Domain 5 of high molecular weight kininogen inhibits collagen-mediated cancer cell adhesion and invasion in association with α-actinin-4

High molecular weight kininogen (HK) is a plasma glycoprotein with multiple functions, including the regulation of coagulation. We previously demonstrated that domain 5 (D5 H ), a functional domain of HK, and its derived peptides played an important role in the vitronectin-mediated suppression of cancer cell adhesion and invasion. However, the underlying mechanisms of the D5 H -mediated suppressive effects remain to be elucidated. Here, we showed that D5 H and its derivatives inhibited the collagen-mediated cell adhesion and invasion of human osteosarcoma MG63 cells. Using purified D5 H fused to glutathione- S -transferase (GST) and D5 H -derived peptides for column chromatography, an actin-binding protein, α-actinin-4, was identified as a binding protein of D5 H with high-affinity for P-5m, a core octapeptide of D5 H . Immunofluorescence microscopy demonstrated that D5 H co-localized with α-actinin-4 inside MG63 cells. In addition, exogenous GST-D5 H added to the culture media was transported into MG63 cells, although GST alone as a control was not. As α-actinin-4 regulates actin polymerization necessary for cell adhesion and is related to the integrin-dependent attachment of cells to the extracellular matrix, our results suggest that D5 H may modulate cell adhesion and invasion together with actinin-4.