Development of a Bio-Assay for Estrogens using Estrogen Receptor Alpha Gene Expression by MCF7 Cells as Biomarker

Abstract

Estrogenic endocrine disruptors (EDCs) have been identified in soil, food, air, and water, and may produce adverse health effects in both humans and wildlife. Various in vitro assays, including the E-screen that measures estrogen dependent proliferation of the MCF-7 human breast cancer cell line, have been developed and implemented to screen for environmental estrogenic EDCs. This study describes a new amendment to the well known E-screen. A direct ELISA to quantify ERα protein levels on MCF-7 cells cultured in a high through put 96-well format were validated as a biomarker for estrogenicity. The ELISA shows that there is an inverse correlation between ERα levels and 17β-estradiol (E2) concentration (R² = 1). The detection range of the assay is between 1 and 1000 nM for E2. Results obtained with the ERα ELISA showed a good inverse correlation with total cellular LDH levels that is conventionally used to quantify MCF-7 cell proliferation. This ELISA was employed to assess environmental water extracts for estrogenicity.

Keywords:

• Bio-assay
• Estrogen receptor alpha gene expression
• Estrogens
• MCF7

ACKNOWLEDGMENT

We would like to thank the National Research Foundation (NRF) of South Africa for financially supporting this study.