MVL-PLA2, a Snake Venom Phospholipase A2, Inhibits Angiogenesis through an Increase in Microtubule Dynamics and Disorganization of Focal Adhesions

Integrins are essential protagonists of the complex multi-step process of angiogenesis that has now become a major target for the development of anticancer therapies. We recently reported and characterized that MVL-PLA2, a novel phospholipase A2 from Macrovipera lebetina venom, exhibited anti-integrin activity. In this study, we show that MVL-PLA2 also displays potent anti-angiogenic properties. This phospholipase A2 inhibited adhesion and migration of human microvascular-endothelial cells (HMEC-1) in a dose-dependent manner without being cytotoxic. Using Matrigel™ and chick chorioallantoic membrane assays, we demonstrated that MVL-PLA2, as well as its catalytically inactivated form, significantly inhibited angiogenesis both in vitro and in vivo. We have also found that the actin cytoskeleton and the distribution of αvβ3 integrin, a critical regulator of angiogenesis and a major component of focal adhesions, were disturbed after MVL-PLA2 treatment. In order to further investigate the mechanism of action of this protein on endothelial cells, we analyzed the dynamic instability behavior of microtubules in living endothelial cells. Interestingly, we showed that MVL-PLA2 significantly increased microtubule dynamicity in HMEC-1 cells by 40%. We propose that the enhancement of microtubule dynamics may explain the alterations in the formation of focal adhesions, leading to inhibition of cell adhesion and migration

Pharmacological Aspects of Vipera xantina palestinae Venom

In Israel, Vipera xantina palestinae (V.x.p.) is the most common venomous snake, accounting for several hundred cases of envenomation in humans and domestic animals every year, with a mortality rate of 0.5 to 2%. In this review we will briefly address the research developments relevant to our present understanding of the structure and function of V.x.p. venom with emphasis on venom disintegrins. Venom proteomics indicated the presence of four families of pharmacologically active compounds: (i) neurotoxins; (ii) hemorrhagins; (iii) angioneurin growth factors; and (iv) different types of integrin inhibitors. Viperistatin, a α1β1selective KTS disintegrin and VP12, a α2β1 selective C-type lectin were discovered. These snake venom proteins represent promising tools for research and development of novel collagen receptor selective drugs. These discoveries are also relevant for future improvement of antivenom therapy towards V.x.p. envenomation

Human Fibrosarcoma Targetting Integrins with Cucurbitacin B Purified from Ecballium elaterium (L.) A. Rich

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Chemical Composition and Biological Activities of Allium roseum L. var. grandiflorum Briq. Essential Oil.

International audienceAllium roseum L. (Alliaceae) endemic mediterranean specie was represented in the North Africa by 12 different taxa. In the present study, chemical composition, antiproliferative, antioxidant and antimicrobial activities of the essential oil extracted from A. roseum var. grandiflorum Briq. bulbs collected in the North of Tunisia were investigated. Chemical characterization has shown methyl methanethiosulfinate as major sulphurous compounds. A. roseum bulbs essential oil provides interesting antiproliferative activity against two human colonic adenocarcinoma HT29 and CACO2 cell lines in dose-dependent manner with a half-maximal inhibition (IC50) of 4.64 µg/mL and 8.22 µg/mL respectively. The antioxidant activity, as determined by FRAP assay, was 285 µmol equivalent Trolox/g of essential oil. The scavenging effect on DPPH radicals of essential oil was estimated as IC50 values at 156 µg/mL. The inhibition of superoxide anion production in a model of cancer cell lines was significant for both lines HT29 and CACO2 with IC50 of 20.25 µg/mL and 29.12 µg/mL respectively. Allium roseum essential oil exhibited antibacterial and antifungal activities with a high effectiveness against Candida albicans given by an MIC value of 0.019 mg/mL. This biological effect appears to be related mainly to the presence of organosulfur compounds

Ecballium elaterium (L.) A. Rich. seed oil: Chemical composition and antiproliferative effect on human colonic adenocarcinoma and fibrosarcoma cancer cell lines

International audienceIn this work the physicochemical characteristics including fatty acids, tocopherols and sterols composition of Ecballium elaterium (L.) A. Rich seed oil was determined. Results showed that linoleic acid (48.64%) and punicic acid (22.38%) were the major polyunsaturated fatty acids. Among the phytosterols, b-sitosterol was the most abundant (396.25 mg/100 g), while the major tocopherol form was c-tocopherol (44.23 mg/100 g). In addition, we evaluated for the first time the effect of E. elaterium seed oil on the growth of human colonic adenocarcinoma (HT29) and fibrosarcoma (HT1080) cell lines. The original finding was its potent antiproliferative effect on both tumour cell lines. This effect was dose-dependent, with half-maximal inhibition values of IC50 = 4.86 lg/ml and 4.16 lg/ml respectively. This pilot study opens the way for further investigation about the potential use of E. elaterium as an anticancer agent

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

International audienceIntegrin 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 mg mL −1), results show that PEO dosedependently inhibits adhesion and migration of HT1080 to fibronectin (IC 50 = 18 mg mL −1) and fibrinogen (IC 50 = 12.86 mg 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 mg mL −1) competitively inhibited the attachment of HT1080 cell to anti-avb3 (>98%), anti-a5b1 (>86%), and to a lesser extent anti-a2 (>50%) immobilized antibodies, suggesting that avb3 and a5b1 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 antiangiogenic 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 α5β1 integrin-mediated adhesion, migration, proliferation of human glioblastoma cell line and angiogenesis

International audienceIntegrins 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 α5β1 integrins. These findings reveal a novel mechanism of action for cucurbitacin B, which displays a potential interest as a specific anti-integrin drug

Structure Function Relationships of KTS Disintegrins and Design of Antiangiogenic Drugs

International audienceDisintegrins are natural toxins found in snake venom having anti angiogenic activity. The KTS disintegrins group appears to be the most interesting as specific blocking agent of tumor growth. We report the chemical synthesis of three KTS disintegrins (Lebestatin, Obtustatin and Viperistatin) carried out with different substitution. The activity of these synthetic peptides (41 aa) and native Lebestatin purified from venom was compared with cell adhesion and migration assays. Synthetic and native Lebestatin inhibit cell adhesion of PC12 cells at 0.2 nM and integrin-dependent migration of CHO cells at 1 nM. This study shows that Lebestatin has the highest activity followed by Obtustatin and then Viperistatin in the two assays. Circular dichroism spectra of these KTS disintegrins show that their folding is similar. Molecular modeling shows that two arginines (8 and 24) and two lysines (21 and 32) have probably their chemical function interacting with integrins in protruding from the surface of Lebestatin. This study should help to design a lead compound to discover a new family of anti-angiogenic drugs

Targetting alphavbeta3 and alpha5beta1 integrins with Ecballium elaterium (L.) A. Rich. seed oil

International audienceIn 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 TM assays, the oil significantly inhibited angiogenesis. The anti-tumor effect of the oil is specifically mediated by avb3 and a5b1 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

Two purified and characterized phospholipases A2 from Cerastes cerastes venom, that inhibit cancerous cell adhesion and migration.

International audienceTwo non-toxic PLA2s were purified to homogeneity from Cerastes cerastes Tunisian snake venom. The purification process employed gel filtration on Sephadex G-75 followed by C18 reverse phase high-pressure liquid chromatography. These two acidic enzymes, namely CC-PLA2-1 and CC-PLA2-2, have a molecular weight of 13,737.52 and 13,705.63 Da, respectively. These two PLA2 are the first reported glycosylated phospholipases A2 purified from snake venom. The rates of glycosylation are 2.5% and 0.5% (w/w), respectively. Specific activities of 1800 U/mg and 2400 U/mg for CC-PLA2-1 and CC-PLA2-2, respectively, were measured at optimal conditions. CC-PLA2-1 and CC-PLA2-2 strongly inhibited coagulation. They also exhibited a marked dose-dependent inhibitory effect on platelet aggregation induced by ADP and arachidonic acid in platelet-rich plasma. Interestingly, CC-PLA2-1 and CC-PLA2-2 inhibited in a dose-dependent manner adhesion of IGR39 melanoma and HT1080 fibrosarcoma cells to fibrinogen and fibronectin. Furthermore, both CC-PLA2-1 and CC-PLA2-2 abolished HT1080 cell migration towards fibrinogen and fibronectin. This activity is reported for the first time for PLA2 enzymes