[Macrovipera lebetina obtusa Snake Venom as a Modulator of Antitumor Effect in S-180 Sarcoma Mouse Model].

Macrovipera lebetina obtusa (MLO) is a venomous snake endemic to Middle East. Here we describe the therapeutic potential of the MLO snake venom. In S-180 sarcoma-bearing mouse model, we showed that the MLO snake venom inhibits tumour growth by 50%. In human dermal microvascular endothelial cells (HMVEC-D), treatment with the MLO snake venom lead to an increase of expression levels of the vascular endothelial growth factor (VEGF), while the level of the expression of caspase 8 did not change. In HMVEC-D cells MLO snake venom induces necroptosis, rather than apoptosis. In the chick embryo chorioallantoic membrane (CAM) assay, exposure to MLO snake venom inhibited bFGF-induced angiogenesis by 22%. Taken together, these results indicate that the MLO snake venom has a potent cytotoxic activity. Regulated necroptic cell death pathway, which is engaged by MLO snake venom, may become a promising novel target for antitumor therapies.

The Synergy of Membranotropic Effect of the Two Pla2 Fractions of Macrovipera lebetina obtusa Venom on the Model Membranes.

It is known that snake venoms are a complex of enzymes and proteins and the interaction of different venom components with the membranes could be significantly enhanced in course of their action in an orchestra. The aim of the proposed investigation is to obtain detailed information about the mechanism and topology of two snake venom PLA2 isoforms from the Macrovipera lebetina obtusa venom in the membrane-binding process. We investigated the impact of the interaction on the properties of the model membrane (namely, GUVs and erythrocytes ghost) for each of these isoforms, as well as their synergetic action if they act simultaneously. The 6-lauroyl-2-dimethylaminonaphthalene and 6-propionyl-2-dimethylaminonaphthalene fluorescence probes were used to allow us to determine the membrane polarity more accurately via a generalized polarization function. Our results show that two types of PLA2 bring viscosity reduction in GUVs membrane and the effect became more potent when these PLA2 acts together. Intriguingly, we have not observed any significant difference in the case of the erythrocytes ghost membrane.

Dimeric Disintegrins from the Steppe Viper V. ursinii Venom.

Four dimeric disintegrins were isolated from the venom of the steppe viper V. ursinii using liquid chromatography. Disintegrins prevented adhesion of MCF7 cells to fibronectin, which indicates their interaction with integrin receptors of the αVß1 type. According to mass spectrometry data, the molar masses of disintegrins are about 14 kDa. The method of peptide mapping established the structure of a new heterodimeric disintegrin weighing 13 995.5 Da and shows that it belongs to the class of RGD/KGD-containing disintegrins.

Morphological changes of proteolipid giant unilamellar vesicles affected by Macrovipera lebetina obtusa venom visualized with fluorescence microscope.

As a rule, zootoxins are complex and biologically active, and therefore the greater part of zootoxins is subjected to biotransformation and interacts with biological membranes. In this case, the interaction of different venom components with the membranes is not always the same. The present study shows how the giant unilamellar vesicles (GUV) from bovine brain proteolipids interact with Macrovipera lebetina obtusa venom. GUV (mean diameter 30 µm) were formed by the electroformation method. We used 8-anilino-1-naphthalenesulfonic acid and pyrene as fluorescence probes, which allowed us to quantify the fluidity changes in the membrane by measuring the fluorescence intensity.