Mesenchymal stem cells (MSCs) are considered for potential use as an ideal vehicle to efficiently deliver therapeutic agents in treatment against cancers including melanoma. However, emerging evidence indicates that MSCs promote tumor growth and progression. Therefore, a comprehensive understanding of the role of MSCs is very important to evaluate the MSCs-based therapy in melanoma. B16 melanoma cells treated by MSC conditioned medium (CM), showed significantly enhanced migration and invasion, which was also confirmed in a lung metastasis mice model in vivo. Later, it was found that MSC CM induced an epithelial mesenchymal transition (EMT) in B16 cells. The ELISA assay showed that transforming growth factor-β (TGF-β) was secreted by MSCs and EMT was also induced by recombinant TGF-β in B16 melanoma cells, which suggests the important role of TGF-β in mediating EMT caused by MSC CM. When TGF-β signaling was inhibited by SB431542, the EMT process was significantly eliminated in vitro and in xenograft tumors in vivo. Snail, as a downstream target of TGF-β signaling and an EMT regulator, was upregulated by MSC CM and inhibited by SB431542, which confirms the key role of TGF-β signaling in EMT induced by MSC CM in B16 cells. Taken together, this study shows that MSC induces EMT in melanoma cells in a paracrine manner, which might be mediated by the TGF-β/Snail signaling pathway. Thus, caution should be exercised when considering MSCs-based therapy in melanoma and also in other cancers. Targeting TGF-β signaling and Snail could be further investigated as potential therapeutic approaches for melanoma.
aDepartment of Plastic Surgery
bDepartment of Burn Surgery, Changhai Hospital
cClinic, Xiang An Sanatorium for Retired Cadres, Second Military Medical University, Shanghai
dQing Dao Sanitarium of Navy
eDepartment of Plastic Surgery, General Hospital of Jinan Military Region, Shandong, China
* Chuan Lv and Haiying Dai contributed equally to the writing of this article.
Correspondence to Chunyu Xue, MD, PhD, Department of Plastic Surgery, Changhai Hospital, Second Military Medical University, 168 Changhai Road, Shanghai 200433, China Tel: +86 213 116 1810; fax: +86 216 556 6349; e-mail: email@example.com
Correspondence to Zhaofan Xia, MD, PhD, Department of Burn Surgery, Changhai Hospital, Second Military Medical University, 168 Changhai Road, Shanghai 200433, China Tel: +86 213 116 1821; fax: +86 216 558 9829; e-mail: firstname.lastname@example.org
Received January 28, 2016
Accepted December 12, 2016