Role of the focal adhesion protein TRIM15 in colon cancer development.

The tripartite motif containing (TRIM) proteins are a large family of proteins that have been implicated in many biological processes including cell differentiation, apoptosis, transcriptional regulation, and signaling pathways. Here, we show that TRIM15 co-localized to focal adhesions through homo-dimerization and significantly suppressed cell migration. Domain mapping analysis indicated that B-box2 and PRY domains were essential for TRIM15 localization to focal adhesions and inhibition of cell migration. Our protein-protein interaction screen of TRIM15 with the integrin adhesome identified several TRIM15 interacting proteins including coronin 1B, cortactin, filamin binding LIM protein1, and vasodilator-stimulated phosphoprotein, which are involved in actin cytoskeleton dynamics. TRIM15 expression was tissue-restricted and downregulated in colon cancer. Level of TRIM15 expression was associated with colon cancer cell migration, as well as both in vitro and in vivo tumor growth. These data provide novel insights into the role of TRIM15 as an additional component of the integrin adhesome, regulating cell migration, and suggest that TRIM15 may function as a tumor suppressor of colon cancer.