In vitro effects of 2-methoxyestradiol on morphology, cell cycle progression, cell death and gene expression changes in the tumorigenic MCF-7 breast epithelial cell line.

In the present study, the antiproliferative mechanism of action of 1 microM 2-methoxyestradiol (2ME) was investigated in the MCF-7 cell line. Measurement of intracellular cyclin B and cytochrome c protein levels, reactive oxygen species formation, cell cycle progression and apoptosis induction were conducted by means of flow cytometry. Morphological changes were evaluated using transmission electron microscopy and fluorescent microscopy by employing Hoechst 33342 and acridine orange. Gene expression changes were conducted by means of microarrays. 2ME-treated cells demonstrated an increase in cyclin B protein levels, hydrogen peroxide formation, intracellular levels of cytochrome c, as well as an increase in early and late stages of apoptosis. In addition, morphological data revealed the presence of autophagic processes. Fluorescent microscopy showed an increase in acridine orange staining and electron microscopy revealed an increase in vacuolar formation in 2ME-treated cells. The gene expression of several genes associated with mRNA translation, autophagy-related processes and genes involved in microtubule dynamics were affected. The study contributes to the mechanistic understanding of 2ME's growth inhibition in MCF-7 cells and highlights the possibility of both apoptotic and autophagic processes being activated in response to 2ME treatment in this cell line. 2010 Elsevier Ltd. All rights reserved.