorded in 100 breast cancer, 100 breast fibroadenoma and<br />compared with 400 women in normal group from 2009 to 2011. AhR overexpression in epithelial<br />cells of premenopausal patients emphasized the susceptibility of these cells to environmental induced<br />reproductive disorders. The AhR overexpression was contributed to ER-/PgR- immunophenotype in<br />malignant tissues. Weight gain (after 18 and after pregnancy), long term (>5yrs) OCP consumption,<br />smoking, severe stress ,history of ovarian cysts, hormonal deregulations, living near PAHs producing<br />sources, were correlated with increased risk of breast cancer and reproductive disorders and were<br />correlated with elevated tissue levels of AhR. It seems that increased risk of breast cancer and other<br />reproductive tumours in Tehran may be the result of exposure to environmental endocrine disruptors.<br />Long term exposure to environmental estrogens can increase the tissue levels of AhR and deregulate<br />the expression pattern of sex steroid receptors and other genes in target tissues.