Paracrine regulation of matrix metalloproteinases contributes to cancer cell invasion by hepatocellular carcinoma-secreted 14-3-3σ.

// Chia-Chia Liu 1, 2, * Tzu-Ching Chang 3, 4, * , Yi-Ting Lin 1, 5 , Yen-Ling Yu 1 , Bor-Sheng Ko 6 , Li-Ying Sung 2 , Jun-Yang Liou 1, 7, 8 1 Institute of Cellular and System Medicine, National Health Research Institutes, Zhunan 350, Taiwan 2 Institute of Biotechnology, National Taiwan University, Taipei 106, Taiwan 3 Graduate Institute of Clinical Medical Science, China Medical University, Taichung 404, Taiwan 4 Metabolomic Medicine Research Center, China Medical University, Taichung 404, Taiwan 5 Institute of Structural Biology, National Tsing Hua University, Hsinchu 300, Taiwan 6 Department of Internal Medicine, National Taiwan University Hospital, Taipei 100, Taiwan 7 Graduate Institute of Basic Medical Science, China Medical University, Taichung 404, Taiwan 8 PhD. Program for Aging, China Medical University, Taichung 404, Taiwan * These authors have contributed equally to this work Correspondence to: Jun-Yang Liou, email: jliou@nhri.org.tw Li-Ying Sung, email: liyingsung@ntu.edu.tw Keywords: 14-3-3σ, hepatocellular carcinoma, invasion, matrix metalloproteinase, paracrine Received: November 24, 2015     Accepted: April 23, 2016     Published: May 09, 2016 ABSTRACT 14-3-3σ overexpression results in enhanced hepatocellular carcinoma (HCC) cell migration and HCC tumor vascular-invasion is significantly associated with 14-3-3σ expression. However, increased expression of 14-3-3σ paradoxically suppresses in vitro cell invasion of HCC. We hypothesize that surrounding tumor-associated stromal cells play a crucial role in 14-3-3σ-regulated HCC cell invasion. In this study, H68 fibroblasts, THP-1 and phorbol-12-myristate-13-acetate (PMA)-treated THP-1 (PMA-THP-1) cells were incubated with conditioned media of control (control-CM) and 14-3-3σ-overepxressing cells (14-3-3σ-CM), followed by co-culture with HCC cells. Invasiveness of HCC cells was examined by a Boyden chamber assay. HCC cells co-cultured with 14-3-3σ-CM treated cells significantly enhanced their invasive ability compared with control-CM treated cells. Moreover, incubation with 14-3-3σ-CM induced differential expression profiles of matrix metalloproteinases (MMPs) in fibroblasts (MMP-1, MMP-2, MMP-9, MMP-12 and MMP-14), THP-1 (MMP-1 and MMP-12) and PMA-THP-1 cells (MMP-2, MMP-12 and MMP-14). In contrast, silencing of 14-3-3σ by siRNA significantly abolished 14-3-3σ-CM induced MMPs. In addition, treatment with recombinant 14-3-3σ (r14-3-3σ) protein exhibits a similar expression profile of MMPs induced by 14-3-3σ-CM in fibroblasts, THP-1 and PMA-THP-1 cells. Finally, knockdown of aminopeptidase N (APN) significantly abrogated r14-3-3σ induced expression of MMPs in HS68 fibroblasts. These results suggest that HCC-secreted 14-3-3σ promotes expression of MMPs in cancerous surrounding cells via an APN dependent mechanism. 14-3-3σ has a paracrine effect in educating stromal cells in tumor-associated microenvironment.