Effects of Bisphenol-A on Directed Differentiation of Human Embryonic Stem Cells to Prostate

Evidence from rodent and adult human stem cell models suggests that early-life BPA exposure can reprogram the prostate and render it more susceptible to carcinogenesis with aging. To determine whether human embryonic prostate cells are similarly sensitive to BPA, the present studies derived two novel models of human prostate development using hESCs. First, a pioneer in vitro model of directed differentiation of hESC into prostatic organoids using sequential exposure to stage-specific growth factors and steroids was generated. Differentiation to prostatic structures was confirmed by immunofluorescence (IF) and RT-PCR for multiple prostate markers. Next, hESCs were exposed to vehicle, 1 or 10 nM BPA throughout culture. Budding and nonbudding structures were quantitated 4 days following transfer to Matrigel. While 1 nM BPA increased total and budding organoid numbers (P<0.01), 10 nM BPA reduced (P<0.05) structure numbers vs vehicle. Continued 3-D culture in BPA did not alter their differentiation to mature organoids at day 30. However, BPA exposures at both doses resulted in focal clusters of resident stem cells within the organoids, a phenotype not observed in controls. RT-PCR for OCT4, NANOG and CD49f confirmed increased expression of stem cell genes in 10 nM BPA vs control (P<0.05). These results indicate that BPA directly targets hESC and disrupts human prostate morphogenesis. To determine whether hESC-derived prostatic tissues are susceptible to developmental BPA reprogramming and carcinogenesis in vivo, hESC colonies were mixed with embryonic rat prostatic mesenchyme and grafted to the renal capsule of nude mice. Mature prostatic-like tissues with human epithelium formed by 30 days; confirmed by multiple markers including PSA. Developmental BPA exposure was modeled by daily oral dosing of host mice (250μg/kg BW) for 14 days after grafting, producing free serum BPA levels of 0.49 ng/mL 20 min post-dosing. Estradiol (E)-driven carcinogenesis was initiated by E+T pellets at one month and at 5 months, prostatic structures were evaluated for pathologic evidence of cancerous lesions. E+T treatment alone did not induce prostate cancer vs T alone (6% vs 0%, respectively). Importantly, developmental BPA alone increased the incidence of total lesions (squamous metaplasia, hyperplasia and intraepithelial neoplasia) from 4% in controls to 28% (P<0.0424) in the BPA exposed grafts. These results indicate that exposure to environmentally relevant levels of BPA during development are sufficient to drive prostate pathology in the mature human prostate epithelium. Taken together, the present studies suggest that the developing human fetal prostate gland may be reprogrammed by BPA making it more susceptible to diseases with aging.