Abstract 1032: Ormeloxifene attenuates metastatic and glycolytic pathways in breast cancer cells

Abstract

Abstract Background: Breast cancer is the second most deadly cancer in female, resulting in over 39,000 deaths in year 2012. Triple negative breast cancer is a subtype of breast cancer characterized by its poor outcome and a lack of targeted therapies. New targeted therapies are therefore an urgent unmet medical need for this patient population. Recent investigations into anti-cancer drug are targeted on repurposing pre-approved and safe drugs for cancer treatment. We report for the first time that a non-steroidal, selective estrogen receptor inhibitor, ormeloxifene (ORM) inhibits Metastasis-associated protein 1 (MTA1) and glycolytic pathway through AMPKα 1/2 inhibition in triple negative breast cancer cells. They are both involved in promoting cancer cell survival, proliferation and metastasis. MTA1 is an initiator of epithelial to mesenchymal transition (EMT) which is responsible for metastasis and poor prognosis. AMPKα 2 is important for glycolysis and promotes tumor survival. Methods: Herein, we investigated the use of ORM for the treatment of breast cancer. We used MB-231 and MCF-7 breast cell lines as prototypical model and investigated the effect of ORM treatment on MTA1 and AMPKα 2 expression pattern. We investigated the effect of ORM on cell proliferation (MTS), clonogenic potential (anchorage dependent growth) of the cells and analyzed its effect on markers of EMT through Western blotting. Further, we performed glycolytic function analysis using Seahorse analyzer and mitochondrial membrane potential analysis by Tetramethylrhodamine, ethyl ester (TMRE). We performed Western blotting to investigate the role of ORM on MTA1 and AMPKα inhibition. Results: Our results suggest that ORM inhibits proliferation of both MB-231 and MCF-7 breast cancer cells at low concentrations. Investigation of the EMT marker profile revealed a dose dependent decrease in the expression of MTA1 in both the cells on ORM treatment. This leads to inhibition of motility and invasion of cells in a concentration dependent manner. Additionally, treatment of MB-231 cells with ORM suppresses vimentin expression, a marker for EMT that aids in rapid metastasis. ORM inhibits transcription factors, Snail and Slug, known to promote epithelial-mesenchymal transitions during tumor development. Importantly, it was observed that ORM also inhibits glycolytic pathway in breast cancer cells independent of mitochondrial membrane depolarization. ORM inhibits total AMPKα and dephosphorylates AMPKα 2 in breast cancer cells. Conclusions: Our findings suggest that ORM effectively targets MTA1 and glycolytic pathway and inhibits breast cancer cell growth and EMT. Overall, this study suggests that ORM can be a potential therapeutic modality for triple negative breast cancer treatment. Citation Format: Aditya Ganju, Vasudha Sundram, Keith Miskimins, Rishi Gara, Sheema Khan, Man Mohan Singh, Subhash C. Chauhan, Meena Jaggi. Ormeloxifene attenuates metastatic and glycolytic pathways in breast cancer cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1032. doi:10.1158/1538-7445.AM2014-1032