Positive ion spectra were acquired in reflectron mode. QS-13 binding inhibits the FAK/PI3K/Akt pathway, a transduction pathway that is mainly involved in tumor cell proliferation and migration. Taken collectively, our results demonstrate the QS-13 peptide binds v3 integrin inside a conformation-dependent manner and is a potent antitumor agent that could target tumor cells through V3. Intro The extracellular matrix (ECM) is definitely a complex structure that is composed of many proteins, proteoglycans and hyaluronic acid. Basement membranes, which are specialized ECMs, are composed of type IV collagen in association with small collagens, laminins, nidogens and perlecan1. Type IV collagen is composed of three chains, out of six possible chains (1(IV)-6(IV))2. Type IV collagen consists of a 7S N-terminal website, an interrupted triple helical website and a globular C-terminal non-collagenous (NC1) website3. Tumor invasion and metastasis require proteolytic degradation of the ECM including numerous proteolytic cascades, such as matrix metalloproteinases (MMP) and the plasminogen/plasmin system. Tumor progression is definitely controlled from the tumor microenvironment, including several intact ECM macromolecules and/or fragments called matrikines4. Among them, the NC1 domains of several collagen chains have been shown to inhibit angiogenesis and tumor growth5C10 integrin binding and through the FAK/PI3K/Akt pathway10C16. Matrikine binding to the receptor and biological activity look like conformation dependent17,18. The NC1 4(IV) website, named Tetrastatin, was shown to exert potent anti-tumor activity both and in a human being melanoma model by reducing the proliferative and invasive properties of melanoma cells through an v3 integrin-dependant mechanism. We also shown the last fifty amino-acids LGR4 antibody of Tetrastatin (AA 180C229, named CS-50) were able to reproduce its inhibitory effects on cell proliferation and invasion tumor growth inside a mouse melanoma model B16-F1 cells were subcutaneously injected into the remaining part of C57Bl6 mice and the tumor volume was measured at days 10, 15 and 20. Tetrastatin and CS-50 treatments induced a decrease in tumor volume of 51 and 52%, respectively, at day time 20 versus control. The N-terminal 13-amino acid fragment from Tetrastatin (AA 217C229), named QS-13, inhibited tumor growth by NVS-PAK1-1 95% (Fig.?1a). Open in a separate window Number 1 QS-13 peptide inhibits tumor growth, SK-MEL-28 melanoma NVS-PAK1-1 cell proliferation, colony formation, migration and invasion. Tumor growth was measured at day time 20 inside a mouse melanoma model (a). Cell proliferation was measured after 72?h of incubation (b). Colony formation in smooth agar was measured after 10 days of incubation (c). Cell migration in scuff wound assay was measured after 48?h of incubation. (d) Cell invasion through Matrigel-coated membranes was measured after 48?h of incubation (e) **p? ?0.01, ***p? ?0.001. QS-13 inhibits melanoma cell proliferation, migration and invasion SK-MEL-28 cell proliferation was measured using WST-1 as the reagent. After 72?h of incubation with peptides, cell proliferation was inhibited by 30% with Tetrastatin and 26% with the CS-50 peptide. QS-13 inhibited cell proliferation by 42% (Fig.?1b). The different peptides were also tested on SK-MEL-28 colony formation in smooth agar. Tetrastatin and CS-50 inhibited cell growth by 64 and 62%, respectively, whereas the inhibitory effect was 80% with the QS-13 peptide (Fig.?1c). In an artificial wound assay, Tetrastatin, CS-50 and QS-13 inhibited cell migration by 27%, NVS-PAK1-1 30% and 30%, respectively (Fig.?1d). In revised Boyden chambers with Matrigel-coated membranes, Tetrastatin, CS-50 and QS-13 inhibited SK-MEL-28 cell invasion by 52%, 44% and 49.5%, respectively (Fig.?1e). Our results demonstrate the QS-13 peptide reproduces the Tetrastatin inhibitory effects and experiments were carried out. The presence of a disulphide relationship in the QS-13 peptide was determined by MALDI-ToF experiments. Taken together, the results of the MD simulations emphasize the part of this disulfide relationship in the structure of the different investigated peptides. The presence of the disulfide relationship restrains the explored construction space, therefore leading to a lower quantity of clusters. In addition, the constraint imposed by the presence of the disulfide relationship leads to a better exposure of the side chains (glutamine and valine central residues as well as arginine and lysine residues). When considering the connection with v3, through docking experiments, we highlighted the importance of the disulfide relationship since it clearly enhances the ideals of.