Overexpression of miR‐17 in gastric cancer is correlated with proliferation‐associated oncogene amplification

The molecular mechanism underlying microRNA (miR)‐17 overexpression has not been clearly evaluated in gastric cancer. We aimed to evaluate the functional roles of miR‐17 in gastric cancer and test its viability as a therapeutic target. We conducted comparative genomic hybridization and expression array analyses on human gastric cancer tissue samples, as well as evaluating the functional roles of miR‐17 in gastric cancer cell lines and transgenic mice. miR‐17 overexpression in gastric cancer patients was associated with copy number gain of proliferation‐associated oncogenes such as MYC, CCNE1, ERBB2, and FGFR2. Copy number gain of MIR17HG gene (13q31.3) was rare, with an overall frequency of 2% in gastric cancers (1 of 51). miR‐17 knockdown suppressed the monolayer and anchorage‐independent growth of FGFR2‐amplified KATO‐III gastric cancer cells. mir‐17–92 TG/TG mice overexpressing the mir‐17–92 cluster under the villin promoter developed spontaneous benign tumors in the intestinal tract (log‐rank P for tumor‐free survival = 0.069). Taken together, miR‐17 overexpression in gastric cancer was rarely associated with MIR17HG gene amplification, but correlated with proliferation‐associated oncogene amplification. Therefore, miR‐17‐targeting approach may benefit patients with gastric cancers harboring proliferation‐associated oncogene amplification.     

胃癌细胞中长链非编码RNA SNHG5与miR-26b间的相互作用

目的探讨胃癌细胞中长链非编码RNA SNHG5与miR-26b的相互作用。方法实时定量PCR检测SNHG5在GES-1胃黏膜正常上皮细胞与胃癌细胞中的表达差异,通过瞬时转染SNHG5过表达质粒,Taq Man定量PCR检测MGC-803细胞中miR-26b及pri-miR-26b的表达变化,同时瞬时转染miR-26b mimics检测其对SNHG5表达的影响。结果 SNHG5在胃癌细胞中的表达明显高于胃黏膜正常上皮细胞GES-1(P0.05),SNHG5能够抑制miR-26b与pri-miR-26b的表达(P0.01),但miR-26b不能对SNHG5的表达产生影响。结论 SNHG5可抑制miR-26b的表达,具体作用机制还需要进一步分析。     

Catenin‐δ1, negatively regulated by miR‐145, promotes tumour aggressiveness in gastric cancer

Increasing evidence supports the association of catenin‐δ1 (CTNND1, p120ctn) with tumour development and progression. However, the mechanism and clinical significance of CTNND1 deregulation in gastric cancer remain unknown. The expression level and cellular localization of CTNND1 were determined by immunohistochemistry in 126 human gastric cancer and 50 non‐tumourous tissues. The cellular localization of CTNND1 and epithelial cadherin (E‐cadherin) were detected by immunofluorescence. Cell proliferation, apoptosis, migration and invasion assays were performed to assess the effect of CTNND1 cDNA or CTNND1 siRNA transfection on gastric cancer cells. Luciferase assay, western blot analysis and in vivo assays were used to determine whether CTNND1 could be regulated by miR‐145. The results demonstrate that the cytoplasmic localization of CTNND1 protein, rather than expression level, was indicative of higher clinical stage, positive lymph node metastasis and poorer prognosis in gastric cancers. CTNND1 could promote gastric cancer cell migration and invasion with little effect on cellular proliferation and apoptosis. CTNND1 was proved to be a direct target gene for miR‐145. Besides suppressing cytoplasmic CTNND1 expression, miR‐145 could recover the membranous localization of CTNND1 and E‐cadherin. We conclude that cytoplasmic CTNND1 can serve as an independent prognostic factor for patients with gastric cancers. MiR‐145 inhibits invasion of gastric cancer cells not only by down‐regulating cytoplasmic CTNND1 expression but also by inducing the translocation of CTNND1 and E‐cadherin from the cytoplasm to the cell membrane through down‐regulating N‐cadherin. Copyright © 2014 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Vascular adhesion protein‐1 as indicator of breast cancer tumor aggressiveness and invasiveness

Recent studies suggest that vascular adhesion protein‐1 (VAP‐1), a 180‐KDa homodimeric glycoprotein, may be associated with cancer‐related events including tumor cell migration, motility, invasion, or metastasis. Therefore, this study applies VAP‐1 immunohistochemical staining to demonstrate the invasiveness component of the breast cancer. The VAP‐1 staining results were compared in 148 breast cancer cases to identify possible correlations with clinical status, including age, tumor size, tumor grade, TNM stage, lymphatic invasion, metastasis, recurrence, and survival rate. Immunohistochemical staining results showed VAP‐1 negative or weak staining in normal ducts and ductal carcinoma in situ (DCIS), but these phenotypes were positively associated with a stiffened VAP‐1 that presented at the invasive front of the lesion. Our data demonstrated that VAP‐1 expression was positively associated with lymphatic invasion, distant metastasis, and patient survival in breast carcinoma. Notably, VAP‐1 expression was found to be significantly correlated with the overall survival (p < 0.0001). Multivariate Cox analysis indicated that VAP‐1 expression was a significant independent prognostic indicator of overall survival in breast carcinoma (p < 0.0001). In conclusion, this study suggests that VAP‐1 is linked to progression of tumor invasion and metastasis in breast carcinoma. VAP‐1 is shown to be a biomarker that can be predict invasive potential and clinical outcome in breast cancer.     

Xenophagy in Helicobacter pylori‐ and Epstein–Barr virus‐induced gastric cancer

Helicobacter pylori and Epstein–Barr virus (EBV) account for roughly 80% and 10%, respectively, of gastric carcinomas worldwide. Autophagy is an evolutionarily conserved and intricately regulated cellular process that involves the sequestration of cytoplasmic proteins and organelles into double‐membrane autophagosomes that eventually fuse with lysosomes for degradation of the engulfed content. Emerging evidence indicates that xenophagy, a form of selective autophagy, plays a crucial role in the pathogenesis of H. pylori‐ and EBV‐induced gastric cancer. Xenophagy specifically recognizes intracellular H. pylori and EBV and physically targets these pathogens to the autophagosomal–lysosomal pathway for degradation. In this connection, H. pylori or EBV‐induced dysregulation of autophagy may be causally linked to gastric tumourigenesis and therefore can be exploited as therapeutic targets. This review will discuss how H. pylori and EBV infection activate autophagy and how these pathogens evade recognition and degradation by the autophagic pathway. Elucidating the molecular aspects of H. pylori‐ and EBV‐induced autophagy will help us better understand the pathogenesis of gastric cancer and promote the development of autophagy modulators as antimicrobial agents. Published by John Wiley & Sons, Ltd     

胃癌组织中CXCL12和CXCR4的表达及意义

目的观察趋化因子CXCL12及其特异性受体CXCR4在人胃癌组织中的表达,探讨其与临床病理参数、预后的关系。方法选择120例胃癌标本,应用免疫组化SP法检测CXCL12和CXCR4在人胃癌组织中的表达,分析CXCL12和CXCR4的表达与患者临床病理参数、术后生存率之间的关系。结果胃癌组织及正常胃黏膜组织中均可检测到CXCL12、CXCR4的表达,但胃癌组织中的表达水平均明显高于正常胃黏膜组织,表达差异有显著性(P<0.05)。CXCL12阳性与CXCR4阳性呈正相关(r=0.276,P<0.05)。胃癌CXCL12和CXCR4的表达水平与肿瘤细胞淋巴结转移及分化程度密切相关(P<0.05),与患者的年龄、性别、肿瘤的大小、浸润深度及远处转移等无关(P>0.05)。CXCL12和CXCR4阳性表达的患者其五年生存率明显低于其阴性表达的患者。结论胃癌中CXCL12和CXCR4的高表达与胃癌的生物学行为及预后密切相关,检测其表达对预测胃癌的转移及判断预后有一定价值。     

miR‐29a inhibition normalizes HuR over‐expression and aberrant AU‐rich mRNA stability in invasive cancer

The activities of RNA‐binding proteins are perturbed in several pathological conditions, including cancer. These proteins include tristetraprolin (TTP, ZFP36) and HuR (ELAVL1), which respectively promote the decay or stability of adenylate‐uridylate‐rich (AU‐rich) mRNAs. Here, we demonstrated that increased stabilization and subsequent over‐expression of HuR mRNA were coupled to TTP deficiency. These findings were observed in breast cancer cell lines with an invasive phenotype and were further confirmed in ZFP36‐knockout mouse fibroblasts. We show that TTP–HuR imbalance correlated with increased expression of AU‐rich element (ARE) mRNAs that code for cancer invasion genes. The microRNA miR‐29a was abundant in invasive breast cancer cells when compared to non‐tumourigenic cell types. When normal breast cells were treated with miR‐29a, HuR mRNA and protein expression were up‐regulated. MiR‐29a recognized a seed target in the TTP 3′ UTR and a cell‐permeable miR‐29a inhibitor increased TTP activity towards HuR 3′ UTR. This led to HuR mRNA destabilization and restoration of the aberrant TTP–HuR axis. Subsequently, the cancer invasion factors uPA, MMP‐1 and MMP‐13, and cell invasiveness, were decreased. The TTP:HuR mRNA ratios were also perturbed in samples from invasive breast cancer patients when compared with normal tissues, and were associated with invasion gene expression. This study demonstrates that an aberrant ARE‐mediated pathway in invasive cancer can be normalized by targeting the aberrant and functionally coupled TTP–HuR axis, indicating a potential therapeutic approach. Copyright © 2013 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Immunohistochemical analysis of colorectal cancer with gastric phenotype: Claudin‐18 is associated with poor prognosis

Claudin‐18 plays a key role in constructing tight junctions, and altered claudin‐18 expression has been documented in various human malignancies; however, little is known about the biological significance of claudin‐18 in colorectal cancer (CRC). The aim of this study is to investigate the significance of claudin‐18 expression in CRC and its association with clinicopathological factors. We performed clinicopathological analysis of claudin‐18 expression in a total of 569 CRCs by immunohistochemistry. Moreover, we investigated the association between claudin‐18 and various markers including gastric/intestinal phenotype (MUC5AC, MUC6, MUC2 and CD10), CDX2, claudin‐3, claudin‐4, p53 and Ki‐67. Claudin‐18 expression was detected in 21 of the 569 CRCs (4%) and was seen exclusively on the cell membrane. Positive expression of claudin‐18 showed a significant correlation with positive expression of MUC5AC (P < 0.0001) and negative expression of CDX2 (P= 0.0013). The prognosis of patients with positive claudin‐18 expression was significantly poorer than in negative cases (P= 0.0106). Multivariate analysis revealed that T grade, M grade and claudin‐18 expression were independent predictors of survival in patients with CRC. We revealed that claudin‐18 expression correlates with poor survival in patients with CRC and is associated with the gastric phenotype.     

Enhanced expression of long noncoding RNA CARLo-5 is associated with the development of gastric cancer

The identification of cancer-associated long non-coding RNAs and the investigation of their molecular and biological functions are vital for understanding the molecular biology and progression of cancer. The CARLo-5, a newly identified long non-coding RNA, was found to be upregulated in colon cancer. However, little is known about its role in gastric cancer. In the present study, a great upregulation of CARLo-5 was observed in gastric cancer compared to paired adjacent normal tissues. Knockdown of CARLo-5 in gastric cancer cell lines significantly inhibited the cell proliferation via inducing G0/G1 cell-cycle arrest and apoptosis. Furthermore, ERK/MAPK pathway was found to be inactivated in the gastric cells after CARLo-5 knockdown. These results indicated that CARLo-5 might serve as a pro-oncogenic lncRNA that promotes proliferation of gastric cancer and activates the ERK/MAPK pathway.     

Up-regulation of cathepsin X in Helicobacter pylori gastritis and gastric cancer

Recently, we identified increased cathepsin X expression in H. pylori-infected gastric mucosa. Here, we describe further up-regulation in gastric cancer and report on the role of inflammatory cytokines required for cathepsin X up-regulation in H. pylori-infected gastric mucosa, as well as on consequences for cellular invasion. Biopsy specimens were taken from the antrum, corpus and cardia of H. pylori-infected and non-infected patients. Gastric cancer samples were obtained from patients undergoing gastric surgery. Cathepsin X was detected in gastric mucosa by quantitative real-time RT-PCR, western blotting and immunohistochemistry. Induction of cathepsin X expression in epithelial and inflammatory cells caused by H. pylori infection was tested in in vitro contact and non-contact co-cultures of AGS cells and monocytic cells. Patients with H. pylori gastritis showed significantly higher cathepsin X mRNA (2.5-fold) and protein (1.6-fold) expression than H. pylori-negative patients. Cathepsin X was also up-regulated in gastric cancer (3-12-fold) compared to non-neoplastic mucosa. Cathepsin X was predominantly expressed by macrophages in the mucosal stroma and in glands of the antral mucosa. In addition, tumour cells stained for cathepsin X in 26 (68%) patients with gastric carcinoma. In general, staining was significantly more common (20 vs. 6 patients) and more intense (3.55 vs. 0.83) in intestinal type gastric cancer than in the diffuse type. In vitro cell culture experiments revealed that intercellular signalling between pathogenicity island (PAI)-positive H. pylori-infected epithelial cells and macrophages via soluble factors in the culture medium seems to be responsible for increased expression of cathepsin X in monocytes. Using antisense oligonucleotides, cathepsin X up-regulation was directly associated with higher invasiveness in vitro. Although no correlation of cathepsin X expression and TNM stage was found, our study demonstrates that cathepsin X plays a role not only in the chronic inflammation of gastric mucosa but also in the tumourigenesis of gastric cancer.