Molecular markers for gastric adenocarcinoma: an update

Prognostic implications of phosphatidylinositol 3-kinase/AKT signaling pathway activation in gastric carcinomas

INTRODUCTION

Activation of the phosphatidylinositol 3-kinase (PI3K)/AKT pathway plays a critical role in carcinogenesis and resistance to anticancer drugs. In this study, gastric carcinomas (GC) were investigated and statistical analyses were performed concerning the correlation between the clinicopathological features and activation of the PI3K/AKT pathway.

MATERIAL AND METHODS

Immunohistochemistry for p-AKT, p-mTOR and PTEN was performed in 239 GC and 200 non-neoplastic gastric tissues. The clinicopathological parameters were recorded from the medical charts. Statistical significance was defined by a p-value < 0.05.

RESULTS

High p-AKT expression was observed in 10% of the normal gastric tissue and in 90% of GC, and it was significantly associated with tumor size (p < 0.001), T3/T4 tumors (p < 0.001), and presence of metastases (p = 0.02). Similarly, p-mTOR positivity was found in GC cells, but not in the normal gastric mucosa, and was correlated with perineural invasion (p = 0.02) and T3/T4 tumors (p = 0.03). On the other hand, PTEN expression was weak and focal in the tumor cells, while in the normal gastric tissue this staining was strong and diffuse. Importantly, the expression of p-mTOR and PTEN was associated with overall survival.

CONCLUSIONS

The results of the present study, characterized by the loss of PTEN expression and higher expression of p-AKT and p-mTOR in the majority of tumor cells, apparently are implicated in the carcinogenesis and progression of GC. The identification of p-mTOR and PTEN expression as prognostic factors corroborates the identification and use of potential target drugs that could be more efficient for the treatment of these patients.

Expression of galectin-1 in carcinoma-associated fibroblasts promotes gastric cancer cell invasion through upregulation of integrin β1

Increased expression of galectin-1 (Gal-1) in carcinoma-associated fibroblasts (CAFs) has been reported to correlate with progression and prognosis in many cancers. However, rarely have reports sought to determine whether high Gal-1 expression in CAFs in gastric cancer is involved in the tumor process, and the specific mechanism by which it promotes the evolution of gastric cancer is still unknown. In this study, we cultured gastric cancer CAFs, which showed strong expression of Gal-1, and established a co-culture system of CAFs with gastric cancer cells. Specific siRNA and in vitro migration and invasion assays were used to explore the effects of the interaction between Gal-1 expression of CAFs and gastric cancer cells on cell migration and invasion. We found that the overexpression of Gal-1 in CAFs enhanced gastric cancer cell migration and invasion, and these stimulatory effects could be blocked by specific siRNA which reduced the Gal-1 expression level. A set of cancer invasion-associated genes were then chosen to identify the possible mechanism of Gal-1-induced cell invasion. Among these genes, integrin β1 expression in cancer cells was considered to be associated with Gal-1 expression. Pre-blocking of the integrin β1 expression in gastric cancer cells with siRNA could interrupt the invasion-promoting effect of CAFs with high Gal-1 expression. Furthermore, immunohistochemical assay confirmed a positive correlation between Gal-1 and integrin β1 expression. Our results showed that high expression of Gal-1 in CAFs might facilitate gastric cancer cell migration and invasion by upregulating integrin β1 expression in gastric cancer.

Association between phosphorylated AMP-activated protein kinase and MAPK3/1 expression and prognosis for patients with gastric cancer

OBJECTIVES

Phosphorylated AMP-activated protein kinase (pAMPK) plays a central role in cellular metabolic sensing and energy balance homeostasis, and interacts with various pathways [e.g., TP53, mTOR, NUAK2 (sucrose nonfermenting-like kinase), MAPK3/1 (ERK) and PDK]. Therefore, the present study analyzed the expression of pAMPK, NUAK2, MAPK3/1 and PDK-1 and their effect on the survival of patients with resected gastric cancer.

METHODS

A total of 621 patients with gastric adenocarcinoma surgically resected with curative intent were enrolled in the study. Immunohistochemical staining for pAMPK, NUAK2, MAPK3/1 and PDK-1 was performed using tissue microarrays of surgical specimens of gastric cancer tissue.

RESULTS

Positive pAMPK, NUAK2, MAPK3/1 and PDK-1 expression was observed in 379 (61.0%), 257 (41.4%), 327 (52.7%) and 67 (10.8%) cases, respectively. Multivariate survival analysis showed a significantly better survival for the patients with positive pAMPK or MAPK3/1 expression than for the patients with a negative expression [pAMPK: disease-free survival (DFS), hazard ratio (HR) = 0.750, 95% confidence interval (CI) = 0.568-0.970, p = 0.030; MAPK3/1: DFS, HR = 0.692, 95% CI = 0.720-0.974, p = 0.021), while NUAK2 or PDK-1 expression had no effect on survival.

CONCLUSION

pAMPK or MAPK3/1 expression was found to be an independent prognostic marker for patients with resected gastric cancer.

Clinical significance of integrin αvβ6 expression effects on gastric carcinoma invasiveness and progression via cancer-associated fibroblasts

Over-expression of integrin αvβ6 and increased numbers of cancer-associated fibroblasts (CAFs) play an important role in the development and progression of cancers. The aim of this study is to investigate the expression level of integrin αvβ6 and CAF numbers, their correlation with clinicopathologic features and their role in the prognosis of human gastric cancers. The expression levels of integrin αvβ6 and α-SMA in CAFs were analyzed by immunohistochemistry. Their correlation with clinicopathologic features, the relationships and the survival time of patients were also analyzed. The integrin αvβ6 expression levels were analyzed mainly in gastric cancers. The α-SMA expression levels were analyzed mainly in gastric cancers and paraneoplastic tissues. Patients with positive integrin β6 and α-SMA expression have a significantly lower overall survival rate than those with negative integrin β6 and α-SMA expression (P < 0.05). A multivariate analysis using a log-rank test indicated that patients with positive integrin β6 and α-SMA expression and/or a diffuse type of gastric cancer had a significantly poorer overall survival rate than did those with negative integrin β6 expression (P < 0.05). Integrin β6 expression correlated significantly with CAF numbers and served as a valuable prognostic indicator for human gastric cancers.

The clinicopathologic association of c-MET overexpression in Iranian gastric carcinomas; an immunohistochemical study of tissue microarrays

Background

c-MET is an oncogene protein that plays important role in gastric carcinogenesis and has been introduced as a prognostic marker and potential therapeutic target. The aim of this study was to evaluate the frequency of c-MET overexpression and its relationship with clinicopathological variables in gastric cancer of Iranian population using tissue microarray.

Methods

In a cross sectional study, representative paraffin blocks of 130 patients with gastric carcinoma treated by curative gastrectomy during a 2 years period of 2008–2009 in two university hospitals in Tehran-Iran were collected in tissue microarray and c-MET expression was studied by immunohistochemical staining.

Results

Finally 124 cases were evaluated, constituted of 99 male and 25 female with the average age of 61.5 years. In 71% (88/124) of tumors, c-MET high expression was found. c-MET high expression was more associated with intestinal than diffuse tumor type (P = 0.04), deeper tumor invasion, pT3 and pT4 versus pT1 and pT2 (P = 0.014), neural invasion (P = 0.002) and advanced TNM staging, stage 3 and 4 versus stage 1 and2 (P = 0.044). The c-MET high expression was not associated with age, sex, tumor location, differentiation grade and distant metastasis, but relative associations with lymph node metastasis (P = 0.065) and vascular invasion (P = 0.078) were observed.

Conclusions

c-MET oncogene protein was frequently overexpressed in Iranian gastric carcinomas and it was related to clinicopathological characteristics such as tumor type, depth of invasion, neural invasion and TNM staging. It can also support the idea that c-MET is a potential marker for target therapy in Iranian gastric cancer.

Virtual slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/9744598757151429

Interaction of coagulation factors and tumor-associated macrophages mediates migration and invasion of gastric cancer

Abundant macrophage infiltration and increased expression of coagulation factors have been observed in cancer patients. The aim of the present study was to determine how the interaction between activated coagulation factors and monocytes/macrophages contributes to gastric cancer (GC) cell migration and invasion. We assessed cytokine/chemokine production of coagulation-factor-treated macrophages by ELISA. The effects of the interaction between coagulation factors and tumor-associated macrophages (TAM) on GC cell migration and invasion were determined by in vitro migration and invasion assay. In addition, we used an in vitro co-culture system of GC cells/TAM treated by coagulation factors to evaluate the effect of coagulation factor/TAM interaction on the human umbilical vein endothelial cell line (HUVEC). We found that the M2-like phenotype of interleukin (IL)-4(high), IL-10(high), transforming growth factor (TGF)-β(high), tumor necrosis factor (TNF)-α(high) was exhibited when the human monocytic cell line THP-1 was stimulated by coagulation factors III (TF), VIIa (FVIIa) and XIIa (FXIIa). For the migration assay, the GC cells (BGC-823 or SGC-7901) that were co-cultured with activated coagulation factor/TAM both showed increased migration. For the invasion assay, both BGC-823 and SGC-7901 cells co-cultured with TF/TAM showed increased invasion. We also found that TAM activated by coagulation factors could induce vascular endothelial growth factor/MMP-9 expression, which could promote invasion of GC cells. The HUVEC co-cultured with TAM (PMA-treated THP-1 macrophages co-cultured with GC cells) expressed high levels of FXIIa. In conclusion, coagulation factors might facilitate GC cell migration and invasion by transforming macrophages toward TAM-like cells. Interaction of coagulation factors and TAM mediates migration and invasion of GC.

Prognostic significance of p53 protein expression in early gastric cancer

Mutations of the p53 tumor suppressor gene have been associated with abnormalities in cell cycle regulation, DNA repair and synthesis, apoptosis, and it has been implicated in the prognosis of advanced gastric cancer. The aim of this study was to evaluate the occurrence of p53 gene mutation and its possible prognostic implications in early gastric cancer. In a retrospective study, we studied 80 patients with early gastric cancer treated surgically between 1982 and 2001. Mutation of p53 gene was investigated in surgical gastric specimens by immunohistochemistry, and results were analyzed in relation to gender, age, macroscopic appearance, size and location of tumor, presence of lymph nodes, Lauren's histological type, degree of differentiation, and the 5-year survival. The expression of p53 was more frequent among the intestinal type (p = 0.003), the differentiated (p = 0.007), and the macroscopically elevated tumors (p = 0.038). Nevertheless, the isolated expression of p53 was not associated with the 5-year survival, or with the frequency of lymph node involvement. The degree of differentiation was detected as an independent factor related to the outcome of patients (0.044). Significantly shorter survival time was found in p53-negative compared with p53-positive patients, when considering the degree of differentiation of tumors, as assessed by Cox regression analysis (0.049). The association of p53 with the intestinal type, the degree of differentiation and morphological characteristics, may reflect the involvement of chronic inflammatory process underlying early gastric cancer. In this population sample, the expression of p53 alone has no prognostic value for early gastric cancer. However, the significant difference in p53 expression between subgroups of degree of differentiation of tumors can influence post-operative outcome of patients and may be related to possible distinct etiopathogenic subtypes.

Pathological prognostic score as a simple criterion to predict outcome in gastric carcinoma

PURPOSE

The aim of this study was to establish a simple criterion to predict prognosis of patients with gastric carcinoma.

METHODS

Two hundred four patients with gastric carcinoma, who had been treated with curative resection, were enrolled. One point was added for each category among four pathological factors of depth of tumor, lymph node metastasis, venous invasion, and lymphatic invasion. Pathological Prognostic Score (PPS) was determined by an aggregate of these points for each category.

RESULTS

There existed a significant difference between survivals of patients with PPS 0 or 1 and 2 or 3 (P = 0.0002). Similarly, there also existed a significant difference between survivals of patients with PPS 2 or 3 and 4 (P = 0.010).

CONCLUSIONS

PPS can be quite simple criteria to predict prognosis of gastric carcinoma with a strict stratification.

No association of vascular endothelial growth factor-A (VEGF-A) and VEGF-C expression with survival in patients with gastric cancer

PURPOSE

Although the vascular endothelial growth factor (VEGF) superfamily has been identified to critically influence tumor-related angiogenesis, the prognostic significance of a VEGF expression in gastric cancer is still controversial. Accordingly, the present study analyzed the VEGF-A and VEGF-C expressions and their impact on the prognosis of patients with gastric cancer.

MATERIALS AND METHODS

Three hundred seventy-five consecutive patients who underwent surgical resection for gastric adenocarcinoma with a curative intent were enrolled in the present study. Immunohistochemical staining for VEGF-A and VEGF-C was performed using the formalin fixed, paraffin embedded tumor tissues.

RESULTS

Positive VEGF-A and VEGF-C expressions were observed in 337 (90.1%) and 278 (74.9%) cases, respectively. The survival analysis showed that the expression of VEGF-A and VEGF-C had no effect on the OS and DFS. On the multivariate analysis that included age, gender and the TNM stage, no significant association between the grade of the VEGF-A or VEGF-C expression and survival was observed.

CONCLUSION

The current study suggests that the tissue expression of VEGF-A or VEGF-C alone is not an independent prognostic marker for patients with surgically resected gastric adenocarcinoma.

Gastric cancer risk predisposition and prognostic significance of vascular endothelial growth factor (VEGF) gene polymorphisms--a case-control study in an Omani population

Vascular endothelial growth factor (VEGF) plays a central role in angiogenesis, tumor growth, and metastasis. We investigated the associations between VEGF gene polymorphisms and gastric cancer (GC) risk predisposition and prognostic characteristics in an Omani population, an ethnic group which has not been studied previously. We analyzed three VEGF polymorphisms (+405 G/C, -460 T/C, and +936 C/T) by the extraction of genomic DNA from peripheral blood of 130 GC patients and 130 control subjects followed by VEGF genotyping using polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) analysis. There were no significant associations between the VEGF polymorphisms and GC risk. There were significant correlations between the +405 C/C genotype and both poor tumor differentiation (P = 0.007) and lymph node metastasis (P = 0.03) and between the -460 T/T genotype and poor tumor differentiation (P = 0.03) with a statistical trend toward lymph node involvement (P = 0.05). VEGF gene polymorphisms had no significant effects on survival, but the VEGF +405 G/G genotype had a statistical trend toward lower survival rate with a hazard ratio of 1.6 [95% CI, 0.9-2.9] compared with the VEGF +405 CC/GC combined genotype (P = 0.049). Multivariate analysis showed that disease stage at diagnosis and the +405 G/G genotype were independent variables of adverse prognostic significance. There were no associations between the six common haplotypes identified and both GC risk predisposition and survival. The current study suggests that VEGF polymorphisms have no role in GC risk predisposition, but may have prognostic significance in GC patients.

GSTP1 determines cis-platinum cytotoxicity in gastric adenocarcinoma MGC803 cells: regulation by promoter methylation and extracellular regulated kinase signaling

Detoxification mechanisms can play a pivotal role in determining tumor cell responses to platinum-based chemotherapy. Glutathione S-transferase-pi (GSTP1) belongs to a supergene family of detoxifying enzymes involved in the prevention of DNA damage and subsequent platinum resistance in numerous cancers. The role of GSTP1 in gastric cancer sensitivity to chemotherapy is, however, not known. In this study, we found that the human gastric cancer cell line MGC803 was significantly more sensitive to cis-platinum (CDDP) than the other gastric cancer lines examined (BGC823 and SGC7901). To explore the potential role of GSTP1 in drug resistance, we measured GSTP1 expression in these cells. GSTP1 mRNA and protein were not detectable in MGC803 cells; both were present in BGC823 and SGC7901 cells. GSTP1 CpG island DNA methylation was examined. We report that promoter hypermethylation was associated with the absence of GSTP1 expression in MGC803 cells. Treatment of these cells with 5-aza-2'-deoxycytidine, a DNA methyltransferase inhibitor, restored GSTP1 expression and suppressed sensitivity to CDDP. The selective mitogen-activated protein kinase/extracellular regulated kinase (ERK) pathway inhibitor PD98059 decreased GSTP1 expression in 5-aza-2'-deoxycytidine-treated cells. A similar decrease was observed in the BGC823 and SGC7901 cell lines, suggesting that mitogen-activated protein kinase/ERK signaling stimulates GSTP1 expression. CDDP sensitivity was also enhanced by PD98059. These observations indicate that somatic promoter hypermethylation and impaired ERK signaling are associated with decreased GSTP1 expression and CDDP sensitivity in gastric cancer cell lines. Evaluation of promoter methylation and ERK activity may be useful for predicting tumor sensitivity to platinum-based chemotherapeutics.

Expression of the antiapoptosis gene Survivin predicts poor prognosis of stage III gastric adenocarcinoma

OBJECTIVE

This study was designed to determine the level of survivin expression and its clinical significance as a prognostic factor in Stage III gastric adenocarcinoma.

METHODS

We performed immunohistochemical staining for survivin, p53 and Bax in formalin-fixed, paraffin-embedded blocks from 157 surgically resected Stage III gastric cancer tissues. To determine the association with clinical course, we reviewed the patients' clinical records.

RESULTS

Of the 157 gastric cancer tissues, 63 (40.1%) cases showed positive expression for survivin protein. There was no significant association between survivin expression and p53 or Bax. For clinicopathologic parameters, large tumor size was closely related to survivin expression (P < 0.05). The 5-year survival rate of patients with positive survivin expression was significantly lower compared with that for survivin-negative cancer patients (P < 0.05). Survivin and p53 were independent prognostic factors in Stage III gastric cancer.

CONCLUSIONS

Survivin protein is an important predictive and prognostic parameter of poor outcome in gastric carcinoma.

Identification of TRAK1 (Trafficking protein, kinesin-binding 1) as MGb2-Ag: a novel cancer biomarker

The present study aimed to describe the characterization of an antibody MGb2 that reacts with an epitope on gastric cancer cells, and identification of MGb2 antigen (MGb2-Ag). Immunostaining revealed its distribution in human tissues and demonstrated that the positive rate of MGb2-Ag was 81.48% in gastric cancer, 100% in gastric signet-ring cell carcinoma and mucinous adenocarcinoma, 13.16% in precancerous conditions, and 0% in chronic superficial gastritis. Using Western blotting, immunoprecipitation and MALDI-TOF MS (matrix assisted laser desorption/ionization time-of-flight mass spectrometry), MGb2-Ag was identified as TRAK1 (Trafficking protein, kinesin-binding 1), a new molecular gained limited recognition. Both MGb2 and commercial anti-TRAK1 Ab recognized prokaryotic expressed TRAK1. Immunostaining characteristics of TRAK1 were identical with MGb2-Ag in continuous sections of paraffin-embedded tissues of gastric tissues. This is the first report that TRAK1/MGb2-Ag is a promising diagnostic marker for gastric cancer and may help to detect signet-ring cell carcinoma and mucinous adenocarcinoma.

Hypoxic silencing of tumor suppressor RUNX3 by histone modification in gastric cancer cells

RUNX3 is a tumor suppressor that is silenced in cancer following hypermethylation of its promoter. The effects of hypoxia in tumor suppressor gene (TSG) transcription are largely unknown. Here, we investigated hypoxia-induced silencing mechanisms of RUNX3. The expression of RUNX3 was downregulated in response to hypoxia in human gastric cancer cells at the transcriptional level. This downregulation was abolished following treatment with the histone deacetylase (HDAC) inhibitor trichostatin A (TSA) and cytosine methylation inhibitor 5-aza-2-deoxycytidine (5-Aza), suggesting that an epigenetic regulatory mechanism may be involved in RUNX3 silencing by hypoxia. DNA methylation PCR and bisulfite-sequencing data revealed that hypoxia did not affect the methylation of RUNX3 promoter. A chromatin immunoprecipitation (ChIP) assay revealed increased histone H3-lysine 9 dimethylation and decreased H3 acetylation in the RUNX3 promoter following hypoxia. Hypoxia resulted in the upregulation of G9a histone methyltransferase (HMT) and HDAC1; additionally, overexpression of G9a and HDAC1 attenuated RUNX3 expression. The overexpression of G9a and HDAC1, but not their mutants, inhibited the nuclear localization and expression of RUNX3. Diminished mRNA expression and nuclear localization of RUNX3 during hypoxia was abolished by siRNA-mediated knockdown of G9a and HDAC1. This study suggests that hypoxia silences RUNX3 by epigenetic histone regulation during the progression of gastric cancer.

Recent advances in conventional and molecular prognostic factors for gastric carcinoma

Despite radical surgery, the prognosis of patients who have gastric carcinoma remains unsatisfactory because of the intrinsic but unpredictable aggressiveness of this malignancy. During the past decade an ever-growing list of molecular prognostic factors has been proposed based on the discovery of the mechanisms underlying gastric cancer aggressiveness. Studies performed in larger and more homogeneous series of patients and adequate statistical analysis are warranted before any of the candidate biomarkers can be implemented in the routine clinical setting for the identification of patients at higher risk and thus for the selection of candidates for adjuvant or more aggressive therapies.

Measurement of circulating levels of VEGF-A, -C, and -D and their receptors, VEGFR-1 and -2 in gastric adenocarcinoma

AIM: To analyze the serum levels and prognostic significance of vascular endothelial growth factor (VEGF) -A, -C, and -D, and their receptors, VEGFR-1 and -2 in gastric adenocarcinomas.

METHODS: The serum levels of VEGF family members were measured in 76 control subjects and 76 patients with gastric adenocarcinoma using an enzyme-linked immunosorbent assay (ELISA). These measurements were correlated with clinco-pathological features and survival rates.

RESULTS: The serum levels of VEGF-A and its receptor, VEGFR-1, were significantly higher in patients with gastric cancer than in healthy donors (t = 2.3, P = 0.02 and t = 4.2, P < 0.0001, respectively). In contrast, the serum levels of VEGF-D were significantly higher in control subjects than in patients (t = 2.9, P = 0.004). There was no significant difference in serum levels of VEGF-C and VEGFR-2 between patients and controls. VEGF-C was associated with advanced tumor stage and presence of metastasis. VEGFR-1 was associated with metastasis, advanced overall stage, tumor differentiation and survival. VEGFR-2 levels were associated with poor tumor differentiation. There was no significant prognostic value for any of the VEGF family members or their receptors except for VEGFR-1 where high levels were associated with a poor overall survival.

CONCLUSION: Serum VEGF levels vary significantly in the same cohort of patients with variable clinico-pathological features and prognostic values. The simultaneous measurement of VEGF receptors levels in sera may overcome the limitations of a single biomarker assay.

Collagens at a glance

Background

The prognosis of gastric cancer patients is difficult to predict because of defects in establishing the surgical-pathological features. Cancer-associated fibroblasts (CAFs) have been found to play prominent role in promoting tumor growth, invasion and metastasis. Thus raises the hypothesis that the extent of CAFs prevalence may help to establish the prognosis of gastric cancer patients.

Methods

Immunochemistry and realtime-PCR experiments were carried out to compare the expression of proteins which are specific markers of CAFs or secreted by CAFs in the tumor and normal tissue specimens. The extent of CAFs' prevalence was graded according to immunochemical staining, and correlation was further analyzed between CAFs' prevalence and other tumor characteristics which may influence the prognosis of gastric cancer patients.

Results

Nearly 80 percent of normal gastric tissues were negative or weak positive for CAFs staining, while more than 60 percent of gastric cancer tissues were moderate or strong positive for CAFs staining. Realtime-PCR results also showed significant elevated expression of FAP, SDF-1 and TGF-β1 in gastric cancer tissues compared to normal gastric tissues. Further analysis showed that CAFs' prevalence was correlated with tumor size, depth of the tumor, lymph node metastasis, liver metastasis or peritoneum metastasis.

Conclusions

Reactive cancer associated fibroblasts (CAFs) were frequently accumulated in gastric cancer tissues, and the prevalence of CAFs was correlated with tumor size, depth of the tumor and tumor metastasis, thus give some supports for establishing the prognosis of the gastric cancer patients.