Glioblastoma Microenvironment and Invasiveness: New Insights and Therapeutic Targets.

Glioblastoma (GBM) is the most common and malignant primary brain cancer in adults. Without treatment the mean patient survival is approximately 6 months, which can be extended to 15 months with the use of multimodal therapies. The low effectiveness of GBM therapies is mainly due to the tumor infiltration into the healthy brain tissue, which depends on GBM cells' interaction with the tumor microenvironment (TME). The interaction of GBM cells with the TME involves cellular components such as stem-like cells, glia, endothelial cells, and non-cellular components such as the extracellular matrix, enhanced hypoxia, and soluble factors such as adenosine, which promote GBM's invasiveness. However, here we highlight the role of 3D patient-derived glioblastoma organoids cultures as a new platform for study of the modeling of TME and invasiveness. In this review, the mechanisms involved in GBM-microenvironment interaction are described and discussed, proposing potential prognosis biomarkers and new therapeutic targets.

Bactridine 2 effect in DRG neurons. Identification of NHE as a second target.

Bactridine 2 (Bact-2) is an antibacterial toxin from Tityus discrepans venom which modifies isoforms 1.2, 1.4 and 1.6 voltage-dependent sodium (Nav) channels. Bactridine-induced Na+ outflow in Yersinia enterocolitica was blocked by amiloride, suggesting that Bact-2 effect was mediated by an amiloride sensitive sodium channel. In this study we show that Bact-2 increases also an outward rectifying current in rat dorsal root ganglia (DRG) sensory neurons; therefore, the nature of the outward rectifying currents was characterized and then the effect of Bact-2 on these currents was studied. These currents are enhanced by amiloride, are decreased by Na+ when an outward pH gradient is present and its reversal potential coincides with that of a Cl-/H+ exchanger, suggesting that rectifying currents are produced by the electrogenic Cl-/H+ exchanger modulated by the Na+/H+ antiporter. Bact-2 also leads to an increase of the outward currents in a similar way to the produced by the inhibition of the Na+/H+ exchanger. Additionally, the subsequent application of Bact-2 after blocking the Na+/H+ exchanger does not produce any further effect, suggesting that Bact-2 modifies the outward current by modulating the activity of the Na+/H+ exchanger. The effect of Bact-2 on pHi regulation was determined using the pH indicator BCECF. The results show that the Na+/H+ exchanger is blocked by amiloride and Na+ free solutions and is modulated by Bact-2 in a similar way as cariporide. This study validates that besides Nav channels, Bact-2 modulates the activity of the Na+/H+ exchanger.

Scorpion toxins modify phytopathogenic fungus physiology. A possible source of new fungicides.

Seven toxins (F1-F7) were purified from Tityus discrepans scorpion venom on a C18 HPLC column. The compounds were fungitoxic on Macrophomina phaseolina. The molecular masses of F1-F7 were (Da) 1061.1, 7328.8, 7288.3, 7268.5, 7104.6, 6924.6, and 6823.3, respectively. It is not known if F1 is a small peptide or some other kind of organic molecule. Compounds F2-F7 were peptides. The most potent was F7, with a minimal inhibition concentration of 0.4 µg/µL and a concentration for 50% inhibition of 0.13 µg/µL. Fungal esterase activity was abolished by F2, F3, and F5 and inhibited by 89, 60, 58, and 54% by F4, F6, F7, and F1, respectively. F1, F2, F5, and F7 induced an increase on hyphae chitin wall and septum thickness. Peptides F3-F6 induced efflux of the fluorescent dye Na-CoroNa Red complex from hyphae. Only F5 and F6 were inhibited by the prokaryote sodium channel blockers amiloride and mibefradil. Gas chromatography-mass spectrometry analysis suggested that F1, F5, F6, and F7 altered sterol biosynthesis either by inhibiting ergosterol biosynthesis or by producing ergosterol analogues. The peptides affect M. phaseolina viability by three mechanisms: decreasing esterase activity, altering Na(+) membrane permeability, and altering wall sterol biosynthesis. It seems that interfering with sterol synthesis is an important mechanism behind the effect of the fungicideal toxins. However, the antifungal effects at short times are indicative of a direct esterase inhibition, which, with the increased membrane leakiness to Na(+), makes the fungus inviable.

Apoptogenic peptides from Tityus discrepans scorpion venom acting against the SKBR3 breast cancer cell line.

Two novel peptides named neopladine 1 and neopladine 2 were purified from Tityus discrepans scorpion venom and found to be active on human breast carcinoma SKBR3 cells. Mass spectrometry molecular masses of neopladine 1 and 2 were 29918 and 30388 Da, respectively. Their N-terminal sequences were determined by Edman degradation. The peptides induced apoptosis of SKBR3 cells but had a negligible effect on non-malignant MA104 monkey kidney cells. Neopladine 1 and 2 induced 6.3 and 4.1% of SKBR3 apoptosis, respectively, in 5 h of exposure; the effect was larger with more prolonged exposures. Inmunohistochemistry showed that neopladines bind to SKBR3 cell surface inducing FasL and BcL-2 expression.