Long pentraxin‐3 as an epithelial–stromal fibroblast growth factor‐targeting inhibitor in prostate cancer

Abstract

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.

Long Pentraxin-3 Inhibits Epithelial–Mesenchymal Transition in Melanoma Cells

“…PTX3 and the PTX3-derived synthetic peptide ARPCA inhibit the mitogenic activity exerted by FGF2 on endothelial and tumor cells (19,21,22,24). Accordingly, recombinant PTX3 protein and the ARPCA pentapeptide inhibited the proliferation of B16-F10 cells following stimulation with FGF2 (Fig.…”

“…For the Matrigel assay, mice were injected subcutaneously with 250 mL of liquid Matrigel containing 1 Â 10 4 melanoma cells (22). After 7 days, plugs were harvested and processed for immunohistochemical analysis as described earlier.…”

“…For alginate implant assay, 7-week-old C57BL/6 mice (Charles River) were injected subcutaneously with 250 mL of 3.0% (w/v) sodium alginate solution (alginic acid dissolved in LPS-free PBS) containing 5 Â 10 4 melanoma cells (22). After 7 days, alginate implants were harvested, embedded in Tissue Tec OCT (Sigma-Aldrich), snap-frozen in liquid nitrogen-cooled isopentane, and analyzed by immunofluorescence microscopy.…”

“…PTX3 shares the C-terminal pentraxin domain with short pentraxins and possesses an unique N-terminal domain (18). PTX3 binds FGF2 (19,20) and other members of the FGF family (21,22) via its N-terminal extension, thus inhibiting FGF2-dependent endothelial cell proliferation in vitro and angiogenesis in vivo (18)(19)(20)23). Accordingly, the acetylated pentapeptide Ac-ARPCA-NH 2 (ARPCA), corresponding to the N-terminal PTX3-(100-104) sequence, represents the minimal FGF-binding peptide able to interfere with FGF/ FGFR interaction (24).…”

“…Accordingly, the acetylated pentapeptide Ac-ARPCA-NH 2 (ARPCA), corresponding to the N-terminal PTX3-(100-104) sequence, represents the minimal FGF-binding peptide able to interfere with FGF/ FGFR interaction (24). Moreover, PTX3 and ARPCA inhibit the FGF-dependent mitogenic, angiogenic, and tumorigenic potential of different tumor cell lines, including breast carcinoma (21) and prostate cancer cells (22).…”