Biology subjects

Belousov, V.

Publications and source records attributed to Belousov, V..

4 recordsLinked to original sources

bioRxiv2024

Downregulation of Gankyrin/PSMD10 affects cancer cell growth and proliferation in glioblastoma: in vitro and in vivo study

AbstractThe oncoprotein Gankyrin/PSMD10 is upregulated in various cancers, including glioblastoma multiforme (GBM), the most difficult tumor to treat. The heterogeneity of this type of tumor requires a multi-targeted approach to overcome radio- and chemoresistance. Here we aim to investigate the effects of Gankyrin inhibition on glioma cell proliferation and its impact on sensitivity to chemotherapy both in vitro and in vivo. We have employed the RNA interference approach as a valuable tool to downregulate the expression of target genes. Small interfering RNA (siRNA) were formulated into lipid nanoparticles (LNP) to facilitate delivery and overcome challenges, including RNase activity. We demonstrate that knockdown of Gankyrin promotes cell growth arrest of murine (GL261, CT-2[A]) and human (U87, GBM23, GBM24) glioma cells and induces the generation of reactive oxygen species and apoptosis. Importantly, Gankyrin inhibition enhances the therapeutic effect of temozolomide in murine glioma cell lines and decreases the IC50 of doxorubicin and cisplatin for U87 and GL261 cells. The therapeutic potential of Gankyrin inhibition was shown in patient-derived glioblastoma stem cells, which are responsible for tumor initiation and resistance to therapy. We showed that downregulation of Gankyrin led to decreased cell proliferation in vitro and improved survival in xenograft glioma model mice. Our results suggest that harnessing siRNA against Gankyrin may serve as a novel therapeutic strategy for glioblastoma therapy in a multi-drug approach and address challenges in current treatment by sensitizing glioma cells to chemotherapy. HighlightsO_LIsiRNA-mediated knockdown of Gankyrin reduced cell proliferation of murine and human glioma cells, induced ROS generation and promoted apoptosis. C_LIO_LIInhibition of Gankyrin increased the therapeutic effect of temozolomide in resistant CT- 2A glioma cells and decreased the IC50 concentration of doxorubicin and cisplatin in U87 and GL261 cells. C_LIO_LIDownregulation of Gankyrin inhibited the growth of patient-derived glioma stem cells and increased the survival of NOD/SCID xenograft glioma model mice C_LI

cancer biology↗

bioRxiv2023

Grubraw, a chemogenetic generator of mitochondrial pyruvate, reveals new mechanisms of mitochondrial metabolic control that underlie the Warburg effect

Upregulation of glycolysis and downregulation of mitochondrial oxidative phosphorylation, termed as the Warburg effect, are characteristic of tumor cells1,2. Restriction of pyruvate flux into the mitochondrial matrix is one of the major mechanisms underlying this phenomenon3. Warburg-type metabolism is beneficial for rapidly proliferating cells, however its function remains unclear. Moreover, it is unknown what the metabolic consequences of activation of mitochondrial respiration in Warburg-type cancer cells are. Here we created a chemogenetic instrument, Grubraw, that generates pyruvate directly in the mitochondrial matrix bypassing restricted pyruvate influx. In cancer cells, Grubraw-driven pyruvate synthesis in the matrix increased mitochondrial membrane potential, oxygen consumption rate, and the amounts of TCA cycle intermediates. In a mouse model of human melanoma xenografts, chemogenetic activation of mitochondria caused a decrease in tumor growth rate. Surprisingly, cancer cells actively exported pyruvate generated by Grubraw in the mitochondria into the extracellular medium. In addition, activation of mitochondria induced downregulation of transcription of the genes that drive cell cycle progression, cell proliferation and DNA replication. Our results demonstrate that cells with Warburg-type metabolism use previously unknown mechanisms of carbon flux control to dispose of excessive mitochondrial pyruvate, and activation of mitochondria in these cells downregulates cellular proliferation.

cancer biology↗

bioRxiv2021

Thioredoxin reductase controls the capacity of peroxiredoxins to limit mitochondrial H2O2 release

H2O2 performs central roles in signaling at physiological levels, while at elevated levels it causes molecular damage. Mitochondria are major producers of H2O2, which has been implied in regulating diverse processes inside and outside the organelle. However, it still remains unclear whether and how mitochondria in intact cells release H2O2. Here we employed the genetically encoded high-affinity H2O2 sensor HyPer7 in mammalian tissue culture cells to investigate different modes of mitochondrial H2O2 release. We found substantial heterogeneity of HyPer7 dynamics between individual cells, and observed H2O2 released from mitochondria directly at the surface of the organelle and in the bulk cytosol, but not in the nucleus nor on the plasma membrane, pointing to steep gradients emanating from mitochondria. These gradients are controlled by cytosolic peroxiredoxins that act redundantly and are present with a substantial reserve capacity. Furthermore, dynamic adaptation of cytosolic thioredoxin reductase levels during metabolic changes results in improved H2O2 handling and explains previously observed cell-to-cell differences. Thus, our data indicate that H2O2-mediated signaling likely occurs close to mitochondria during specific metabolic conditions. HIGHLIGHTSO_LIMitochondrial H2O2 can be detected in the cytosol in intact human cells C_LIO_LIMitochondrial H2O2 gradients are steep and controlled by peroxiredoxins 1 and 2 C_LIO_LIPeroxiredoxins 1 and 2 complement for each other C_LIO_LIPeroxiredoxins 1 and 2 are present with a substantial reserve capacity C_LIO_LIMetabolism-induced changes of reducing processes control peroxiredoxin activity C_LI

biochemistry↗

bioRxiv2021

Monitoring oxidative inflammatory processes in live cells and tissue with Hypocrates, a genetically encoded biosensor for hypochlorite

Hypochlorous acid, an aggressive oxidant, is important in immune defense against pathogens. The current lack of tools to monitor the dynamics of hypochlorous acid in live cells and tissue hinders a better understanding of inflammatory processes. We engineered a genetically encoded biosensor, Hypocrates, for the visualization of hypochlorous acid. Hypocrates consists of a circularly permuted yellow fluorescent protein integrated into the structure of the transcription repressor NemR from E. coli. We determined sensitivity, selectivity, reaction rates, and the X-ray structure of this ratiometric redox biosensor, and tested the response of Hypocrates in HeLa Kyoto cells at varying hypochlorite concentrations. By combining Hypocrates with the biosensor HyperRed, we visualized the dynamics of hypochlorous acid and hydrogen peroxide in a zebrafish tail fin injury model.

immunology↗