A Pleiotrophin C-terminus peptide induces anti-cancer effects through RPTPβ/ζ

<p>Abstract</p> <p>Background</p> <p>Pleiotrophin, also known as HARP (Heparin Affin Regulatory Peptide) is a growth factor expressed in various tissues and cell lines. Pleiotrophin participates in multiple biological actions including the induction of cellular proliferation, migration and angiogenesis, and is involved in carcinogenesis. Recently, we identified and characterized several pleiotrophin proteolytic fragments with biological activities similar or opposite to that of pleiotrophin. Here, we investigated the biological actions of P(122-131), a synthetic peptide corresponding to the carboxy terminal region of this growth factor.</p> <p>Results</p> <p>Our results show that P(122-131) inhibits <it>in vitro </it>adhesion, anchorage-independent proliferation, and migration of DU145 and LNCaP cells, which express pleiotrophin and its receptor RPTPβ/ζ. In addition, P(122-131) inhibits angiogenesis <it>in vivo</it>, as determined by the chicken embryo CAM assay. Investigation of the transduction mechanisms revealed that P(122-131) reduces the phosphorylation levels of Src, Pten, Fak, and Erk¹/₂. Finally, P(122-131) not only interacts with RPTPβ/ζ, but also interferes with other pleiotrophin receptors, as demonstrated by selective knockdown of pleiotrophin or RPTPβ/ζ expression with the RNAi technology.</p> <p>Conclusions</p> <p>In conclusion, our results demonstrate that P(122-131) inhibits biological activities that are related to the induction of a transformed phenotype in PCa cells, by interacing with RPTPβ/ζ and interfering with other pleiotrophin receptors. Cumulatively, these results indicate that P(122-131) may be a potential anticancer agent, and they warrant further study of this peptide.</p

Suppression of Tumor Growth and Angiogenesis by a Specific Antagonist of the Cell-Surface Expressed Nucleolin

BACKGROUND: Emerging evidences suggest that nucleolin expressed on the cell surface is implicated in growth of tumor cells and angiogenesis. Nucleolin is one of the major proteins of the nucleolus, but it is also expressed on the cell surface where is serves as a binding protein for variety of ligands implicated in cell proliferation, differentiation, adhesion, mitogenesis and angiogenesis. METHODOLOGY/PRINCIPAL FINDINGS: By using a specific antagonist that binds the C-terminal tail of nucleolin, the HB-19 pseudopeptide, here we show that the growth of tumor cells and angiogenesis are suppressed in various in vitro and in vivo experimental models. HB-19 inhibited colony formation in soft agar of tumor cell lines, impaired migration of endothelial cells and formation of capillary-like structures in collagen gel, and reduced blood vessel branching in the chick embryo chorioallantoic membrane. In athymic nude mice, HB-19 treatment markedly suppressed the progression of established human breast tumor cell xenografts in nude mice, and in some cases eliminated measurable tumors while displaying no toxicity to normal tissue. This potent antitumoral effect is attributed to the direct inhibitory action of HB-19 on both tumor and endothelial cells by blocking and down regulating surface nucleolin, but without any apparent effect on nucleolar nucleolin. CONCLUSION/SIGNIFICANCE: Our results illustrate the dual inhibitory action of HB-19 on the tumor development and the neovascularization process, thus validating the cell-surface expressed nucleolin as a strategic target for an effective cancer drug. Consequently, the HB-19 pseudopeptide provides a unique candidate to consider for innovative cancer therapy

Tumor stiffening reversion through collagen crosslinking inhibition improves T cell migration and anti-PD-1 treatment

Only a fraction of cancer patients benefits from immune checkpoint inhibitors. This may be partly due to the dense extracellular matrix (ECM) that forms a barrier for T cells. Comparing five preclinical mouse tumor models with heterogeneous tumor microenvironments, we aimed to relate the rate of tumor stiffening with the remodeling of ECM architecture and to determine how these features affect intratumoral T cell migration. An ECM-targeted strategy, based on the inhibition of lysyl oxidase, was used. In vivo stiffness measurements were found to be strongly correlated with tumor growth and ECM crosslinking but negatively correlated with T cell migration. Interfering with collagen stabilization reduces ECM content and tumor stiffness leading to improved T cell migration and increased efficacy of anti-PD-1 blockade. This study highlights the rationale of mechanical characterizations in solid tumors to understand resistance to immunotherapy and of combining treatment strategies targeting the ECM with anti-PD-1 therapy

Targeting surface nucleolin with a multivalent pseudopeptide delays development of spontaneous melanoma in RET transgenic mice

<p>Abstract</p> <p>Background</p> <p>The importance of cell-surface nucleolin in cancer biology was recently highlighted by studies showing that ligands of nucleolin play critical role in tumorigenesis and angiogenesis. By using a specific antagonist that binds the C-terminal tail of nucleolin, the HB-19 pseudopeptide, we recently reported that HB-19 treatment markedly suppressed the progression of established human breast tumor cell xenografts in the athymic nude mice without apparent toxicity.</p> <p>Methods</p> <p>The <it>in vivo </it>antitumoral action of HB-19 treatment was assessed on the spontaneous development of melanoma in the RET transgenic mouse model. Ten days old RET mice were treated with HB-19 in a prophylactic setting that extended 300 days. In parallel, the molecular basis for the action of HB-19 was investigated on a melanoma cell line (called TIII) derived from a cutaneous nodule of a RET mouse.</p> <p>Results</p> <p>HB-19 treatment of RET mice caused a significant delay in the onset of cutaneous tumors, several-months delay in the incidence of large tumors, a lower frequency of cutaneous nodules, and a reduction of visceral metastatic nodules while displaying no toxicity to normal tissue. Moreover, microvessel density was significantly reduced in tumors recovered from HB-19 treated mice compared to corresponding controls. Studies on the melanoma-derived tumor cells demonstrated that HB-19 treatment of TIII cells could restore contact inhibition, impair anchorage-independent growth, and reduce their tumorigenic potential in mice. Moreover, HB-19 treatment caused selective down regulation of transcripts coding matrix metalloproteinase 2 and 9, and tumor necrosis factor-α in the TIII cells and in melanoma tumors of RET mice.</p> <p>Conclusions</p> <p>Although HB-19 treatment failed to prevent the development of spontaneous melanoma in the RET mice, it delayed for several months the onset and frequency of cutaneous tumors, and exerted a significant inhibitory effect on visceral metastasis. Consequently, HB-19 could provide a novel therapeutic agent by itself or as an adjuvant therapy in association with current therapeutic interventions on a virulent cancer like melanoma.</p

Effets anti-tumoraux de peptides issus de la structure du facteur de croissance HARP via les récepteurs ALK et RPTPb

HARP est un facteur de croissance jouant un rôle-clé dans la progression et dans l invasion tumorale. C est une molécule multifonctionnelle possédant des activités mitogène, transformante et angiogène. L activité de HARP est mediée par deux types de récepteurs transmembranaires; RPTPb et ALK. La structure de HARP est constituée de deux domaines homologues aux TSR motifs et de deux régions basiques aux extrémités N- et C-terminaux. Les travaux précédents de notre équipe ont montré l implication de la région C-terminal de HARP dans ses activités dépendantes de ALK. Le but de mon travail de thèse a été d approfondir ces recherches et plus particulièrement sur les relations structure-fonction de HARP. Dans ce dessein, nous avons synthétisé deux peptides dérivant de l extrémité C-terminal de HARP: les peptides P111-124 et P122-131. Le peptide P111-124 a inhibé les activités mitogène et transformante de HARP dans un modèle de cancer de prostate humain, entrant en compétition avec la fixation de HARP sur son récepteur ALK. Ce peptide inhibe également la croissance tumorale de ces cellules dans les souris athymiques et des études pharmacocinétiques ont confirmé la présence du peptide dans la tumeur et sa bio distribution efficace après l injection intraveineuse. Le peptide P122-131 a inhibé la migration cellulaire, l adhésion et l angiogénèse induite par HARP via RPTPb. Des études de biosensor, utilisant les peptides correspondant aux domaines C-terminal et TSR de HARP nous ont permis de mieux comprendre le mécanisme d action de HARP via les voies de signalisation HARP/ALK/héparine/RPTPb. Enfin, des études portant sur la recherche d autres partenaires ont mis en évidence que HARP entre en interaction avec de nombreuses molécules telles que FGF2, FGF-BP, VEGF, NPN-1, HGF/SF, S100A4 et OPN. En conclusion, ce travail ouvre de nouvelles perspectives portant sur l étude du mécanisme moléculaire de HARP et sur l utilisation potentielle de deux peptides ciblant ALK et RPTPb dans le traitement du cancer.HARP is a heparin-binding growth factor, which plays a key role in tumor growth and invasion. It is a multifunctional polypeptide with mitogenic, transforming and angiogenic activities. HARP mediates its diverse functions through its main transmembrane receptors: RPTPb and ALK. Structurally, HARP contains two TSR homologous domains and two basic clusters in its N and C-termini. Previous studies from our laboratory have reported that the ALK-dependent biological activities of HARP were related to its C-terminal region including the amino acid residues 111-136. The aim of this thesis was to further elucidate the structure-function relationship of HARP. In this aim, we designed two synthetic peptides derived from the Cterminal region. P111-124 inhibited the mitogenic and transforming activities of HARP in a prostatic cancer cell model, by specifically competing with HARP for binding to ALK. The peptide inhibited the tumor growth of these cells in nude mice and the in vivo pharmacokinetic studies indicated the efficient targeting of the peptide to the tumor. P122-131 inhibited HARPinduced cell migration, adhesion and in vivo angiogenesis, by binding to RPTPb. The biosensor studies using the C-terminal and TSR peptides allowed us to better understand the mechanisms that underpin the signaling features of HARP/ALK/heparin/RPTPb. Finally, the binding assays with biosensor revealed the interaction of HARP with a subset of proteins including FGF2, FGFBP, VEGF, NPN-1, HGF/SF, S100A4 and OPN. In conclusion, this thesis yielded new insights in mechanism of action of HARP. The discovery of new molecular partners for HARP implies new avenues for regulatory interplay of the protein. The thesis also highlights the potential of the two anti-tumoral peptides targeting ALK and RPTPb, as therapeutical agents against cancer.PARIS12-Bib. électronique (940280011) / SudocSudocFranceF