Identification of TAX2 peptide as a new unpredicted anti-cancer agent

Abstract

The multi-modular glycoprotein thrombospondin-1 (TSP-1) is considered as a key actor within the tumor microenvironment. Besides, TSP-1 binding to CD47 is widely reported to regulate cardiovascular function as it promotes vasoconstriction and angiogenesis limitation. Therefore, many studies focused on targeting TSP-1:CD47 interaction, aiming for up-regulation of physiological angiogenesis to enhance post-ischemia recovery or to facilitate engraftment. Thus, we sought to identify an innovative selective antagonist for TSP-1:CD47 interaction. Protein-protein docking and molecular dynamics simulations were conducted to design a novel CD47-derived peptide, called TAX2. TAX2 binds TSP-1 to prevent TSP-1:CD47 interaction, as revealed by ELISA and co-immunoprecipitation experiments. Unexpectedly, TAX2 inhibits in vitro and ex vivo angiogenesis features in a TSP-1-dependent manner. Consistently, our data highlighted that TAX2 promotes TSP-1 binding to CD36-containing complexes, leading to disruption of VEGFR2 activation and downstream NO signaling. Such unpredicted results prompted us to investigate TAX2 potential in tumor pathology. A multimodal imaging approach was conducted combining histopathological staining, MVD, MRI analysis and μCT monitoring for tumor angiography longitudinal follow-up and 3D quantification. TAX2 in vivo administrations highly disturb syngeneic melanoma tumor vascularization inducing extensive tumor necrosis and strongly inhibit growth rate and vascularization of human pancreatic carcinoma xenografts in nude mice.

Matricellular TSP-1 as a target of interest for impeding melanoma spreading: towards a therapeutic use for TAX2 peptide

“…S2, see Fig. S1 for histologic analysis scoring grids), which is consistent with previous observations made in a syngeneic allograft model [14]. Of note, no treatment-related toxicity was reported as no adverse clinical signs nor body weight loss (Fig.…”

“…In a previous work, we identified and validated TAX2 cyclic peptide as an orthosteric antagonist for TSP-1:CD47 interaction [14]. Here, we first confirmed by SPR spectroscopy that TAX2 peptide binds TSP-1 whereas a scrambled peptide does not (Fig.…”

“…Among TSP-1 matricellular receptors, CD47 appeared as a main hub within this network, hereby presenting itself as a putative key mediator of TSP-1-mediated modulation of malignant progression. We therefore considered TAX2, a previously validated cyclic peptide that binds TSP-1 at the CD47 binding site [14], to investigate the effects of disrupting TSP-1:CD47 interaction in A375 human melanoma xenografts. In this model, TAX2 systemic administrations decrease tumor viable tissue by inducing tumor necrosis and inhibit tumor-associated vascularization as well as blood flow, while remarkably limiting tumor invasiveness.…”

“…TAX2 peptide (CEVSQLLKGDAC) acting as a specific antagonist for TSP-1:CD47 interaction [14] was synthesized and purified by Genecust (Dudelange, Luxembourg) and then controlled for composition and purity through electrospray ionization-mass spectrometry (ESI-MS) and HPLC. Disulfide bridge cyclisation was ensured by Raman spectroscopy.…”

“…We previously designed and characterized an innovative cyclopeptide, named TAX2, which specifically targets TSP-1 at the CD47-binding site [14]. This peptide can compete with CD47 for the binding of TSP-1.…”