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The fibroblast growth factor (FGF)/FGF receptor (FGFR) system plays a crucial role in cancer by affecting tumor growth, angiogenesis, drug resistance, and escape from anti-angiogenic anti-vascular endothelial growth factor therapy. The soluble pattern recognition receptor long-pentraxin 3 (PTX3) acts as a multi-FGF antagonist. Here we demonstrate that human PTX3 overexpression in transgenic mice driven by the Tie2 promoter inhibits tumor growth, angiogenesis, and metastasis in heterotopic, orthotopic, and autochthonous FGF-dependent tumor models. Using pharmacophore modeling of the interaction of a minimal PTX3-derived FGF-binding pentapeptide with FGF2, we identified a small-molecule chemical (NSC12) that acts as an extracellular FGF trap with significant implications in cancer therapy., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Fibroblast growth factor-8b (FGF8b) affects the epithelial/stromal compartments of steroid hormone-regulated tumors by exerting an autocrine activity on cancer cells and a paracrine pro-angiogenic function, thus contributing to tumor progression. The FGF8b/FGF receptor (FGFR) system may therefore represent a target for the treatment of steroid hormone-regulated tumors. The soluble pattern recognition receptor long pentraxin-3 (PTX3) binds various FGFs, including FGF2 and FGF8b, thus inhibiting the angiogenic and tumorigenic activity of androgen-regulated tumor cells. Nevertheless, the complex/proteinaceous structure of PTX3 hampers its pharmacological exploitation. In this context, the acetylated pentapeptide Ac-ARPCA-NH2 (ARPCA), corresponding to the N-terminal amino acid sequence PTX3(100-104), was identified as a minimal FGF2-binding peptide able to antagonize the biological activity of FGF2. Here, we demonstrate that ARPCA binds FGF8b and inhibits its capacity to form FGFR1-mediated ternary complexes with heparan sulphate proteoglycans. As a FGF8b antagonist, ARPCA inhibits FGFR1 activation and signalling in endothelial cells, hampering the angiogenic activity exerted in vitro and in vivo by FGF8b. Also, ARPCA suppresses the angiogenic and tumorigenic potential of prototypic androgen/FGF8b-dependent Shionogi 115 mammary carcinoma cells and of androgen/FGF8b/FGF2-dependent TRAMP-C2 prostate cancer cells. In conclusion, ARPCA represents a novel FGF8b antagonist with translational implications for the therapy of steroid hormone-regulated tumors.

During melanoma progression, malignant melanocytes are reprogrammed into mesenchymal-like cells through to an epithelial-mesenchymal transition (EMT) process associated with the acquisition of an invasive, prometastatic phenotype. The fibroblast growth factor-2 (FGF2)/FGF receptor (FGFR) system plays a pivotal role in melanoma, leading to autocrine/paracrine induction of tumor cell proliferation and angiogenesis. Long pentraxin-3 (PTX3) interacts with FGF2, and other FGF family members, inhibiting FGF-dependent neovascularization and tumor growth. Here, PTX3 protein and the PTX3-derived acetylated pentapeptide Ac-ARPCA-NH2 inhibit FGF2-driven proliferation and downstream FGFR signaling in murine melanoma B16-F10 cells. Moreover, human PTX3-overexpressing hPTX_B16-F10 cells are characterized by the reversed transition from a mesenchymal to an epithelial-like appearance, inhibition of cell proliferation, loss of clonogenic potential, reduced motility and invasive capacity, downregulation of various mesenchymal markers, and upregulation of the epithelial marker E-cadherin. Accordingly, PTX3 affects cell proliferation and EMT transition in human A375 and A2058 melanoma cells. Also, hPTX_B16-F10 cells showed a reduced tumorigenic and metastatic activity in syngeneic C57BL/6 mice. In conclusion, PTX3 inhibits FGF/FGFR-driven EMT in melanoma cells, hampering their tumorigenic and metastatic potential. These data represent the first experimental evidence about a nonredundant role of the FGF/FGFR system in the modulation of the EMT process in melanoma and indicate that PTX3 or its derivatives may represent the basis for the design of novel therapeutic approaches in FGF/FGFR-dependent tumors, including melanoma., (©2013 AACR.)

Fibroblast growth factors (FGFs) exert autocrine/paracrine functions in prostate cancer by stimulating angiogenesis and tumour growth. Here dihydrotestosterone (DHT) up-regulates FGF2 and FGF8b production in murine TRAMP-C2 prostate cancer cells, activating a FGF-dependent autocrine loop of stimulation. The soluble pattern recognition receptor long pentraxin-3 (PTX3) acts as a natural FGF antagonist that binds FGF2 and FGF8b via its N-terminal domain. We demonstrate that recombinant PTX3 protein and the PTX3-derived pentapeptide Ac-ARPCA-NH2 abolish the mitogenic response of murine TRAMP-C2 cells and human LNCaP prostate cancer cells to DHT and FGFs. Also, PTX3 hampers the angiogenic activity of DHT-activated TRAMP-C2 cells on the chick embryo chorioallantoic membrane (CAM). Accordingly, human PTX3 overexpression inhibits the mitogenic activity exerted by DHT or FGFs on hPTX3_TRAMP-C2 cell transfectants and their angiogenic activity. Also, hPTX3_TRAMP-C2 cells show a dramatic decrease of their angiogenic and tumourigenic potential when grafted in syngeneic or immunodeficient athymic male mice. A similar inhibitory effect is observed when TRAMP-C2 cells overexpress only the FGF-binding N-terminal PTX3 domain. In keeping with the anti-tumour activity of PTX3 in experimental prostate cancer, immunohistochemical analysis of prostate needle biopsies from primary prostate adenocarcinoma patients shows that parenchymal PTX3 expression, abundant in basal cells of normal glands, is lost in high-grade prostatic intraepithelial neoplasia and in invasive tumour areas. These results identify PTX3 as a potent FGF antagonist endowed with anti-angiogenic and anti-neoplastic activity in prostate cancer., (Copyright © 2013 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.)

Objective: Angiogenesis is regulated by the balance between pro- and antiangiogenic factors and by extracellular matrix protein interactions. Fibroblast growth factor 2 (FGF2) is a major proangiogenic inducer inhibited by the interaction with the soluble pattern recognition receptor long pentraxin 3 (PTX3). PTX3 is locally coexpressed with its ligand tumor necrosis factor-stimulated gene-6 (TSG-6), a secreted glycoprotein that cooperates with PTX3 in extracellular matrix assembly. Here, we characterized the effect of TSG-6 on PTX3/FGF2 interaction and FGF2-mediated angiogenesis., Methods and Results: Solid phase binding and surface plasmon resonance assays show that TSG-6 and FGF2 bind the PTX3 N-terminal domain with similar affinity. Accordingly, TSG-6 prevents FGF2/PTX3 interaction and suppresses the inhibition exerted by PTX3 on heparan sulfate proteoglycan/FGF2/FGF receptor complex formation and on FGF2-dependent angiogenesis in vitro and in vivo. Also, endogenous PTX3 exerts an inhibitory effect on vascularization induced by FGF2 in a murine subcutaneous Matrigel plug assay, the inhibition being abolished in Ptx3-null mice or by TSG-6 treatment in wild-type animals., Conclusion: TSG-6 reverts the inhibitory effects exerted by PTX3 on FGF2-mediated angiogenesis through competition of FGF2/PTX3 interaction. This may provide a novel mechanism to control angiogenesis in those pathological settings characterized by the coexpression of TSG-6 and PTX3, in which the relative levels of these proteins may fine-tune the angiogenic activity of FGF2.