IL-6 promotes growth and epithelial-mesenchymal transition of CD133+ cells of non-small cell lung cancer

Abstract

// Soo Ok Lee 1 , Xiaodong Yang 1 , Shanzhou Duan 1 , Ying Tsai 1 , Laura R. Strojny 1 , Peter Keng 1 , Yuhchyau Chen 1 1 Department of Radiation Oncology, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA Correspondence to: Yuhchyau Chen, e-mail: yuhchyau_chen@urmc.rochester.edu Soo Ok Lee, e-mail: soook_lee@urmc.rochester.edu Keywords: non-small cell lung cancer, IL-6, CD133+, cancer stem cells, self-renewal Received: July 01, 2015      Accepted: November 21, 2015      Published: December 12, 2015 ABSTRACT We examined IL-6 effects on growth, epithelial-mesenchymal transition (EMT) process, and metastatic ability of CD133+ and CD133– cell subpopulations isolated from three non-small cell lung cancer (NSCLC) cell lines: A549, H157, and H1299. We developed IL-6 knocked-down and scramble (sc) control cells of A549 and H157 cell lines by lentiviral infection system, isolated CD133+ and CD133– sub-populations, and investigated the IL-6 role in self-renewal/growth of these cells. IL-6 showed either an inhibitory or lack of effect in modulating growth of CD133– cells depending on intracellular IL-6 levels, but there was higher self-renewal ability of IL-6 expressing CD133+ cells than IL-6 knocked down cells, confirming the promoter role of IL-6 in CD133+ cells growth. We then examined tumor growth of xenografts developed from CD133+ cells of A549IL-6si vs. A549sc cell lines. Consistently, there was retarded growth of tumors developed from A549IL-6si, CD133+ cells compared to tumors originating from A549sc, CD133+ cells. The effect of IL-6 in promoting CD133+ self-renewal was due to hedgehog (Hhg) and Erk signaling pathway activation and higher Bcl-2/Bcl-xL expression. We also investigated whether IL-6 regulates the EMT process of CD133− and CD133+ cells differently. Expression of the EMT/metastasis-associated molecules in IL-6 expressing cells was higher than in IL-6 knocked down cells. Together, we demonstrated dual roles of IL-6 in regulating growth of CD133– and CD133+ subpopulations of lung cancer cells and significant regulation of IL-6 on EMT/metastasis increase in CD133+ cells, not in CD133– cells.