BACKGROUND: Previous studies have reported that statins are less toxic to the human body and have greater antitumor activity;however,few studies have addressed the antitumor effect of statins combined with tumor necrosis factor-related apoptosis inducing ligand (TRAIL).OBJECTIVE: To explore the effect of TRAIL combined with mevastatin on the proliferation and apoptotic cell death of a human glioma cell line SWO-38,and to study its mechanism of action.DESIGN,TIME AND SETTING: An in vitro control experiment was performed at the Central Laboratory of the Third Hospital Affiliated to Sun Yat-sen University,between January and April 2009.MATERIALS: The human SWO-38 cell line was provided by Cell Research,Department of Animal Experimental Center of Sun Yat-sen University;human recombinant soluble TRAIL by R&D,USA;and mevastatin by Sigma,USA.METHODS: SWO-38 cells were separately incubated in TRAIL (100,200,300,400,and 500 μg/L) and mevastatin (5,10,20,30,and 40 μmol/L) for 72 hours.In addition,SWO-38 cells were incubated in TRAIL (300 μg/L),mevastatin (30 μmol/L),and a solution containing both TRAIL and mevastatin for 12,24,48 and 72 hours.MAIN OUTCOME MEASURES: Cell proliferation was detected using methyl thiazolyl tetrazolium assay;cell apoptosis was observed using Hoechst 33258 staining and fluorescence microscopy and was measured using Annexin V/ propidium iodide flow cytometry;TRAIL R1/DR4 and TRAIL R2/DR5 protein expressions levels were measured using indirect immunofluorescence staining combined with flow cytometry in the recombinant soluble TRAIL (rsTRAIL,300 μg/L),mevastatin (30 μmol/L) and combination groups;TRAIL R1/DR4 and TRAIL R2/DR5 mRNA expression was detected using realtime polymerase chain reaction.RESULTS: rsTRAIL,mevastatin and their combination inhibited tumor proliferation in a timeand dose-dependent manner.The proliferation inhibitory rate and apoptosis rate of human SWO-38 cells in the combined group were significantly greater than the rsTRAIL or mevastatin alone group (P < 0.01).TRAIL R1/DR4 and TRAIL R2/DR5 protein and mRNA expressions were increased in the combination group compared with mevastatin or rsTRAIL alone after 72 hours (P < 0.01).CONCLUSION: Both rsTRAIL and mevastatin inhibit the proliferation and apoptosis of the human glioma cell line SWO-38,while their combination enhances the antitumor effect.The mechanism of action possibly correlates to the upregulation of TRAIL R1/DR4 and TRAIL R2/DR5 mRNA expression by mevastatin,thereby enhancing the cell sensitivity to rsTRAIL. BACKGROUND: Previous studies have reported that statins are less toxic to the human body and have greater antitumor activity; however, few studies have addressed the antitumor effect of statins combined with tumor necrosis factor-related apoptosis inducing ligand (TRAIL) .OBJECTIVE: To explore the effect of TRAIL combined with mevastatin on the proliferation and apoptotic cell death of a human glioma cell line SWO-38, and to study its mechanism of action. DIGNIGN, TIME AND SETTING: An in vitro control experiment was performed at the Central Laboratory of the Third Hospital Affiliated to Sun Yat-sen University, between January and April 2009. MIALIALS: The human SWO-38 cell line was provided by Cell Research, Department of Animal Experimental Center of Sun Yat-sen University; human recombinant soluble TRAIL by R & D , USA; and mevastatin by Sigma, USA. METHODS: SWO-38 cells were separately incubated in TRAIL (100,200,300,400, and 500 μg / L) and mevastatin (5,10,20,30, and 40 μmol / L) .In addit ion, SWO-38 cells were incubated in TRAIL (300 μg / L), mevastatin (30 μmol / L), and a solution containing both TRAIL and mevastatin for 12, 24, 48 and 72 hours. MAIN OUTCOME MEASURES: Cell proliferation was detected using methyl thiazolyl tetrazolium assay; cell apoptosis was observed using Hoechst 33258 staining and fluorescence microscopy and was measured using Annexin V / propidium iodide flow cytometry; TRAIL R1 / DR4 and TRAIL R2 / DR5 protein expressions levels were measured using indirect immunofluorescence staining combined with flow cytometry in the recombinant soluble TRAIL (rsTRAIL, 300 μg / L), mevastatin (30 μmol / L) and combination groups; TRAIL R1 / DR4 and TRAIL R2 / DR5 mRNA expression was detected using realtime polymerase chain reaction. mevastatin and their combination inhibited tumor proliferation in a time and dose-dependent manner. The proliferation inhibitory rate and apoptosis rate of human SWO-38 cells in the combined group were significantly greater than the rsTRAIL or meVastatin alone group (P <0.01) .TRAIL R1 / DR4 and TRAIL R2 / DR5 protein and mRNA expressions were increased in the combination group compared with mevastatin or rsTRAIL alone after 72h (P <0.01) .CONCLUSION: Both rsTRAIL and mevastatin inhibit the proliferation and apoptosis of the human glioma cell line SWO-38, while their combination enhances the antitumor effect. The mechanism of action may correlate to the upregulation of TRAIL R1 / DR4 and TRAIL R2 / DR5 mRNA expression by mevastatin, thereby enhancing the cell sensitivity to rsTRAIL.