Significance of lymphatic invasion and cancer invasion-related proteins on lymph node metastasis in gastric cancer

Molecular Insight into Gastric Cancer Invasion-Current Status and Future Directions

Gastric cancer (GC) is one of the most common malignancies worldwide. There has been no efficient therapy for stage IV GC patients due to this disease's heterogeneity and dissemination ability. Despite the rapid advancement of molecular targeted therapies, such as HER2 and immune checkpoint inhibitors, survival of GC patients is still unsatisfactory because the understanding of the mechanism of GC progression is still incomplete. Invasion is the most important feature of GC metastasis, which causes poor mortality in patients. Recently, genomic research has critically deepened our knowledge of which gene products are dysregulated in invasive GC. Furthermore, the study of the interaction of GC cells with the tumor microenvironment has emerged as a principal subject in driving invasion and metastasis. These results are expected to provide a profound knowledge of how biological molecules are implicated in GC development. This review summarizes the advances in our current understanding of the molecular mechanism of GC invasion. We also highlight the future directions of the invasion therapeutics of GC. Compared to conventional therapy using protease or molecular inhibitors alone, multi-therapy targeting invasion plasticity may seem to be an assuring direction for the progression of novel strategies.

Clinical significance of additional gastrectomy after non-curative endoscopic submucosal dissection for early gastric cancer: a retrospective single-center study

Purpose

Additional surgery is recommended for patients after a non-curative endoscopic submucosal dissection (ESD) to prevent residual cancer (RC) or lymph node metastasis (LNM). We aimed to evaluate the clinicopathologic characteristics of patients who underwent an additional gastrectomy after a non-curative ESD procedure and identify the risk factors of RC and LNM.

Methods

We retrospectively assessed the clinicopathological factors of 73 patients who underwent additional gastrectomy following a non-curative ESD between January 2009 and December 2019 at our center.

Results

RC and LNM rates after additional gastrectomy were 9.6% and 8.2%, respectively. Invasion deeper than 500 μm (P=0.045), positive horizontal resection margin (P<0.001), and positive ESD margin (P=0.001) were identified as statistically significant factors in univariate analysis for RC, but not in multivariate analysis. Lymphatic invasion was the only risk factor found to be significant in both univariate and multivariate analyses (P=0.005 and P=0.012).

Conclusion

Additional gastrectomy is necessary to prevent RC or LNM after non-curative ESD. Lymphatic invasion was also associated with LNM in patients who underwent an additional gastrectomy after a non-curative ESD, and in such cases, active treatment is required.

The role of claudin-4 in the development of gastric cancer

Gastric cancer is one of most challenging cancers and a significant cause of death worldwide. Gastric cancer is, associated with a high incidence and recurrence rate of metastatic disease and poor survival for those with metastatic disease. Claudin-4 is a transmembrane protein that plays an important role in tight junctions. Increasing experimental research has demonstrated that claudin-4 plays an important role in the progression of gastric cancer, including the occurrence of epithelial to mesenchymal transition, intestinal metaplasia, and gastric cancer. In addition, claudin-4 regulates cell proliferation, invasion, migration and apoptosis. Claudin-4 may represent a potential biomarker for gastric cancer patient prognosis and is useful in the classification of gastric cancer. Therefore, in this review, we summarize current information on claudin-4 and gastric cancer, describing the role of claudin-4 in gastric cancer progression and its application in clinical treatment to provide a basis for further research and promote the claudin-4 gene as a potential target to diagnose and treat gastric cancer.

Lymphatic Invasion Might Be Considered as an Upstaging Factor in N0 and N1 Gastric Cancer

(Background) The aim of this study was to investigate the prognostic impact of lymphatic invasion in gastric cancer, focusing on survival differences between N stage groups. (Methods) A total of 398 consecutive patients who underwent curative gastrectomy for primary gastric adenocarcinoma from January 2006 to December 2015 were analyzed retrospectively using data from a prospectively collected registry database. We compared various clinicopathological features and survival differences between lymphatic invasion-positive and -negative groups. (Results) Of the 398 patients, 141 (35.4%) showed lymphatic invasion. The lymphatic invasion-positive subgroup had poorer prognosis than the lymphatic invasion-negative subgroup in N0 (five-year survival rate: 87.8% vs. 73.6%, p = 0.048) and N1 (87.2% vs. 50%, p = 0.007) stage patients. The odds ratio (OR) of lymphatic invasion to five-year survival rate was 2.078 (95% confidence interval (CI), 1.103-3.916; p = 0.024). The presence of lymphatic invasion had worse effect on survival than age (OR, 1.807; 95% CI, 1.024-2.242; p = 0.029) or tumor depth (OR, 1.286; 95% CI, 1.078-1.897; p = 0.013) in N0 and N1 stage patients. The overall survival of patients with lymphatic invasion was not different from that of patients at a one-higher N stage without lymphatic invasion at any N stage. (Conclusions) The presence of lymphatic invasion may be the most important independent prognostic factor in N0 and N1 gastric cancer and might be an upstaging factor of N stage at any N stage. Therefore, in addition to the number of metastasized lymph nodes, the presence of lymphatic invasion should be included in N stage determination.

The Prognosis Value of Lymphatic Vessel Invasion in pN0 Gastric Cancer Patients with Insufficient Examined Lymph Nodes

OBJECTIVES

To investigate the prognosis value of lymphatic vessel invasion (LVI) in pN0 gastric cancer patients with insufficient examined lymph nodes (ELNs).

METHODS

Clinicopathologic and prognostic data of pN0 gastric cancer patients with insufficient ELNs who underwent radical surgery in our institution were retrospectively studied.

RESULTS

Firstly, we confirmed that less than 16 but not less than 30 ELNs were insufficient ELNs in the present study. Of the 350 pN0 patients with < 16 ELNs, 64 patients (18.29%) had LVI. The overall survival (OS) of patients with LVI was significantly poorer than those without LVI. Multivariate analysis suggested that LVI was one of the independent factors predicting prognosis of pN0 patients with < 16 ELNs. Further analyses suggested that there were similar prognoses between pN0 patients with < 16 ELNs who had LVI and pN1 patients, and between pN0 patients with < 16 ELNs who had no LVI and pN0 patients with ≥ 16 ELNs, respectively. Therefore, we proposed a novel pN classification, in which LVI-positive pN0 gastric cancer with < 16 ELNs was classified as pN1 disease. Two-step multivariate analysis demonstrated that the novel pN classification was more suitable for prognostic assessment than the original one.

CONCLUSIONS

LVI is a powerful and independent prognostic factor for pN0 gastric cancer patients with < 16 ELNs, and node-negative gastric cancer with < 16 ELNs which had LVI should be considered as node-positive disease. LVI is an effective indicator identifying patients stage migration happens to in pN0 patients with < 16 ELNs.

Identification of differentially expressed miRNAs in early-stage cervical cancer with lymph node metastasis across The Cancer Genome Atlas datasets

Background and aim

Previous studies have suggested that lymph node metastasis (LNM) in early-stage cervical cancer (CESC) may affect the prognosis of patients and the outcomes of subsequent adjuvant therapy. However, research focused on miRNA expression in early-stage CESC patients with LNM remains limited. Therefore, it is necessary to identify prognostic miRNAs and determine their molecular mechanisms.

Methods

We evaluated the differentially expressed genes in early-stage CESC patients with LNM compared to patients without LNM and evaluated the prognostic significance of these differentially expressed genes by analyzing a public dataset from The Cancer Genome Atlas. Potential molecular mechanisms were investigated by gene ontology, the Kyoto Encyclopedia of Genes and Genomes, and protein–protein interaction network analyses.

Results

According to the The Cancer Genome Atlas data, hsa-miR-508, hsa-miR-509-2, and hsa-miR-526b expression levels were significantly lower in early-stage CESC patients with LNM than in patients without LNM. A multivariate analysis suggested that three miRNAs were prognostic factors for CESC (P<0.05). The target genes were identified to be involved in the MAPK, cAMP, PI3K/Akt, mTOR, and estrogen cancer signaling pathways. Protein–protein interaction network analysis showed that TP53, MMP1, NOTCH1, SMAD4, and NFKB1 were the most significant hub proteins.

Conclusion

Our results indicate that hsa-miR-508, hsa-miR-509-2, and hsa-miR-526b may be potential diagnostic biomarkers for early-stage CESC with LNM, and serve as prognostic predictors for patients with CESC.

CT volumetry for gastric adenocarcinoma: association with lymphovascular invasion and T-stages

Purpose

To determine whether gross tumor volume of resectable gastric adenocarcinoma on multidetector computed tomography could predict presence of lymphovascular invasion and T-stages.

Results

Gross tumor volume increased with the lymphovascular invasion (r = 0.426, P < 0.0001) and T stage (r = 0.656, P < 0.0001). Univariate analysis showed gross tumor volume could predict lymphovascular invasion (P < 0.0001). Multivariate analyses indicated gross tumor volume as an independent risk factor of lymphovascular invasion (P = 0.026, odds ratio = 2.284). The Mann-Whitney U test showed gross tumor volume could distinguish T2 from T3, T1 from T2–T4a, T1–T2 from T3–T4a and T1–T3 from T4a (P = 0.000). In the development cohort, gross tumor volume could predict lymphovascular invasion (cutoff, 15.92 cm³; AUC, 0.760), and distinguish T2 from T3 (cutoff, 10.09 cm³; AUC, 0.828), T1 from T2-T4a (cutoff, 8.20 cm³; AUC, 0.860), T1-T2 from T3-T4a (cutoff, 15.88 cm³; AUC, 0.883), and T1-T3 from T4a (cutoff, 21.53 cm³; AUC, 0.834). In validation cohort, gross tumor volume could predict presence of lymphovascular invasion (AUC, 0.742), and distinguish T2 from T3 (AUC, 0.861), T1 from T2-T4a (AUC, 0.859), T1–T2 from T3–T4a (AUC, 0.875), and T1–T3 from T4a (AUC, 0.773).

Materials and Methods

360 consecutive patients with gastric adenocarcinoma were retrospectively identified. Gross tumor volume was evaluated on multidetector computed tomography images. Statistical analysis was performed to determine whether gross tumor volume could predict presence of lymphovascular invasion and T-stages. Cutoffs of gross tumor volume were first investigated in 212 patients and then validated in an independent 148 patients using area under the receiver operating characteristic curve (AUC) for predicting lymphovascular invasion and T-stages.

Conclusions

Gross tumor volume of resectable gastric adenocarcinoma at multidetector computed tomography demonstrated capability in predicting lymphovascular invasion and distinguishing T-stages.

Predictive value for lymph node metastasis of epithelial-mesenchymal transition and cancer stem cell marker expression in early gastric cancer

BACKGROUND

Minimally invasive therapies, including endoscopic mucosal resection or sentinel node navigation surgery, have been widely applied in early gastric cancer because of their benefits in promoting patient quality of life. However, lymph node dissection is beyond the capability of endoscopic therapy, and in sentinel node navigation surgery, the potential for skip metastasis is not negligible. Therefore, the possibility of lymph node metastasis is the most important factor to consider when deciding whether to apply the minimally invasive therapies. In the present study, the significance of epithelial mesenchymal transition and stem cell marker expression in lymph node metastasis in early gastric cancer was investigated.

METHODS

We evaluated the significance of the expression of 5 epithelial mesenchymal transition-related markers (E-cadherin, MMP7, S100A, Snail-1, and HGF) and 6 stem cell markers (ALDH1, SOX2, CD24, CD44, CD54, and CD133) in 119 early gastric cancer specimens using immunohistochemistry. Because protein expression is heterogeneous in gastric cancer, we analyzed the expression of these markers in two selected regions (one each at the superficial zone and the deep invasive front).

RESULTS

Expression of E-cadherin, MMP7, HGF, and CD133 at the deep invasive front was associated with the absence of lymph node metastasis (P=0.013, 0.018, <0.001, and 0.026, respectively). Presence of diffuse-type component, lymphatic invasion, and lack of expression of HGF and CD133 at the deep invasive front were independent predictive markers of lymph node metastasis (P=0.019, <0.001, 0.015, and 0.047, respectively).

CONCLUSIONS

Lymph node metastasis is strongly associated with expression status of HGF and CD133 at the deep invasive front, suggesting the usefulness of these proteins as independent predictive markers of lymph node metastasis in early gastric cancer.

Gastrointestinal mucosal barrier function and diseases

The gastrointestinal mucosal barrier plays an essential role in the separation of the inside of the body from the outside environment. Tight junctions (TJs) are the most important component for construction of a constitutive barrier of epithelial cells, and they regulate the permeability of the barrier by tightly sealing the cell-cell junctions. TJ proteins are represented by claudins, occludin, junctional adhesion molecules, and scaffold protein zonula occludens. Among these TJ proteins, claudins are the major components of TJs and are responsible for the barrier and the polarity of the epithelial cells. Gastrointestinal diseases including reflux esophagitis, inflammatory bowel disease, functional gastrointestinal disorders, and cancers may be regulated by these molecules, and disruption of their functions leads to chronic inflammatory conditions and chronic or progressive disease. Therefore, regulation of the barrier function of epithelial cells by regulating the expression and localization of TJ proteins is a potential new target for the treatment of these diseases. Treatment strategies for these diseases might thus be largely altered if symptom generation and/or immune dysfunction could be regulated through improvement of mucosal barrier function. Since TJ proteins may also modify tumor infiltration and metastasis, other important goals include finding a good TJ biomarker of cancer progression and patient prognosis, and developing TJ protein-targeted therapies that can modify patient prognosis. This review summarizes current understanding of gastrointestinal barrier function, TJ protein expression, and the mechanisms underlying epithelial barrier dysregulation in gastrointestinal diseases.

Tight junction protein claudin 4 in gastric carcinoma and its relation to lymphangiogenic activity

BACKGROUND AND STUDY AIMS

Gastric cancer is the second most common cause of cancer-related death worldwide. Claudins are a family of tight junction proteins that are biologically relevant in many cancer progression steps. This study aimed to investigate the expression of the intestinal claudin (claudin 4) in gastric carcinoma and to evaluate its relation to the different clinicopathologic prognostic parameters, especially lymphangiogenesis (production of new lymphatic vessels, measured by lymphovascular density (LVD)) and lymphovascular invasion (LVI).

PATIENTS AND METHODS

Fifty-five gastric carcinoma specimens were immunohistochemically stained for claudin 4 and D2-40 (for detection of lymphatic vessel endothelium).

RESULTS

High expression of claudin 4 was detected in 26 of 55 (47.3%) cases. Low expression of claudin 4 was related to poorly differentiated type (p=0.001), non-intestinal (diffuse) type (p=0.001), deeper tumour invasion (p<0.001), lymph node metastasis (p=0.001), and higher stage (p=0.001). In addition, higher LVD was related to poorly differentiated types (p=0.001), non-intestinal type (p=0.001), lymph node metastasis (p=0.015), and higher tumour, node, metastasis (TNM) stage (p=0.001). LVI was related to lymph node metastasis (p=0.025), higher TNM stage (p=0.001), and LVD (p=0.001). Claudin 4 significantly correlated with both LVD (p=0.009) and LVI (p=0.009).

CONCLUSIONS

High expression of claudin 4 was associated with the more differentiated intestinal-type gastric carcinoma and lost in poorly differentiated diffuse type. So, claudin 4 may be used as one of the differentiating markers between the two major types of gastric carcinoma (intestinal vs. diffuse). LVD and LVI were related to higher incidence of lymph node metastasis and therefore could be used as predictive markers for lymph node metastasis in limited specimens during early gastric carcinoma to determine the need for more invasive surgery. Low expression of claudin 4 was related to lymphangiogenesis. This may shed light on the relation of tight junction protein expression and lymphangiogenesis.

Tight junction disruption: Helicobacter pylori and dysregulation of the gastric mucosal barrier

Long-term chronic infection with Helicobacter pylori (H. pylori) is a risk factor for gastric cancer development. In the multi-step process that leads to gastric cancer, tight junction dysfunction is thought to occur and serve as a risk factor by permitting the permeation of luminal contents across an otherwise tight mucosa. Mechanisms that regulate tight junction function and structure in the normal stomach, or dysfunction in the infected stomach, however, are largely unknown. Although conventional tight junction components are expressed in gastric epithelial cells, claudins regulate paracellular permeability and are likely the target of inflammation or H. pylori itself. There are 27 different claudin molecules, each with unique properties that render the mucosa an intact barrier that is permselective in a way that is consistent with cell physiology. Understanding the architecture of tight junctions in the normal stomach and then changes that occur during infection is important but challenging, because most of the reports that catalog claudin expression in gastric cancer pathogenesis are contradictory. Furthermore, the role of H. pylori virulence factors, such as cytotoxin-associated gene A and vacoulating cytotoxin, in regulating tight junction dysfunction during infection is inconsistent in different gastric cell lines and in vivo, likely because non-gastric epithelial cell cultures were initially used to unravel the details of their effects on the stomach. Hampering further study, as well, is the relative lack of cultured cell models that have tight junction claudins that are consistent with native tissues. This summary will review the current state of knowledge about gastric tight junctions, normally and in H. pylori infection, and make predictions about the consequences of claudin reorganization during H. pylori infection.

Upregulation of nucleostemin in colorectal cancer and its effects on cell malignancy

Objective

Nucleostemin (NS) is a new protein localized in the nucleolus of most stem cells and tumor cells, which regulates their self-renewal and cell cycle progression. The aim of this study was to investigate the expression of NS in colorectal cancer (CRC) and the effects of NS knockdown in the Sw620 cell line to provide basis for clinical target therapy.

Methods

NS expression in 372 patients with CRC and 367 normal participants was assessed using immunohistochemistry. The expression level of NS gene was evaluated by polymerase chain reaction. Then, the relationship among NS expression, clinicopathological features, and prognosis was analyzed. Silencing of NS expression was achieved by using NS-specific small-interfering RNAs. The viability and growth rate of Sw620 cells were determined by proliferation and invasion assays. Cell cycle distribution of the cells was analyzed by flow cytometry.

Results

High NS expression was positively related with node metastasis, distant metastasis, and TNM stage. In Kaplan–Meier survival analysis, patients with low NS expression always had significantly longer survival time than those with high expression. Moreover, our results showed that knockdown of NS expression inhibited proliferation and viability of Sw620 cells in a time-dependent manner. Cell cycle studies revealed that NS depletion resulted in G1 cell cycle arrest at short times of transfection (24 hours), followed with apoptosis at longer times (48 hours and 72 hours), suggesting that post-G1 arrest apoptosis occurred in Sw620 cells.

Conclusion

Overall, these results point to the essential role of NS in Sw620 cells; thus, this gene might be considered a promising target for treatment of CRC.

MALAT2-activated long noncoding RNA indicates a biomarker of poor prognosis in gastric cancer

The purpose of this study is to investigate the role of the long noncoding RNA metastasis associated lung adenocarcinoma transcript 2 (MALAT2) in the prognosis of stage II/III gastric cancer (GC) patients. The expression of MALAT2 was evaluated in cancer tissues from 146 stage II/III GC patients undergoing radical resection and 60 paired normal samples using quantitative real-time reverse transcriptase PCR. Differences in the expression of MALAT2 between 23 GC and paired normal colonic mucosa samples were analysed with the Wilcoxon test. Relationships between the expression level of MALAT2, patient clinico-pathological parameters and disease-free survival and overall survival were analysed using the uni-variate Kaplan-Meier method and the multivariate COX regression model. The quantitative polymerase chain reaction results showed that MALAT2 was frequently over-expressed in cancer tissues and this over-expression was found to significantly correlate with lymph node metastasis and tumor stage. The ectopic expression of MALAT2 contributed to the migration of human GC SGC-7901 cells, whereas knockdown of MALAT2 inhibited the migration of the SGC-7901 cells in vitro. Further investigation into the underlying mechanisms responsible for the migratory effects revealed that MALAT2 induced the epithelial-mesenchymal transition (EMT) through an MEK/extracellular signal-regulated kinase-dependent mechanism as treatment with the MEK inhibitor, U0126, decreased migration and reversed the EMT in the MALAT2 over-expressed SGC-7901 cells. The expression of MALAT2 is upregulated in GC tissues, and a higher expression level of MALAT2 might serve as a negative prognostic marker in stage II/III GC patients which implies the potential application of MALAT2 in the therapeutic treatment of GC.Cancer Gene Therapy advance online publication, 27 February 2015; doi:10.1038/cgt.2015.6.

MMP-9 is increased in the pathogenesis of gastric cancer by the mediation of HER2

Human epidermal growth factor receptor 2 (HER2) overexpression is not only closely associated with the tumor growth, but is also related to tumor invasion. We here aimed to investigate the mechanism of HER2 mediation in the pathogenesis of gastric cancer. The human gastric cancer cell lines SGC-7901, MKN-45, AGS, the immortalized cell line GES-1 derived from normal gastric mucosa. Cell transfection and selection of stable cell lines and the gene and protein levels of HER2 and Matrix metalloproteinase-9 (MMP-9) were examined to determine the molecular relationship between them in the pathogenesis of gastric cancer. The human gastric cancer cell lines SGC-7901, MKN-45, AGS, the immortalized cell line GES-1 derived from normal gastric mucosa. Cell transfection and selection of stable cell lines and the gene and protein levels of HER2 and MMP-9 were examined to determine the molecular relationship between them in the pathogenesis of gastric cancer. We demonstrated that vector-based shRNA significantly knocked down the expression of HER2 and considerably inhibited both the migration and invasion of gastric cancer cells. HER2 knockdown resulted in the downregulation of the expression of MMP-9, whereas HER2 overexpression improved the transcription of MMP-9 through the activation of an MMP-9 promoter. The promoter region of MMP-9 between -2500 and -2000 bp was found to be crucial for the upregulation of HER2-mediated transcription. Furthermore, a truncated promoter (-70 to +63) did not display any transcriptional activity. Cell invasion activity was almost completely inhibited when MMP-9 was knocked down. Conversely, the overexpression of MMP-9 partly rescued the invasion ability of cell strains with knockdown HER2. These findings help further understanding of the molecular mechanisms through which HER2 promotes malignancy, and suggest that targeting both HER2 and MMP-9 may be required to effectively block HER2 signaling in gastric cancer therapy.

HER-2-induced PI3K signaling pathway was involved in the pathogenesis of gastric cancer

Human epidermal growth factor receptor-2 (HER-2) overexpression was closely associated with the tumor growth and invasion, we here aimed to investigate the mechanism of HER-2 mediation in the pathogenesis of gastric cancer (GC). We first detected the expression of HER-2 in GC cell line SGC-7901 and then examined the levels of nuclear factor-κB (NF-κB), matrix metalloproteinase-9 (MMP-9) and intercellular adhesion molecule-1 (ICAM-1) and the association between them by molecular methods. Statistical analysis was used to compare the significance. We further detected the possible molecular mechanism involved in their relationship in the SGC-7901 genesis. The MMP-9, NF-κB and secretory type (s-ICAM-1) levels were significantly greater in peripheral blood serum from SGC-7901 than healthy control GES-1 (P<0.01). ICAM-1, MMP-9 and NF-κB mRNA and protein levels were more highly expressed in SGC-7901 than healthy control GES-1. The expression levels of NF-κB, MMP-9 and ICAM-1 were positively related in GC cell line SGC-7901, which was HER-2 positive. The HER-2 positive SGC-7901 secreted more transforming growth factor beta 1 (TGF-β1) and resultantly activated MMP-9 to enhance s-ICAM-1 secretion and further studies showed that phosphatidylinositol-3 kinase (PI3K)/Akt/NF-κB signaling pathway was involved in GC pathogenesis. The GC cells that express the HER-2 oncogene spur the activation of NF-κB that can upregulate the expression of ICAM-1 and induce the expression of MMP-9, which hydrolyzes ICAM-1 into s-ICAM-1 to promote tumor immune escape. TGF-β1-induced PI3K/Akt/NF-κB signaling pathway was involved in the pathogenesis of GC and they could be a new target for cancer therapy. The GC cells that express the HER-2 oncogene spur the activation of NF-κB that can upregulate the expression of ICAM-1 and induce the expression of MMP-9, which hydrolyzes ICAM-1 into s-ICAM-1 to promote tumor immune escape. TGF-β1-induced PI3K/Akt/NF-κB signaling pathway was involved in the pathogenesis of GC and they could be a new target for cancer therapy.

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.

Down-regulation of claudin-18 is associated with the proliferative and invasive potential of gastric cancer at the invasive front

Background

Claudins are known as tight junction proteins, and their expression pattern in gastric cancer is still controversial. The relationship between the expression patterns of tight junction proteins and tumor proliferation in early gastric cancer is still far from clear.

Aims

To investigate the expression patterns of claudin-18 and Ki-67 in early gastric cancer at the invasive front and surrounding normal gastric mucosa and to investigate the biological function of claudin-18 in the proliferation and invasion of cancer cells.

Methods

Seventy-five early gastric cancer lesions removed via endoscopic mucosal resection or endoscopic submucosal resection were evaluated. All gastric cancer lesions were diagnosed as differentiated adenocarcinoma using the Japanese Classification of Gastric Carcinoma. To assess epithelial proliferation, immunostaining with Ki-67 was performed, and the labeling index was calculated. To assess the expression of epithelial tight junction proteins, immunofluorescent staining of claudin-18 was performed. The immunoreactivity of claudin-18 was graded according to the number of stained cells. Correlation analysis was performed by Spearman’s rank correlation coefficient. Transfection of claudin-18 small interfering RNA (siRNA) was accomplished in MKN74, a claudin-18-positive gastric cancer cell line, to investigate the effect of claudin-18 on proliferation and invasion of cancer cells.

Results

Claudin-18 was significantly down-regulated in gastric cancer compared to surrounding gastric normal mucosa or intestinal metaplasia. The Ki-67 labeling index of gastric cancer at the invasive front was inversely correlated with the claudin-18 level, but that at the mucosal lesion was not correlated. Claudin-18 knockdown significantly promoted the proliferation of MKN74 compared with control siRNA-transfected cells. MKN74 invasion increased significantly with claudin-18 siRNA transfection compared with control siRNA transfection.

Conclusions

Down-regulation of claudin-18 is associated with the proliferative potential at the invasive front of gastric cancer, suggesting that it has a pivotal role in gastric cancer progression.

Claudins and gastric carcinogenesis

Gastric carcinoma arises from aberrant growth of normal gastric mucosa. There is increasing evidence that claudins (CLDNs) may play a critical role in the significant steps of gastric tumorigenesis, from metaplasia to metastasis. The CLDN family which consists of at least 27 member proteins is known to mediate selective permeability in cellular tight junctions. It is now established that CLDNs are differentially altered in gastric cancer and CLDN proteins are believed to play different roles in the growth and progression of gastric cancer.

Assessment of vascular invasion in gastric cancer: A comparative study

AIM: To evaluate and compare detection of lymphatic and blood vessel invasion (LVI and BVI) by hematoxylin-eosin (HE) and immunohistochemistry (IHC) in gastric cancer specimens, and to correlate with lymph node status.

METHODS: IHC using D2-40 (a lymphatic endothelial marker) and CD34 (a pan-endothelial marker) was performed to study LVI and BVI in surgical specimens from a consecutive series of 95 primary gastric cancer cases. The results of the IHC study were compared with the detection by HE using McNemar test and kappa index. The morphologic features of the tumors and the presence of LVI and BVI were related to the presence of lymph node metastasis. A χ² test was performed to obtain associations between LVI and BVI and other prognostic factors for gastric cancer.

RESULTS: The detection rate of LVI was considerably higher than that of BVI. The IHC study identified eight false-positive cases and 13 false-negative cases for LVI, and 24 false-positive cases and 10 false-negative cases for BVI. The average Kappa value determined was moderate for LVI (κ = 0.50) and low for BVI (κ = 0.20). Both LVI and BVI were statistically associated with the presence of lymph node metastasis (HE: P = 0.001, P = 0.013, and IHC: P = 0.001, P = 0.019). The morphologic features associated with LVI were location of the tumor in the distal third of the stomach (P = 0.039), Borrmann’s macroscopic type (P = 0.001), organ invasion (P = 0.03) and the depth of tumor invasion (P = 0.001). The presence of BVI was related only to the depth of tumor invasion (P = 0.003).

CONCLUSION: The immunohistochemical identification of lymphatic and blood vessels is useful for increasing the accuracy of the diagnosis of vessel invasion and for predicting lymph node metastasis.

Down-regulation of claudin-3 is associated with proliferative potential in early gastric cancers

BACKGROUND

Claudins are tight junction (TJ) proteins, and the relationship between the level of expression and localization of TJ protein, and tumor aggressiveness in early gastric cancer (GC) is still far from clear.

AIMS

To investigate the expression of claudins and Ki-67 in early GC cells and surrounding normal gastric mucosa.

METHODS

A total of 53 early GC lesions removed via endoscopic mucosal resection or endoscopic submucosal resection were evaluated. All of the GCs were characterized as well to moderately differentiated adenocarcinoma. The labeling index (LI) of Ki-67 was calculated for each sample. To assess the prevalence of epithelial TJs, immunofluorescent staining for claudin-3, claudin-4, and claudin-7 was performed. The immunoreactivity was graded according to the percentage of stained cells.

RESULTS

Claudin-3, claudin-4, and claudin-7 expression at TJs in GC and intestinal metaplasia were significantly higher than that in gastric mucosa with no intestinal metaplasia. The Ki-67 LI of GC specimens was inversely correlated with claudin-3 expression, but not with claudin-4 or claudin-7 expression. Claudin-3 expression was significantly lower at the submucosal invasive front of GCs.

CONCLUSIONS

The down-regulation of claudin-3 was associated with the proliferative potential of GC cells, indicating that claudins may have a pivotal role in the progression of GC.

Galectin-3 facilitates cell motility in gastric cancer by up-regulating protease-activated receptor-1 (PAR-1) and matrix metalloproteinase-1 (MMP-1)

BACKGROUND

Galectin-3 is known to regulate cancer metastasis. However, the underlying mechanism has not been defined. Through the DNA microarray studies after galectin-3 silencing, we demonstrated here that galectin-3 plays a key role in up-regulating the expressions of protease-activated receptor-1 (PAR-1) and matrix metalloproteinase-1 (MMP-1) PAR-1 thereby promoting gastric cancer metastasis.

METHODOLOGY/PRINCIPAL FINDINGS

We examined the expression levels of Galectin-3, PAR-1, and MMP-1 in gastric cancer patient tissues and also the effects of silencing these proteins with specific siRNAs and of over-expressing them using specific lenti-viral constructs. We also employed zebrafish embryo model for analysis of in vivo gastric cancer cell invasion. These studies demonstrated that: a) galectin-3 silencing decreases the expression of PAR-1. b) galectin-3 over-expression increases cell migration and invasion and this increase can be reversed by PAR-1 silencing, indicating that galectin-3 increases cell migration and invasion via PAR-1 up-regulation. c) galectin-3 directly interacts with AP-1 transcriptional factor, and this complex binds to PAR-1 promoter and drives PAR-1 transcription. d) galectin-3 also amplifies phospho-paxillin, a PAR-1 downstream target, by increasing MMP-1 expression. MMP-1 silencing blocks phospho-paxillin amplification and cell invasion caused by galectin-3 over-expression. e) Silencing of either galectin-3, PAR-1 or MMP-1 significantly reduced cell migration into the vessels in zebrafish embryo model. f) Galectin-3, PAR-1, and MMP-1 are highly expressed and co-localized in malignant tissues from gastric cancer patients.

CONCLUSIONS/SIGNIFICANCE

Galectin-3 plays the key role of activating cell surface receptor through production of protease and boosts gastric cancer metastasis. Galectin-3 has the potential to serve as a useful pharmacological target for prevention of gastric cancer metastasis.

MMP-2 and MMP-9 in lymph-node-positive bladder cancer

Background

Matrix metalloproteinases (MMP), particularly MMP-2 and MMP-9, participate in tumour progression and metastasis in various cancers. Their significance in urothelial cancer of the bladder (UCB) is unclear. Expression analysis of MMP-2 and MMP-9 in tissue microarrays (TMA) constructed of corresponding samples from histopathological normal urothelium, tumour centre and invasion front of primary tumours and lymph-node (LN) metastases might help to elucidate their relevance in UCB.

Method

MMP-2 and MMP-9 expression was evaluated in TMA of 150 surgically treated LN-positive UCB patients. Biomarker expression was correlated with tumour characteristics (primary tumour and LN stage, number, total diameter and extracapsular extension of LN metastases) and overall survival.

Results

While there was a significant increase in MMP-9 expression from normal urothelium over primary tumours to metastases (median scores: 20, 50, 65; p<0.005), no such trend was observed in MMP-2 (median scores: 5, 22, 10; p<0.005). A comparison of expression in the tumour centre and the invasion front showed no difference in both MMP. No association between expression and histopathological tumour characteristics was identified. There was a non-significant trend for a more favourable outcome for patients with high MMP-2 expression in primary tumours.

Conclusion

In LN-positive UCB, MMP-2 and MMP-9 expression was not increased at the invasion front, suggesting an infiltration strategy independent of MMP-2 and MMP-9 activity. Larger series are needed to detect a potential significant trend for favourable outcome in cancers with high MMP-2 expression.