Identification of crucial genes of pediatric inflammatory bowel disease in remission by protein-protein interaction network and module analyses.

BACKGROUND: Although the main treatments of inflammatory bowel disease (IBD) aim at the induction and maintenance of clinical remission, several studies have demonstrated inflammation still present in clinical remission. The goal of this study was to analyze the gene expression profiles between the pediatric IBD and control samples, aiming to further investigate the underlying therapeutic target in remission. METHODS: Gene expression profiles data of GSE33943 were downloaded from Gene Expression Omnibus, which included 45 pediatric IBD samples and 13 control samples. The differentially expressed genes (DEGs) between IBD and control samples were identified by LIMMA package in R and the function of DEGs were predicted by Gene Ontology and KEGG pathway enrichment analyses using GeneAnswer package. Furthermore, a protein-protein interaction (PPI) network was constructed through the STRING database and functional module was obtained using ClusterONE. RESULTS: A total of 224 DEGs were screened between IBD and control samples. These DEGs (e.g. up-regulated FAS and down-regulated CCL5) were mainly enriched in cytokine‒cytokine receptor interaction and chemokine signaling pathway. In addition, some hub genes (e.g. up-regulated PSMA2 and PSMA6) were obtained through PPI network and functional module. These two genes were involved in Proteasome alpha-subunit and conserved site by functional module analysis. CONCLUSIONS: The immune and Proteasome mechanisms are still active during remission and FAS, PMSF6 and PMSF2 may be underlying targets for therapy of this disease.

[Risk analysis of the canceration of colorectal large polyps].

OBJECTIVE: To analyze the risk factors of carcinogenesis of large colorectal polyps (diameter ≥ 10 mm) found by colonoscopy. METHODS: Clinicopathological and follow-up data of 418 consecutive patients who were diagnosed as colorectal polyps with diameter≥10 mm by colonoscopy at two endoscopy centers of the Affiliated Wuxi Second People's Hospital, Nanjing Medical University (n=207) and Zhongshan Hospital, Fudan University (n=211) from January 2015 to December 2016 were retrospectively collected. High-grade intraepithelial neoplasia and cancer were defined as malignancy in this study. Chi square test was used for univariate analysis, and logistic regression was used for multivariate analysis (in patients with multiple polyps, if the pathological findings were all low grade intraepithelial neoplasia, one polyp with the largest diameter was selected to enter the model; in patients with high grade intraepithelial neoplasia, one polyp of high grade intraepithelial neoplasia with the largest diameter was selected to enter the model). Associated risk factors of malignancy were analyzed. RESULTS: Among the 418 patients, 278(66.5%) were male and 140(33.5%) were female, with mean age of (58.7±10.2) (range 15-87) years old. Of 398 patients undergoing endoscopic treatment with resected 456 polyps, 142 cases with 150 polyps were malignant, including 134 polyps of high-grade intraepithelial neoplasia and 16 polyps of intra-mucosal cancer. The other 20 patients showed negative elevation signs after endoscopic submucosal injection and were transferred to surgery, of whom 20 polyps were resected. Histological examination of these 20 polyps indicated invasive cancer. Univariate analysis showed that age ≥ 50 years [40.5% (150/370) vs. 25.0% (12/48), χ² =4.323, P=0.041], multiple polyps [77.5%(31/40) vs. 34.7%(131/378), χ² =12.900, P=0.001], polyp locating at rectum [59.0%(36/61) vs. 32.3%(134/415), χ² =22.736, P=0.000], polyp diameter ≥31 mm [74.1%(20/27) vs. 33.4%(150/449), χ² =36.493, P=0.000] and tubular villous adenoma [67.4%(120/178) vs. 16.8%(50/298), χ² =71.810, P=0.000] were associated with malignancy. Multivariate analysis showed that age ≥ 50 years(OR=2.473, 95%CI:1.209-5.058, P=0.013), multiple polyps (OR=2.472, 95%CI: 1.300-4.702, P=0.006), polyp locating at rectum (OR=1.253, 95%CI: 1.091-1.439, P=0.001) and the polyp diameter ≥31 mm (OR=1.500, 95%CI:1.196-1.881, P=0.000) were independent risk factors for malignancy of large colorectal polyps. The mean follow-up time was (9.6±4.2) months. During the follow-up period, 86 patients (20.5%) who received endoscopic resection developed recurrent adenoma which all were successfully removed by colonoscopic polypectomy. Two patients(0.5%) developed colon cancer 6 months after endoscopic resection and both underwent radical surgery and chemotherapy. Their previous pathology from endoscopic resection was tubular villous adenoma and high grade intraepithelial neoplasia. All the patients were alive during the follow-up period. CONCLUSIONS: Age ≥50 years old, multiple polyps, polyps locating at rectum and polyps with diameter ≥ 31 mm are the risk factors of malignancy. Emphasized examination should be recommended for those with the above mentioned risk factors to avoid missed diagnosis and misdiagnosis. The choice of endoscopic treatment must be reasonable for curative resection.

Dysregulation of tristetraprolin and human antigen R promotes gastric cancer progressions partly by upregulation of the high-mobility group box 1.

Aberrant expression of ARE-binding proteins (ARE-BPs) plays an important role in several diseases, including cancer. Both tristetraprolin (TTP) and human antigen R (HuR) are important ARE-BPs and always play opposite roles in regulating target mRNAs. Our previous work has demonstrated that TTP expression is decreased in gastric cancer (GC). In this study, we reported that HuR was elevated in GC cell lines and gastric cancer patients and that decreased TTP expression partly contributed to the elevated HuR levels by regulating its mRNA turnover. We also observed that dysregulation of TTP and HuR elevated the high-mobility group box 1 (HMGB1) expression in different ways. HuR promoted HMGB1 expression at translational level, while TTP regulated HMGB1 mRNA turnover by destabilizing its mRNA. Increased HuR promoted cancer cell proliferation and the metastasis potential partly by HMGB1. Using immunohistochemistry, we observed that both positive cytoplasmic and high-expression of nuclear HuR were associated with poor pathologic features and survival of GC patients. In conclusion, this study demonstrated that dysregulation of the TTP and HuR plays an important role in GC. Moreover, high HuR nuclear expression or aberrant cytoplasmic distribution may serve as a predictor of poor survival.

MicroRNA-429 inhibits gastric cancer migration and invasion through the downregulation of specificity protein 1.

microRNAs (miRs) have been reported to have an important role in tumorigenesis and tumor progression. Although miR-429 has been shown to be downregulated in gastric cancer (GC), the function of miR-429 in the metastasis of GC has yet to be investigated. In the present study, GC cells were transfected with miR-429, and reverse transcription-quantitative polymerase chain reaction, cell migration assays, cell invasion assays, western blot analysis and luciferase assays were conducted to investigate the role of miR-429 in GC cells. It was demonstrated that miR-429 expression was markedly increased following transfection of the cells with miR-429. Furthermore, miR-429 was shown to inhibit the migration and invasion of GC cell lines. In addition, this study provided evidence that miR-429 directly targets specificity protein 1 in GC cells. The results of the present study may enhance current knowledge regarding the molecular basis of cancer metastasis and provide a potential therapeutic strategy for GC.

The Cross-talk between Tristetraprolin and Cytokines in Cancer.

Cytokines are small secreted proteins serving as vital mediators that mediate the host immune responses. Transcription and post-transcription play a critical role in cytokine expression through the regulation of message RNA (mRNA) cytoplasmic localization, translation initiation and decay. Researches have been conducted to reveal regulatory mechanisms of cytokines production in cells involved in cancer. AU-rich element (ARE) can regulate the degradation and translation of mRNA by connecting with specific ARE binding proteins. It is now clear that tristetraprolin (TTP), as the most common ARE binding protein, negatively regulates many aspects of the cytokines through binding to the AREs in the 3'-untranslated region (3'UTR) of mRNA. Furthermore, some certain cytokines have an impact on TTP expression and function. Therefore, the cross-regulation between cytokines and TTP has come into sight. The complicated regulatory networks between cytokines and TTP are closely related to tumorigenesis. In this review, we summarize specific regulatory mechanisms of cytokine mRNAs. We focus on how TTP negatively regulates inflammatory and oncogenic cytokines expression after combining with AREs, we also pay attention to some cytokines mediating the expression of TTP and their cross-talk in various cancers in detail.

Decreased circadian component Bmal1 predicts tumor progression and poor prognosis in human pancreatic ductal adenocarcinoma.

The circadian clock has been demonstrated playing important roles in human tumorigenic process; however, the detailed clinical implications of circadian disruption on tumors have not been well understood. In this study, we investigated the expression pattern of Bmal1, the core component of the circadian system, in human pancreatic ductal adenocarcinoma (PDA). Our immunohistochemistry analysis showed that the protein level of Bmal1 was significantly decreased in tumor tissues from 87 patients with PDA compared with adjacent non-cancerous tissues. Low Bmal1 expression was associated with the TNM/clinical stage, histological differentiation, and vascular invasion of PDA; but no significant relevance to patient age, gender, the tumor location, or the size. Furthermore, Kaplan-Meier survival analysis revealed that PDA patients with low Bmal1 expression had shorter overall survival (OS) times as well as disease-free times (DFS) compared to the patients with high Bmal1 expression. Lastly, univariate and multivariate analyses identified low Bmal1 expression as an independent prognostic factor for poor survival outcome for patients with PDA. Collectively, our present study demonstrated that the decreased expression of Bmal1 is correlated with the tumor progression and poor prognosis in human PDA, which implicated its potential to be used as a biomarker for diagnosis and prognosis of PDA.

GAS5 Inhibits Gastric Cancer Cell Proliferation Partly by Modulating CDK6.

INTRODUCTION: As it is not clear whether growth arrest-specific 5 (GAS5) inhibits gastric cancer (GC) cell proliferation by regulating cell cycle, we analyzed the effect of GAS5 on cell cycle regulation of GC cells and explored the underlying mechanism. METHODS: We measured GAS5 levels in GC tissues and corresponding normal tissues, and analyzed the role of GAS5 in regulation of cell proliferation and cell cycle in GC cells using CCK-8 assay and flow cytometry. We also measured the expression of P21 and CDK6 proteins after transfection of AGS and MGC-803 cells with pLJM-GAS5 and GAS5 siRNA, respectively, by western blotting. RESULTS: GAS5 expression was significantly lower in GC tissues relative to normal tissues, and its lower expression was correlated with larger tumor size and a more advanced clinical stage of GC. GAS5 induced growth arrest of GC cells through inhibition of G1-S phase translation. The action of GAS5 may be mediated by upregulation of P21 and suppression of CDK6. CONCLUSION: These data enhance our understanding of the important role that GAS5 plays in the molecular etiology of GC and suggest a potential of GAS5 as a new therapeutic target for GC treatment.

MiR-148a regulates MEG3 in gastric cancer by targeting DNA methyltransferase 1.

The long non-coding RNA MEG3 has been reported to be a tumor suppressor in a number of malignant tumors including gastric cancer. Several studies have shown that the regulation of MEG3 may attribute to the promoter hypermethylation. However, the mechanism of MEG3 regulation in gastric cancer is still not well understood. MiR-148a can suppress gastric tumorigenesis through regulating the expression of target genes such as DNA methyltransferase 1(DNMT-1). We examined the expression of MEG3 in 52 gastric cancer samples using quantitative real-time PCR and found the down-regulation of MEG3 in both gastric cancer tissues and cell lines. The positive correlation of MEG3 and miR-148a was further confirmed in SGC-7901 and BGC-823 gastric cancer cell lines. Hypermethylation of MEG3 differentially methylated regions was identified by methylation-specific PCR, and MEG3 expression was increased with the inhibition of methylation with siRNA to DNMT-1 in gastric cancer cells. In addition, transfection of MEG3 siRNA into gastric cancer cells diminished the suppression of proliferation induced by overexpression of miR-148a. Our results suggest that the suppression of miR-148a may contribute to the down-regulation of MEG3 in gastric cancer by modulation of DNMT-1.

MicroRNA-148a can regulate runt-related transcription factor 3 gene expression via modulation of DNA methyltransferase 1 in gastric cancer.

Underexpression of the gene runt-related transcription factor 3 (RUNX3), an important tumor suppressor, is known to contribute to gastric cancer progression. However, the mechanism underlying aberrant RUNX3 expression has not been fully elucidated. We investigated the role of microRNA-148a (miR-148a) and DNA methyltransferases (DNMTs) in RUNX3 promoter methylation and gene expression. RUNX3 mRNA, RUNX3 protein, and methylation levels were assayed in human gastric cancer tissues and matched normal tissues, and AGS and BGC-823 cells by real-time reverse transcription PCR, Western blot, and methylation-specific PCR, respectively. A correlation between RUNX3 mRNA levels and that of miR-148a was also investigated in gastric cancer tissues. We found that RUNX3 mRNA levels were significantly downregulated in gastric cancer tissues compared with their matched normal tissues, and were closely associated with miR-148a expression. After treatment of human gastric cancer AGS and BGC-823 cells with the DNA methylation inhibitor 5-aza-2'-deoxycytidine, a significant increase in RUNX3 mRNA, RUNX3 protein, and the non-methylated form of the RUNX3 promoter were observed relative to untreated cells. Enforced expression of miR-148a, which can modulate DNMT1 and DNMT3B, also increased the expression of RUNX3 in gastric cancer cells. Knockdown of DNMT1 was associated with increased levels of RUNX3 mRNA and RUNX3 protein, while knockdown of DNMT3B did not have any effect on these in BGC-823 cells. Our results show that miR-148a may regulate RUNX3 expression through modulation of DNMT1-dependent DNA methylation in gastric cancer and highlight a miRNA-epigenetics regulation mechanism of gene expression.

MicroRNA-148a is silenced by hypermethylation and interacts with DNA methyltransferase 1 in gastric cancer.

Studies have shown that microRNA-148a (miR-148a) was proved to be silenced while DNA methyltransferase 1 (DNMT1) was over-expressed in gastric cancer. But the mechanism of aberrant expression of miR-148a and DNMT1 and their relationships in gastric cancer are still unknown. The aims of this study were to investigate the expression profile of miR-148a and DNMT1 and reveal whether they have any relationships. We used reverse-transcriptase quantitative real-time PCR, methylation-specific PCR and Western blot to measure the level of miR-148a expression, DNA methylation level and DNMT1 expression, respectively. Gastric cancer cells were transfected with plasmid or siRNA or treated with 5-aza-2'-deoxycytidine. Cell proliferation and apoptosis were detected by cell counting and flow cytometric analysis. In this study, we demonstrated that gastric cancer tissues and cell lines displayed a consistent down-regulation of miR-148a and hypermethylation of promoter region. DNMT1 was over-expressed in primary tumors and cell lines, while knockdown of DNMT1 using siRNA could decrease methylation level of miR-148a promoter and restore its expression. Furthermore, ectopic over-expression of miR-148a in cancer cell lines caused reduction in DNMT1 expression and inhibited cell proliferation, but no obvious change was found in apoptosis rate. These results suggest that miR-148a is inactivated by DNA hypermethylation of promoter region in gastric cancer, which is mediated through DNMT1 over-expression. Additionally, the silence of miR-148a reduces its suppression to DNMT1 in gastric cancer, and this may in turn result in over-expression of DNMT1 and promote DNA hypermethylation.