ABSTRACT
Aim To evaluate the effect of expression inhibition of spermine oxidase(SMO)on the actitumor activity of polyamine analogue CPENSpm (N~1-cyclopropylmethyl-N~(11)-ethylnorspermine).Methods siRNA technique was used to inhibit expression of SMO in human lung cancer line A549.QT-RT-PCR and enzyme activity assay was performed to determine the expression level of SMO.The cell proliferation was detected by MTT assay.The apoptosis of A549 cells were evaluated by DNA degradation and Sub-G_1/flow cytometry assay.Results The A549 cell line with silenced SMO expression was successfully obtained.Basic SMO mRNA and enzyme activity levels in the SMO-siRNA plasmid transfected cells were 0.53% and 14% lower than that in the control cells respectively. Treating A549 control cells by 10 μmol·L~(-1) CPENSpm for 24 hours resulted in a 10-folds up-regulation of SMO in mRNA level and 20-fold increase in enzyme activity,but this drug-induced SMO expression was obviously prevented in SMO-siRNA plasmid transfected cells.MTT assay demonstrated that SMO expression inhibition decreased the sensitivity of A549 cells to CPENSpm exposure(0～20 μmol·L~(-1)).DNA degradation and sub-G_1 assay proved a deceased ability of CPENSpm to induce apoptosis in SMO-siRNA plasmid transfected cells.Conclusion Up-regulation of SMO by CPENSpm is possibly one of the molecular basics for its antitumor activity.
ABSTRACT
AIM: To prepare recombinant human spermine oxidase (SMO) and polyclonal antibody against human SMO by gene recombination techniques. METHODS: Human SMO cDNA was amplified from total RNA of A549 cells through reverse transcription PCR. The cDNA was then cloned into pET-15b to construct SMO prokaryotic expression vector. After transforming, the vector was induced to express recombinant SMO by IPTG in E. coli BL21 (DE_3). Recombinant SMO was purified by Ni-NTA resin under denaturing condition and then was dialyzed to renature. The enzyme activity of recombinant SMO was analyzed by chemical fluorescent method. SMO polyclonal antibody was prepared by using recombinant human SMO protein purified by polyacrylamide gel electrophoresis as antigen to inoculate rabbit intradermally. The titer and specificity of anti-sera were determined by ELISA, Western blot and Immune Cell Chemistry. RESULTS: Purified and dialyzed recombinant human SMO has the specificicity of oxidizing the spermine. The polyclonal antibody has high titer and specificity against human SMO. CONCLUSION: This research established a method for prokaryotic expression, purification and polyclonal antibody preparation of human SMO. The method lays a foundation for the future functional research of SMO.
ABSTRACT
Objective To investigate whether difluromethylornithine (DFMO) can be used in the treatment of human leukemia. Methods The cell proliferation was detected by MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium)] assay after treatment of human lymphocyte Jurkat cells by DFMO (0 to 10 mmol/L) for 24 to 72 h. Enzyme activity of spermine oxidase (SMO) and acetylpolyamine oxidase (PAO) was determined by chemiluminesence assay. DNA fragmentation assay was used to evaluate cell apoptosis. Fluorescent dye assay was performed to determine the changes in mitochondrial membrane potential. Western blotting was used to determine Bax content. Casepase-3 enzyme activity was measured by spectrophotometric method. Results DFMO treatment inhibited the proliferation of Jurkat cells significantly in a dosage- and time-dependent manner (P