RESUMO
Breast cancer is the most common type of diagnosed cancers in women, difficult to treat, and has received international attention because of its aggressive nature and inherent drug resistance mechanisms. Development of a better selective estrogen receptor modulator with good therapeutic profile and less toxicity is very crucial in this scenario. This study was undertaken to evaluate and compare the in vitro and in vivo antitumor activities of ormeloxifene with other clinically used breast cancer drugs. Cytotoxic activity of ormeloxifene was compared with standard drugs, 4-hydroxytamoxifene and Adriamycin. Ormeloxifene (50 µM) concentration showed cytotoxicity of 75% and 82% in MDAMB-231 and 24% and 80% in MCF-7 cells, respectively, after 72 and 144 hr of incubation as displayed by cell viability assay. The same concentration of ormeloxifene was shown to exert 74% caspase-7 activation in MCF-7 cells after 24 hr of incubation by fluorescence resonance energy transfer assay. Cell cycle analysis proved that there was an increase in sub-G1 peak to 64.4% and 33.9% in MDAMB-231 and MCF-7 cells, respectively, after treatment using ormeloxifene (50 µM) for 48 hr. The nonobese diabetic-severe combined immunodeficiency mice bearing tumor xenografts of triple negative MDAMB-231 cells treated with ormeloxifene (3 mg/kg bw) showed significant regression in relative tumor volume compared to control. From the results obtained and as evidenced from prior literature, ormeloxifene in addition to contraceptive use, can be repositioned for the development of an efficacious anticancer drug. These data present the preclinical part of a well concerted effort to place ormeloxifene into further clinical trials.
