Probing the role of mesenchymal stem cells in salivary gland cancer on biomimetic microdevices.

Mesenchymal stem cells (MSCs) are the progenitors of stromal cells, which have been found to interact with cancer cells and represent an important target for cancer therapies. Salivary gland cancer is an aggressive malignant epithelial tumor and can easily disseminate to distant sites in vivo. In this work, we probed the role of MSCs in salivary gland cancer in an in vivo like tumor microenvironment by using a series of functional microfluidic devices for 2D and 3D assays. The results demonstrated that MSCs could be recruited by salivary gland cancer cells (ACC-M) and this effect was potentially mediated by TGF-β secreted by cancer cells. In addition, MSCs exhibited the ability to squeeze into ACC-M spheroids by dispersing the cell-cell connection and reducing the expression of E-cadherin in cancer cells. In particular, MSCs exhibited the ability to enhance the invasion of salivary cancer under a chemokine CXCL12 gradient, indicating the involvement of a CXCL12-CXCR4 pathway and the tumor-promoting properties of MSCs in cancer progression. This study recreated an in vivo-like tumor microenvironment by constructing a series of functional microdevices and explored the role of MSCs in ACC invasion for the first time. It provides a unique platform to open up new options to target stromal cells for cancer therapy and also analyzed the potential risk of using MSCs as drug delivery carriers for therapeutic purposes in carcinoma treatment.