UCH-L1Regular The Adaptation To Hypoxia Of Glioblastoma Multiforme Cells

Objective: To investigate the effects of UCH-L1on viability and malignant featuresof glioma cells under hypoxia, and to explore the molecular mechanisms involved.Methods: The expression of UCH-L1in glioma cells U251and T98G was silencedby UCH-L1-targted siRNA. Under hypoxia condition,1) the invasion of glioma cellswas assessed by wound-healing assay and Matrigel invasion assay;2) the cell proliferationwas assessed by clonogenic assay; cell viability was assessed by trypan blue assay;3)glycolysis was assessed using the lactate and glucose assay kit;4) expression of UCH-L1and the apoptosis proteins and HIF-1α were determined using Western blot.Results:1) the results of wound-healing assay and matrigel invasion assay showedthat the migration and invasion of human glioma cells U251and T98G were decreasedafter silencing of UCH-L1expression under hypoxia, suggesting that UCH-L1canpromote malignant invasion and migration of glioma cells;2) the results of clonogenicassay and trypan blue assay showed that under hypoxia, the proliferation and viability ofhuman glioma cells U251and T98G were decreased after silencing of UCH-L1expression,suggesting that UCH-L1contributes to proliferation and viability of glioma cells underhypoxia;3) under hypoxia the level of cleaved caspase3and cleaved PARP weresignificantly increased after silencing of UCH-L1expression, suggesting that UCH-L1caninhibit apoptosis of glioma cells;4) after knockdown of UCH-L1, the secretion of lactatewas increased and consumption of glucose was decreased in glioma cells, suggesting thatUCH-L1can promote glycolysis under hypoxia;5) in hypoxia the level of HIF-1α wassignificantly decreased in glioma cells subjected to silencing of UCH-L1expression butwas partial recovered in the presence of the proteasome inhibitors MG132or LAC,suggesting that UCH-L1can regulate the level of HIF-1α protein via theubiquitin-proteasome pathway;6) under hypoxia, the glioma cells treated with the proteinsynthesis inhibitor CHX and subjected to silencing of UCH-L1expression showed reduced level of HIF-1α protein, suggesting that UCH-L1has stabilizing effect on HIF-1α protein.Conclusion: UCH-L1is able to enhance glycolysis in glioma cells, contribute toinhibition of apoptosis, and promote the invasion, migration, survival and proliferation ofglioma cells under hypoxia, these effects may be mediated, at least in part, thought itsstabilizing effect on the glycolytic protein, HIF-1α.