The estrogenic proliferative effects of two alkylphenols and a preliminary mechanism exploration in MCF-7 breast cancer cells.

Bisphenol A (BPA) and 4-cumylphenol (4-CP), as estrogen-like chemicals, are ubiquitous in the environment media and associated with the occurrence and development of hormone-dependent tumors. However, the combinatorial effects of these two structurally similar alkylphenols are not well informed. In the present study, the classic breast cancer cell line MCF-7 was used as in vitro model to estimate the estrogenic proliferative effects of BPA and 4-CP. MTT assay, reactive oxygen species, cell apoptosis, cell cycle, and real-time fluorescent quantitative Step One Plus Real-time PCR System (Applied Biosystems, CA, USA) were applied to explore their proliferative mechanisms. MTT results showed that both BPA and 4-CP ranging from 10-9 to 10-5 M stimulated cell proliferation in a nonmonotonic dose-response manner. Along with the proliferative effects, cell cycle was progressed from G0/G1 to S and G2/M phase. Meanwhile, the expression levels of ERα, pS2, and Bcl-2 mRNA were also upregulated. In contrast, 4-CP and BPA at high dose (10-4 M) obviously displayed antiproliferative effects in MCF-7 cells via inducing cell apoptosis and blocking cell cycle in G0/G1 phase. As expected, the relative expression levels of ERα, pS2, and Bcl-2 mRNA were decreased, whereas Bax mRNA was increased. Interestingly, the proliferative or antiproliferative effects of 4-CP were higher than that of BPA. Moreover, coexposure of lower concentrations BPA and 4-CP significantly induced cell proliferation in a synergistic manner. These findings indicated that the potential environmental risks of coexposure of BPA and 4-CP were greater than either of them.