Pentachloropseudilin Impairs Angiogenesis by Disrupting the Actin Cytoskeleton, Integrin Trafficking and the Cell Cycle.

Class 1 myosins (Myo1s) were the first unconventional myosins identified and humans have eight known Myo1 isoforms. The Myo1 family is involved in the regulation of gene expression, cytoskeletal rearrangements, delivery of proteins to the cell surface, cell migration and spreading. Thus, the important role of Myo1s in different biological processes is evident. In this study, we have investigated the effects of pentachloropseudilin (PClP), a reversible and allosteric potent inhibitor of Myo1s, on angiogenesis. We demonstrated that treatment of cells with PClP promoted a decrease in the number of vessels. The observed inhibition of angiogenesis is likely to be related to the inhibition of cell proliferation, migration and adhesion, as well as to alteration of the actin cytoskeleton pattern, as shown on a PClP-treated HUVEC cell line. Moreover, we also demonstrated that PClP treatment partially prevented the delivery of integrins to the plasma membrane. Finally, we showed that PClP caused DNA strand breaks, which are probably repaired during the cell cycle arrest in the G1 phase. Taken together, our results suggest that Myo1s participate directly in the angiogenesis process.

Shedding Lights on Crude Venom from Solitary Foraging Predatory Ant Ectatomma opaciventre: Initial Toxinological Investigation.

Some species of primitive predatory ants, despite living in a colony, exercise their hunting collection strategy individually; their venom is painful, paralyzing, digestive, and lethal for their prey, yet the toxins responsible for these effects are poorly known. Ectatomma opaciventre is a previously unrecorded solitary hunting ant from the Brazilian Cerrado. To overcome this hindrance, the present study performed the in vitro enzymatic, biochemical, and biological activities of E. opaciventre to better understand the properties of this venom. Its venom showed several proteins with masses ranging from 1-116 kDa, highlighting the complexity of this venom. Compounds with high enzymatic activity were described, elucidating different enzyme classes present in the venom, with the presence of the first L-amino acid oxidase in Hymenoptera venoms being reported. Its crude venom contributes to a state of blood incoagulability, acting on primary hemostasis, inhibiting collagen-induced platelet aggregation, and operating on the fibrinolysis of loose red clots. Furthermore, the E. opaciventre venom preferentially induced cytotoxic effects on lung cancer cell lines and three different species of Leishmania. These data shed a comprehensive portrait of enzymatic components, biochemical and biological effects in vitro, opening perspectives for bio-pharmacological application of E. opaciventre venom molecules.

The relationship between clinics and the venom of the causative Amazon pit viper (Bothrops atrox).

Snake venoms are complex mixtures of proteins with toxic activities, with many distinct isoforms, affecting different physiological targets, comprised in a few protein families. It is currently accepted that this diversity in venom composition is an adaptive advantage for venom efficacy on a wide range of prey. However, on the other side, variability on isoforms expression has implications in the clinics of human victims of snakebites and in the efficacy of antivenoms. B. atrox snakes are responsible for most of the human accidents in Brazilian Amazon and the type and abundance of protein families on their venoms present individual variability. Thus, in this study we attempted to correlate the individual venom proteome of the snake brought to the hospital by the patient seeking for medical assistance with the clinical signs observed in the same patient. Individual variability was confirmed in venoms of the 14 snakes selected for the study. The abundance of each protein family was quite similar among the venom samples, while the isoforms composition was highly variable. Considering the protein families, the SVMP group presented the best correlation with bleeding disorders and edema. Considering individual isoforms, some isoforms of venom metalloproteinase (SVMP), C-type lectin-like toxins (CTL) and snake venom serine proteinases (SVSP) presented expression levels that with statistically significant positive correlation to signs and symptoms presented by the patients as bleeding disorders, edema, ecchymosis and blister formation. However, some unexpected data were also observed as the correlation between a CTL, CRISP or LAAO isoforms with blister formation, still to be confirmed with a larger number of samples. Although this is still a small number of patient samples, we were able to indicate that venom composition modulates clinical manifestations of snakebites, to confirm at the bedside the prominent role of SVMPs and to include new possible toxin candidates for the development of toxin inhibitors or to improve antivenom selectiveness, important actions for the next generation treatments of snakebites.

Human breast cancer cell death induced by BnSP-6, a Lys-49 PLA2 homologue from Bothrops pauloensis venom.

This work shows the antitumoral effects of BnSP-6, a Lys 49 PLA2 isolated from Bothrops pauloensis venom, on human breast cancer MDA-MB-231 cells. BnSP-6 caused a dose-dependent cytotoxicity and inhibited cell adhesion. Interestingly, cytotoxic activity of BnSP-6 was significantly lower against MCF10A, a non-tumorigenic breast cell line, suggesting that this PLA2 presented a possible preference for targets in cancer cells. Analysis of cell death on MDA-MB-231 cells showed that BnSP-6 stimulated the autophagy process, as evidenced by labeling of autophagic vacuoles. Moreover, apoptosis assays showed that BnSP-6 induced both early and late apoptosis. Apoptosis of MDA-MB-231 cells was also confirmed by up-regulation of different genes related to the apoptosis pathway, such as TNF, TNFRSF10B, TNFRSF1A and CASP8 and decreased expression of anti-apoptotic genes (BCL2 and BCL2L). In addition, BnSP-6 caused a remarkable increase in gene expression of BRCA2 and TP53 tumor suppressors. Finally, BnSP-6 induced down-regulation of Angiopoetin 1 gene (potent pro-angiogenic factor) and inhibited adhesion and migration of MDA-MB-231 cells suggesting pharmaceutical applications of this PLA2 as an antiangiogenic and anti-metastatic agent. Taken together, our results show that the PLA2 BnSP-6 presents anticancer potential that can be exploited as prototype for the design of new therapies.