Highlights

Fenhexamid (Fen) increased cell viability and growth of MCF-7 breast cancer cells.

Fen induced promotion of cell cycle and survival by expansions of related proteins.

Fen diminished the apoptosis by reduction of BAX/BCL-2 protein ratio.

Fen may play a role as an EDC in ER-expressing breast cancers.

Abstract

Fenhexamid (Fen), a fungicide used to treat gray mold of fruits and vegetables, is reported to function as an endocrine disrupting chemical via the estrogen receptors (ER), despite low-toxicity of the pesticide. In this study, we elucidated that the disrupting effects of Fen are exerted via the ER and phosphatidylinositol 3-kinase (PI3K) pathways in breast cancer models. The WST assay, live cell monitoring, cell cycle analysis, colony formation assay, apoptotic analysis by JC-1 dyeing, and Western blot analysis were applied in ER positive MCF-7 and ER negative MDA-MB-231 breast cancer cells, after exposure to 17β-estradiol (E2), Fen, ICI 182,780 (ICI; an ER antagonist) and/or Pictilisib (Pic; a PI3K inhibitor). Exposure to E2 and Fen induced the cell growth and survival ability of MCF-7 cells by increasing the S-phase cells and regulating the cell cycle-related proteins (Cyclin D1 and E1, p21 and p27). In addition, E2 and Fen treatment resulted in elevated levels of the survival-related proteins (Survivin and PCNA), and inhibited apoptosis by increasing the mitochondrial membrane potential and regulating the apoptosis-related proteins (BAX, BCL-2, and Caspase-9). These changes were reversed to the same level as the control group when exposed to their respective inhibitors, thereby indicating that the changes are exerted via the ER and PI3K pathways. In particular, co-treatment with these inhibitors induced greater inhibition than single treatment. Conversely, no alterations were observed in the ER-negative MDA-MB-231 breast cancer cells. Taken together, these results indicate that Fen promotes the growth of breast cancer cells via the ER and/or PI3K pathways, similar to the E2 mechanism. Although a relatively safe pesticide, Fen possibly exerts its influence as an endocrine disrupting chemical in ER-positive breast cancer cells via the ER and PI3K pathways.