High Expression of EIF4G2 Mediated by the TUG1/Hsa-miR-26a-5p Axis Is Associated with Poor Prognosis and Immune Infiltration of Gastric Cancer.

Objective: Eukaryotic translation initiation factor 4 gamma 2 (EIF4G2) is involved in the occurrence and development of various tumors. However, the effect of EIF4G2 in gastric cancer (GC) has not been fully explored. The purpose of this study was to explore the function and mechanism of EIF4G2 in GC. Methods: The Tumor Immune Estimation Resource 2.0 database was used to analyze EIF4G2 expression in various cancers and the relationship between EIF4G2 expression and tumor-infiltrating immune cells. Gene Expression Profiling Interactive Analysis was utilized to assess the EIF4G2 expression level and its effect on survival in GC. UALCAN was conducted to analyze EIF4G2 expression in various subgroups of GC. The Kaplan-Meier plotter was employed for survival analysis. Receiver operator characteristic (ROC) curve analysis was applied to evaluate the diagnostic role of EIF4G2 in GC. LinkedOmics was used to identify the co-expressed genes and Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathways. The Tumor-Immune System Interaction database was employed to analyze the correlation between EIF4G2 expression and tumor-infiltrating lymphocytes. The starBase web platform was used to predict the upstream microRNAs and long noncoding RNAs. Results: EIF4G2 expression was upregulated in GC tissues compared to normal controls. High expression of EIF4G2 indicated poor prognosis in GC. ROC analysis revealed that EIF4G2 had good diagnostic ability to distinguish GC from normal tissues. Immune infiltration analysis indicated that EIF4G2 expression may be involved in the modulation of tumor immune infiltration in GC. Finally, we determined that the Taurine Upregulated 1 (TUG1)/hsa-miR-26a-5p/EIF4G2 axis was the most likely regulatory pathway involved in GC development. Conclusions: EIF4G2 was upregulated in GC and elevated expression of EIF4G2 indicated unfavorable prognosis. Moreover, EIF4G2 expression may be involved in the regulation of tumor immune cell infiltration. The TUG1/hsa-miR-26a-5p axis is a likely upstream regulatory mechanism of EIF4G2 in GC. EIF4G2 may thus serve as a prognosis biomarker and present a new therapeutic target.

Stat3 is involved in angiotensin II-induced expression of MMP2 in gastric cancer cells.

The expression of matrix metalloproteinase-2 (MMP2) has been linked with tumor invasion, angiogenesis, and metastasis. It has been reported that angiotensin II (Ang II) can induce MMP2 expression in gastric cancer cells. However, the molecular basis for Ang II regulates MMP2 expression in gastric cancer cells remains unclear. The aim of our study is to explore whether angiotensin II could induce MMP2 expression mediated through the Stat signaling pathway and its potential mechanism. Electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP)-binding assays was employed to determine the DNA-STAT binding activity. MMP2 and VEGF expression was analyzed with real-time PCR and Western blots. To examine the role of Stat3 in angiotensin II-induced MMP2 expression, A JAK-specific inhibitor and AG490 were used. Angiotensin II activated STAT-DNA binding activity in dose-dependent manners in gastric cancer cells. AG490 markedly inhibited angiotensin II-induced Stat3 activation and the expression of MMP2 and VEGF in gastric cancer cells. These results indicate that Stat3 may at least in part mediate angiotensin II-induced MMP2 mRNA expression in human gastric cancer cells. The activation of the JAK/Stat3 signaling pathway plays an important role in the progression of gastric cancer and that blockade of JAK/Stat3 signals may provide a novel therapeutic strategy for gastric cancer.

HNF1α Controls Liver Lipid Metabolism and Insulin Resistance via Negatively Regulating the SOCS-3-STAT3 Signaling Pathway.

This study is aimed at evaluating the effects, functions, and mechanism of HNF1α on hepatic glycolipid metabolism. In this study, free fatty acid- (FFA-) induced steatosis of hepatocyte liver cell LO2 was used as an in vitro model. The methods of Oil Red O staining, RT-qPCR, western blot, and immunofluorescence staining were used to detect LO2-regulated HNF1α expression and its effects on FFA-induced LO2 cell steatosis, the insulin signaling and SOCS-3-STAT3 signaling pathways, the expression of lipid metabolism-related regulators, and phosphorylation. With increased FFA induction time, the expression of HNF1α in the LO2 fatty degeneration hepatic cells gradually decreased. Downregulation of HNF1α expression aggravated FFA-induced steatosis of LO2 hepatocytes. HNF1α promotes activation of the insulin pathway and oxidative breakdown of fat and inhibits lipid anabolism. Inhibitors of STAT3 can reverse the regulation of decreased HNF1α expression on the insulin signaling pathway and fat metabolism. We also confirmed this pathway using HNF1α-/- mice combining treatment with STAT3 inhibitor NSC 74859 in vivo. HNF1α regulates hepatic lipid metabolism by promoting the expression of SOCS-3 and negatively regulating the STAT3 signaling pathway.

Angiotensin II type 1 receptor antagonist suppress angiogenesis and growth of gastric cancer xenografts.

Angiotensin II (Ang II) has been reported to promote tumor progression, tumor growth and angiogenesis in many cancers. We previously observed that angiotensin II type 1 receptors (AT1R) were upregulated in human gastric cancer and may be involved in the progression of gastric cancer. We studied the effects of AT1R antagonist on angiogenesis and growth in gastric cancer xenografts to observe the mechanism action of AT1R in the gastric cancer. The results showed that the growth of gastric cancer cells was significantly suppressed by treatment with AT1R antagonist. In vivo, TCV-116, at doses of both 2 and 5 mg/kg/day, significantly suppressed tumor growth in mice (47.3 and 70.2%). Microvessel density was significantly decreased by TCV-116 (3.4 +/- 0.9 and 2.8 +/- 0.5 per field) compared with the control group (12.9 +/- 1.1 per field), and VEGF expression was significantly suppressed by AT1R antagonist. These results demonstrate that AT1R plays an important role in the progression of gastric cancer. Suppression tumor angiogenesis could be one of the mechanisms by which AT1R antagonist suppresses the growth of gastric cancer. These findings also provide a theoretical basis for the future clinical application of AT1R antagonist against gastric cancer.

Angiotensin II type 1 receptor expression in human gastric cancer and induces MMP2 and MMP9 expression in MKN-28 cells.

Angiotensin II (Ang II), a main effector peptide in the renin-angiotensin system, acts as a growth-promoting and angiogenic factor via angiotensin II receptor1 (AT1R). In this study, we investigated the expression of angiotensin II type1 receptor (AT1R) in gastric cancer and the effects of Ang II on the expression of MMP2 and MMP9 in the human gastric cancer cell line MKN-28 cells. The expression of the Ang II type I receptor was examined by western and immunocytochemistry in gastric cancer cell lines and detected by real-time PCR and immunohistochemistry in normal and gastric cancer tissues. The expression of MMP2 and MMP9 were detected by real-time PCR and western after treatment with Ang II and/or AT1R antagonist. AT1R were expressed in all human gastric cancer lines and the expression of AT1R was significantly higher in cancer tissues than that in normal gastric tissues (P < 0.01). Furthermore, Ang II promoted the expression of MMP2 and MMP9 in MKN-28 cells, and the stimulatory effects of Ang II could be blocked by AT1R antagonist. These results suggest that AT1R is involved in the progression of gastric cancer and may promote the angiogenesis of gastric cancer cell line (MKN-28), and these effects may be associated with the upregulation of MMP2 and MMP9.