MiR-449a promotes breast cancer progression by targeting CRIP2

Abstract

// Wei Shi 1 , Jeff Bruce 1 , Matthew Lee 1 , Shijun Yue 1 , Matthew Rowe 1 , Melania Pintilie 2 , Ryunosuke Kogo 1 , Pierre-Antoine Bissey 1 , Anthony Fyles 3, 4 , Kenneth W. Yip 1 , Fei-Fei Liu 1, 3, 4, 5 1 Princess Margaret Cancer Centre, University Health Network, Toronto, Canada 2 Division of Biostatistics, Princess Margaret Cancer Centre, University Health Network, Toronto, Canada 3 Department of Radiation Oncology, Princess Margaret Hospital, Toronto, Canada 4 Department of Radiation Oncology, University of Toronto, Toronto, Canada 5 Department of Medical Biophysics, University of Toronto, Toronto, Canada Correspondence to: Fei-Fei Liu, e-mail: Fei-Fei.Liu@rmp.uhn.on.ca Keywords: breast cancer, miR-449a, metastasis, CRIP2, prognostic marker Received: December 18, 2015     Accepted: February 14, 2016     Published: February 26, 2016 ABSTRACT The identification of prognostic biomarkers and their underlying mechanisms of action remain of great interest in breast cancer biology. Using global miRNA profiling of 71 lymph node-negative invasive ductal breast cancers and 5 normal mammary epithelial tissues, we identified miR-449a to be highly overexpressed in the malignant breast tissue. Its expression was significantly associated with increased incidence of patient relapse, decreased overall survival, and decreased disease-free survival. In vitro , miR-449a promoted breast cancer cell proliferation, clonogenic survival, migration, and invasion. By utilizing a tri-modal in silico approach for target identification, Cysteine-Rich Protein 2 (CRIP2; a transcription factor) was identified as a direct target of miR-449a, corroborated using qRT-PCR, Western blot, and luciferase reporter assays. MDA-MB-231 cells stably transfected with CRIP2 demonstrated a significant reduction in cell viability, migration, and invasion, as well as decreased tumor growth and angiogenesis in mouse xenograft models. Our data revealed that overexpression of miR-449a suppresses CRIP2, which then affects the tumor vasculature, likely via NF-κB/p65 complex-mediated transcription of VEGF. These finding define an oncogenic function of miR-449a in human breast cancer, and highlight the importance of this pathway in driving aggressive behaviour.