Interaction of cancer cells with mesenchymal stem cells: implications in metastatic progression

Mesenchymal stem cells (MSCs) are multipotent stem cells that reside in various parts of the body like adipose tissue, bone marrow and umbilical cord with an ability to differentiate into chondrocytes, adipocytes and osteocytes. Rigorous research has helped us understand that MSCs home to wound sites and this homing mechanism has been used in the treatment of many inflammatory diseases. It is now emerging that MSCs are an important component of the tumor microenvironment (TME) and contribute to tumor plasticityTumor plasticity: Plasticity in tumor cells refers to the ability to undergo molecular and phenotypic changes due to environmental cues or genetic alterations.. MSCs are one of the key players within the TME and can either inhibit or promote tumor cell growth by distinct types of cellular interaction. These multifunctional cells can reorganize the tumor stromaStroma: It refers to the supportive tissue consisting of connective tissue or blood vessels around an organ or tumor. which, in turn, can trigger changes in metastatic behavior and promote dedifferentiation to develop cancer stem-like cells. On the contrary, MSCs have been proposed as ideal candidates as drug delivery agents in treatment of various cancers. The double-edged role of MSCs in tumor has made it difficult to pinpoint whether MSCs promote or inhibit tumor growth and progression. During cancer progression, tumor cells undergo molecular and phenotypic changes as a result of microenvironmental cues, genetic and epigenetic alterations and treatment-imposed selective pressures which contribute to tumor heterogeneity and therapy resistance. So, understanding the mechanisms underlying the tumor plasticity may deliver new strategies for targeting cancer metastasis and resistance to therapy. Accordingly, this review focuses on diverse mechanisms of interaction between MSCs and cancer cells with emphasis on different types of intercellular communication affecting tumor progression and metastasis.