Myoferlin regulates epithelial cancer cell plasticity and migration through autocrine TGF-β1 signaling

// Victoria R. Barnhouse 1, * , Jessica L. Weist 1, 2, * , Vasudha C. Shukla 1 , Samir N. Ghadiali 1, 3, 4 , Douglas A. Kniss 1, 5 and Jennifer L. Leight 1, 2 1 Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, 43210 Ohio, USA 2 The James Comprehensive Cancer Center, The Ohio State University, Columbus, 43210 Ohio, USA 3 Dorothy M. Davis Heart and Lung Research Institute, College of Medicine and Wexner Medical Center, The Ohio State University, Columbus, 43210 Ohio, USA 4 Department of Internal Medicine (Division of Pulmonary, Critical Care and Sleep Medicine), College of Medicine and Wexner Medical Center, The Ohio State University, Columbus, 43210 Ohio, USA 5 Department of Obstetrics and Gynecology (Division of Maternal-Fetal Medicine and Laboratory of Perinatal Research), College of Medicine and Wexner Medical Center, The Ohio State University, Columbus, 43210 Ohio, USA * These authors contributed equally to this work Correspondence to: Jennifer L. Leight, email: leight.1@osu.edu Keywords: myoferlin; TGF-beta; cancer; epithelial-mesenchymal transition; mesenchymal-epithelial transition Received: January 15, 2018      Accepted: March 15, 2018      Published: April 10, 2018 ABSTRACT Epithelial cancer cells can undergo an epithelial-mesenchymal transition (EMT), a complex genetic program that enables cells to break free from the primary tumor, breach the basement membrane, invade through the stroma and metastasize to distant organs. Myoferlin (MYOF), a protein involved in plasma membrane function and repair, is overexpressed in several invasive cancer cell lines. Depletion of myoferlin in the human breast cancer cell line MDA-MB-231 (MDA-231 MYOFKD ) reduced migration and invasion and caused the cells to revert to an epithelial phenotype. To test if this mesenchymal-epithelial transition was durable, MDA-231 MYOFKD cells were treated with TGF-β1, a potent stimulus of EMT. After 48 hr with TGF-β1, MDA-231 MYOFKD cells underwent an EMT. TGF-β1 treatment also decreased directional cell motility toward more random migration, similar to the highly invasive control cells. To probe the potential mechanism of MYOF function, we examined TGF-β1 receptor signaling. MDA-MB-231 growth and survival has been previously shown to be regulated by autocrine TGF-β1. We hypothesized that MYOF depletion may result in the dysregulation of TGF-β1 signaling, thwarting EMT. To investigate this hypothesis, we examined production of endogenous TGF-β1 and observed a decrease in TGF-β1 protein secretion and mRNA transcription. To determine if TGF-β1 was required to maintain the mesenchymal phenotype, TGF-β receptor signaling was inhibited with a small molecule inhibitor, resulting in decreased expression of several mesenchymal markers. These results identify a novel pathway in the regulation of autocrine TGF-β signaling and a mechanism by which MYOF regulates cellular phenotype and invasive capacity of human breast cancer cells.