Carcinoma Associated Fibroblast Like Differentiation of Human Mesenchymal Stem Cells

Carcinoma associated fibroblasts (CAFs) have recently been implicated in important aspects of epithelial solid tumor biology such as neoplastic progression, tumor growth, angiogenesis, and metastasis. However, neither the source of CAFs nor the differences between CAFs and fibroblasts from non-neoplastic tissue have been well defined. In this study we demonstrate that human bone marrow-derived mesenchymal stem cells (hMSCs) exposed to tumor-conditioned medium (TCM) over a prolonged period of time assume a CAF-like myofibroblastic phenotype. More importantly, these cells exhibit functional properties of CAFs including sustained expression of stromal derived factor 1 (SDF-1) and the ability to promote tumor cell growth both in vitro and in an in vivo co-implantation model and expression of myofibroblast markers including α-smooth muscle actin and fibroblast surface protein. hMSCs induced to differentiate to a myofibroblast-like phenotype using 5-azacytidine do not promote tumor cells growth as efficiently as hMSCs cultured in tumor-conditioned medium nor do they demonstrate increased SDF-1 expression. Furthermore, gene expression profiling revealed similarities between TCM exposed hMSCs and carcinoma associated fibroblasts. Taken together these data suggest that hMSCs are a source of carcinoma associated fibroblasts and can be used in the modeling of tumor-stroma interactions. To our knowledge this is the first report demonstrating that hMSCs become activated and resemble carcinoma associated myofibroblasts upon prolonged exposure to conditioned medium from MDAMB231 human breast cancer cells. Keywords: differentiation