Serum protein and genetic tumor markers of gastric carcinoma

Long non-coding RNA profiles in plasma exosomes of patients with gastric high-grade intraepithelial neoplasia

Long non-coding (lnc) RNAs in circulating exosomes are a new class of promising cancer biomarkers; however, their expression in exosomes derived from gastric high-grade intraepithelial neoplasia (GHGIN) has not been reported. In the present study, differentially expressed (DE) lncRNAs were analyzed in the peripheral blood collected from 5 patients with GHGIN and 5 healthy donors using high-throughput sequencing. Reverse transcription-quantitative PCR analysis was performed on 6 randomly selected DE lncRNAs to validate the reliability of the sequencing results. The potential roles of the DE lncRNAs in GHGIN were investigated using Gene Ontology (GO) and Kyoto Encyclopedia of Gene and Genome (KEGG) pathway enrichment analyses. A total of 25,145 lncRNAs were identified in all the samples and 83 DE lncRNAs were further screened, including 76 upregulated and 7 downregulated DE lncRNAs. GO and KEGG analyses predicted that the DE lncRNAs played notable roles in ‘protein/macromolecule glycosylation’, ‘regulation of protein ubiquitination’, ‘renin-angiotensin system’ and ‘MAPK signaling pathways’. A lncRNA-micro (mi)RNA-mRNA interaction network was constructed and used to perform association analyses. It was found that 83 lncRNAs were abnormally expressed in GHGIN, with some potential functions associated with gastric cancer. Furthermore, the lncRNA-miRNA-mRNA interaction network indicated that 7 DE lncRNAs may play a notable role in the occurrence and development of GHGIN. The results of the present study showed the expression profiles of lncRNAs in human GHGIN, elucidated some of the molecular changes associated with GHGIN and improved the understanding of the molecular mechanisms underlying GHGIN and gastric cancer.

Comparative proteomic analysis of human malignant ascitic fluids for the development of gastric cancer biomarkers

OBJECTIVES

Malignant ascites is a sign of peritoneal seeding, which is one of the most frequent forms of incurable distant metastasis. Because the development of malignant ascites is associated with an extremely poor prognosis, determining whether it resulted from peritoneal seeding has critical clinical implications in diagnosis, choice of treatment, and active surveillance. At present, the molecular characterizations of malignant ascites are especially limited in case of gastric cancer. We aimed to identify malignant ascites-specific proteins that may contribute to the development of alternative methods for diagnosis and therapeutic monitoring and also increase our understanding of the pathophysiology of peritoneal seeding.

DESIGN & METHODS

First, comprehensive proteomic strategies were employed to construct an in-depth proteome of ascitic fluids. Label-free quantitative proteomic analysis was subsequently performed to identify candidates that can differentiate between malignant ascitic fluilds of gastric cancer patients from benign ascitic fluids. Finally, two candidate proteins were verified by ELISA in 84 samples with gastric cancer or liver cirrhosis.

RESULTS

Comprehensive proteome profiling resulted in the identification of 5347 ascites proteins. Using label-free quantification, we identified 299 proteins that were differentially expressed in ascitic fluids between liver cirrhosis and stage IV gastric cancer patients. In addition, we identified 645 proteins that were significantly expressed in ascitic fluids between liver cirrhosis and gastric cancer patients with peritoneal seeding. Finally, Gastriscin and Periostin that can distinguish malignant ascites from benign ascites were verified by ELISA.

CONCLUSIONS

This study identified and verified protein markers that can distinguish malignant ascites with or without peritoneal seeding from benign ascites. Consequently, our results could be a significant resource for gastric cancer research and biomarker discovery in the diagnosis of malignant ascites.

Potential Biomarkers in Diagnosis of Human Gastric Cancer

The high incidence of gastric cancer (GC) and its consequent mortality rate severely threaten human's health. It is not frequently diagnosed until a relatively advanced stage. Surgery is the only potentially curative treatment. Thus, early screening and diagnosis are critical for patients with GC. The tumor marker assays used currently for detecting GC are simple and rapid, but the usage is limited by its low sensitivity and specificity. Here, we provide a brief description of some new potential markers and new biotechnological methods for the diagnosis of GC, hoping to find out more effective approaches for early detection of GC.

Sensitivity of gastric cancer cells to chemotherapy drugs in elderly patients and its correlation with cyclooxygenase-2 expression

OBJECTIVE

To explore the sensitivity of gastric cancer cells to chemotherapy drugs in elderly patients and its correlation with cyclooxygenase-2 (COX-2) expression in cancer tissue.

MATERIALS AND METHODS

Forty-three elderly patients with gastric cancer (observation group) and 31 young patients with gastrointestinal tumors (control group) who were all diagnosed by pathology and underwent surgery in the 89th Hospital of Chinese People's Liberation Army were selected. Drug sensitivity testing of tumor cells in primary culture was carried out in both groups using a methyl thiazolyl tetrazolium (MTT) method, and the expression of COX-2 and the factors related to multi-drug resistance (MDR) in cancer tissue were assessed by immunohistochemistry.

RESULTS

The inhibition rates (IR) of vincristine (VCR), 5-fluorouracil (5-FU), oxaliplatin (L-OHP), mitomycin (MMC) and epirubicin (eADM) on tumor cells in the observation group were dramatically lower than in the control group, with statistical significance (P<0.05 or P<0.01). The positive rates of COX-2, glutathione s-transferase-π (GST-π) and P glycoprotein (P-gp) expression in cancer tissue in the observation group were all higher than in control group (P<0.05), while that of DNA topoisomerase IIα (TopoIIα) expression lower than in the control group (P<0.01). In the observation group, COX-2 expression in cancer tissue had a significantly-positive correlation with GST-π and P-gp (r=0.855, P=0.000; r=0.240, P=0.026), but a negative correlation with TopoIIα (r=-0.328, P=0.002). In the control group, COX-2 expression in cancer tissue was only correlated with P-gp positively (r=0.320, P=0.011). Bivariate correlation analysis displayed that COX-2 expression in cancer tissue in the observation group had a significantly-negative correlation with the IRs of 5-FU, L-OHP, paclitaxel (PTX) and eADM in tumor cells (r=-0.723, P=0.000; r=-0.570, P=0.000; r=-0.919, P=0.000; r=-0.781, P=0.000), but with hydroxycamptothecine (HCPT), VCR and 5-FU in the control group (r=-0.915, P=0.000; r=-0.890, P=0.000; r=-0.949, P=0.000).

CONCLUSIONS

Gastric cancer cells in elderly patients feature stronger MDR, which may be related to high COX-2 expression.

Challenges of deciphering gastric cancer heterogeneity

Gastric cancer is in decline in most developed countries; however, it still accounts for a notable fraction of global mortality and morbidity related to cancer. High-throughput methods are rapidly changing our view and understanding of the molecular basis of gastric carcinogenesis. Today, it is widely accepted that the molecular complexity and heterogeneity, both inter- and intra-tumour, of gastric adenocarcinomas present significant obstacles in elucidating specific biomarkers for early detection of the disease. Although genome-wide sequencing and gene expression studies have revealed the intricate nature of the molecular changes that occur in tumour landscapes, the collected data and results are complex and sometimes contradictory. Several aberrant molecules have already been tested in clinical trials, although their diagnostic and prognostic utilities have not been confirmed thus far. The gold standard for the detection of sporadic gastric cancer is still the gastric endoscopy, which is considered invasive. In addition, genome-wide association studies have confirmed that genetic variations are important contributors to increased cancer risk and could participate in the initiation of malignant transformation. This hypothesis could in part explain the late onset of sporadic gastric cancers. The elaborate interplay of polymorphic low penetrance genes and lifestyle and environmental risk factors requires additional research to decipher their relative impacts on tumorigenesis. The purpose of this article is to present details of the molecular heterogeneity of sporadic gastric cancers at the DNA, RNA, and proteome levels and to discuss issues relevant to the translation of basic research data to clinically valuable tools. The focus of this work is the identification of relevant molecular changes that could be detected non-invasively.

Serum angiopoietin-like protein 2 as a potential biomarker for diagnosis, early recurrence and prognosis in gastric cancer patients

Chronic inflammation of gastric mucosa by Helicobacter pylori infection can initiate gastric carcinogenesis. As angiopoietin-like protein 2 (ANGPTL2) mediates inflammation and inflammation-associated carcinogenesis, we investigated the functional and clinical significance of ANGPTL2 in human gastric cancer (GC). SiRNA knockdown studies were performed for the functional assessment of ANGPTL2 in GC cell lines. ANGPTL2 expression was evaluated immunohistochemically in 192 tissue specimens from GC patients. In addition, we screened serum ANGPTL2 levels from 32 GC patients and 23 healthy controls; and validated these results in 194 serum samples from GC patients and 45 healthy controls by ELISA. ANGPTL2 knockdown caused anoikis and inhibited proliferation, invasion and migration in GC cells. ANGPTL2 expression was upregulated in GC tissues compared to normal gastric mucosa; and high ANGPTL2 expression was significantly associated with tumor progression, early recurrence (P = 0.003) and poor prognosis (P = 0.007). Serum ANGPTL2 in GC patients was significantly higher than for healthy controls (P < 0.05), and accurately distinguished GC patients from healthy control (AUC = 0.865). The validation step confirmed significantly higher serum ANGPTL2 levels in GC patients than healthy controls (P < 0.0001). Receiver operating characteristic curves yielded robust AUC value (0.831) accompanied by high sensitivity (73.0%) and specificity (82.2%) in distinguishing GC patients from healthy controls. High serum ANGPTL2, rather than its expression in matched tissues, was significantly associated with tumor progression, and emerged as an independent marker for recurrence (HR: 5.05, P = 0.0004) and prognosis (HR: 3.6, P = 0.01). Serum ANGPTL2 expression is a potential noninvasive biomarker for diagnosis, early recurrence and prognosis of GC patients.

Aberrant methylation patterns in cancer: a clinical view

Epigenetic mechanisms, such as DNA methylation, DNA hydroxymethylation, post-translational modifications (PTMs) of histone proteins affecting nucleosome remodelling, and regulation by small and large non-coding RNAs (ncRNAs) work in concert with cis and trans acting elements to drive appropriate gene expression. Advances in detection methods and development of dedicated platforms and methylation arrays resulted in an explosion of information on aberrantly methylated sequences linking deviations in epigenetic landscape with the initiation and progression of complex diseases. Here, we consider how DNA methylation changes in malignancies, such as breast, pancreatic, colorectal, and gastric cancer could be exploited for the purpose of developing specific diagnostic tools. DNA methylation changes can be applicable as biomarkers for detection of malignant disease in easily accessible tissues. Methylation signatures are already proving to be an important marker for determination of drug sensitivity. Even more, promoter methylation patterns of some genes, such as MGMT, SHOX2, and SEPT9, have already been translated into commercial clinical assays aiding in patient assessment as adjunct diagnostic tools. In conclusion, the changes in DNA methylation patterns in tumour cells are slowly gaining entrance into routine diagnostic tests as promising biomarkers and as potential therapeutic targets.

Increased expression of P2RY2, CD248 and EphB1 in gastric cancers from Chilean patients

BACKGROUND

Gastric cancer (GC) ranks as one of the major causes of mortality due to cancer worldwide. In Chile, it is currently the leading cause of cancer death. Identification of novel molecular markers that may help to improve disease diagnosis at early stages is imperative.

MATERIALS AND METHODS

Using whole-genome DNA microarrays we determined differential mRNA levels in fresh human GC samples compared to adjacent healthy mucosa from the same patients. Genes significantly overexpressed in GC were validated by RT-PCR in a group of 14 GC cases.

RESULTS

The genes CD248, NSD1, RAB17, ABCG8, Ephb1 and P2RY2 were detected as the top overexpressed in GC biopsies. P2RY2, Ephb1 and CD248 showed the best sensitivity for GC detection with values of 92.9%, 85.7% and 64.3% (p<0.05), respectively. Specificity was 85.7%, 71.4% and 71.4% (p<0.05), for each respectively.

Combined use of lysyl oxidase, carcino-embryonic antigen, and carbohydrate antigens improves the sensitivity of biomarkers in predicting lymph node metastasis and peritoneal metastasis in gastric cancer

The purpose of this study was to determine whether lysyl oxidase (LOX) is a useful marker of metastasis in gastric cancer (GC) patients in combination with tumor markers carcino-embryonic antigen (CEA), carbohydrate antigen 724 (CA724), carbohydrate antigen 19-9 (CA19-9), and carbohydrate antigen 125 (CA125). There were 215 GC patients (67 without metastasis, 102 with lymph node metastasis, and 46 with peritoneal metastasis) who presented to the Affiliated Cancer Hospital of Guangxi Medical University between May 2009 and November 2012 that were enrolled in this study. The LOX expression level and the serum concentration of the four tumor markers were evaluated preoperatively. All patients underwent computed tomography (CT) and ultrasonography (US) before surgery. Statistical analysis, including receiver operating characteristic (ROC) curve analysis, area under the curve (AUC) analysis, and logistic regression analysis, was performed to evaluate the diagnostic value of these markers in predicting metastasis in GC. For predicting lymph node metastasis in GC, the sensitivity of LOX, CEA, CA724, CA199, and CA125 was 44.12, 12.75, 21.57, 23.53, and 15.69 %, respectively, and increased to 79.41 % in combination. For predicting peritoneal metastasis in GC, the sensitivity of these markers was 56.52, 23.91, 34.78, 36.96, and 34.78 %, respectively, and increased to 91.30 % in combination. Combining LOX with CEA, CA724, CA199, and CA125 could increase the sensitivity of predicting lymph nodes metastasis and peritoneal metastasis in GC. Surgeons can use these markers to determine the best treatment options for patients. Additional large-scale, prospective, multicenter studies are urgently needed to further confirm the results of this study.

Role of c-Src activity in the regulation of gastric cancer cell migration

Gastric cancer is associated with increased migration and invasion. In the present study, we explored the role of c-Src in gastric cancer cell migration and invasion. BGC-823 gastric cancer cells were used to investigate migration following treatment of these cells with the c-Src inhibitors, PP2 and SU6656. Migration and invasion were analyzed by wound healing and Transwell assays. Western blot analysis was used to detect the expression of MT1-MMP and VEGF-C, while the activity of MMP2 and MMP9 was monitored with gelatin zymography assay. Immunoprecipitation was used to detect interactions among furin, pro-MT1-MMP and pro-VEGF-C. MT1-MMP and VEGF-C expression levels were inhibited by PP2 and SU6656 treatment, in accordance with decreased c-Src activity. Similarly, the zymography assay demonstrated that the activity of MMP2 and MMP9 was decreased following PP2 or SU6656 treatment. Blockade of c-Src also inhibited the invasive and migratory capacity of BGC-823 cells. Notably, c-Src interacted with furin in vivo, while interactions between furin and its substrates, pro-MT1-MMP and pro-VEGF-C, were decreased by c-Src inhibitors. In conclusion, the interaction among furin and pro-MT1-MMP or pro-VEGF-C or other tumor-associated precursor enzymes can be regulated by c-Src activity, thus reducing or changing the expression of these enzymes in order to reduce the development of gastric cancer, invasion and metastasis.