Objective To investigate the mechanism of histone deacetylase inhibitors in proliferation of glioma cells. Methods (1) Glioma cell line U251 was cultured in vitro and treated with Trichostatin A (TSA) at 0.1, 0.2, 0.5, 1.0 or 2.0 μmol/L for 48 h to determine the IC50 for TSA, and then, cells were treated with TSA at the IC50 concentration (0.5 μmol/L) for 8, 16, 24, 48 h; 1 μmol/L M344, 0.5 μmol/L LBH589, 6 mmol/L NaBu and 6 mmol/L VPA were used to treat the cells for 48 h and same volume of solvent was given to cells for 48 h as control group; MTT assay was performed to determine cell viability. (2) Western blotting was performed to test the Jun N-terminal kinase (JNK) expression and phosphorylated JNK (p-JNK) level in the U251 cells after being treated with 0.5 μmol/L TSA for 8, 16 and 24 h. (3) Western blotting and MTT assay were employed to detect the c-Jun expression and phosphorylated c-Jun (p-c-Jun) level, and cell viability in the U251 cells of control group, 10 μmol/L SP600125 treatment group (JNK inhibitor) and 1 μmol/L CEP11004 treatment group (MLK3, a direct upstream kinase of JNK). (4) Western blotting and MTT assay were employed to detect the c-Jun and Flag expressions, and cell viability in the U251 cells of pcDNA3.1 transfected group, pcDNA3.1 + TSA transfected group, pMKK7-JNK1 transfected group and pMKK7-JNK1 + TSA transfected group. Results (1) The viability of cells of 0.1, 0.2, 0.5, 1.0 or 2.0 μmol/L TSA treated group was significantly lower than that in the control group, and the higher the TSA concentration, the lower the viability of cells; the viability of cells of 0.5 μmol/L TSA treated for 16, 24, 36 and 48 h groups was significantly lower than that in the control group, and the longer the TSA treatment, the lower the viability of cells. (2) The viability of 1 μmol/L M344, 0.5 μmol/L LBH589, 6 mmol/L NaBu and 6 mmol/L VPA treatment groups was significantly lower than that in the control group (P<0.05). (3) As compared with those in the control group, the p-JNK expression was significantly decreased in the cells after 0.5 μmol/L TSA treatment for 16 and 24 h, and the p-c-Jun protein expression and the cell viability were significantly decreased in the cells of 10 μmol/L SP600125 and 1 μmol/L CEP11004 treatment groups (P<0.05). (4) As compared with that in the pcDNA3.1 transfected group, cell viability in the U251 cells of pcDNA3.1+TSA transfected group, pMKK7-JNK1 transfected group and pMKK7-JNK1+TSA transfected group was significantly increased(P<0.05). Conclusion Histone deacetylase inhibitors reduce the proliferation of glioma cell U251 through inhibiting JNK activity. Key words: Glioma; Trichostatin A; JNK; Proliferation