Proliferating changes of human neuroblastoma cell line U251 cells treated with temozolomide.

Objective To investigate the proliferation and the cell cycle effect of temozolomide(TMZ) on human neuroblastoma cell line U251 cells.Methods U251 cells were treated with 6 different concentrations of TMZ(10,25,50,100,200,400 μmol/L) 24,48,72 h and with 5 antineoplastic agents(CTX,ADM,MTX,VCR,DDP)72 h respectively.The morphological changes of the cells were observed under light microscopes.Cell viability was accessed by using colorimetric MTT assay.U251 cells were treated with 50 and 100 μmol/L TMZ 72 h.Cell cycle progression and apoptosis ratio were measured by using flow cytometry.Results Inhibition ratio of 6 different concentrations of TMZ were 4.23%,7.43%,31.63%,64.53%,82.18% and 86.15% respectively.The IC50 of TMZ was 81 μmol/L.There were significant difference between the control group and the groups over 50 μmol/L(P0.01).Inhibition ratio of different concentrations TMZ increased gradually as time went by.Inhibition ratio of ADM,MTX,VCR and DDP were 26.22%,39.27%,44.59%,54.56% and 55.28% respectively.There were significant difference between the TMZ group and the ADM,the MTX group respectively(P0.01).There were no significant difference between the TMZ group and the VCR,the DDP group respectively(P0.05).The flow cytometry showed that U251 cells responded to TMZ by undergoing G2/M arrest and very few cells underwent apoptosis.Conclusions TMZ inhibits the viability of malignant glioma cells in a time-and dose-dependent manner,and induces G2/M arrest but not apoptosis in vitro.The function of TMZ killing U251 cells in vitro is better than that of the other four drugs