Prevention and inhibition of nasopharyngeal carcinoma growth by attenuated salmonella SGN1 / 中国药理学通报

Aim To study the inhibitory effect of attenuated salmonella SGN1, overexpressing methioninase, on nasopharyngeal carcinoma (NPC) and the underlying mechanism. Methods The cell proliferation, cell cycle, cell apoptosis, clony formation and migration a-bility of 5-8F, HNE-2, CNE-2 cells were measured u-sing flow cytometry assay, clone formation assay, and wound assay after the methionine restriction treatment. 5-8F, HNE-2, CNE-2 cells were infected with SGN1 at the multiplicity of infection (MOI) of 1: 100 for 5 hours, followed with the measurement of cell growth. A xenograft model was constructed by subcutaneous injection of 5-8F cells in mice to observe the inhibitory effect of SGN1 on nasopharyngeal carcinoma. Results Compared with the control group, methionine restriction significantly inhibited the proliferation, migration ability, and clone formation of nasopharyngeal carcinoma cells and blocked the G

Study on Expression Condition Optimization of Two Recombinant Methioninases and Their Inhibitory Effects on Human Lung Adenocarcinoma Cells GLC / 中国药房

OBJECTIVE： To optimize the expression induction condition of two recombinant methioninases， and to investigate their inhibitory effects on the proliferation of human lung adenocarcinoma cells GLC. METHODS： Recombinant methioninases expression plasmid PGEX-4T1-4A1-MGL and PGEX-4T1-3B8-MGL were transfected into competent Escherichia coli Dh5α， and induced by isopropyl-β-D-thiogalactoside. Using the expression level of target protein as index， the initial OD600 nm value before induction， culture temperature and induction time were optimized by single factor test. The recombinant methioninase 4A1-MGL and 3B8-MGL were purified by affinity chromatography. The concentration of recombinant methioninase was detected by Coomassie blue method. The purity of the product was detected by sodium lauryl benzene sulfonate-polyacrylamide gel electrophoresis； its activity was detected by spectrophotometry. The proliferation of cells was detected by MTT assay after treated with low-dose， medium-dose and high-dose of recombinant methioninases （4A1-MGL or 3B8-MGL was 0.1， 0.2， 0.4 U/mL） for 24， 48， 74 h. Inhibitory rate of cells were calculated. RESULTS： The optimal induction condition of two recombinant methioninases included that initial OD600 nm of 0.9， culture temperature of 37 ℃， induction time of 5 h. The results of validation test showed that protein expression level of 4A1-MGL was 1.52±0.04， that of 3B8-MGL was 1.28±0.03 （RSD＜3％，n＝3）. After purification， the concentration， purity and activity of 4A1-MGL were （0.70±0.02）mg/mL， （96.42±3.15）％ and （0.45±0.02）    U/mg； and those of 3B8-MGL were （0.56±0.02）mg/mL， （97.43±2.96）％ and （0.91±0.03）U/mg. After treated with low-dose and medium-dose of 4A1-MGL and 3B8-MGL for 48 and 72 h， treated with high-dose of 4A1-MGL and 3B8-MGL for 24， 48 and 72 h， inhibitory rate of GLC cell was increased significantly， and high-dose group for 72 h was significantly higher than low-dose and medium-dose groups at same time point （P＜0.05）. CONCLUSIONS： The induction conditions of recombinant methioninase expression are successfully optimized in this study. The obtained 4A1-MGL and 3B8-MGL could inhibit the proliferation of GLC cells in a dose-dependent manner.

Purification and characterization of a novel thermo stable L-methioninase from Streptomyces sp. DMMMH4 and its evaluation for anticancer activity.

L-methioninase has been purified 2.55-fold from the crude extract of Streptomyces sp. DMMMH4. The purification procedure was carried out by heat treatment and gel filtration on Sephadex G-200 column chromatography. SDS-PAGE electrophoresis showed a migrating protein band molecular mass of 47 kDa. The kinetic properties determined for the purified enzyme displayed optimum activity at 70OC and thermal stability were 70OC for 30 min. The enzyme showed maximum activity at pH 6 using acetate buffer 0.05M and was relatively stable across a broad range of pH values (5.5-8 pH). The enzyme strongly inhibited by Cr+2, Fe+2, Ni+2, Cd+2, PMSF, β-mercaptoethanol and SDS while Hg+2,Cu+2 and iodoacetate completely inhibited the enzyme activity at a final concentration of 10mM. The purified enzyme exhibited a Km of 0.7, 0.15 and 0.25 mM for L-methionine, DL-ethionine and L-cystine respectively. Cytotoxicity test demonstrate that enzyme was active against liver HepG2, breast MCF-7, lung A549, prostate PC3 and colon HCT116 cancer cell lines and has negligible toxicity toward a normal melanocyte cell line HFB4.

Comparative study of a new alkaline L-methioninase production by Aspergillus ustus AUMC 10151 in submerged and solid-state fermentation

Twenty four fungal species were screened for their ability to produce alkaline L-methioninase on methionine-glucose liquid medium. Aspergillus ustus AUMC 10151 displayed the highest yield of enzyme (10.8 U/mg protein), followed by A. ochraceus and Fusarium proliferatum. Upon optimization of the submerged fermentation (SmF)conditions, the maximum enzyme yield (18.23 U/mg protein) was obtained on a medium containing L-methionine (0.5%), sucrose (0.95%), KH2PO4 (0.1%) and 175 rpm. Seven agro-industrial by-products were screened as substrates for L-methioninase production under solid-state fermentation (SSF). Wheat bran resulted 38.1 U/mg protein, followed by rice bran (27.6 U/mg protein) and soya bean meal (26.6 U/mg protein). Maximum alkaline L-methioninase (99.56U/mg protein) was achieved at initial moisture content of 71.5%, inoculum size of 2.0 mL of spore suspension, initial pH 8.5, incubation period eight days at 30°C and supplementation of the salt basal medium with pyridoxine(100 μg/mL) and beet molasses (20% v/v). The productivity of L-methioninase by A. ustus under SSF was higher than that of SmF about 5.45 fold under optimum conditions.