The role of miR200c in leptin-mediated triple-negative breast cancer progression to an epithelial-to-mesenchymal transition.

Abstract

e12548 Background: Almost 40% of women with breast cancer are obese at diagnosis. Obesity is associated with a worse prognosis in triple negative breast cancer (TNBC). Preclinical studies have shown that leptin is an important factor associated with TNBC by promoting cancer stem cell (CSC) enrichment and/or epithelial-to-mesenchymal transition (EMT). Transcription factors SNAIL, TWIST and ZEB are critical components in enhancing EMT in cancer cells. The specific mechanism(s) by leptin regulates SNAIL, TWIST and ZEB expression remain unclear, limiting the development of effective interventions to improve outcomes in obese TNBC patients. Recent studies have demonstrated that miR200c, downstream of leptin receptor signaling, regulates the expression of SNAIL1, TWIST and ZEB. We will test the hypothesis that leptin contributes to obesity-induced EMT/CSC in TNBC through modulation of miR200c. Methods: Ob-R (leptin receptor) expression was suppressed in TNBC MDA-MB-231 and E-Wnt cells using shRNA (Ob-R null). Ob-R and Ob-R null cells were exposed to sera pooled from lean or obese women, as well as lean sera supplemented with leptin, after which expression of SNAIL, TWIST, ZEB and miR200c was measured by qPCR, while activation of the JAK-STAT pathway was assessed by Western blotting. Results: TNBC cells exposed to obese and high leptin conditions demonstrated increased expression of EMT markers compared to levels expressed under lean conditions. The Ob-R WT and null cells were used to determine the specific role of leptin signaling in regulating expression of SNAIL, TWIST and ZEB through miR200c. Conclusions: Both obese and high leptin conditions result in increased expression of EMT regulators, suggesting that effective targeting of this pathway may provide clinical benefit in the obese breast cancer patient. Elucidating the specific mediators of this pathway will guide development of novel and more potent medical therapies.