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.

Key words::

• BUTYL BENZYL PHTHALATE
• DI-n-BUTYL PHTHALATE
• DI-2-ETHYLHEXYL PHTHALATE
• PI3K/AKT SIGNALING PATHWAY
• MCF-7 BREAST CANCER CELLS

Conflict of interest The authors report no conflict of interest. The authors alone are responsible for the content and writing of this paper.

Source of funding This study was supported by the Medical Research Center (Chang Gung Memorial Hospital, Keelung) and a research grant from the Clinical Monitoring Research Program (CMRPG2B0441) of Chang Gung Memorial Hospital, Keelung.