1. Temozolomide Affects The Expression Of AQP4 By Up-regulating P38 MAPK Signaling Pathway And Affects The Biological Behavior Of Glioma Cells. 2. The Expression Changes Of MCT1 And 4 In U251 Cells After Oxygen Deprivation And Its Mechanism

ObjectiveGlioma is the most common and lethal central nervous system tumors.Temozolomide(TMZ)is a standard first-line drug for malignant glioma,however,the intracellular and molecular mechanisms behind this anti-cancer effect have yet to be fully understood.The aim of the present study was to determine whether TMZ inhibits proliferation,invasion of glioma cells in vitro and whether this effect can be mediated through modulation of aquaporin 4(AQP4)and phosphorylation of the MAPK pathway.MethodsThe viability of glioma cells was evaluated using MTT assay.The cell cycle distribution was detected with flow cytometry.Migration ability and invasion ability were tested by scratch assays and transwell assays,respectively.The levels of AQP4 and MAPK were measured using immunoblot analyses.ResultsOur results showed that TMZ inhibited proliferation,migration and invasion,and induced G2/M arrest in U87 and U251 glioma cell lines.These changes were associated with a decreased in the levels of AQP4 expression as well as activation phosphorylated level of p38.Treatment with a p38 chemical activator(anisomycin)resulted in similar effects as TMZ treatment on glioma cells.And p38 chemical inhibitor(SB203580)could block these effects produced by TMZ,suggesting a direct up-regulation of the p38 signaling pathway.ConclusionWe identified that TMZ might have therapeutic potential for controlling proliferation,invasion of malignant glioma by inhibiting AQP4 expression through activation of p38 MAPK pathway,and lay the foundation of finding a new therapeutic target.Objective To exam the expression patterns of monocarboxylate transporter 1,4 and lactate transporting in U251 malignant glioma cells with oxygen-glucose deprivation(OGD)so as to explore the possible the role of MCT 1,4 in proliferating,aggressiveness for human glioma cells.Methods U251 cells were randomly divided into two groups,namely,control group and OGD group.The cultures were incubated for certain periods(1,3,6 hours)with oxygen-glucose deprivation.Cell survival rate was evaluated using MTT assay.The cell morphology was observed by HE staining.The lactic acid concentration was measured by lactate assay kit.The expression patterns of MCT1,4 were detected by immunofluorescence and Western blotting.Results Compared with those of control group,cell viability decreased(P<0.05)and lactate content increased in OGD group with oxygen-glucose deprivation time(P<0.05),and lactic acid content decreased by adding 4-CIN,the inhibitor of MCTs(P<0.05).The MCT1,4 expression increased in the OGD group than in control group and continuously increased with the extension of oxygen-glucose deprivation time(P<0.05).Conclusion The levels of MCT1,4 increase and cell viability decreases in U251 glioma cells with the up-regulation of lactic acid content after OGD.The lactic acid content decreases by adding 4-CIN.The above results suggest that MCT1,4 may contribute to lactate transport of malignant glioma microenvironment,and regulate its proliferation and survival.