Abstract: Objective: To investigate the effects and molecular mechanisms of 2-12alkyl-6-methoxycyclohexa-2,5-diene-1,4-dione(DMDD) on diffuse large B lymphoma (DLBCL).Methods: In animal experiments, 4-week-aged BALB/C mice were divided into 5 groups, 20 mice in each group. Mice were inguinal injected with DLBCL cell line OCI-LY19 cells 0.1 ml at the concention of 1 × 10⁷ /ml. Two days later, mice were treated with DMDD at the doses of 0, 1, 5, 25 and 125 mg/kg by intragastric administration respectively, once /2 days. Ten mice of each group were killed on the 18th day of administration, and the tumor tissues were weighed. The survival time of the remaining mice were recorded. In cell experiments, OCI-LY19 cells were added to 96-well culture plates, 100 μl 1×10⁵ cells/ml per well, then 100 μl DMDD was added to the well and the final concentrations were 0, 1, 5, 25 and 125 μmol/L respectively. The cells were treated with DMDD for 0, 24, 48 and 72 h, three wells in each group. The cell proliferation activity was detected by MTS assay. According to the results of cell proliferation experiments, OCI-LY19 cells were treated with DMDD at the concentrations of 0 μmol/L, 5 μmol/L and 25 μmol/L for 24 h. The apoptosis rate was analyzed by flow cytometry, the nuclear type was observed by hoechst staining, the mitochondrial membrane potential was observed by JC-1 staining, cytotoxicity of drugs was evaluated by LDH release experiment, gene expression and transcription were analyzed by qPCR and Western blot.Results: Compared with 0 mg/kg drug group, DMDD at the dose of 1～125 mg/kg could inhibit the growth of tumor tissue in mice and prolong their survival time (P＜0.01). Cell experiments showed: in DMDD group, the proliferation activity of OCI-LY19 cells was decreased significantly and the level of apoptosis was increased significantly (P＜0.01), nuclear fragmentation, agglutination, apoptotic bodies occurred and mitochondrial membrane potential was decreased, the LDH release rate was increased significantly (P＜0.01), the expressions of caspase-3 and bax genes and the phosphorylation level of Ikappa B alpha in cells were up-regulated significantly, the protein expression levels of bcl-2, bcl-xL, jak2 and stat3 were inhibited significantly (P＜0.01).Conclusion: DMDD can inhibit the expressions of JAK2, STAT3 and p-Ikappa B alpha in JAK2/STAT3 and NF-kappa B signal pathways, down-regulate BCL-2/BAX and activate Caspase-3, finally, activate the endogenous pathway of mitochondrial apoptosis in OCI-LY19 cells and promote the apoptosis of DLBCL cells, inhibit proliferation of OCI-LY19 cells. It has inhibitive effects on DLBCL.

Key words: DMDD, diffuse large B lymphoma (DLBCL), cell apoptosis, signal pathway, mice, survival time