Influence of 2-methoxyestradiol-bis-sulphamate on cell growth, morphology and cell death in MCF-7 and MCF-12A cells

Abstract

2-methoxyestradiol (2ME2) is an endogenous estradiol metabolite that has antiproliferative, antiangiogenic and antitumor activity with low levels of toxicity that is orally active. Several promising analogues of 2ME2 have been identified in recent years. 2-methoxyestradiol-bis-sulphamate (2-MeOE2bisMATE), a bis-sulphamoylated derivative of 2ME2 is an anti-proliferative agent and is more potent than 2ME2. However, several questions remain regarding the action mechanism of 2-MeOE2bisMATE. The aim of this preclinical in vitro study was to investigate the influence 2-MeOE2bisMATE on the cell growth, morphology and cell death in a breast cancer (MCF-7) and a non-tumorigenic epithelial breast cell line (MCF-12A). Differential effects of 2-MeOE2bisMATE on MCF-7 and MCF-12A cell lines were investigated by means of dose- (0.2-1micromolar) and time-dependent studies (24 hours, 48 hours and 72 hours) using spectrophotometry (crystal violet staining), fluorescent microscopy (Hoechst 33342, propidium iodide and acridine orange) and light microscopy (haematoxylin and eosin staining). Preliminary studies indicate that 2-MeOE2bisMATE decreased cell numbers to 75% in MCF-7 cells in contrast to 93% in MCF-12A cells after 24 hours of exposure. Exposure of 48 hours resulted in 47% growth reduction in MCF-7 cells and 81% in MCF-12A cells; while 72 hour exposure resulted in 41% growth reduction in MCF-7 and 78% in MCF-12A respectively. Light microscopy revealed apoptotic characteristics including a metaphase block. Fluorescent microscopy revealed hypercondensed chromatin, apoptotic bodies and autophagy characteristics (increased lysosomal staining). MCF-7 cells were also more susceptible to 2-MeOE2bisMATE than MCF-12A cells. Future studies will include analysis of cell cycle progression and apoptosis identification (Annexin V) by means of flow cytometry. Scanning electron microscopy and transmission electron microscope will be conducted for confirmation of the above-mentioned results already obtained of the in vitro effects on morphology after exposure to 2-MeOE2bisMATE. The knowledge obtained from this study will contribute to the in vitro studies regarding the action mechanism of 2-MeOE2bisMATE. The latter shows therapeutic potential, however the effects on tumorigenic and non-tumorigenic cell lines remain unclear and warrant further investigation.