Molecular dynamics simulations of the effects of lipid oxidation on the permeability of cell membranes.

The formation of transient pores in their membranes is a well-known mechanism of permeabilization of cells exposed to high-intensity electric pulses. However, the formation of such pores is not able to explain all aspects of the so-called electroporation phenomenon. In particular, the reasons for sustained permeability of cell membranes, persisting long after the pulses' application, remain elusive. The complete resealing of cell membranes takes indeed orders of magnitude longer than the time for electropore closure as reported from molecular dynamics (MD) investigations. Lipid peroxidation has been suggested as a possible mechanism to explain the sustainable permeability of cell membranes. However, theoretical investigations of membrane lesions containing excess amounts of hydroperoxides have shown that the conductivities of such lesions were not high enough to account for the experimental measurements. Here, expanding on these studies, we investigate quantitatively the permeability of cell membrane lesions that underwent secondary oxidation. MD simulations and free energy calculations of lipid bilayers show that such lesions provide a better model of post-pulse permeable and conductive electropermeabilized cells. These results are further discussed in the context of sonoporation and ferroptosis, respectively a procedure and a phenomenon, among others, in which, alike electroporation, substantial lipid oxidation might be triggered.

Role of PFKFB3 and PFKFB4 in Cancer: Genetic Basis, Impact on Disease Development/Progression, and Potential as Therapeutic Targets.

Glycolysis is a crucial metabolic process in rapidly proliferating cells such as cancer cells. Phosphofructokinase-1 (PFK-1) is a key rate-limiting enzyme of glycolysis. Its efficiency is allosterically regulated by numerous substances occurring in the cytoplasm. However, the most potent regulator of PFK-1 is fructose-2,6-bisphosphate (F-2,6-BP), the level of which is strongly associated with 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase activity (PFK-2/FBPase-2, PFKFB). PFK-2/FBPase-2 is a bifunctional enzyme responsible for F-2,6-BP synthesis and degradation. Four isozymes of PFKFB (PFKFB1, PFKFB2, PFKFB3, and PFKFB4) have been identified. Alterations in the levels of all PFK-2/FBPase-2 isozymes have been reported in different diseases. However, most recent studies have focused on an increased expression of PFKFB3 and PFKFB4 in cancer tissues and their role in carcinogenesis. In this review, we summarize our current knowledge on all PFKFB genes and protein structures, and emphasize important differences between the isoenzymes, which likely affect their kinase/phosphatase activities. The main focus is on the latest reports in this field of cancer research, and in particular the impact of PFKFB3 and PFKFB4 on tumor progression, metastasis, angiogenesis, and autophagy. We also present the most recent achievements in the development of new drugs targeting these isozymes. Finally, we discuss potential combination therapies using PFKFB3 inhibitors, which may represent important future cancer treatment options.

3PO as a Selective Inhibitor of 6-Phosphofructo-2-Kinase/Fructose-2,6-Biphosphatase 3 in A375 Human Melanoma Cells.

BACKGROUND/AIM: The occurrence of BRAFV600E mutation causes an up-regulation of the B-raf kinase activity leading to the stabilization of hypoxia-inducible factor 1-alpha (HIF-1α) - the promoter of the 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3) enzyme. The aim of the study was to examine the effect of the (2E)-3-(3-Pyridinyl)-1-(4-pyridinyl)-2-propen-1-one (3PO), as an inhibitor of PFKFB3, on human melanoma cells (A375) with endogenous BRAFV600E mutation. MATERIALS AND METHODS: A375 cells were exposed to different concentrations of 3PO and the following tests were performed: docking, cytotoxicity assay, immunocytochemistry staining glucose uptake, clonogenic assay, holotomography imaging, and flow cytometry. RESULTS: Our studies revealed that 3PO presents a dose-dependent and time-independent cytotoxic effect and promotes apoptosis of A375 cells. Furthermore, the obtained data indicate that 3PO induces cell cycle arrest in G1/0 and glucose uptake reduction. CONCLUSION: Taking all together, our research demonstrated a here should be proapoptotic and antiproliferative effect of 3PO on A375 human melanoma cells.

Molecular mechanism of vSGLT inhibition by gneyulin reveals antiseptic properties against multidrug-resistant gram-negative bacteria.

Faced with the worldwide spread of multidrug-resistant (MDR) bacterial strains, together with a lack of any appropriate treatment, urgent steps to combat infectious diseases should be taken. Usually, bacterial components are studied to understand, by analogy, the functioning of human proteins. However, molecular data from bacteria gathered over the past decades provide a sound basis for the search for novel approaches in medical care. With this current work, we want to direct attention to inhibition of the vSGLT glucose transporter from Vibrio parahaemolyticus belonging to the sodium solute symporter (SSS) family, to block sugar transport into the bacterial cell and, as a consequence, to limit its growth. Potential bacteriostatic properties can be drawn from commercially available drugs developed for human diseases. This goal can also be reached with natural components from traditional herbal medicine. The presented data from the numerical analysis of 44 known inhibitors of sodium glucose symporters shed light on potential novel approaches in fighting Gram-negative multidrug-resistant microorganisms. Graphical abstract Molecular view on vSGLT channel inhibition by gneyulin B, the compound of natural origin.