223 PROGRESSION OF BREAST CANCER WAS CAUSED BY TREATMENT WITH BENZOPHENONE-1 AND NONYL-PHENOL VIA ALTERATION OF CELL CYCLE AND METASTASIS-RELATED GENES IN A CELLULAR MODEL

Abstract

Endocrine disrupting chemicals (EDC) are defined as environmental compounds that may result in adverse health problems such as cancer proliferaition and metastasis in humans. Benzophenone-1 (2,4-dihydroxybenzophenone, BP-1) and nonyl-phenol (NP) are known as typical EDCs. They are discharged from numerous industrial products including plastics, pesticides, drugs, detergents, and cosmetics. In this study, we examined the effect of BP-1 and NP on the growth of MCF-7 human breast cancer cells expressing oestrogen receptors (ER) in comparison with E2 to assess their risk in cancer progression. In cell viability assay, BP-1 (10^–5, 10^–6, and 10^–7 M) and NP (10^–6 and 10^–7 M) were determined to induce the proliferation of MCF-7 cells as well as E2 (10^–9 M) was compared to a negative control treated with DMSO (P < 0.05). Next, to confirm that BP-1 and NP increase growth and metastasis of MCF-7 cells, the alterations in transcriptional and translational levels of related markers, i.e. cyclin D1, p21, and cathepsin D, were examined by reverse-transcription (RT)-PCR and Western blot assay. Cyclin D1 is a factor responsible for G1/S cell cycle transition and p21 is a potent cyclin-dependent kinase (CDK) inhibitor that arrests cell cycle in G1 phase. Cathepsin D is one of the proteases that are responsible for cancer progression and metastasis. Treatment of MCF-7 breast cancer cells with BP-1 (10^–5 M) or NP (10^–6 M) resulted in up-regulation of cyclin D1 and cathepsin D and down-regulation of p21 at transcriptional and translational levels as well as E2 (10^–9 M) compared to a negative control treated with DMSO (P < 0.05). In addition, E2, BP-1, or NP-induced alterations of these genes were reversed by the presence of ICI 182 780 (10^–8 M), an ER antagonist, suggesting that the changes in these gene expressions may be regulated by ER-dependent signalling pathway. In conclusion, these results suggest that BP-1 and NP, like E2, may accelerate the growth of MCF-7 breast cancer cells by regulating cell-cycle-related genes through ER-mediated signalling pathway. Furthermore, these EDCs can adversely affect human health by promoting cancer metastasis through the amplification of cathepsin D via ER-dependent signalling pathway.