Filamin B Enhances the Invasiveness of Cancer Cells into 3D Collagen Matrices.

Numerous types of cancer cells migrate into extracellular tissues. This phenomenon is termed invasion, and is associated with poor prognosis in cancer patients. In this study, we demonstrated that filamin B (FLNb), an actin-binding protein, is highly expressed in cancer cell lines that exhibit high invasiveness, with a spindle morphology, into 3D collagen matrices. In addition, we determined that knockdown of FLNb in invasive cancer cells converts cell morphology from spindle-shaped, which is associated with high invasiveness, to round-shaped with low invasiveness. Furthermore, di-phosphorylation of myosin regulatory light chain (MRLC) and phosphorylation of focal adhesion kinase (FAK) are inhibited in FLNb-knockdown cancer cells. These results suggest that FLNb enhances invasion of cancer cells through phosphorylation of MRLC and FAK. Therefore, FLNb may be a new therapeutic target for invasive cancers.