There is increasing evidence that mesenchymal stem cells (MSCs) have the ability to migrate and engraft into
tumor sites and exert stimulatory effects on
cancer cell growth, invasion and even
metastasis through direct and/or indirect interaction with
tumor cells. However, these pro-tumorigenic effects of MSCs are still being discovered and may even involve opposing effects. MSCs can be friends or enemies of
cancer cells: they may stimulate
tumor development by regulating immune surveillance, growth, and angiogenesis. On the other hand, they may inhibit
tumor growth by inhibiting survival signaling such as Wnt and Akt pathway. MSCs have also been proposed as an attractive candidate for the delivery of anti-
tumor agents, owing to their ability to home into
tumor sites and to secrete
cytokines. Detailed information about the mutual interactions between
tumor cells and MSCs will undoubtedly lead to safer and more effective clinical
therapy for
tumors. In this article, we summarize a number of findings to provide current information on the potential roles of MSCs in
tumor development; we then discuss the therapeutic potential of engineered MSCs to reveal any meaningful clinical applications.