3-Bromopyruvate: A new strategy for inhibition of glycolytic enzymes in Leishmania amazonensis

Molecular probe to visualize the effect of a glycolytic inhibitor on reducing NADH levels in a cellular system

The reduced form of nicotinamide adenine dinucleotide, commonly known as NADH, is an essential coenzyme existing in living organisms. Due to its involvement in various biological process, fluorescence imaging of intracellular NADH levels in different pathological conditions has emerged as an interesting area of research. We report here the exploration of a fluorescent probe, MQ-CN-BTZ, as a dual-channel NADH imaging agent (green and red channels) for cellular systems. Interestingly, depending on the ratio between the probe and NADH concentration in the solution phase, the probe showed emission at ∼529 nm and ∼656 nm when excited at 475 nm. It should be noted that the probe showed a very large Stokes shift of ∼180 nm with respect to the longer-wavelength emission with a good fluorescence response towards NADH. In general, such a large Stokes shift is highly beneficial for imaging applications, largely due to the better separation between the emission and excitation spectra and reduced spectral overlap. Finally, the probe was utilized to image a glycolysis pathway event by employing 3-bromopyruvic acid (3-BrPA) as a glycolytic inhibitor that significantly inhibits the activity of the enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH), which is involved in a crucial step of glycolysis. As the depletion of the NADH levels corresponds to the inactivity of GADPH upon treatment with the inhibitor, we attempted to image the modulation of the NADH concentration in the cellular system in the presence of the inhibitor 3-BrPA, indicating the importance of the glycolysis step in elevating NADH levels. Overall, the present study attempts to demonstrate the importance of a molecular probe for fluorescence imaging of intracellular NADH in the presence of a glycolytic inhibitor.

STK32C modulates doxorubicin resistance in triple-negative breast cancer cells via glycolysis regulation

Understanding the mechanisms underlying doxorubicin resistance in triple-negative breast cancer (TNBC) holds paramount clinical significance. In our study, we investigate the potential of STK32C, a little-explored kinase, to impact doxorubicin sensitivity in TNBC cells. Our findings reveal elevated STK32C expression in TNBC specimens, associated with unfavorable prognosis in doxorubicin-treated TNBC patients. Subsequent experiments highlighted that STK32C depletion significantly augmented the sensitivity of doxorubicin-resistant TNBC cells to doxorubicin. Mechanistically, we unveiled that the cytoplasmic subset of STK32C plays a pivotal role in mediating doxorubicin sensitivity, primarily through the regulation of glycolysis. Furthermore, the kinase activity of STK32C proved to be essential for its mediation of doxorubicin sensitivity, emphasizing its role as a kinase. Our study suggests that targeting STK32C may represent a novel therapeutic approach with the potential to improve doxorubicin's efficacy in TNBC treatment.

Triose Phosphate Isomerase Structure-Based Virtual Screening and In Vitro Biological Activity of Natural Products as Leishmania mexicana Inhibitors

Cutaneous leishmaniasis (CL) is a public health problem affecting more than 98 countries worldwide. No vaccine is available to prevent the disease, and available medical treatments cause serious side effects. Additionally, treatment failure and parasite resistance have made the development of new drugs against CL necessary. In this work, a virtual screening of natural products from the BIOFACQUIM and Selleckchem databases was performed using the method of molecular docking at the triosephosphate isomerase (TIM) enzyme interface of Leishmania mexicana (L. mexicana). Finally, the in vitro leishmanicidal activity of selected compounds against two strains of L. mexicana, their cytotoxicity, and selectivity index were determined. The top ten compounds were obtained based on the docking results. Four were selected for further in silico analysis. The ADME-Tox analysis of the selected compounds predicted favorable physicochemical and toxicological properties. Among these four compounds, S-8 (IC50 = 55 µM) demonstrated a two-fold higher activity against the promastigote of both L. mexicana strains than the reference drug glucantime (IC50 = 133 µM). This finding encourages the screening of natural products as new anti-leishmania agents.

Iron Uptake Controls Trypanosoma cruzi Metabolic Shift and Cell Proliferation

(1) Background: Ionic transport in Trypanosoma cruzi is the object of intense studies. T. cruzi expresses a Fe-reductase (TcFR) and a Fe transporter (TcIT). We investigated the effect of Fe depletion and Fe supplementation on different structures and functions of T. cruzi epimastigotes in culture. (2) Methods: We investigated growth and metacyclogenesis, variations of intracellular Fe, endocytosis of transferrin, hemoglobin, and albumin by cell cytometry, structural changes of organelles by transmission electron microscopy, O₂ consumption by oximetry, mitochondrial membrane potential measuring JC-1 fluorescence at different wavelengths, intracellular ATP by bioluminescence, succinate-cytochrome c oxidoreductase following reduction of ferricytochrome c, production of H₂O₂ following oxidation of the Amplex^® red probe, superoxide dismutase (SOD) activity following the reduction of nitroblue tetrazolium, expression of SOD, elements of the protein kinase A (PKA) signaling, TcFR and TcIT by quantitative PCR, PKA activity by luminescence, glyceraldehyde-3-phosphate dehydrogenase abundance and activity by Western blotting and NAD⁺ reduction, and glucokinase activity recording NADP⁺ reduction. (3) Results: Fe depletion increased oxidative stress, inhibited mitochondrial function and ATP formation, increased lipid accumulation in the reservosomes, and inhibited differentiation toward trypomastigotes, with the simultaneous metabolic shift from respiration to glycolysis. (4) Conclusion: The processes modulated for ionic Fe provide energy for the T. cruzi life cycle and the propagation of Chagas disease.