Lentivirus-mediated RNA silencing of c-Met markedly suppresses peritoneal dissemination of gastric cancer in vitro and in vivo.

AIM: To investigate the expression of c-Met in peritoneal free cancer cells isolated from human gastric cancer ascites, and its relationship to peritoneal dissemination of gastric cancer. METHODS: Peritoneal free cancer cells (PFCCs) were isolated from ascites specimens of gastric cancer patients. c-Met expression in PFCCs was detected with immunocytochemistry. In human gastric cancer cell line SGC7901, c-Met expression was detected using RT-PCR and Western blot, and was suppressed with lentivirus-mediated RNAi. The proliferation of SGC7901 cells was measured using MTT assay, and the invasion ability was detected with invasion assay. The adhesion of SGC7901 cells to peritoneum was observed in human peritoneal mesothelial cells (HPMCs) monolayer in vitro and in mice in vivo. RESULTS: PFCCs were isolated from ascites of 6 out of 10 gastric cancer patients. c-Met expression in PFCCs was detected in 5 of the 6 gastric cancer patients. In SGC7901 cells, Lentivirus-mediated RNAi significantly reduced both c-Met mRNA and protein expression, which resulted in suppressing the cell proliferation, invasion and adhesion to peritoneum. The expression of α3ß1 integrin and E-cadherin was significantly inhibited in SGC7901 cells transfected with Lenti-miRNAc-Met. In the peritoneal dissemination model of gastric cancer, intraperitoneal injection of Lenti-miRNAc-Met markedly suppressed the tumor Progression of SGC7901 cells. CONCLUSION: c-Met is expressed in PFCCs from the ascites of gastric cancer patients. Down-regulation of c-Met expression markedly suppresses the multistep process of peritoneal dissemination, thus may be a potential target for the treatment of gastric cancer.

[Effects of p-hydroxybenzoic acid and phloroglucinol on mitochondria function and root growth in cotton (Gossypium hirsutum L.) seedling roots.] / å¯¹ç¾ŸåŸºè‹¯ç”²é ¸å’Œé—´è‹¯ä¸‰é šå¯¹æ£‰èŠ±å¹¼è‹—æ ¹ç³»çº¿ç²’ä½“åŠŸèƒ½å’Œæ ¹ç³»ç”Ÿé•¿çš„å½±å“.

With early-maturing cotton cultivar CCRI-50 widely grown in China as experimental material, water culture experiment was conducted to study the effects of p-hydroxybenzoic acid and phloroglucinol with different concentrations (0.8, 4.0, and 20.0 mmol·L-1) on generation rate of reactive oxygen, changes of antioxidant enzyme activities and mitochondria function of cotton roots. Results showed that p-hydroxybenzoic acid and phloroglucinol treatments inhibited the cotton root growth, reduced SOD, POD, CAT and H+-ATPase activities in root mitochondria, increased the generation rate of O2-· and H2O2 content. In addition, they also increased the opening of mitochondrial permeability transition pores (MPTP), decreased the membrane fluidity and cytochrome c/a (Cyt c/a). Difference of mitochondria function between p-hydroxybenzoic acid and phloroglucinol treatments was minor at concentration of 0.8 mmol·L-1, while the inhibition to root growth and mitochondria function under treatment of p-hydroxybenzoic acid at concentration of 4.0 and 20.0 mmol·L-1 was stronger than that of phloroglucinol. Above all, p-hydroxybenzoic acid and phloroglucinol inhibited antioxidant enzyme activity and mitochondrial function in cotton seedling roots, and the inhibition depended on dose of phenolic acids. The inhibition to root growth and mitochondria function between p-hydroxybenzoic acid and phloroglucinol treatment was different, and p-hydroxybenzoic acid had stronger inhibition than phloroglucinol at the concentration more than 4.0 mmol·L-1.

[Effects of nitrogen application rates on nitrogen uptake and utilization of direct-seeded cotton after wheat harvest].

An experiment was carried out to study the effects of different nitrogen application rates (0, 60, 120, 150, 180 and 240 kg N · hm⁻²) on the nitrogen uptake, utilization and distribution of short season cotton cultivar (CCRI-50) which was directly seeded after wheat harvest. Results showed that nitrogen application increased the nitrogen uptake of cotton at different growth stages, with the highest increment at the peak flowering-boll opening stage. Nitrogen application changed the percentages of nitrogen uptake among different growth stages. The percentages of nitrogen uptake decreased from seedling to peak flowering stage, but increased from peak flowering to boll maturing stage. In addition, nitrogen application reduced the decreasing speed of nitrogen concentration in middle and upper fruiting branches at later growth stages. Direct-seeded cotton had nitrogen and biomass accumulation in the lower and middle reproductive branches. With the nitrogen application of 150-180 kg · hm⁻², the lint yield, NARE (nitrogen apparent recovery efficiency) and the economic coefficient of biomass and nitrogen were relatively higher, and the eigenvalues of dynamic model of nitrogen content and nitrogen accumulation were relatively coordinate. Excessively high nitrogen application (over 180 kg N · hm⁻²) decreased biomass and nitrogen amount of reproductive organ in lower and middle branches, narrow rise of yield, and lower nitrogen use efficiency. However, excessively low nitrogen application (lower than 150 kg N · hm⁻²) also resulted in lower economic coefficient of biomass and nitrogen and yield. These results suggested the optimum nitrogen application rate 150-180 kg N · hm⁻² for direct-seeded cotton after wheat harvest in lower reaches of Yangtze River.

[Effects of nitrogen application rate on potassium uptake and utilization of direct-seeded cotton after wheat harvest]. / æ–½æ°®é‡å¯¹éº¦åŽç›´æ’­æ£‰é’¾ç´ å¸æ”¶åˆ©ç”¨çš„å½±å“.

By using cotton cultivar CCRI-50 as material, field experiments were conducted in the summer seasons of 2013 and 2014 at the experimental station of Jiangsu Academy of Agricultural Sciences (Nanjing, China) to study the effects of different nitrogen application rates (0, 60, 120, 150, 180 and 240 kg N·hm-2) on the potassium uptake and utilization of the cotton plant that was direct-seeded after wheat harvest. Data suggested that the elevated nitrogen application rates increased the cotton potassium uptake of all growth stages, and the largest increment was observed at the peak flowering-boll opening stage. Nitrogen application also changed the uptake percentage of potassium uptake of each stage, i.e., the percentage of potassium uptake decreased in the stage from seedling to peak flowering, while increased in the stage from peak flowering to boll maturing. In addition, the elevated nitrogen applications reduced the decreasing rate of nitrogen concentration in upper fruiting branches, but promoted the decreasing rate in middle and low fruiting branches at later growth stages. As the nitrogen application rate increased, the marginal effect of potassium uptake (promoted amount of potassium uptake due to 1 kg increase of N application) increased first and then decreased, and the lint production efficiency of potassium descended steadily. In cotton plants that were direct-seeded after wheat harvest, potassium and biomass were mainly accumulated in the lower and middle fruiting branches. At the 150 and 180 kg N·hm-2 application levels, much more potassium was allocated to the reproductive organs and the characters and the eigenvalues of simulated curves of potassium concentration and total potassium accumulation were more optimized than those at the higher or the lower N application levels. At the high nitrogen application (more than 180 kg N·hm-2) level, the marginal effect of potassium uptake and lint production efficiency decreased, and at the lower nitrogen application (less than 150 kg N·hm-2) level, lint yield was lower due to the decrease of economic coefficient of biomass and potassium in the middle and low fruiting branches.

[Effects of drought and waterlogging on carbohydrate contents of cotton boll and its relationship with boll biomass accumulation at the flowering and bolling stage].

Cotton cultivar NuCOTN 33B was planted in isolated pools treated with drought or waterlogging for 7 or 14 d to explore their effects on cotton boll carbohydrate content and its relationship with the biomass accumulation. The results showed that the drought treatment reduced the carbohydrate content of cotton boll shell on middle fruit branches, but had a weak effect on cotton boll shells on lower fruit branches. Soluble sugar, starch and sucrose contents of cotton boll shell on upper fruit branches under the drought condition and on whole plant branches under waterlogging treatment changed similarly, namely, the soluble sugar and starch content increased, while the sucrose content went down firstly and then increased later, which indicated that the exportation of sucrose from boll shell was inhibited and became worse with the increase of waterlogging duration. Compared with the boll shell, the carbohydrate contents of cotton seed were less affected by the drought and waterlogging treatments at the flowering and bolling stage. Under the treatments of drought and 7 d-waterlogging, the biomass accumulation of cotton bolls on the middle fruit branches initiated earlier but lasted less days, and the maximum speed at lower and upper fruit branches reduced, while the treatment of waterlogging for 14 d caused the decline of maximum speed of biomass accumulation of bolls on whole branches. On the other side, the correlation analysis showed the significant positive relationships among the boll biomass, the maximum speed and the contents of soluble sugar and sucrose in the boll shell respectively. In conclusion, the treatment of drought and waterlogging at the flowering and bolling stage retarded the outward transportation of sucrose from cotton bolls, changed the boll biomass accumulation characteristics, and therefore were detected as the important cause of cotton boll total biomass reduction.