Lower concentrations of phthalates induce proliferation in human breast cancer cells

Abstract

Objective To explore the effect and pathway of phthalates on the growth of MCF-7 breast cancer cells.Methods MCF-7 cells were treated with benzyl butyl phthalate (BBP), di-n-butyl phthalate (DBP), and di-2-ethylhexyl phthalate (DEHP) (10−10–10−4 mol/l). After incubation for 24, 48, 72, and 92 h, the cells were harvested and extracted for 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The proteins involving proliferative and apoptotic pathways were evaluated by Western blot analysis.Results MTT assay revealed cell toxicity at more than 10−5 mol/l for DEHP and at 10−4 mol/l for both BBP and DBP in MCF-7 cells. Cell proliferation was significantly increased at 10−8–10−5 mol/l of BBP and DBP, and at 10−8–10−6 mol/l of DEHP treatment. Proliferating cell nuclear antigen (PCNA) was substantially increased in cultures with DEHP (10−8–10−6 mol/l), BBP (10−8–10−5 mol/l), and DBP (10−7–10−5 mol/l). Obvious increases in PI3K, p-AKT, and PCNA were noted in cultures with 17β-estradiol, BBP, DBP, and DEHP. Estrogen receptor α expression was also notably increased in treatment with estradiol, BBP, DBP, and DEHP.Conclusions The present study demonstrates that, even at a very low concentration, BBP, DBP, and DEHP were not only still capable of inducing a proliferative effect through the PI3K/AKT signaling pathway but also displaying estrogenic activity. Therefore, the current reference doses for phthalates defined by governments should be further evaluated.