奥利司他通过抑制SREBP-1/FASN脂质合成调控上皮-间质转化干预胶质母细胞瘤贝伐单抗耐药OA

Objective To investigate the potential mechanism by which orlistat intervenes in bevacizumab resistance in glioblastoma(GBM),with a focus on its effects on sterol regulatory element-binding protein 1(SREBP-1)/fatty acid synthase(FASN)-associated lipid metabolic regulation and epithelial-mesenchymal transition(EMT)-related molecular phenotypes.Methods Bioinformatics analysis was performed to identify the intersecting targets of orlistat and GBM,followed by analysis of potential core targets and related biological processes.In vitro experiments were conducted to evaluate the effects of orlistat on bevacizumab-resistant U87,U251 and SHG-44 cells.Cell viability was assessed using the methyl thiazolyl tetrazolium(MTT)assay.Cell migration and invasion were evaluated using wound-healing and Transwell assays,respectively.Intracellular triglyceride(TG)content was measured by enzyme-linked immunosorbent assay(ELISA).The expression of lipid metabolism-and EMT-related genes and proteins was detected by reverse transcription quantitative real-time polymerase chain reaction(RT-qPCR)and Western blot.Results A total of 45 intersecting targets between orlistat and GBM were identified.These targets included SREBF1,FASN and EGFR,and were mainly enriched in cancer-related pathways,PI3K-AKT,MAPK,HIF-1 and VEGF-related signaling pathways,as well as lipid metabolism-related biological processes.In vitro experiments showed that the viability of bevacizumab-resistant U87,U251,and SHG-44 cells decreased with increasing concentrations of orlistat,with statistically significant differences observed at some concentrations compared with the 0 μmol/L treatment within the orlistat group(P<0.01,P<0.001).Compared with the DMSO control group,orlistat treatment significantly reduced the migration rates of U87,U251 and SHG-44 cells(P<0.05,P<0.01),reduced the numbers of invading cells(P<0.05,P<0.001),and significantly decreased intracellular TG level in all three cell lines(all P<0.000 1).RT-qPCR results showed decreased mRNA expression of FASN,SREBF1 and some mesenchymal phenotype-related genes.Significant differences were observed in FASN,CDH2 and SNAI1 expression in U251 cells and in SREBF1 and SNAI2 expression in U87 cells(P<0.01,P<0.000 1).CDH1 mRNA expression showed an increasing trend,but the difference was not statistically significant(P>0.05).Western blot results showed an increasing trend in E-cadherin protein expression and decreasing trends in N-cadherin,Vimentin,Snail,Slug,SREBP-1 and FASN protein expression.The expression of Vimentin,Snail and Slug in U251 cells and FASN in U87 cells was significantly decreased(P<0.05),whereas the remaining differences were not statistically significant(P>0.05).Conclusions Orlistat reduced the viability of bevacizumab-resistant GBM cells and inhibited their migration and invasion.These effects may be associated with decreased intracellular TG levels,modulation of SREBP-1/FASN-related lipid metabolic regulation,and regulation of EMT-related molecular phenotypes.