High Expression Of Drug-resistance-associated C18-Glycosphingolipids In Glioma

Part Ⅰ Expression of the C18-GSLs in glioma.Objective: To study which GSLs are associated to glioma as well as their exactstrctures.Methods: major neutral GSLs expression profiles from human glioma tissues wereanalyzed by electrospray ionization linear ion trap mass spectrometry (ESI-LIT MS)and their exact strcture were indentified by MSnanalysisResults:The MS profile of human brain tissues were shown by ESI-LIT MS(2) The MSnprofile analysis of human brain tissues shown that there was a high expression ofC18-GlcCer, C18-LacCer, C18-Gb3and C18-Gb4in glioma.Conclusion: High expression of the C18-GSLs in glioma. Part Ⅱ High expression of C18-glycosphingolipids are associated todrug-resistance in gliomaObjective: To study the relationship between the overexpression of C18-GSLs anddrug resistance in glioma.Methods:(1) Scanned the GSLs profile of the glioma cell lines and detected theirIC50of VM-26by MTT assay.(2) Establishmed a stable VM-26resistant U251sublinein in vitro by co-culturing with VM-26and then detected the alteration of C18-GSLs aswell as expression of MDR1, MRP1gene of them compared with the parental cells.(3)Inhibited CerS1(which synthesizes C18ceramide) by RNAi assay and then detected thealteration of C18ceramide.(4) CerS1expression of glioma were detected by real-timePCR and immunohistochemistry assay. Results:(1) Higher levels of C18-GSLs in A172cells with a higher IC50(10μg/ml)to teniposide whereas U251cells with lower levels of C18-GSLs had a lower IC50(0.4μg/ml) were found by MTT assay.(2) After the stable drug resistant cell line(U251/VM-26)(IC50=25μg/ml) was induced by co-culturing with teniposide U251, weobserved an increased expression of MDR1and MRP1, as well as elevated C18-GSLsin drug resistant glioma cells (p<0.05) compared with the parent cells.(3) Silence ofCerS1by siRNA did not alter the IC50of WM-26, the levels of C18free ceramide andC18-GSLs in A172cells.(4) CerS1were ovexpressed but without the levels of C18freeceramide in glioma tissues and cell lines.Conclusion: Glioma-associated C18-GSLs may be involved in drug resistance ofglioma.