Inhibitory effect of phenolic extract from squirting cucumber (Ecballium elaterium (L.) A. Rich) seed oil on integrin-mediated cell adhesion, migration and angiogenesis.

Integrin targeted therapies by natural bioactive compounds have attracted attention in the field of oncology and cancer treatment. This study evaluates the potential of phenolic extract from the medicinal herb Ecballium elaterium L. seed oil (PEO) to inhibit the adhesion and migration of the highly invasive human fibrosarcoma cell line HT1080. At safe concentrations (up to 40 µg mL-1), results show that PEO dose-dependently inhibits adhesion and migration of HT1080 to fibronectin (IC50 = 18 µg mL-1) and fibrinogen (IC50 = 12.86 µg mL-1). These observations were associated with the reduction of cell motility and migration velocity as revealed in the Boyden chamber and random motility using two-dimensional assays, respectively. Additional experiments using integrin blocking antibodies showed that PEO at the highest safe concentration (40 µg mL-1) competitively inhibited the attachment of HT1080 cell to anti-αvß3 (>98%), anti-α5ß1 (>86%), and to a lesser extent anti-α2 (>50%) immobilized antibodies, suggesting that αvß3 and α5ß1 integrins were selectively targeted by PEO. Moreover, PEO specifically targeted these integrins in human microvascular endothelial cells (HMEC-1) and dose-dependently blocked the in vitro tubulogenesis. In the CAM model, PEO inhibited the VEGF-induced neoangiogenesis confirming its anti-angiogenic effect. Collectively, these results indicate that PEO holds promise for the development of natural integrin-targeted therapies against fibrosarcoma.

Cucurbitacin B purified from Ecballium elaterium (L.) A. Rich from Tunisia inhibits α5ß1 integrin-mediated adhesion, migration, proliferation of human glioblastoma cell line and angiogenesis.

Integrins are essential protagonists in the complex multistep process of cancer progression and are thus attractive targets for the development of anticancer agents. Cucurbitacin B, a triterpenoid purified from the leaves of Tunisian Ecballium elaterium exhibited an anticancer effect and displayed anti-integrin activity on human glioblastoma U87 cells, without being cytotoxic at concentrations up to 500nM. Here we show that cucurbitacin B affected the adhesion and migration of U87 cells to fibronectin in a dose-dependent manner with IC50 values of 86.2nM and 84.6nM, respectively. Time-lapse videomicroscopy showed that cucurbitacin B significantly reduced U87 cells motility and affected directional persistence. Cucurbitacin B also inhibited proliferation with IC50 value of 70.1nM using Crystal Violet assay. Moreover, cucurbitacin B efficiently inhibited in vitro human microvascular endothelial cells (HMEC) angiogenesis with concentration up to 10nM. Interestingly, we demonstrate for the first time that this effect was specifically mediated by α5ß1 integrins. These findings reveal a novel mechanism of action for cucurbitacin B, which displays a potential interest as a specific anti-integrin drug.

Targetting αvß3 and α5ß1 integrins with Ecballium elaterium (L.) A. Rich. seed oil.

In the present study, the effect of Ecbalium elaterium seed oil on adhesion, migration and proliferation of human brain cancer cell line (U87) was determined. Treatment of U87 cell line with the seed oil resulted in strong inhibition of their adhesion to fibrinogen (Fg), fibronectin (Fn). It also reduced their migration and proliferation in a dose-dependent manner without being cytotoxic. Concomitantly, by using Matrigel™ assays, the oil significantly inhibited angiogenesis. The anti- tumor effect of the oil is specifically mediated by αvß3 and α5ß1 integrins. The presence of integrin antagonists in seed oil from E. elaterium could be used for the development of anticancer drugs with targeted "multi-modal" therapies combining anti-adhesif, antiproliferative, antimetastasic and anti-angiogenic, approaches.