Examining crosstalk between CD44 and integrins and its effects on cell migration and traction force in glioblastoma.

Abstract

Cell migration is a major driver of invasion and metastasis during cancer progression. For cells to migrate, they utilize the actin-myosin cytoskeleton and adhesion molecules to interrogate the external environment and generate traction force. CD44 is an adhesion receptor that is overexpressed in glioblastoma and several other tumors. It plays a role in several processes that contribute to cancer metastasis such as: migration, proliferation, and invasion. CD44 primarily binds to hyaluronic acid in the extracellular matrix (ECM), while integrins primarily bind to collagen and fibronectin. Inside of the cell, integrins and CD44 use adaptor proteins to link to the actin cytoskeleton. Here, we explore the crosstalk between integrin and CD44-mediated cell mechanics. First, traction force microscopy was used on U251WT(WT) and U251 CD44KO glioma cells in integrin-binding conditions. Counterintuitively, we found that traction force in CD44KO cells were higher compared to WT. This supports the idea of crosstalk between CD44 and integrins, where if one is depleted, the other increases to compensate. We further tested this idea by measuring traction force for WT cells treated with IM7, a CD44 blocking antibody, to untreated WT cells. Upon blocking CD44, we consistently observe an increase in cell traction for IM7 treated cells compared to untreated. We also measured traction forces for CD44-binding conditions, by using IM7 as a coating on our polyacrylamide gels. When integrins were blocked on cells seeded onto IM7, traction force increased. We have also measured differences in cell migration under integrin vs CD44 binding conditions. Our data suggest a model of crosstalk between integrins and CD44 where signals can be sent either: CD44-to-integrin or integrin-to-CD44. The outcome of these studies may lead to novel avenues for multi-receptor targeting cancer therapies.