Exosomes derived from SW 480 colorectal cancer cells promote cell migration in HepG 2 hepatocellular cancer cells via the mitogen-activated protein kinase pathway

Exosomes are membrane-derived extracellular vesicles that have recently been recognized as important mediators of intercellular communication. In the present study, we investigated the effects of exosomes derived from SW480 colorectal cancer cells in recipient HepG2 hepatocellular cancer cells. We demonstrated that SW480-derived exosomes were taken up by the recipient HepG2 cells via dynamin-dependent endocytosis and were localized to the HepG2 lysosomes. In addition, SW480-derived exosomes induced the phosphorylation of extracellular signal-regulated kinase (ERK)1/2 following their uptake into HepG2 cells. Of note, these changes occurred during the early phase after exosome treatment. Furthermore, SW480-derived exosomes promoted the migration of recipient HepG2 cells in a wound-healing assay, which was suppressed by pretreatment with U0126, an upstream inhibitor of ERK1/2. These results indicated that SW480-derived exosomes activated a classical mitogen-activated protein kinase pathway in recipient HepG2 cells via dynamin-dependent endocytosis and subsequently enhanced cell migration by ERK1/2 activation. Our results provide new insights into the regulation of cellular functions by exosomes. Introduction Exosomes are extracellular vesicles that are 40-200 nm in diameter and are constitutively released from most cell types, including epithelial cells (1), endothelial cells (2), cancer cells (3), dendritic cells (4), mesenchymal stem cells (5), and B lymphocytes (6). Exosomes, initially observed in differentiating reticulocytes three decades ago (7), have recently been identified to perform several important functions as mediators of intercellular communication. Valadi et al reported that exosomes containing mRNAs and miRNAs could be delivered to other cells (8). In addition, Zhang et al demonstrated that microvesicles derived from human monocytic THP-1 cells delivered miR-150 to human endothelial HMEC-1 cells, in which elevated exogenous miR-150 effectively reduced c-myb expression and enhanced cell migration (9). In general, exosomes derived from cancer cells are considered to induce cancerous malignant alterations in recipient cells, such as cell proliferation, extracellular matrix remodelling, cell migration, and angiogenesis (10-12). However, exosomelike nanoparticles derived from cancer cells have also been shown to induce apoptosis in other cancer cell types (13). We have previously shown that exosomes derived from the colorectal cancer cell line SW480, were taken up by the HepG2 hepatocellular cancer cells and A549 lung cancer cells (14). However, the detailed functions of SW480-derived exosomes are not well understood; therefore, we further investigated the effects of SW480-derived exosomes on recipient HepG2 cells. In the present study, we showed that the uptake of SW480-derived exosomes by HepG2 cells occurred by dynamin-dependent endocytosis, and these exosomes were localized to the lysosomes in HepG2 cells. In addition, SW480-derived exosomes promoted the migration of HepG2 cells via the activation of a classical mitogen-activated protein Exosomes derived from SW480 colorectal cancer cells promote cell migration in HepG2 hepatocellular cancer cells via the mitogen-activated protein kinase pathway MITSURU CHIBA1,2, NARUMI WATANABE3, MIKI WATANABE3, MAKI SAKAMOTO3, AKIKA SATO3, MIZUKI FUJISAKI3, SHIORI KUBOTA3, SATORU MONZEN2,4, ATSUSHI MARUYAMA5, NAOKI NANASHIMA1,2, IKUO KASHIWAKURA2,4 and TOSHIYA NAKAMURA1,2 1Department of Biomedical Sciences, Division of Medical Life Sciences, Hirosaki University Graduate School of Health Sciences; 2Research Center for Biomedical Sciences, Hirosaki University Graduate School of Health Sciences; 3Department of Medical Technology, Hirosaki University School of Health Sciences; 4Department of Radiological Life Sciences, Division of Medical Life Sciences, Hirosaki University Graduate School of Health Sciences, Hirosaki, Aomori 036-8564; 5Department of Stress Response Science, Hirosaki University Graduate School of Medicine, Hirosaki, Aomori 036-8562, Japan Received October 1, 2015; Accepted November 4, 2015 DOI: 10.3892/ijo.2015. 3255 Correspondence to: Dr Mitsuru Chiba, Department of Biomedical Sciences, Division of Medical Life Sciences, Hirosaki University Graduate School of Health Sciences, 66-1 Hon-cho, Hirosaki, Aomori 036-8564, Japan E-mail: mchiba32@hirosaki-u.ac. jp