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Glutamate-ammonia ligase (GLUL, also known as glutamine synthetase) is a crucial enzyme that catalyzes ammonium and glutamate into glutamine in the ATP-dependent condensation. Although GLUL plays a critical role in multiple cancers, the expression and function of GLUL in gastric cancer remain unclear. In the present study, we have found that the expression level of GLUL was significantly lower in gastric cancer tissues compared with adjacent normal tissues, and correlated with N stage and TNM stage, and low GLUL expression predicted poor survival for gastric cancer patients. Knockdown of GLUL promoted the growth, migration, invasion and metastasis of gastric cancer cells in vitro and in vivo, and vice versa, which was independent of its enzyme activity. Mechanistically, GLUL competed with β-Catenin to bind to N-Cadherin, increased the stability of N-Cadherin and decreased the stability of β-Catenin by alerting their ubiquitination. Furthermore, there were lower N-Cadherin and higher β-Catenin expression levels in gastric cancer tissues compared with adjacent normal tissues. GLUL protein expression was correlated with that of N-Cadherin, and could be the independent prognostic factor in gastric cancer. Our findings reveal that GLUL stabilizes N-Cadherin by antagonizing β-Catenin to inhibit the progress of gastric cancer.
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AIM: In this study, CD147 antibody was used to carry out targeted modification of nanoparticles for protein kinase Cε (PKCε)-siRNA gene therapy to target lung cancer cells.The inhibitory effects of the nanoparticles on the proliferation and invasion of the lung cancer cells were observed.METHODS: The magnetic nanoparticles targeting CD147 protein were assembled as gene vector.The expression of CD147 in the lung cancer cells was observed under laser scanning confocal microscope.The cells were divided into CP group, CN group and LP group as the experimental groups. Targeted nanoparticles were used as CA group.Non-transfected cells were used as control group.The cell transfection was carried out with 250 ng plasmids/well in 6-well plate.The effect of nanocontrast agent on the cell endocytosis was observed under laser scanning confocal microscope.The mRNA expression of PKCε was detected by RT-qPCR.The protein expres-sion of Ki67, MMP3, PKCε, Wnt1 and GAPDH was determined by Western blot.The cell proliferation ability was detec-ted with colony formation assay.The cell invasion ability was detected by Transwell method.RESULTS: The expression of CD147 protein in the human lung cancer A549 cells was confirmed by immunofluorescence staining.The endocytosis of siRNA into the A549 cells in CP group was observed with the highest efficiency as compared with CN group and LP group. The relative mRNA expression of PKCε in the A549 cells of CP group, CN group, LP group and CA group were (9.76 ± 0.18)%, (98.51 ±0.32)%, (99.17 ±0.16)% and (99.68 ±0.11)%, respectively.The difference between CP group and control group was statistically significant (P <0.05).No significant difference among CN group, LP group and control group was observed.The protein expression of PKCε, Ki-67, MMP3 and Wnt1 in CP group was significantly reduced, and the protein expression levels among CN group, LP group and control group had no significant difference.The colony number in CP group was significantly smaller than that in control group (P <0.05).The effective colony numbers in CN group, LP group and CA group had no significant difference as compared with control group.The number of the invading cells in CP group was significantly less than that in control group (P <0.05).The numbers of the invading cells in CN group, LP group and CA group had no significant difference as compared with control group.CONCLUSION: Nanogene vector targe-ting CD147 can carry PKCε-siRNA to conduct gene therapy efficiently on the lung cancer cells to achieve effective inhibito-ry effects on the proliferation and invasion of the lung cancer cells.
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AIM:To explore the mechanism of p21-activated kinase 4 (PAK4) on non-small-cell lung cancer (NSCLC) migration and invasion.METHODS:After A549 and NCI-H520 cell lines were transfected with PAK4-siRNA or negative control , the expression of PAK4 at mRNA and protein levels was detected by real-time PCR and Western blot , re-spectively .The invasion and migration of A 549 cells and NCI-H520 cells were measured by Matrigel invasion assay and Transwell migration assay.LIMK1, cofilin, and their respective phosphorylation were examined by Western blot .The inter-action of PAK4 and LIMK1 was investigated by co-immunoprecipitation assay .The relationship between PAK4 and LIMK1 phosphorylation was examined by a protein kinase assay in the A 549 cells and NCI-H520 cells.The expression of PAK4 and p-LIMK1 in 10 human NSCLC tissues was examined by Western blot .A549 cells and NCI-H520 cells were individually or commonly transfected with PAK4-siRNA or LIMK1 plasmid in order to observe the cell migration and invasion .RE-SULTS:After A549 cells and NCI-H520 cells were transfected with PAK4-siRNA for 48 h, the expression of PAK4 at mR-NA and protein levels , and the numbers of invasion and migration cells in PAK 4-siRNA group were lower than those in con-trol group.Compared with control group , the phosphorylation of LIMK1 and cofilin was lower in PAK4-siRNA group, whereas the total expression levels of LIMK 1 and cofilin did not change .The results of co-immunoprecipitation assays showed that PAK4 specifically interacted with LIMK1 in A549 and NCI-H520 cells.LIMK1 phosphorylation in the presence of PAK4 (K350M) was significantly lower than that in the presence of PAK 4 (WT) or PAK4 (S445N) in the protein ki-nase assay.The PAK4 upregulation was positively correlated with the level of p-LIMK1 (P<0.05).After A549 cells and NCI-H520 cells were co-transfected with PAK4-siRNA and LIMK1 plasmid, the migration and invasion cell numbers in co-transfection group were higher than those in PAK 4-siRNA transfection group .CONCLUSION: PAK4 promotes the inva-sive and migratory abilities of NSCLC , which is mediated by LIMK 1 phosphorylation .
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AIM:To investigate the expression and clinical significance of PAK4 in the cell lines and tissues of non-small cell lung cancer (NSCLC).METHODS:PAK4 expression in human bronchial epithelial (HBE) cells, NSCLC cell lines, NSCLC tissues and adjacent non-tumor tissues were assessed by immunohistochemistry, real-time PCR and Western blot.Prognostic value of PAK4 expression was evaluated by Kaplan-Meier analysis and Cox regression.RE-SULTS:PAK4 was over-expressed in the NSCLC cell lines at both mRNA and protein levels compared with HBE cells ( P<0.05).PAK4 was over-expressed in the NSCLC tissues at both mRNA and protein levels compared with adjacent non-tumor tissues (P<0.05).PAK4 was over-expressed in the metastatic NSCLC tissues compared with the primary NSCLC tissues (P<0.05).Higher PAK4 staining scores were positively correlated with differentiation, lymph node metastasis, distant metastasis, and clinical stage.Kaplan-Meier analysis and log-rank test showed that overall survival was significantly different between the patients with up-regulated PAK4 and the patients with down-regulated PAK4 ( P<0.05) .PAK4 over-expression was associated with NSCLC progression.CONCLUSION:Increased PAK4 expression was associated with tumor invasion, metastasis and prognosis in the patients with NSCLC.PAK4 is an important prognostic marker and potential ther-apeutic target in NSCLC.
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BACKGROUND: Nanosphere, an ideal nonviral gene delivery vector, is not excellence of immunogenicity and oncogenicity. Nanotechnology and gene interference are used to block hypoxia-inducible factor 1 alpha (HIF-1α) expression in esophageal squamous carcinoma tissue and decrease tolerance of malignant cells to chemotherapeutics. Theoretically, they become effective methods to inhibit malignant cell growth of esophageal squamous carcinoma. OBJECTIVE: To study the inhibitory effect of small interference RNA targeting HIF-1α (siRNA-HIF-1α) nanospheres on human esophageal squamous cancer TE-1 cell growth. DESIGN, TIME AND SETTING: Based on in vitro cultured esophageal squamous cancer TE-1 cells, a completely randomized controlled study was performed at the Central Laboratory, the Third Hospital Affiliated to Sun Yat-sen University from January 2007 to December 2008. MATERIALS: siRNA-HIF-1α was synthesized by Shanghai Bioengineering Company; siRNA-HIF-1α nanospheres were prepared using solvent evaporation technique; human esophageal squamous cancer TE cell strain was provided by Shanghai Cell Bank of the Chinese Academy of Sciences. METHODS: TE-1 cells cultured in vitro were assigned into four groups: saline, gene-free nanospheres, siRNA-HIF-1α, and siRNA-HIF-1α nanospheres groups. MAIN OUTCOME MEASURES: HIF-1α mRNA expression was detected by RT-PCR; HIF-1α protein expression was detected by Western blot; apoptosis of TE-1 cells was determined by flow cytometry; TE-1 cell growth was examined by MTT. RESULTS: At 72 hours after treatment, both HIF-1α mRNA expression and HIF-1α protein expression in the siRNA-HIF-1α nanospheres group were significantly less than other three groups (P < 0.01), but apoptotic rate was significantly greater than other three groups (P < 0.01). TE-1 cell growth was remarkably inhibited in the siRNA-HIF-1α nanospheres group, which was significantly different compared with other three groups (P < 0.01).CONCLUSION: siRNA-HIF-1α nanospheres can specifically reduce both HIF-1α mRNA and HIF-1α protein expressions in esophageal squamous carcinoma TE-1 cells, significantly increase tumor cell apoptosis, and remarkably inhibit TE-1 cell growth.