Cell cycle regulators, APC/beta-catenin, NF-kappaB and Epstein-Barr virus in gastric carcinomas

Wnt3a/β-Catenin/CBP Activation in the Progression of Cervical Intraepithelial Neoplasia

Piwil2 reprograms HPV-infected reserve cells in the cervix into tumor-initiated cells (TICs) and upregulates Wnt3a expression sequentially, which leads to cervical intraepithelial neoplasia (CIN) and ultimately squamous cell carcinoma (SCC). However, little is known regarding Wnt signaling in the maintenance of TIC stemness during the progression of cervical lesions. We herein investigated the expression of canonical Wnt3a signaling and related genes by microarray data set analysis and immunohistochemical (IHC) staining of samples obtained by biopsy of normal cervix, low- and high-grade CIN, and invasive SCC tissue. Array data analyzed by GEO2R showed higher expression levels of Wnt signaling and their target genes, significant upregulation of stemness-associated markers, and notably downregulated cell differentiation markers in CIN and SCC tissues compared with those in the normal cervix tissue. Further, Gene Set Enrichment Analysis (GSEA) revealed that Wnt pathway-related genes significantly enriched in SCC. IHC staining showed gradually increased immunoreactivity score of Wnt3a and CBP and notable translocation of β-catenin from the membrane to the cytoplasm and nucleus during the lesion progression. The intensity and proportion of P16, Ki67 and CK17 staining also increased with the progression of cervical lesions, whereas minimal to negative Involucrin expression was observed in CIN2/3 and SCC. Therefore, canonical Wnt signaling may contribute to the progression of CIN to SCC and may be a potential therapeutic target.

EBV-miR-BART10-3p and EBV-miR-BART22 promote metastasis of EBV-associated gastric carcinoma by activating the canonical Wnt signaling pathway

PURPOSE

Epstein-Barr virus (EBV)-associated gastric carcinoma (EBVaGC) constitutes the largest subpopulation in EBV-associated tumors worldwide. To date, 44 mature EBV-encoded microRNAs (EBV miRNAs) have been identified, but their roles in EBVaGC development are still poorly understood. In this study, we aimed to investigate the roles and targets of ebv-miR-BART10-3p (BART10-3p) and ebv-miR-BART22 (BART22) in EBVaGC.

METHODS

EBV miRNA expression in EBVaGCs was evaluated by deep sequencing and qRT-PCR, and relationships between BART10-3p or BART22 expression and clinicolpathological characteristics and survival rates of patients with EBVaGC were analyzed. The roles of BART10-3p and BART22 and their underlying mechanisms were further investigated through exogenous overexpression or silencing in EBVaGC cells, and validated in clinical EBVaGC tissue samples.

RESULTS

BART10-3p and BART22 were found to be highly expressed in the EBVaGC cell lines SNU719 and YCCEL1. Higher expression of BART10-3p or BART22 in primary EBVaGC samples was significantly associated with lymph node metastasis and a worse 5-year overall survival. BART10-3p and BART22 promoted cell migration and invasion by targeting adenomatous polyposis coli (APC) and Dickkopf 1 (DKK1), thereby activating the Wnt signaling pathway and, consequently, upregulating downstream Twist and downregulating downstream E-cadherin. In 874 primary gastric carcinoma samples, APC and DKK1 were found to be lower expressed in EBVaGC than in EBV-negative samples, and their expression levels were inversely correlated with those of BART10-3p and BART22 in 71 EBVaGC samples.

CONCLUSIONS

From our data we conclude that BART10-3p and BART22 play vital roles in promoting EBVaGC metastasis by targeting APC and DKK1 and, subsequently, activating the Wnt signaling pathway, thereby providing novel prognostic biomarkers and potential therapeutic targets for EBVaGC.

WNT and β-Catenin in Cancer: Genes and Therapy

The WNT pathway is a pleiotropic signaling pathway that controls developmental processes, tissue homeostasis, and cancer. The WNT pathway is commonly mutated in many cancers, leading to widespread research into the role of WNT signaling in carcinogenesis. Understanding which cancers are reliant upon WNT activation and which components of the WNT signaling pathway are mutated is paramount to advancing therapeutic strategies. In addition, building holistic insights into the role of WNT signaling in not only tumor cells but also the tumor microenvironment is a vital area of research and may be a promising therapeutic strategy in multiple immunologically inert cancers. Novel compounds aimed at modulating the WNT signaling pathway using diverse mechanisms are currently under investigation in preclinical/early clinical studies. Here, we review how the WNT pathway is activated in multiple cancers and discuss current strategies to target aberrant WNT signaling.

Apc gene suppresses intracranial aneurysm formation and rupture through inhibiting the NF-κB signaling pathway mediated inflammatory response

Background: Intracranial aneurysm (IA) is a critical acquired cerebrovascular disease that may cause subarachnoid hemorrhage, and nuclear factor-κB (NF-κB)-mediated inflammation is involved in the pathogenesis of IA. Adenomatous polyposis coli (Apc) gene is a tumor suppressor gene associated with both familial and sporadic cancer. Herein, the purpose of our study is to validate effect of Apc gene on IA formation and rupture by regulating the NF-κB signaling pathway mediated inflammatory response. Methods: We collected IA specimens (from incarceration of IA) and normal cerebral arteries (from surgery of traumatic brain injury) to examine expression of Apc and the NF-κB signaling pathway related factors (NF-κB p65 and IκBα). ELISA was used to determine levels of monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor-α (TNF-α), interleukin (IL)-1β (IL-1β), and IL-6. IA model was established in rats, and Apc-siRNA was treated to verify effect of Apc on IA formation and rupture. Next, regulation of Apc on the NF-κB signaling pathway was investigated. Results: Reduced expression of Apc and IκBα, and increased expression of NF-κB p65 were found in IA tissues. MCP-1, TNF-α, IL-1β, and IL-6 exhibited higher levels in unruptured and ruptured IA, which suggested facilitated inflammatory responses. In addition, the IA rats injected with Apc-siRNA showed further enhanced activation of NF-κB signaling pathway, and up-regulated levels of MCP-1, TNF-α, IL-1β, IL-6, MMP-2, and MMP-9 as well as extent of p65 phosphorylation in IA. Conclusion: Above all, Apc has the potential role to attenuate IA formation and rupture by inhibiting inflammatory response through repressing the activation of the NF-κB signaling pathway.

Prognostic Role of Metastatic Lymph Node Ratio in Papillary Thyroid Carcinoma

Background

The aim of this study is to elucidate the clinicopathological significances, including the prognostic role, of metastatic lymph node ratio (mLNR) and tumor deposit diameter in papillary thyroid carcinoma (PTC) through a retrospective review and meta-analysis.

Methods

We categorized the cases into high (≥ 0.44) and low mLNR (< 0.44) and investigated the correlations with clinicopathological parameters in 64 PTCs with neck level VI lymph node (LN) metastasis. In addition, meta-analysis of seven eligible studies was used to investigate the correlation between mLNR and survival.

Results

Among 64 PTCs with neck level VI LN metastasis, high mLNR was found in 34 PTCs (53.1%). High mLNR was significantly correlated with macrometastasis (tumor deposit diameter ≥ 0.2 cm), extracapsular spread, and number of metastatic LNs. Based on linear regression test, mLNR was significantly increased by the largest LN size but not the largest metastatic LN (mLN) size. High mLNR was not correlated with nuclear factor κB or cyclin D1 immunohistochemical expression, Ki-67 labeling index, or other pathological parameters of primary tumor. Based on meta-analysis, high mLNR significantly correlated with worse disease-free survival at the 5-year and 10-year follow-up (hazard ratio [HR], 4.866; 95% confidence interval [CI], 3.527 to 6.714 and HR, 5.769; 95% CI, 2.951 to 11.275, respectively).

Conclusions

Our data showed that high mLNR significantly correlated with worse survival, macrometastasis, and extracapsular spread of mLNs. Further cumulative studies for more detailed criteria of mLNR are needed before application in daily practice.

Chibby is a weak regulator of β-catenin activity in gastric epithelium

The canonical Wnt-β-catenin pathway is important in normal development. Mutations in β-catenin or proteins involved with regulating its phosphorylation or localization result in its nuclear accumulation where it activates its target genes and stimulates cell proliferation. This pathway is dysregulated in many different types of cancer, including gastric cancer (GC). Chibby (Cby) is a 14-kDa protein that inhibits β-catenin localization to the nucleus and represses β-catenin-induced transcriptional activity. In the current study, we examined the expression and function of Cby in normal and cancerous human gastric tissue. Reverse-transcription polymerase chain reaction and immunohistochemistry revealed that Cby is expressed in human stomach and localized to glandular elements. Immunohistochemical staining intensity of Cby was decreased in GC tissue when compared with normal gastric epithelium. In AGS cells, a human gastric carcinoma cell line, Cby expression was low. Stable AGS cell transfectants overexpressing Cby were prepared. Cby overexpression did not affect proliferation rates or β-catenin levels. However, confocal microscopy and subcellular fractionation studies revealed that Cby overexpression resulted in a small decrease in nuclear β-catenin. Moreover, Cby overexpression caused a molecular weight shift in nuclear β-catenin and resulted in decreased β-catenin signaling in AGS cells as measured by the TopFlash assay. However, Cby overexpression did not affect c-Myc protein levels. To conclude, Cby expression was decreased in GC samples and Cby expression altered β-catenin localization in cultured GC cells. However, Cby did not affect cell proliferation rates or β-catenin-induced protein expression. Cby may be involved in the early events in the pathogenesis of GC.

Prognostic value of Dickkopf-1 and ß-catenin expression in advanced gastric cancer

Background

Dickkopf-1 (DKK1) is a Wnt/ß-catenin pathway antagonist related to gastric cancer (GC) carcinogenesis. However, the prognostic role of combined DKK1 and ß-catenin expression in advanced GC (AGC) is not clear.

Methods

In total, 158 patients with AGC who underwent gastric resection were enrolled in this study. DKK1 and ß-catenin expression was evaluated in whole tumor sections by immunohistochemistry.

Results

DKK1 expression was high in 73 (46.2%) patients, while ß-catenin expression was positive in 51 (32.3%) patients. The expression of DKK1 was positively correlated with that of ß-catenin (P < 0.001). The combined expression of DKK1 and ß-catenin was significantly associated with high N stage (N2 and N3) (P = 0.042). In addition, patients with high DKK expression demonstrated poorer overall (OS) (P < 0.001) and disease-free survival (DFS) (P = 0.001). However, there were no differences between high DKK1 expression with ß-catenin positivity and high DKK1 expression with ß-catenin negativity (OS, P = 0.379: DFS, P = 0.255). Multivariate analysis revealed that high DKK1 alone or high DKK1 with ß-catenin positivity were independent prognostic factors for both OS (high DKK1: hazard ratio [HR], 2.130; 95% confidence interval [CI]; 1.370–3.312, P = 0.001; high DKK1 with ß-catenin positivity: HR, 2.140; 95% CI, 1.343–3.409: P = 0.001) and DFS (high DKK1: HR, 2.092; 95% CI, 1.180–3.708; P = 0.012; high DKK1 with ß-catenin positivity: HR, 2.357; 95% CI, 1.291–4.306; P = 0.005).

Conclusion

Our results indicate that high DKK1 expression regardless of ß-catenin positivity is a crucial prognostic factor for predicting tumor recurrence and survival in patients with resected AGC.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4420-8) contains supplementary material, which is available to authorized users.

Epstein-Barr Virus Gene BARF1 Expression is Regulated by the Epithelial Differentiation Factor ΔNp63α in Undifferentiated Nasopharyngeal Carcinoma

Epstein-Barr Virus (EBV) BamHI-A rightward frame 1 (BARF1) protein is considered a viral oncogene in epithelial cells and has immune-modulating properties. During viral lytic replication BARF1 is expressed as an early gene, regulated by the immediate early EBV protein R. However, in viral latency BARF1 is exclusively expressed in epithelial tumors such as nasopharyngeal (NPC) and gastric carcinoma (GC) but not in lymphomas, indicating that activation of the BARF1 promoter is cell type specific. Undifferentiated NPC is characterized by high expression of ΔNp63 isoforms of the epithelial differentiation marker p63, a member of the p53 family of transcription factors. Transcription factor binding site analysis indicated potential p53 family binding sites within the BARF1 promoter region. This study investigated ability of various p53 family members to transactivate the BARF1 promoter. Using BARF1 promoter luciferase reporter constructs we demonstrate that only p63 isoform ΔNp63α is capable of transactivating the BARF1 promoter, but not the TAp63 isoforms, p53 or p73. Direct promoter binding of ΔNp63α was confirmed by Chromatin Immune Precipitation (ChIP) analysis. Deletion mutants of the BARF1 promoter revealed multiple ΔNp63 response elements to be responsible for BARF1 promoter transactivation. However, ΔNp63α alone was not sufficient to induce BARF1 in tumor cells harboring full EBV genomes, indicating that additional cofactors might be required for full BARF1 regulation. In conclusion, in EBV positive NPC and GC, BARF1 expression might be induced by the epithelial differentiation marker ΔNp63α, explaining BARF1 expression in the absence of lytic reactivation.

NF-κB Signaling in Gastric Cancer

Gastric cancer is a leading cause of cancer death worldwide. Diet, obesity, smoking and chronic infections, especially with Helicobacter pylori, contribute to stomach cancer development. H. pylori possesses a variety of virulence factors including encoded factors from the cytotoxin-associated gene pathogenicity island (cagPAI) or vacuolating cytotoxin A (VacA). Most of the cagPAI-encoded products form a type 4 secretion system (T4SS), a pilus-like macromolecular transporter, which translocates CagA into the cytoplasm of the host cell. Only H. pylori strains carrying the cagPAI induce the transcription factor NF-κB, but CagA and VacA are dispensable for direct NF-κB activation. NF-κB-driven gene products include cytokines/chemokines, growth factors, anti-apoptotic factors, angiogenesis regulators and metalloproteinases. Many of the genes transcribed by NF-κB promote gastric carcinogenesis. Since it has been shown that chemotherapy-caused cellular stress could elicit activation of the survival factor NF-κB, which leads to acquisition of chemoresistance, the NF-κB system is recommended for therapeutic targeting. Research is motivated for further search of predisposing conditions, diagnostic markers and efficient drugs to improve significantly the overall survival of patients. In this review, we provide an overview about mechanisms and consequences of NF-κB activation in gastric mucosa in order to understand the role of NF-κB in gastric carcinogenesis.

The Wnt pathway: a key network in cell signalling dysregulated by viruses

Viruses are obligate parasites dependent on host cells for survival. Viral infection of a cell activates a panel of pattern recognition receptors that mediate antiviral host responses to inhibit viral replication and dissemination. Viruses have evolved mechanisms to evade and subvert this antiviral host response, including encoding proteins that hijack, mimic and/or manipulate cellular processes such as the cell cycle, DNA damage repair, cellular metabolism and the host immune response. Currently, there is an increasing interest whether viral modulation of these cellular processes, including the cell cycle, contributes to cancer development. One cellular pathway related to cell cycle signalling is the Wnt pathway. This review focuses on the modulation of this pathway by human viruses, known to cause (or associated with) cancer development. The main mechanisms where viruses interact with the Wnt pathway appear to be through (i) epigenetic modification of Wnt genes; (ii) cellular or viral miRNAs targeting Wnt genes; (iii) altering specific Wnt pathway members, often leading to (iv) nuclear translocation of β-catenin and activation of Wnt signalling. Given that diverse viruses affect this signalling pathway, modulating Wnt signalling could be a generalised critical process for the initiation or maintenance of viral pathogenesis, with resultant dysregulation contributing to virus-induced cancers. Further study of this virus-host interaction may identify options for targeted therapy against Wnt signalling molecules as a means to reduce virus-induced pathogenesis and the downstream consequences of infection. Copyright © 2016 John Wiley & Sons, Ltd.

A clinical prognostic scoring system for resectable gastric cancer to predict survival and benefit from paclitaxel- or oxaliplatin-based adjuvant chemotherapy

Background

Gastrectomy with D2 lymphadenectomy is a standard procedure of curative resection for gastric cancer (GC). The aim of this study was to develop a simple and reliable prognostic scoring system for GC treated with D2 gastrectomy combined with adjuvant chemotherapy.

Methods

A prognostic scoring system was established based on clinical and laboratory data from 579 patients with localized GC without distant metastasis treated with D2 gastrectomy and adjuvant chemotherapy.

Results

From the multivariate model for overall survival (OS), five factors were selected for the scoring system: ≥50% metastatic lymph node rate, positive lymphovascular invasion, pathologic TNM Stage II or III, ≥5 ng/mL preoperative carcinoembryonic antigen level, and <110 g/L preoperative hemoglobin. Two models were derived using different methods. Model A identified low- and high-risk patients for OS (P<0.001), while Model B differentiated low-, intermediate-, and high-risk patients for OS (P<0.001). Stage III patients in the low-risk group had higher survival probabilities than Stage II patients. Both Model A (area under the curve [AUC]: 0.74, 95% confidence interval [CI]: 0.69–0.78) and Model B (AUC: 0.79, 95% CI: 0.72–0.83) were better predictors compared with the pathologic TNM classification (AUC: 0.62, 95% CI: 0.59–0.71, P<0.001). Adjuvant paclitaxel- or oxaliplatin-based or triple chemotherapy showed significantly better outcomes in patients classified as high risk, but not in those with low and intermediate risk.

Conclusion

A clinical three-tier prognostic risk scoring system was established to predict OS of GC treated with D2 gastrectomy and adjuvant chemotherapy. The potential advantage of this scoring system is that it can identify high-risk patients in Stage II or III who may benefit from paclitaxel- or oxaliplatin-based regimens. Prospective studies are needed to confirm these results before they are applied clinically.

Expression of aurora kinase A correlates with the Wnt-modulator RACGAP1 in gastric cancer

Canonical Wnt signaling is involved in gastric carcinogenesis. The aim of this study was to identify the link between Wnt signaling and aurora kinase A (AURKA), a target for the treatment of gastrointestinal cancers. Publicly available microarray data were used to identify phenotype‐specific protein–protein interaction (PPI) subnetworks. The in silico analysis revealed a gastric cancer‐specific PPI subnetwork consisting of 2745 proteins and 50,935 interactions. We focused on the link of AURKA to a Wnt‐specific interaction module consisting of 92 proteins. There was a direct association of AURKA with Rac GTPase‐activating protein 1 (RACGAP1), as well as with CTNBB1 (β‐catenin) and CDKN1A as second‐order interactors. Differential expression analysis revealed a significant downregulation of both AURKA and RACGAP1 in gastric cancer compared to noncancer controls. Biopsies from a prospective cohort of 56 patients with gastric cancer (32 intestinal type, 24 diffuse type) and 20 noncancer controls were used for validation of the identified targets. The RT‐PCR data confirmed a strong correlation of AURKA and RACGAP1 gene expression both in the tumor, the tumor‐adjacent and the tumor‐distant mucosa. RACGAP1 in the tumor was also associated with CTNBB1 expression, and inversely associated with CDKN1A gene expression. Immunohistochemistry confirmed expression of the RACGAP1 protein in gastric cancer and the tumor‐adjacent mucosa. RACGAP1 expression was not associated with tumor stage, grading, Lauren type, Helicobacter pylori infection, or age. In conclusion, AURKA is directly associated with the expression of RACGAP1, a modulator of the canonical Wnt signaling pathway.

Implication of Leptin-Signaling Proteins and Epstein-Barr Virus in Gastric Carcinomas

We investigated the clinicopathological implications of leptin-signaling proteins and Epstein-Barr virus (EBV)-infection status in gastric carcinomas. Immunohistochemistry for leptin signalling-related proteins (leptin, leptin-receptor, pSTAT3, ERK, pAkt, mTOR and HIF-1 alpha), and in situ hybridization for EBV-encoded small RNAs was performed in 343 cases of gastric carcinomas. The siRNA against leptin-receptor was transfected into three stomach cancer cell lines, and western blot for caspase 3 was performed. The TNM stage was a prognostic factor in all 343 patients, and was negatively correlated with expression of leptin, pSTAT3, ERK, pAkt, mTOR and HIF-1 alpha (P < 0.05). Leptin-receptor expression was correlated with poor survival in 207 patients of the advanced gastric cancer (AGC) subgroup, 139 of the Lauren diffuse group, and in 160 patients with lymph node metastasis (P < 0.05, respectively). Additionally, in stomach cancer cells, cleaved caspase 3 level increased by leptin-receptor inhibition, that is, apoptosis increased. Interestingly, EBV-positive AGC (n = 29) tended to show better survival of patients than EBV-negative AGC (n = 178) (P = 0.06). pAkt expression was related with a good survival of 32 patients (9%) in the EBV-positive subgroup, but was not an independent prognostic factor. Among, leptin signaling-related proteins, expressions of leptin-receptor and mTOR were different between EBV-positive subgroup and EBV-negative subgroup (P < 0.05, respectively). In conclusion, leptin-signaling proteins and EBV status show different significance on patient survival, according to subsets of gastric carcinomas. The leptin-receptor may predict poor patient prognosis in the AGC, Lauren diffuse and lymph node metastasis subgroups, while EBV-positive status can show a good prognosis in the AGC. Each leptin signaling-related protein may be differently involved in carcinogenesis of EBV-negative and EBV-positive subsets.

Role of the Wnt/β-catenin pathway in gastric cancer: An in-depth literature review

Gastric cancer remains one of the most common cancers worldwide and one of the leading cause for cancer-related deaths. Gastric adenocarcinoma is a multifactorial disease that is genetically, cytologically and architecturally more heterogeneous than other gastrointestinal carcinomas. The aberrant activation of the Wnt/β-catenin signaling pathway is involved in the development and progression of a significant proportion of gastric cancer cases. This review focuses on the participation of the Wnt/β-catenin pathway in gastric cancer by offering an analysis of the relevant literature published in this field. Indeed, it is discussed the role of key factors in Wnt/β-catenin signaling and their downstream effectors regulating processes involved in tumor initiation, tumor growth, metastasis and resistance to therapy. Available data indicate that constitutive Wnt signalling resulting from Helicobacter pylori infection and inactivation of Wnt inhibitors (mainly by inactivating mutations and promoter hypermethylation) play an important role in gastric cancer. Moreover, a number of recent studies confirmed CTNNB1 and APC as driver genes in gastric cancer. The identification of specific membrane, intracellular, and extracellular components of the Wnt pathway has revealed potential targets for gastric cancer therapy. High-throughput “omics” approaches will help in the search for Wnt pathway antagonist in the near future.

Interference with the β-catenin gene in gastric cancer induces changes to the miRNA expression profile

Aberrant activation of the Wnt/β-catenin signaling pathway plays a major role in carcinogenesis and the progression of many malignant tumors, especially gastric cancer (GC). Some research has suggested that expression of the β-catenin protein is associated with clinicopathologic factors and affects the biological behaviors of GC cells. However, the mechanism of these effects is not yet clear. Studies show that the Wnt/β-catenin pathway regulates some miRNAs. We hypothesize that oncogenic activation of β-catenin signaling is involved in the formation of GC through regulating certain microRNAs (miRNAs). The results of the current study demonstrate that expression of the β-catenin protein is associated with many clinicopathologic characteristics including the degree of differentiation, depth of tumor invasion, tumor site, and 5-year survival rate. We found that silencing the expression of β-catenin with lentiviruses could delay cell proliferation, promote apoptosis, weaken the invasive power of GC cells, and increase the sensitivity of GC cells to 5-fluorouracil in vitro. Using miRNA microarrays to detect changes in the miRNA transcriptome following interference with β-catenin in GC cells, we found that miR-1234-3p, miR-135b-5p, miR-210, and miR-4739 were commonly upregulated and that miR-20a-3p, miR-23b-5p, miR-335-3p, miR-423-5p, and miR-455-3p were commonly downregulated. These data provide a theoretical basis for the potential interaction between miRNA and the β-catenin signaling pathway in GC.

Characteristics of neck level VI lymph nodes in papillary thyroid carcinoma: correlation between nodal characteristics and primary tumor

Little is known about the pathological characteristics of metastatic and nonmetastatic lymph nodes (LNs) in papillary thyroid carcinoma (PTC). The aim of this study was to elucidate the pathological characteristics of neck level VI nodes and correlations with clinicopathological parameters. We investigated the clinicopathological features of 124 classical PTCs and characteristics of 850 dissected neck level VI LNs. Immunohistochemistry for nuclear factor-κB (NF-κB) and Ki-67 was performed on primary tumors, and correlations with nodal characteristics were investigated. Nodal metastasis at neck level VI was identified in 68 of 124 PTCs (54.8 %) and was significantly correlated with tumor size, tumor multifocality, extrathyroidal extension, and tumor stage. LN metastasis was significantly correlated with larger mean LN size (P < 0.001), larger size of the largest LN (P < 0.001), and more LNs (P < 0.001). The mean size of metastatic LNs (n = 233) was significantly larger than nonmetastatic LNs (n = 617) (P < 0.001). Primary tumor diameter significantly correlated with the largest LN size (P = 0.014, R (2) = 0.049), but not mean size or number of LNs by linear regression analysis. NF-κB and Ki-67 proliferation indexes were not significantly correlated with larger nodal size. These results suggested that characteristics of nodes and primary tumor would be useful criteria for making decisions about preoperative surveillance of nodal metastasis.

Abnormal β-catenin immunohistochemical expression as a prognostic factor in gastric cancer: A meta-analysis

AIM: To evaluate the effect of β-catenin immunohistochemical expression on the prognosis of gastric cancer (GC).

METHODS: We searched Pubmed and Embase to identify eligible studies. The search ended on November 10, 2013, with no lower date limit. The citation lists associated with the studies were used to identify additional eligible studies. We included studies reporting sufficient information to estimate the HR and 95%CI, and information to estimate the OR in the analysis of clinicopathological features. The qualities of these studies were assessed using the Newcastle-Ottawa Quality Assessment Scale. HRs and ORs and their variance were calculated and pooled using Review Manager Version 5.2.

RESULTS: A total of 24 studies were identified and comprised 3404 cases. β-catenin expression was significantly correlated with poor overall survival (OS) in GC patients (HR = 1.85, 95%CI: 1.39-2.46), but showed a significant degree of heterogeneity (I² = 71%, P < 0.0001). Subgroup analysis indicated that an abnormal pattern of β-catenin expression had an unfavorable effect on OS (HR = 1.79, 95%CI: 1.39-2.32). However, accumulation in the nucleus or loss of membrane did not influence the survival of GC patients independently. Moreover, the combined OR of β-catenin indicated that β-catenin expression was associated with Lauren classification (OR = 1.98, 95%CI: 1.19-3.29), lymph node metastasis (OR = 2.00, 95%CI: 1.44-2.77), distant metastasis (OR = 2.69, 95%CI: 1.35-5.38) and grade of differentiation (OR = 2.68, 95%CI: 1.66-4.34). β-catenin expression did not correlate with TNM stage (OR = 1.34 95%CI: 0.96-1.86), the depth of invasion (OR = 1.48, 95%CI: 0.94-2.33) or vascular invasion (OR = 1.11, 95%CI: 0.70-1.76).

CONCLUSION: Abnormal β-catenin immunohistochemical expression may be associated with tumor progression and could be a predictive factor of poor prognosis in patients with GC.

Adenomatous polyposis coli gene involvement in ileal enterochromaffin cell neuroendocrine neoplasms

The adenomatous polyposis coli gene is a key tumor suppressor gene. Alterations in this gene have been found in most sporadic colon cancers; associated with familial adenomatous polyposis; and found in neoplasms of other organs, such as the liver, stomach, lung, breast, and cerebellar medulloblastoma. In the heterogeneous group of neuroendocrine neoplasms of the gastrointestinal tract, the involvement of adenomatous polyposis coli is debated, and only occasional reports found adenomatous polyposis coli alterations in foregut and midgut neuroendocrine neoplasms, with adenomatous polyposis coli mutations only in the latter. To elucidate the penetrance of adenomatous polyposis coli alterations in ileal neuroendocrine neoplasms, we performed DNA fragment analysis (loss of heterozygosity for 5q22-23 and 5q23) and sequencing on the mutation cluster region of the adenomatous polyposis coli gene on 30 ileal enterochromaffin cell neuroendocrine neoplasms. Adenomatous polyposis coli gene mutations were detected in 23% of cases (7/30); in particular, 57% were missense and 14%, nonsense/frameshift, all novel and different from those reported in colorectal or other cancers. Loss of heterozygosity analysis demonstrated a deletion frequency of 15% (4/27). No association was found with features of tumor progression. Our observations support the involvement of somatic adenomatous polyposis coli alterations in tumorigenesis of ileal enterochromaffin cell neuroendocrine neoplasms; the mechanisms of adenomatous polyposis coli gene inactivation appear to be different from those reported in other tumor types.

A viral-human interactome based on structural motif-domain interactions captures the human infectome

Protein interactions between a pathogen and its host are fundamental in the establishment of the pathogen and underline the infection mechanism. In the present work, we developed a single predictive model for building a host-viral interactome based on the identification of structural descriptors from motif-domain interactions of protein complexes deposited in the Protein Data Bank (PDB). The structural descriptors were used for searching, in a database of protein sequences of human and five clinically important viruses; therefore, viral and human proteins sharing a descriptor were predicted as interacting proteins. The analysis of the host-viral interactome allowed to identify a set of new interactions that further explain molecular mechanism associated with viral infections and showed that it was able to capture human proteins already associated to viral infections (human infectome) and non-infectious diseases (human diseasome). The analysis of human proteins targeted by viral proteins in the context of a human interactome showed that their neighbors are enriched in proteins reported with differential expression under infection and disease conditions. It is expected that the findings of this work will contribute to the development of systems biology for infectious diseases, and help guide the rational identification and prioritization of novel drug targets.

Epstein-Barr virus-encoded BARF1 promotes proliferation of gastric carcinoma cells through regulation of NF-κB

In Epstein-Barr virus (EBV)-infected gastric carcinoma, EBV-encoded BARF1 has been hypothesized to function as an oncogene. To evaluate cellular changes induced by BARF1, we isolated the full-length BARF1 gene from gastric carcinoma cells that were naturally infected with EBV and transfected BARF1 into EBV-negative gastric carcinoma cells. BARF1 protein was primarily secreted into culture supernatant and only marginally detectable within cells. Compared with gastric carcinoma cells containing empty vector, BARF1-expressing gastric carcinoma cells exhibited increased cell proliferation (P < 0.05). There were no significant differences in apoptosis, invasion, or migration between BARF1-expressing gastric carcinoma cells and empty vector-transfected cells. BARF1-expressing gastric carcinoma cells demonstrated increased nuclear expression of nuclear factor kappa B (NF-κB) RelA protein and increased NF-κB-dependent cyclin D1. The expression of p21(WAF1) was diminished by BARF1 transfection and increased by NF-κB inhibition. Proliferation of naturally EBV-infected gastric carcinoma cells was suppressed by BARF1 small interfering RNA (siRNA) (P < 0.05). Immunohistochemical analysis of 120 human gastric carcinoma tissues demonstrated increased expression of cyclin D1 and reduced expression of p21(WAF1) in EBV-positive samples versus EBV-negative gastric carcinomas (P < 0.05). In conclusion, the secreted BARF1 may stimulate proliferation of EBV-infected gastric carcinoma cells via upregulation of NF-κB/cyclin D1 and reduction of the cell cycle inhibitor p21(WAF1), thereby facilitating EBV-induced cancer progression.

Epstein-Barr virus and gastric cancer

Gastric cancer ranks second among malignancies in terms of global incidence. Epstein-Barrvirus (EBV)-associated gastric carcinoma (EBVaGC) is a recently recognized entity, which is defined by the presence of EBV in gastric carcinoma cells. EBVaGC represents about 10% of gastric carcinoma cases worldwide. It is estimated that there are over 80000 new EBVaGC cases in the world annually. EBVaGC shows some distinct clinical and pathological characteristics. The observation that EBV-encoded small RNA is expressed in cancer cells but not in surrounding normal epithelial cells strongly suggests that EBV plays an etiological role in gastric carcinogenesis. In this review, we discuss the relationship between EBV and gastric carcinogenesis.

Acute WNT signalling activation perturbs differentiation within the adult stomach and rapidly leads to tumour formation

A role for WNT signalling in gastric carcinogenesis has been suggested due to two major observations. First, patients with germline mutations in adenomatous polyposis coli (APC) are susceptible to stomach polyps and second, in gastric cancer, WNT activation confers a poor prognosis. However, the functional significance of deregulated WNT signalling in gastric homoeostasis and cancer is still unclear. In this study we have addressed this by investigating the immediate effects of WNT signalling activation within the stomach epithelium. We have specifically activated the WNT signalling pathway within the mouse adult gastric epithelium via deletion of either glycogen synthase kinase 3 (GSK3) or APC or via expression of a constitutively active β-catenin protein. WNT pathway deregulation dramatically affects stomach homoeostasis at very short latencies. In the corpus, there is rapid loss of parietal cells with fundic gland polyp (FGP) formation and adenomatous change, which are similar to those observed in familial adenomatous polyposis. In the antrum, adenomas occur from 4 days post-WNT activation. Taken together, these data show a pivotal role for WNT signalling in gastric homoeostasis, FGP formation and adenomagenesis. Loss of the parietal cell population and corresponding FGP formation, an early event in gastric carcinogenesis, as well as antral adenoma formation are immediate effects of nuclear β-catenin translocation and WNT target gene expression. Furthermore, our inducible murine model will permit a better understanding of the molecular changes required to drive tumourigenesis in the stomach.

Gastric stem cells and gastric cancer stem cells

The gastric epithelium is continuously regenerated by gastric stem cells, which give rise to various kinds of daughter cells, including parietal cells, chief cells, surface mucous cells, mucous neck cells, and enteroendocrine cells. The self-renewal and differentiation of gastric stem cells need delicate regulation to maintain the normal physiology of the stomach. Recently, it was hypothesized that cancer stem cells drive the cancer growth and metastasis. In contrast to conventional clonal evolution hypothesis, only cancer stem cells can initiate tumor formation, self-renew, and differentiate into various kinds of daughter cells. Because gastric cancer can originate from gastric stem cells and their self-renewal mechanism can be used by gastric cancer stem cells, we review here how critical signaling pathways, including hedgehog, Wnt, Notch, epidermal growth factor, and bone morphogenetic protein signaling, may regulate the self-renewal and differentiation of gastric stem cells and gastric cancer stem cells. In addition, the precancerous change of the gastric epithelium and the status of isolating gastric cancer stem cells from patients are reviewed.

Activation of nuclear factor-κB contributes to growth and aggressiveness of papillary thyroid carcinoma

Nuclear factor-κB (NF-κB) is involved in proliferation, angiogenesis, and metastasis in various malignancies; however, the role of NF-κB in papillary thyroid carcinoma (PTC) has not been fully elucidated. The purpose of this study was to elucidate the role and clinicopathological significance of the NF-κB signaling pathway in PTC. We investigated NF-κB RelA expression in 122 patients with conventional PTC by immunohistochemistry, and evaluated the correlation between RelA expression and clinicopathological parameters, including BRAF(V600E) mutation. Nuclear expression of NF-κB RelA, regardless of cytoplasmic expression, was identified in 91 of 122 PTCs (74.6%), and was more frequent in PTCs larger than 1cm (overt PTC) (P=0.001). There were significant differences in clinicopathological parameters, such as extrathyroidal extension (P=0.031), nodal metastasis (P=0.021) and BRAF(V600E) mutation (P=0.039), between NF-κB-positive and negative PTCs. Proliferation index was strongly associated with NF-κB activation (P=0.045) but not with BRAF(V600E) mutation (P=0.141). Taken together, our results suggest that NF-κB RelA activation contributes, at least in part, to tumor growth and aggressiveness of PTC after tumor transformation. The expression pattern of NF-κB may serve as a prognostic marker and a potential therapeutic target.

A clinical-biological risk stratification model for resected gastric cancer: prognostic impact of Her2, Fhit, and APC expression status

BACKGROUND

To obtain a prognostic stratification model for resected gastric cancer patients.

PATIENTS AND METHODS

Clinicopathological and molecular data (expression of Cdx2, Apc, β-catenin, E-cadherin, Fhit, p53, and human epidermal growth factor receptor-2 (Her2); HER2 and TOPO2A gene copy number; PIK3CA mutations; microsatellite instability) were correlated to cancer-specific/overall survival (CSS/OS) using a Cox model. Individual patient probability (IPP) was estimated by logistic equation. A continuous score to identify risk-classes was derived according to the model ratios.

RESULTS

Two-hundred eight patients were studied (median follow-up 20 months). At multivariate analysis, sex, stage, margins, location, nodes, Apc, and Fhit were independent predictors for CSS; the same factors (and age and Her2, except Fhit) predicted OS. Multivariate model predicted IPP with high prognostic accuracy (0.90 for CSS; 0.91 for OS). A two-class model significantly separated low- and high-risk patients for CSS (23.4% and 85.6%, P < 0.0001) and OS (21.4% and 82.0%, P < 0.0001). A three-class model differentiated low-, intermediate-, and high-risk patients for CSS (6.3%, 35.3%, and 88.0%, P < 0.0001) and OS (6.1%, 34.6%, and 86.5%, P < 0.0001).

CONCLUSIONS

A risk classification system comprising the immunohistochemical expression of three proteins (Apc, Fhit, and Her2) and five clinicopathological parameters (stage, resected nodes, margins, location, and sex) accurately separates the resected gastric cancer patients into three classes of risk.

Epstein-Barr virus-associated gastric carcinoma in Brazil: comparison between in situ hybridization and polymerase chain reaction detection

Epstein-Barr virus (EBV) has been associated with 10% of gastric carcinomas. The aim of this study was to determine the frequency of EBV in gastric carcinomas in Brazil assessed by in situ hybridization (ISH) and PCR, which would contribute to the characterization of the clinical and pathological aspects of EBV-associated gastric carcinomas. One hundred and ninety-two gastric carcinoma cases were collected at hospitals in two Brazilian states. Seventy-three out of 151 cases were PCR(+), while 11/160 cases were ISH(+). Nine out of eleven ISH(+) cases displayed a diffuse staining pattern and 2 out of 11 a focal pattern. Both techniques showed that the EBV(+) cases were characterized by their association with males, older patients, lower gastric region, intestinal type, advanced stage and poorly to moderately differentiated tumors. The concordance between the two techniques was 55.8% (Cohen's kappa index = 0.034). Four cases were ISH(+)/PCR(-), while 49 cases were PCR(+)/ISH(-). Only two cases showed stained lymphocytes by ISH and one of them was PCR(-). The observed discrepancy between the two techniques could not be explained just by the elevated accuracy of PCR. ISH(+)/PCR(-) carcinomas may be encountered if EBV is not present in the whole tumor tissue or if there are polymorphisms in the sequences of the viral genome amplified. On the other hand, the high frequency of PCR(+) results associated with the absence of ISH staining in lymphocytes and/or tumors cells suggests that the virus may be present in tumor cells or other cell types without expressing EBER1, the target of the ISH technique.

Altered expression and localization of connexin32 in human and murine gastric carcinogenesis

BACKGROUND

Intercellular communication via gap junctions, composed of protein subunits called connexins (Cxs), plays a key role in controlling cell growth, differentiation and carcinogenesis. Impaired gap junctional intercellular communication has been reported in various cancers and diseases.

AIMS

We investigated Cx32 expression patterns and semiquantitatively assessed Cx32 expression in cancers and preneoplastic lesions. To determine if cell proliferation is correlated with Cx32 expression, we evaluated Ki67 expression in a gastric cancer mouse model.

METHODS

In human and mouse, normal stomach and gastric adenocarcinoma tissues were used for immunohistochemical analyses.

RESULTS

Cx32 was detected at cell-cell (intercellular) contact points in normal cells and exhibited punctate intercellular and intracytoplasmic staining in cancer cells. The frequency of Cx32 loss of expression was significantly higher in human adenocarcinomas than in normal stomach. As tumor cells were less differentiated, Cx32 expression levels and intercellular and intracytoplasmic staining were also significantly lower. The Cx32 expression pattern in the mouse gastric cancer model was similar in several important respects to that of human. In mucous metaplasia of the mouse stomach, Cx32 was mainly expressed in the cytoplasm of epithelial cells. There was also an inverse correlation between Cx32 expression and cell proliferation in mouse tumors. However, there was no difference in the levels of Cx32 mRNA between normal and cancerous tissues.

CONCLUSIONS

These findings suggest that altered Cx32 expression, a loss of intercellular Cx32 and a gain of intracytoplasmic Cx32 in the form of punctate "dot", plays an important role in the formation of gastric adenocarcinomas.