Matrix Assembly Induction and Cell Migration and Invasion Inhibition by a 13-Amino Acid Fibronectin Peptide

Abstract

Fibronectin (FN) is an extracellular matrix (ECM)pro Fibronectin (FN)1 is an adhesive heterodimeric glycoprotein present in the extracellular matrix (ECM) of connective tissues in disulfide cross-linked insoluble fibrils and in the blood in dimeric soluble form. FN contains three types of homologous repeats (I-III), organized in functional domains, connected by flexible, protease-sensitive segments, which allow the binding of the molecule to ECM components (fibrin, heparin, collagen, FN, and integrin receptors) (1-3). Through these multiple interactions, FN provides a scaffold for ECM assembly and takes part in different physiological and pathological processes (4 -7).One of the earliest observations concerning FN was that in vitro transformed and tumor-derived cells often fail to deposit a matrix, whereas the normal counterparts do have a matrix (8, 9). Because addition of FN to tumor-derived cultured cells improves cell adhesion and induces ECM and cytoskeleton organization, supporting the normal cell morphology, FN has been associated with the normal cell phenotypes (6, 10, 11). The inability of the transformed cells to deposit the ECM has been related to the proteolytic fragmentation of FN generated by the enhanced levels of proteases released by tumors and transformed cells (12)(13)(14), as well as to the down-regulation of the expression of integrin receptors binding to FN and supporting ECM assembly (7). Along these lines are also observations that an excessive ECM, containing collagens and FN, i.e. desmoplasia, is often deposited in stroma surrounding invasive carcinomas (15). It has been proposed that this stromal response temporarily antagonizes tumor growth and invasion (14, 16). Thus, the absence of an ECM of FN is associated with the transformed phenotype, whereas the presence of the ECM restricts cell invasion and migration in many tumor cells. The transition from assembly to nonassembly of the ECM may therefore be an important stage in cancer progression.The assembly of FN into fibrils in vitro and in vivo requires multiple binding sites within FN including an N-terminal region consisting of the first five type I repeats (17-21), the RGD cell-binding site (22-23), the synergistic cell adhesive regions (24 -25), the I 12 repeat involved in the stabilization of FN fibrils (26), and a site located at or near the junction of type I 9 and type III 1 repeats (27-28). In addition, an FN-FN-binding site has been identified in a 14-kDa FNfg containing the first two type III repeats (29). A 76-amino acid FN peptide, including this site, corresponding to a C-portion of the type-III 1 repeat, has been shown to convert FN into a polymeric fibrillar form called superfibronectin (sFN) (29). sFN resembles the matrix fibrils produced by cultured fibroblasts, is highly adhesive, can inhibit cell spreading and migration in vitro, prevents tumor formation in nude mice injected with human tumorigenic cells, and has a strong antimetastatic activity (30). Recently, the

Phenotypic characterization of mouse embryonic fibroblasts lacking heat shock factor 2

“…The extracellular protein fibronectin is part of the extracellular matrix and disregulated in cancer cells [20]. In correlation with the marked proliferation defects observed in Hsf2 -/-MEFs, these cells displayed an increase in fibronectin staining in immunocytochemistry experiments, as well as revealed profound remodeling of the fibronectin network (Fig.…”

Characterization of a von Hippel Lindau Pathway Involved in Extracellular Matrix Remodeling, Cell Invasion, and Angiogenesis

“…It was reported that loss of ECM integrity influences cellular transformation and tumorigenesis in vivo (26). Therefore, we examined whether inactivation of the VHL-ECM assembly pathway contributes to tumorigenesis.…”

Human Fibroblasts with Mutations in COL5A1 and COL3A1 Genes Do Not Organize Collagens and Fibronectin in the Extracellular Matrix, Down-regulate α2β1 Integrin, and Recruit αvβ3 Instead of α5β1 Integrin

“…Quantitative evaluation of fluorescence associated with the FN-and COLL-ECM organized by control and EDS cells, was performed as previously reported (25). The fluorescent images, with the same spatial resolution and comparable light intensity, were captured by a CCD black and white TV camera mounted on a Zeiss Axiovert 10S/H fluorescence microscope.…”

“…Human skin fibroblasts adhere in vitro through the organization of an ECM mainly composed of FN and types III, V, and VI COLLs (3,24). FN can bind to COLLs through several COLL binding sites (25), and FN binding sites in COLL molecules have been reported (26). Many data indicate the interdependence of FN and COLL network assembly; in particular, in several cell systems, the assembly of COLLs has been shown to depend on FN organization (3,27), whereas, in others, COLLs have been shown to influence FN fibrillogenesis (26,28).…”