An Autophagy-Associated MITF-GAS5-miR-23 Loop Attenuates Vascular Oxidative and Inflammatory Damage in Sepsis.

BACKGROUND: Sepsis induces GAS5 expression in the vascular endothelium, but the molecular mechanism is unclear, as is the role of GAS5 in sepsis. METHODS AND RESULTS: We observed that GAS5 expression in the endothelium was significantly upregulated in a sepsis mouse model. ChIP-PCR and EMSA confirmed that the oxidative stress (OS)-activated MiT-TFE transcription factor (MITF, TFE3, and TFEB)-mediated GAS5 transcription. In vitro, GAS5 overexpression attenuated OS and inflammation in endothelial cells (ECs) while maintaining the structural and functional integrity of mitochondria. In vivo, GAS5 reduced tissue ROS levels, maintained vascular barrier function to reduce leakage, and ultimately attenuated sepsis-induced lung injury. Luciferase reporter assays revealed that GAS5 protected MITF from degradation by sponging miR-23, thereby forming a positive feedback loop consisting of MITF, GAS5, and miR-23. Despite the fact that the OS-activated MITF-GAS5-miR-23 loop boosted MITF-mediated p62 transcription, ECs do not need to increase mitophagy to exert mitochondrial quality control since MITF-mediated Nrf2 transcription exists. Compared to mitophagy, MITF-transcribed p62 prefers to facilitate the autophagic degradation of Keap1 through a direct interaction, thereby relieving the inhibition of Nrf2 by Keap1, indicating that MITF can upregulate Nrf2 at both the transcriptional and posttranscriptional levels. Following this, ChIP-PCR demonstrated that Nrf2 can also transcribe MITF, revealing that there is a reciprocal positive regulatory association between MITF and Nrf2. CONCLUSION: In sepsis, the ROS-activated MITF-GAS5-miR-23 loop integrated the antioxidant and autophagy systems through MITF-mediated transcription of Nrf2 and p62, which dynamically regulate the level and type of autophagy, as well as exert antioxidant and anti-inflammatory effects.

Influence of Dichloroacetate on Wilms'Tumor in vitro.

OBJECTIVE: To investigate the effect of dichloroacetate (DCA) on Wilms' tumor (WT) G401 cells. METHODS: CCK-8 assay was used to detect the influence of DCA on G401 cells viability and 10 mmol/L DCA was selected for subsequent experiments. The expression of glycolysis-related enzymes, such as hexokinase 2 (HK2), pyruvate kinase M2 (PKM2), lactic acid dehydrogenase A (LDHA), pyruvate dehydrogenase kinase 1 (PDK1), and pyruvate dehydrogenase (PDH), were detected by qRT-PCR and western blot. The extracellular lactic acid and glucose concentrations were measured by the lactic acid assay kit and glucose oxidase method kit respectively. Flow cytometry was used to detect the effect of DCA on G401 cells apoptosis. The invasion and migration ability of G401 cells were detected by Transwell assay and wound-healing assay. RESULTS: The results showed that DCA reduced glycolysis-related enzymes expression, inhibited lactic acid production, and glucose consumption. DCA also suppressed cells growth, induced cells apoptosis and inhibited cells invasion and migration. CONCLUSION: Inhibition of aerobic glycolysis by DCA can reduce the viability of G401 cells, promote cells apoptosis and inhibit cells invasion and migration. Therefore, aerobic glycolysis may be a potential therapeutic target for Wilms' tumor.

PDGF-BB/PDGFRß promotes epithelial-mesenchymal transition by affecting PI3K/AKT/mTOR-driven aerobic glycolysis in Wilms' tumor G401 cells.

Wilms' tumor (WT) is the most common pediatric renal malignancy. PDGFRß belongs to the type III receptor tyrosine kinase family and is known to be involved in tumor metastasis and angiogenesis. Here, we studied the effect and underlying mechanism of PDGFRß on WT G401 cells. Transwell assay and wound-healing assay were used to detect the effect of PDGFRß on G401 cells invasion and migration. Western blot and immunofluorescence were used to detect the expression of EMT-related genes. The expression of PI3K/AKT/mTOR pathway proteins was detected by Western blot. The relationship between PDGFRß and aerobic glycolysis was studied by assessing the expression of glycolysis-related enzymes detected by qRT-PCR and Western blot. The activity of HK, PK, and LDH was detected by corresponding enzyme activity kits. The concentration of lactic acid and glucose was detected by Lactic Acid Assay Kit and Glucose Assay Kit-glucose oxidase method separately. To investigate the mechanism of PDGFRß in the development of WT, the changes of glucose and lactic acid were analyzed after blocking PI3K pathway, aerobic glycolysis, or PDGFRß. The key enzyme was screened by Western blot and glucose metabolism experiment after HK2, PKM2, and PDK1 were inhibited. The results showed that PDGFRß promoted the EMT process by modulating aerobic glycolysis through PI3K/AKT/mTOR pathway in which PKM2 plays a key role. Therefore, our study of the mechanism of PDGFRß in G401 cells provides a new target for the treatment of WT.

PDGFRß modulates aerobic glycolysis in osteosarcoma HOS cells via the PI3K/AKT/mTOR/c-Myc pathway.

Osteosarcoma is a malignant tumor abundant in vascular tissue, and its rich blood supply may have a significant impact on its metabolic characteristics. PDGFRß is a membrane receptor highly expressed in osteosarcoma cells and vascular wall cells, and its effect on osteosarcoma metabolism needs to be further studied. In this study, we discussed the effect and mechanism of action of PDGFRß on glucose metabolism in human osteosarcoma (HOS) cells. GSEA, Pearson's correlation test, and PPI correlation analysis indicated positive regulation of PDGFRß on aerobic glycolysis in osteosarcoma. The results of qPCR and western blot further confirmed the prediction of bioinformatics. Glucose metabolism experiments proved that PDGF/PDGFRß could effectively promote aerobic glycolysis in osteosarcoma cells. In addition, the mitochondrial membrane potential (ΔΨm) experiment proved that the metabolic change triggered by PDGFRß was not caused by mitochondrial damage. The PI3K pathway inhibitor LY294002, MEK pathway inhibitor U0126, or Warburg effect inhibitor DCA was used to perform western blot and glucose metabolism experiments, and the results showed that PDGFBB/PDGFRß mainly activated the PI3K/AKT/mTOR/c-Myc pathway to promote aerobic glycolysis in osteosarcoma HOS cells. The newly elucidated role of PDGFRß provides a novel metabolic therapeutic target for osteosarcoma.

Down-regulation of PDGFRß suppresses invasion and migration in osteosarcoma cells by influencing epithelial-mesenchymal transition.

Osteosarcoma (OS) is the most common malignant bone tumor primarily influencing children and adults. Approximately one-fifth of patients have micrometastasis in the lungs when OS is diagnosed. Platelet-derived growth factor receptor (PDGFR) beta (PDGFRß) is a subtype of PDGFR. PDGFRß has been noted to be highly expressed in OS cell lines and patient specimens, and is associated with metastasis and poor prognosis of OS. However, mechanistic insights into the exact role of PDGFRß in OS pathogenesis and development are still lacking. Here we assessed the effects of PDGFRß on invasive and migratory abilities, such as the epithelial-mesenchymal transition and phosphatidylinositol 3-kinase (PI3K), Akt and mammalian target of rapamycin (mTOR) pathways in HOS cells. Depleting PDGFRß resulted in reduced migration of HOS cells in the small interfering RNA duplexes specific for the PDGFRß group compared with the mock and scramble-treated groups in Transwell invasion assays. Using wound-healing assays, we demonstrate the rate of wound healing in the PDGF-BB-stimulated group was higher compared with the mock-treated group. Western blot showed that down-regulation of PDGFRß decreased the expression of stromal phenotype markers and phosphorylation pathway proteins (PI3K, AKT and mTOR), but the epithelial phenotype marker was increased in HOS cells. Treating HOS cells with PDGF-BB revealed a treatment time-dependent increase of phosphorylated, but not total, PI3K, AKT and mTOR. Taken together, we suggest that PDGFRß plays an important role in OS invasion, migration and epithelial-mesenchymal transition by influencing the PI3K, Akt and mTOR pathways, hence highlighting PDGFRß as a potential therapeutic target for OS.

Influence of glucose transporter 1 activity inhibition on neuroblastoma in vitro.

Most cancer cells predominantly produce their energy through a high rate of glycolysis in the presence of abundant oxygen. Glycolysis has become a target of anticancer strategies. Previous researches showed that glucose transporter 1 (GLUT1) inhibitor is effective as anticancer agents. This study assessed the effects of the selective GLUT1 inhibitor WZB117 on regulation of neuroblastoma (NB) cell line SH-SY5Y viability, cell cycle and glycolysis in vitro. SH-SY5Y cells were grown and treated with WZB117 for up to 72 h and then subjected to cell viability, qRT-PCR, Western blot and flow cytometry analysis. Level of ATP and LDH was also analyzed. The result showed that WZB117 treatment reduced tumor cells viability, downregulated level of GLUT1 protein. Moreover, WZB117 treatment arrested tumor cells at the G0-G1 phase of the cell cycle, induced tumor cells to undergo necrosis instead of apoptosis. In addition, WZB117 treatment downregulated the levels of intracellular ATP, LDH and glycolytic enzymes. Thus, WZB117-induced GLUT1 inhibition suppressed tumor cell growth, induced cell cycle arrest and reduced glycolysis metabolites in NB cells in vitro. This study suggested that GLUT1 can be used as a potential therapeutic target for NB.

[Inhibiting the expression of glucose transporter 1 reduces the proliferation, invasion and migration of neuroblastoma cells].

Objective To study the effect of inhibiting the expression of glucose transporter 1 (GLUT1) in neuroblastoma cells on the proliferation, invasion and migration of tumor cells. Methods The specific small molecule inhibitor WZB117 was used to inhibit the expression of GLUT1 in neuroblastoma cells. The expression of GLUT1 mRNA was detected by real-time quantitative PCR; the expression of GLUT1 protein was detected by Western blotting; the ability of cell proliferation was detected by CCK-8 assay; the ability of cell invasion and migration were detected by TranswellTM invasion and migration assay, respectively. Results After treated with WZB117, the expression level of GLUT1 mRNA increased, while the protein expression level decreased in the neuroblastoma cells. Cell proliferation was inhibited, and the ability of cell invasion and migration were reduced. Conclusion Inhibiting the expression of GLUT1 in neuroblastoma cells might attenuate the malignant biological behaviors of tumor cells.