Identification of potential biomarkers and their clinical significance in gastric cancer using bioinformatics analysis methods.

BACKGROUND: Alternative splicing (AS) is an important mechanism for regulating gene expression and proteome diversity. Tumor-alternative splicing can reveal a large class of new splicing-associated potential new antigens that may affect the immune response and can be used for immunotherapy. METHODS: The RNA-seq transcriptome data and clinical information of stomach adenocarcinoma (STAD) cohort were downloaded from The Cancer Genome Atlas (TCGA) database data portal, and data of splicing events were obtained from the SpliceSeq database. Predicting genes were validated by Asian cancer research group (ACRG) cohort and Oncomine database. RT-qPCR was used to analysis the expression of ECT2 in STAD. RESULTS: A total of 32,166 AS events were identified, among which 2,042 AS events were significantly associated with patients survival. Biological pathway analysis indicated that these genes play an important role in regulating gastric cancer-related processes such as GTPase activity and PI3K-Akt signaling pathway. Next, we derived a risk signature, using alternate acceptor, that is an independent prognostic marker. Moreover, high ECT2 expression was associated with poorer prognosis in STAD. Multivariate survival analysis demonstrated that high ECT2 expression was an independent risk factor for overall survival. Gene set enrichment analysis revealed that high ECT2 expression was enriched for hallmarks of malignant tumors. The ACRG cohort and Oncomine also showed that high ECT2 expression was associated with poorer prognosis in gastric cancer patients. Finally, RT-qPCR showed ECT2 expression was higher in STAD compared to the normal tissues. CONCLUSION: This study excavated the alternative splicing events in gastric cancer, and found ECT2 might be a biomarkers for diagnosis and prognosis.

Transcriptomic analysis of the effects of Toll-like receptor 4 and its ligands on the gene expression network of hepatic stellate cells.

BACKGROUND: Intact Toll-like receptor 4 (TLR4) has been identified in hepatic stellate cells (HSCs), the primary fibrogenic cell type in liver. Here, we investigated the impact of TLR4 signaling on the gene expression network of HSCs by comparing the transcriptomic changes between wild-type (JS1) and TLR4 knockout (JS2) murine HSCs in response to two TLR4 ligands, lipopolysacchride (LPS), or high-mobility group box 1 (HMGB1). RESULTS: Whole mouse genome microarray was performed for gene expression analysis. Gene interaction and co-expression networks were built on the basis of ontology and pathway analysis by Kyoto Encyclopedia of Genes and Genomes (KEGG). Gene expression profiles are markedly different between Wild type (JS1) and TLR4 knockout (JS2) HSCs under basal conditions or following stimulation with LPS or HMGB1. The differentially expressed genes between TLR4 intact and null HSCs were enriched in signaling pathways including p53, mTOR, NOD-like receptor, Jak-STAT, chemokine, focal adhesion with some shared downstream kinases, and transcriptional factors. Venn analysis revealed that TLR4-dependent, LPS-responsive genes were clustered into pathways including Toll-like receptor and PI3K-Akt, whereas TLR4-dependent, HMGB1-responsive genes were clustered into pathways including metabolism and phagosome signaling. Genes differentially expressed that were categorized to be TLR4-dependent and both LPS- and HMGB1-responsive were enriched in cell cycle, ubiquitin mediated proteolysis, and mitogen-activated protein kinase (MAPK) signaling pathways. CONCLUSIONS: TLR4 mediates complex gene expression alterations in HSCs. The affected pathways regulate a wide spectrum of HSC functions, including inflammation, fibrogenesis, and chemotaxis, as well as cell growth and metabolism. There are common and divergent regulatory signaling downstream of LPS and HMGB1 stimulation via TLR4 on HSCs. These findings emphasize the complex cascades downstream of TLR4 in HSCs that could influence their cellular biology and function.

[Effects of cordyceps acid and cordycepin on the inflammatory and fibrogenic response of hepatic stellate cells].

OBJECTIVE: To investigate the effects of cordyceps acid and cordycepin on the inflammatory phenotype and fibrogenic property of hepatic stellate cells (HSCs). METHODS: An immortalized mouse HSC line (JS1) was stimulated with lippolysaccharide (LPS; 100 ng/ml) to induce an inflammatory response with or without co-administration of cordyceps acid or cordycepin in various concentrations (10, 50, or 200 mumol/L). Effects of the treatments on the chemokine monocyte chemotactic protein-1 (MCP-1) mRNA expression in the cells and the protein secretion in the cell culture supernatants were determined by reverse transcription and real-time quantitative PCR (RT-PCR) and enzyme-linked immunosorbent assay (ELISA), respectively. In addition, JS1 cells were treated with transforming growth factor-b1 (TGFb1; 10 ng/ml) to induce a fibrogenic response with or without co-administration of cordyceps acid or cordycepin in various concentrations (10, 50, or 200 mumol/L). Effects on the expression of fibrogenic proteins including collagen type I and a-smooth muscle actin (a-SMA), were investigated by Western blot. RESULTS: High-concentration (200 mumol/L) treatments of both cordyceps acid and cordycepin significantly inhibited the LPS-induced up-regulation of MCP-1 transcription and secretion (mRNA: 2.07 +/- 0.29 vs. 3.35 +/- 0.26, t = 15.90 and 1.15 +/- 0.23 vs. 4.17 +/- 0.61, t = 8.93; protein: 1.88 +/- 0.06 vs. 2.33 +/- 0.06, t = 10.39 and 1.47 +/- 0.25 vs. 1.97 +/- 0.04, t = 4.60; all P less than 0.05). All concentrations of cordyceps acid and cordycepin inhibited the TGFb1-induced up-regulation of collagen type I and a-SMA protein expression. However, the effects were more robust with the 200 mumol/L concentrations (P less than 0.05). CONCLUSION: Cordyceps acid and cordycepin ameliorate the LPS-induced inflammatory phenotype and TGFb1-induced fibrogenic response of cultured HSCs. These effects may contribute significantly to the drugs' therapeutic mechanisms to inhibit and resolve liver fibrosis.

[HMGB1-mediated activation of TLR4 signaling in hepatic stellate cells].

To determine the potential of the high mobility group box-1 protein 1 (HMGB1) to activate Toll-like receptor 4 (TLR4) signaling in hepatic stellate cells (HSCs) and investigate the subsequent transition of HSC towards the inflammatory phenotype. Three immortalized mouse HSC cell lines, wild-type (JS1), TLR4-/- (JS2) and MyD88-/- (JS3), were subcultured in plates and divided into groups of normal control (untreated), postive control (lipopolysaccaride, LPS treatment), and experimental (HMGB1 treatment). All groups were transfected with luciferase reporter plasmids carrying responsive elements for either the nuclear factor-kappa B (NF-kB) or activator protein-1 AP-1 transcription factors. Following stimulation with normal saline, LPS (100 ng/mL) or HMGB1 (100 ng/mL), the activation of NF-kB or AP-1 was detected by a dual-luciferase reporter assay system. The induction of monocyte chemotactic protein-1 (MCP-1) transcription was determined by measuring the mRNA levels using real time quantitative reverse transcription PCR (qRT-PCR). The secreted protein levels of MCP-1 were determined by enzyme-linked immunosorbent assay (ELISA) of the culture supernatants. Activation of NF-kB- and AP-1-responsive reporters was significantly up-regulated in JS1 cells treated with HMGB1 or LPS, and the activation was coincident with markedly up-regulated transcription and secretion of MCP-1. However, HMGB1 and LPS treatment produced no responsive of the NF-kB and AP-1 reporters, and no increase in expression or secretion of MCP-1, in JS2 or JS3 cells. As an endogeous ligand of TLR4, HMGB1 may activate TLR4 signaling and the TLR4-mediated inflammatory response of HSC.

High mobility group box 1 activates Toll like receptor 4 signaling in hepatic stellate cells.

AIMS: The aim of the present study was to investigate the effect of high mobility group box 1 (HMGB1), a damage pattern molecule that signals the presence of necrosis, on TLR4 signaling in hepatic stellate cells (HSC). MAIN METHODS: Immortalized mouse HSC lines JS1, JS2, and JS3 that were either TLR4(+/+), TLR4(-/-), or MyD88(-/-) were transfected with NF-κB or AP-1 responsive luciferase reporter plasmids, followed by stimulation with 100 ng/ml lipopolysacchride (the exogenous TLR4 ligand) or 100 ng/ml HMGB1. The activation of NF-κB or AP-1 activities was determined by a dual-luciferase reporter assay system. The cells were also stimulated with LPS or HMGB1 and collected for the determination of chemotactic cytokine MCP-1 mRNA or proteins secretion. In a separate experiment, the cells were co-stimulated with 10 µg/ml TGF-ß1 and LPS or HMGB1 and collected for assessment of fibrogenic mRNA and protein expression. KEY FINDINGS: HMGB1 stimulation markedly up-regulated MCP-1 mRNA expression and protein secretion, and enhanced TGF-ß1-stimulated collagen α2(I) and α-SMA expression in JS1 cells. This was associated with enhanced activation of NF-κB and AP-1 responsive luciferase reporters. On the contrary, JS2 and JS3 cells were hyporesponsive to both LPS and HGMB1 stimulation compared to JS1 cells. SIGNIFICANCE: As an endogenous ligand of TLR4, HMGB1 activates TLR4 signaling in HSCs to enhance their inflammatory phenotype, indicating that TLR4 signaling need not rely solely on gut-derived LPS for activation during liver injury. HMGB1 also has a synergistic effect with TGF-ß1 to stimulate fibrogenic protein expression, which is likely to be TLR4 dependent.