A chemical biology screen reveals a role for Rab21-mediated control of actomyosin contractility in fibroblast-driven cancer invasion.

Carcinoma-associated fibroblasts (CAFs) can promote the progression of tumours in many ways. They can remodel the extracellular matrix to generate an environment that enables the invasion of cancer cells. We hypothesised that compounds that prevent matrix remodelling by CAFs would block their ability to promote carcinoma cell invasion. We designed a screen for compounds that interfere with CAF-promoted matrix remodelling. Hits from this screen were investigated in organotypic invasion models of squamous cell carcinoma (SCC). We find that lovastatin and simvastatin reduce matrix remodelling by fibroblasts and thereby reduce SCC invasion. This class of compounds exert their effects partly through disrupting the function of Rab proteins, and we show a new role for Rab21 in promoting cancer cell invasion promoted by CAFs. Rab21 is required for CAFs to promote the invasion of cancer cells. It enables the accumulation of integrin alpha5 at the plasma membrane and subsequent force-mediated matrix remodelling.