Biomarkers for gastric cancer: Progression in early diagnosis and prognosis (Review)

Integrated analysis of the role of PR/SET domain 14 in gastric cancer

BACKGROUND

Gastric cancer is one of the most common tumors worldwide, and most patients are deprived of treatment options when diagnosed at advanced stages. PRDM14 has carcinogenic potential in breast and non-small cell lung cancer. however, its role in gastric cancer has not been elucidated.

METHODS

We aimed to elucidate the expression of PRDM14 using pan-cancer analysis. We monitored the expression of PRDM14 in cells and patients using quantitative polymerase chain reaction, western blotting, and immunohistochemistry. We observed that cell phenotypes and regulatory genes were influenced by PRDM14 by silencing PRDM14. We evaluated and validated the value of the PRDM14-derived prognostic model. Finally, we predicted the relationship between PRDM14 and small-molecule drug responses using the Connectivity Map and The Genomics of Drug Sensitivity in Cancer databases.

RESULTS

PRDM14 was significantly overexpressed in gastric cancer, which identified in cell lines and patients' tissues. Silencing the expression of PRDM14 resulted in apoptosis promotion, cell cycle arrest, and inhibition of the growth and migration of GC cells. Functional analysis revealed that PRDM14 acts in epigenetic regulation and modulates multiple DNA methyltransferases or transcription factors. The PRDM14-derived differentially expressed gene prognostic model was validated to reliably predict the patient prognosis. Nomograms (age, sex, and PRDM14-risk score) were used to quantify the probability of survival. PRDM14 was positively correlated with sensitivity to small-molecule drugs such as TPCA-1, PF-56,227, mirin, and linsitinib.

CONCLUSIONS

Collectively, our findings suggest that PRDM14 is a positive regulator of gastric cancer progression. Therefore, it may be a potential therapeutic target for gastric cancer.

Prognostic significance of serum tumor markers in various pathologic subtypes of gastric cancer

PURPOSE

This study aimed to assess the utility of 6 serum tumor markers in prognosis between gastric adenocarcinoma and gastric signet ring cell carcinoma (SRCC).

METHODS

A cohort of 3131 cases of gastric adenocarcinoma and 275 cases of gastric SRCC was assembled. The serum levels of carcinoembryonic antigen (CEA), carbohydrate antigen 19-9 (CA19-9), carbohydrate antigen 125, alpha fetoprotein (AFP), carbohydrate antigen 242 (CA242), and carbohydrate antigen 724 (CA724) were measured in all cases. The study analyzed the association between the levels of these 6 tumor markers and the prognosis of gastric adenocarcinoma and SRCC.

RESULTS

The study revealed that gastric SRCC exhibited lower concentrations of CEA (P < .001) and CA19-9 (P = .002), along with reduced positive rates of CEA (P = .041), CA19-9 (P = .003), AFP (P < .001), and CA242 (P = .006), while displaying higher positive rates of CA724 (P = .024) than gastric adenocarcinoma. Nevertheless, the receiver operating characteristic curve demonstrated that serum tumor markers did not hold clinical significance in differentiating between gastric adenocarcinoma and SRCC. Survival analysis substantiated that the combined criteria of serum tumor markers stood as an independent risk factor for both gastric adenocarcinoma and SRCC. Notably, the nomogram indicated that serum tumor markers exerted a more substantial influence on the prognosis of gastric adenocarcinoma than on gastric SRCC.

CONCLUSION

The study concluded that the combined criteria of serum tumor markers emerge as independent risk factors for both subtypes of gastric cancer. Furthermore, this combined approach exhibited enhanced efficacy in prognosticating the outcome of gastric adenocarcinoma compared with gastric SRCC.

Clinical molecular subtyping reveals intrinsic mesenchymal reprogramming in gastric cancer cells

The mesenchymal cancer phenotype is known to be clinically related to treatment resistance and a poor prognosis. We identified gene signature-based molecular subtypes of gastric cancer (GC, n = 547) based on transcriptome data and validated their prognostic and predictive utility in multiple external cohorts. We subsequently examined their associations with tumor microenvironment (TME) features by employing cellular deconvolution methods and sequencing isolated GC populations. We further performed spatial transcriptomics analysis and immunohistochemistry, demonstrating the presence of GC cells in a partial epithelial-mesenchymal transition state. We performed network and pharmacogenomic database analyses to identify TGF-β signaling as a driver pathway and, thus, a therapeutic target. We further validated its expression in tumor cells in preclinical models and a single-cell dataset. Finally, we demonstrated that inhibition of TGF-β signaling negated mesenchymal/stem-like behavior and therapy resistance in GC cell lines and mouse xenograft models. In summary, we show that the mesenchymal GC phenotype could be driven by epithelial cancer cell-intrinsic TGF-β signaling and propose therapeutic strategies based on targeting the tumor-intrinsic mesenchymal reprogramming of medically intractable GC.

The Number of Positive Tumor Markers (NPTM) Achieves Higher Value in the Prognosis Prediction of Gastric Cancer

Purpose

The clinical application of combined tumor markers is still limited. We aim to explore the value of the combination of multiple tumor markers in gastric cancer (GC) prognosis.

Methods

The prognostic significance was evaluated using Kaplan-Meier log-rank survival analysis and multivariable Cox regression analysis. The estimated area under the curve (AUC) was compared to evaluate the discriminatory ability of different indicators. A nomogram was constructed based on the results of multivariable cox regression, and its performance was evaluated by Harrell's concordance index and calibration curve.

Results

NPTM (number of positive tumor markers) displayed independent prognostic significance whether in the whole cohort or in patients with different stages. Patients with the all-negative tumor markers had a worse prognosis after postoperative chemotherapy in all cohort (P = 0.023) or in age ≤60 subgroup (P = 0.012), while patients with positive tumor markers had a better prognosis after postoperative chemotherapy in stage III (P = 0.012). The AUC value of NPTM is higher than any individual tumor marker. The 1-, 3-, and 5-year AUC values of the CTNM (combination of NPTM and pTNM) increased by 5%, 4.8%, and 3.6%, respectively, compared with TNM staging system. The nomogram constructed including NPTM showed its high accuracy (C - index = 0.706) versus TNM staging system (C - index = 0.646) and CTNM (C - index = 0.681).

Conclusions

NPTM was an independent predictor of gastric cancer prognosis, showing more accurate prognostic performance than individual tumor markers. Especially its significance in guiding postoperative adjuvant chemotherapy regimens and predicting prognosis by combination with TNM staging system may have a better clinical application value.

Abnormally Expressed lncRNAs as Potential Biomarkers for Gastric Cancer Risk: A Diagnostic Meta-Bioinformatics Analysis

Background and Aims

Abnormal expression of lncRNAs is relevant to the occurrence and development of gastric cancer (GC), but the significance remains inconclusive. We performed a diagnostic meta-bioinformatics analysis to elucidate the association between lncRNA expression and GC risk.

Methods

Published datasets were selected from PubMed, Embase, CNKI, and Web of Science, up to 1st December 2021. The pooled sensitivity (SEN), specificity (SPE), positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and area under the curve (AUC) were calculated to evaluate the diagnostic value. RNA sequencing data were downloaded for validation.

Results

54 studies with 4671 patients and 4652 matched controls were included in the meta-analysis. The pooled SEN, SPE, PLR, NLR, DOR, and AUC were 0.71, 0.76, 2.9, 0.39, 8, and 0.79, respectively. Subgroup analyses showed that the DOR and AUC of intergenic lncRNAs, circulating lncRNAs, larger sample size (>200), and high-quality (NOS score ≥ 7) groups were superior to antisense lncRNAs, tissue lncRNAs, smaller sample size (≤200), and low-quality (NOS score < 7) groups, respectively. However, only circulating lncRNAs had significantly higher diagnostic utility than that tissue lncRNAs. Nine differentially expressed lncRNAs in the meta-analysis were verified in TCGA-STAD. PVT1 was the most effective single lncRNA, with AUC of 0.949, SEN of 0.808, and SPE of 0.969, while PVT1 and C5orf66-AS1 were the most effective combination, with AUC of 0.972, SEN of 0.941, and SPE of 0.937.

Conclusion

Abnormally expressed lncRNAs, especially circulating lncRNAs, might be potential diagnostic biomarkers for GC risk. A novel combined model of lncRNAs might achieve better GC diagnosis performance.

Bioinformatics Analysis and Structure of Gastric Cancer Prognosis Model Based on Lipid Metabolism and Immune Microenvironment

OBJECTIVES

The reprogramming of lipid metabolism is a new trait of cancers. However, the role of lipid metabolism in the tumor immune microenvironment (TIME) and the prognosis of gastric cancer remains unclear.

METHODS

Consensus clustering was applied to identify novel subgroups. ESTIMATE, TIMER, and MCPcounter algorithms were used to determine the TIME of the subgroups. The underlying mechanisms were elucidated using functional analysis. The prognostic model was established using the LASSO algorithm and multivariate Cox regression analysis.

RESULTS

Three molecular subgroups with significantly different survival were identified. The subgroup with relatively low lipid metabolic expression had a lower immune score and immune cells. The differentially expressed genes (DEGs) were concentrated in immune biological processes and cell migration via GO and KEGG analyses. GSEA analysis showed that the subgroups were mainly enriched in arachidonic acid metabolism. Gastric cancer survival can be predicted using risk models based on lipid metabolism genes.

CONCLUSIONS

The TIME of gastric cancer patients is related to the expression of lipid metabolism genes and could be used to predict cancer prognosis accurately.

Synaptotagmin 11 scaffolds MKK7-JNK signaling process to promote stem-like molecular subtype gastric cancer oncogenesis

Background

Identifying biomarkers related to the diagnosis and treatment of gastric cancer (GC) has not made significant progress due to the heterogeneity of tumors. Genes involved in histological classification and genetic correlation studies are essential to develop an appropriate treatment for GC.

Methods

In vitro and in vivo lentiviral shRNA library screening was performed. The expression of Synaptotagmin (SYT11) in the tumor tissues of patients with GC was confirmed by performing Immunohistochemistry, and the correlation between the expression level and the patient’s survival rate was analyzed. Phospho-kinase array was performed to detect Jun N-terminal kinase (JNK) phosphorylation. SYT11, JNK, and MKK7 complex formation was confirmed by western blot and immunoprecipitation assays. We studied the effects of SYT11 on GC proliferation and metastasis, real-time cell image analysis, adhesion assay, invasion assay, spheroid formation, mouse xenograft assay, and liver metastasis.

Results

SYT11 is highly expressed in the stem-like molecular subtype of GC in transcriptome analysis of 527 patients with GC. Moreover, SYT11 is a potential prognostic biomarker for histologically classified diffuse-type GC. SYT11 functions as a scaffold protein, binding both MKK7 and JNK1 signaling molecules that play a role in JNK1 phosphorylation. In turn, JNK activation leads to a signaling cascade resulting in cJun activation and expression of downstream genes angiopoietin-like 2 (ANGPTL2), thrombospondin 4 (THBS4), Vimentin, and junctional adhesion molecule 3 (JAM3), which play a role in epithelial-mesenchymal transition (EMT). SNU484 cells infected with SYT11 shRNA (shSYT11) exhibited reduced spheroid formation, mouse tumor formation, and liver metastasis, suggesting a pro-oncogenic role of SYT11. Furthermore, SYT11-antisense oligonucleotide (ASO) displayed antitumor activity in our mouse xenograft model and was conferred an anti-proliferative effect in SNU484 and MKN1 cells.

Conclusion

SYT11 could be a potential therapeutic target as well as a prognostic biomarker in patients with diffuse-type GC, and SYT11-ASO could be used in therapeutic agent development for stem-like molecular subtype diffuse GC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-022-02420-3.

Prediction of Gastric Cancer-Related Proteins Based on Graph Fusion Method

Gastric cancer is a common malignant tumor of the digestive system with no specific symptoms. Due to the limited knowledge of pathogenesis, patients are usually diagnosed in advanced stage and do not have effective treatment methods. Proteome has unique tissue and time specificity and can reflect the influence of external factors that has become a potential biomarker for early diagnosis. Therefore, discovering gastric cancer-related proteins could greatly help researchers design drugs and develop an early diagnosis kit. However, identifying gastric cancer-related proteins by biological experiments is time- and money-consuming. With the high speed increase of data, it has become a hot issue to mine the knowledge of proteomics data on a large scale through computational methods. Based on the hypothesis that the stronger the association between the two proteins, the more likely they are to be associated with the same disease, in this paper, we constructed both disease similarity network and protein interaction network. Then, Graph Convolutional Networks (GCN) was applied to extract topological features of these networks. Finally, Xgboost was used to identify the relationship between proteins and gastric cancer. Results of 10-cross validation experiments show high area under the curve (AUC) (0.85) and area under the precision recall (AUPR) curve (0.76) of our method, which proves the effectiveness of our method.

Clinical Value of Serum Thrombospondin-2 Combined with CA19-9 in Early Diagnosis of Gastric Cancer

Gastric cancer (GC) is a kind of common cancer worldwide. Too late in diagnosis results in poor prognosis of patients with GC. Thrombospondin-2 (THBS2) is a type of secreted protein that has been found to be a diagnostic biomarker in a variety of cancers. Our study aimed to uncover the clinical value of THBS2 in early detection for patients with gastric cancer. THBS2 was upregulated in gastric cancer tissue compared with normal tissue via analyzing data obtained from The Cancer Genome Atlas (TCGA) database. Additionally, the enzyme-linked immunosorbent assay revealed that the level of serum THBS2 and carcinoembryonic antigen, CA19-9, was higher dramatically in patients with early gastric cancer (EGC) than that in healthy control (HC) in addition to patients with benign gastric tumor (BGT), which suggested that THBS2 indeed associated with GC. Receiver operator characteristic (ROC) curve assay was conducted to demonstrate that serum THBS2 was similar to CA19-9 to distinguish patients with early gastric cancer from healthy control and patients with benign gastric tumor and that THBS2 combined with CA19-9 improved the detective performance of THBS2 for early gastric cancer. Furthermore, we applied the gene set enrichment analysis assay to analyze signaling pathways related to THBS2. We found that THBS2 positively controlled MAPK and WNT signaling pathways, which indicated that THBS2 might exert its functions via the pathway mentioned above. Thus, our study expounded that serum THBS2 could serve as a vital early diagnostic marker for patients with gastric cancer.

GARP Correlates With Tumor-Infiltrating T-Cells and Predicts the Outcome of Gastric Cancer

Accepting the crucial role of the immune microenvironment (TME) in tumor progression enables us to identify immunotherapeutic targets and develop new therapies. Glycoprotein A repetitions predominant (GARP) plays a vital part in maintaining regulatory T cell (Treg)-mediated immune tolerance. The impact of GARP in TME of gastric cancer is still worth exploring. We investigated public genomic datasets from The Cancer Genome Atlas and Gene Expression Omnibus to analyze the possible role of GARP and its relationship with TME of gastric cancer. Fluorescence-based multiplex immunohistochemistry and immunohistochemistry for T-cell immune signatures in a series of tissue microarrays were used to validate the value of GARP in the TME. We initially found that GARP expression was upregulated in gastric carcinoma cells, and diverse levels o3f immune cell infiltration and immune checkpoint expression were detected. Gene expression profiling revealed that GARP expression was related to the TME of gastric cancer. GARP upregulation was usually accompanied by increased FOXP3+ Treg and CD4+ T cell infiltration. In addition, GARP expression had positive relationships with CTLA-4 and PD-L1 expression in gastric cancer. Cox regression analysis and a nomogram highlighted that the probability of poor overall survival was predicted well by GARP or GARP+CD4+ T cell. Taken together, this research underlines the potential effect of GARP in regulating survival and tumor-infiltrating T-cells. In addition, the function of CD4+ T cell immune signatures in the prognosis can be clinically meaningful, thereby providing a new idea for the immunotherapeutic approach.

Histone Methyltransferases Useful in Gastric Cancer Research

Gastric cancer (GC) is one of the most frequent tumors in the world. Stomach adenocarcinoma is a heterogeneous tumor, turning the prognosis prediction and patients’ clinical management difficult. Some diagnosis tests for GC are been development using knowledge based in polymorphisms, somatic copy number alteration (SCNA) and aberrant histone methylation. This last event, a posttranslational modification that occurs at the chromatin level, is an important epigenetic alteration seen in several tumors including stomach adenocarcinoma. Histone methyltransferases (HMT) are the proteins responsible for the methylation in specific amino acids residues of histones tails. Here, were presented several HMTs that could be relating to GC process. We use public data from 440 patients with stomach adenocarcinoma. We evaluated the alterations as SCNAs, mutations, and genes expression level of HMTs in these aforementioned samples. As results, it was identified the 10 HMTs most altered (up to 30%) in stomach adenocarcinoma samples, which are the PRDM14, PRDM9, SUV39H2, NSD2, SMYD5, SETDB1, PRDM12, SUV39H1, NSD3, and EHMT2 genes. The PRDM9 gene is among most mutated and amplified HMTs within the data set studied. PRDM14 is downregulated in 79% of the samples and the SUV39H2 gene is down expressed in patients with recurred/progressed disease. Several HMTs are altered in many cancers. It is important to generate a genetic atlas of alterations of cancer-related genes to improve the understanding of tumorigenesis events and to propose novel tools of diagnosis and prognosis for the cancer control.

Impact of the phytochemicals cocktail "breast safeguard" in regulating the interplay between redox signalling and murine adenocarcinoma cell proliferation, survival and angiogenesis

Phytochemicals are natural plant extracts with a potent antioxidant, anti-inflammatory and anticancer characteristics by acting as a cell signalling modulator. This study aims to evaluate the effect of a commercial cocktail of phytochemicals "Breast safeguard" (BSG) in upregulating the expression of antioxidant enzymes to counteract signalling pathways that promote Ehrlich cells progression. The potent antioxidant activity and total phenolics and flavonoids contents of BSG was chemically validated, BSG treated mice showed a significant reduction at the tumor size, along with significant reduction in the expression of prognostic markers CEA and TNFα and induction of cell cycle arrest at G1/S phase as well as downregulation of Ki67. BSG supplementation significantly diminished H2O2, NO, MDA levels and upregulated the expression of SOD, CAT, GPx and GSH antioxidant enzymes in plasma and tumor tissues. BSG treatment markedly activated P53/Bax/Bcl2/c-caspase 3 signalling for cell apoptosis and attenuated the expression of antiapoptotic survivin protein. Meanwhile, BSG significantly diminished the expression of VEGF as an indication of angiogenesis inhibition. In conclusion, BSG exerted a significant upregulation of antioxidant enzymes which may be involved in upregulating P53/Bax/c-caspase 3 expression and attenuation of cell proliferation and angiogenesis.

A novel mechanism driving poor-prognostic gastric cancer: overexpression of the transcription factor Krüppel-like factor 16 promotes growth and metastasis of gastric cancer through regulating the Notch pathway

Gastric cancer (GC) is one of the most common malignant tumors worldwide and has high rates of morbidity and mortality. This study investigated the role of Krüppel-like factor 16 (KLF16) in GC. Real-time polymerase chain reaction, Western blotting, and immunohistochemistry were used to examine the expression of KLF16 in gastric cells and tissues. Gene overexpression and silencing were applied to study the involvement of KLF16 in GC cell growth and metastasis along with its underlying mechanism. The results indicate that KLF16 overexpression is significantly associated with nodal status, distant metastasis, staging, degree of differentiation, vascular invasion, and patient survival. Multivariate Cox proportional hazards regression model analysis revealed that the overexpression of KLF16 is an independent prognostic biomarker of GC. The in vitro study revealed that up-regulated KLF16 accelerates cell growth and metastasis, whereas the inhibition of KLF16 suppresses these cellular activities. The results of an animal study also indicated that the overexpression and silencing of KLF16 accelerate and repress xenograft proliferation and metastasis. Further studies of affected cell growth and metastasis revealed that KLF16 modulates the cell cycle and epithelial-mesenchymal transition through transcriptional regulation of microfibrillar-associated protein 5. Collectively, these results reveal that KLF16 overexpression is a potential prognostic biomarker and therapeutic target for the treatment of GC.

Cytotoxicity and growth-inhibiting activity of Astragalus polysaccharides against breast cancer via the regulation of EGFR and ANXA1

Astragalus polysaccharide (APS) has been frequently used as an adjuvant agent responsible for its immunoregulatory activity to enhance efficacy and reduce toxicity of chemotherapy used in the management of breast cancer. However, the other synergism mechanism of APS remains unclear. This study was performed to evaluate the potential targets and possible mechanism behind APS in vivo direct anti-tumor activity on breast cancer. Multiple biological detections were conducted to investigate the protein and mRNA expression levels of key targets. In total, 116 down-regulated and 73 up-regulated differential expressed genes (DEGs) were examined from 7 gene expression datasets. Top ten hub genes were obtained in four typical protein-protein interaction (PPI) network of DEGs involved in each specific biological process (BP, cell cycle, cell proliferation, cell apoptosis and death) that was related to inhibitory activity of APS in vitro against breast cancer cell lines. Four common DEGs (EGFR, ANXA1, KIF14 and IGF1) were further identified in the above four BP-PPI networks, among which EGFR and ANXA1 were the hub genes that were potentially linked to the progression of breast cancer. The results of biological detections indicated that the expression of EGFR in breast cancer cells was down-regulated, while the expression of ANXA1 was markedly increased in response to APS. In conclusion, the present study may provide potential molecular therapeutic targets and a new insight into the mechanism of APS against breast cancer.

SFRP4 drives invasion in gastric cancer and is an early predictor of recurrence

OBJECTIVE

Gastric cancer patients generally have a poor outcome, particularly those with advanced-stage disease which is defined by the increased invasion of cancer locally and is associated with higher metastatic potential. This study aimed to identify genes that were functional in the most fundamental hallmark of cancer, namely invasion. We then wanted to assess their value as biomarkers of gastric cancer progression and recurrence.

DESIGN

Data from a cohort of patients profiled on cDNA expression arrays was interrogated using K-means analysis. This genomic approach classified the data based on patterns of gene expression allowing the identification of the genes most correlated with the invasion of GC. We evaluated the functional role of a key protein from this analysis in invasion and as a biomarker of recurrence after curative resection.

RESULTS

Expression of secreted frizzled-related protein 4 (SFRP4) was identified as directly proportional to gastric cancer invasion. This finding was validated in multiple, independent datasets and its functional role in invasion was also confirmed using invasion assays. A change in serum levels of SFRP4 after curative resection, when coupled with AJCC stage, can accurately predict the risk of disease recurrence after curative therapy in an assay we termed PredictR.

CONCLUSIONS

This simple ELISA-based assay can help predict recurrence of disease after curative gastric cancer surgery irrespective of adjuvant therapy. The results require further evaluation in a prospective trial but would help in the rational prescription of cancer therapies and surveillance to prevent under or over treatment of patients after curative resection.

Combining Serum DNA Methylation Biomarkers and Protein Tumor Markers Improved Clinical Sensitivity for Early Detection of Colorectal Cancer

Background

Colorectal cancer (CRC) is one of the leading causes of cancer deaths worldwide and in China. Early CRC screening is the best approach to reduce its incidence and mortality rates. The ColoDefense test, a multiplex qPCR assay simultaneously detecting both methylated SEPT9 and SDC2 genes, has demonstrated improved clinical performance on either methylation biomarker alone for CRC screening with both blood and stool samples.

Method

Leftover blood chemistry test samples from 125 CRC, 35 advanced adenoma, and 35 small polyp patients and 92 healthy control subjects were examined by the ColoDefense test. Among these samples, the levels of three circulating tumor markers, CEA, AFP, and CA19-9, were also measured for 106 CRC, 28 advanced adenoma, and 20 small polyp patients and all control subjects.

Results

Due to the smaller volume and extended storage in nonfrozen state, the ColoDefense test with these samples exhibited reduced performance for all stages of CRC and advanced adenomas. The performance of CEA, AFP, and CA19-9 and their various combinations was also evaluated for CRC screening to identify the tumor marker combinations with the best performance. When combined with the ColoDefense test, the identified combinations did improve the clinical performance.

Conclusion

These results suggested a rational path towards developing a CRC screening method that takes advantage of leftover blood chemistry test samples. The successful development of such a method will undoubtedly help promote early CRC screening by increasing its accessibility for the general public.

Identification of LncRNA Prognostic Markers for Ovarian Cancer by Integration of Co-expression and CeRNA Network

Background

Ovarian cancer (OC), one of the most prevalent gynecological malignancies, is characterized by late detection and dismal prognosis. Recent studies show that long non-coding RNAs (lncRNAs) in competitive endogenous RNA (ceRNA) networks influence immune infiltration and cancer prognosis. However, the function of lncRNA in OC immune infiltration and prognosis remains unclear.

Methods

Transcriptomes of 378 OC samples and clinical data were retrieved from the TCGA repository. Modules related to immune cells were identified using weighted gene co-expression network analysis (WGCNA). Functional enrichment analysis and survival analysis were then performed for the identification of immune-related lncRNAs in the brown module using Cox regression model. Finally, a ceRNA network was constructed by using the lncRNAs and mRNAs from the brown module.

Results

We found lncRNAs and mRNAs in the brown module to be significantly associated with immune cells in OC and identified 4 lncRNAs as potential OC prognostic markers. We further established that lncRNAs in the ceRNA network influence OC immune infiltration and prognosis by regulating miRNA, ultimately modulating mRNA levels.

Conclusion

We have identified 4 lncRNAs as independent immune prognostic factors for OC. Furthermore, our findings offer novel insight into lncRNAs as OC immune and prognostic biomarkers.

Sustained Helicobacter pylori infection accelerates gastric dysplasia in a mouse model

More than 80% of gastric cancer is attributable to stomach infection with Helicobacter pylori (Hp). Gastric preneoplastic progression involves sequential tissue changes, including loss of parietal cells, metaplasia and dysplasia. In transgenic mice, active KRAS expression recapitulates these tissue changes in the absence of Hp infection. This model provides an experimental system to investigate additional roles of Hp in preneoplastic progression, beyond its known role in initiating inflammation. Tissue histology, gene expression, the immune cell repertoire, and metaplasia and dysplasia marker expression were assessed in KRAS+ mice +/-Hp infection. Hp+/KRAS+ mice had severe T-cell infiltration and altered macrophage polarization; a different trajectory of metaplasia; more dysplastic glands; and greater proliferation of metaplastic and dysplastic glands. Eradication of Hp with antibiotics, even after onset of metaplasia, prevented or reversed these tissue phenotypes. These results suggest that gastric preneoplastic progression differs between Hp+ and Hp- cases, and that sustained Hp infection can promote the later stages of gastric preneoplastic progression.

Decrease of peripheral blood mucosal-associated invariant T cells and impaired serum Granzyme-B production in patients with gastric cancer

Mucosal-associated invariant T (MAIT) cells are an invariant T cell subset, which have been reported to play an antimicrobial role in infectious diseases. However, little is known about it in malignant diseases and tumors, especially in gastric cancer (GC). So in this study, we aim to examine the frequency, phenotype, partial functional capacity and clinical relevance of this cells from GC patients’ peripheral blood by flow cytometry. It was shown that the frequency of peripheral blood MAIT cells was negatively correlated with their increasing age in healthy adults. Importantly, comparing to the healthy controls (HC), the frequency and the absolute number of MAIT cells from GC patients’ peripheral blood with or without chemotherapy were both significantly lower than those. For the phenotype, the proportion of CD4⁻MAIT cell subset in GC patients without chemotherapy was lower than in HC, but higher than in GC patients with chemotherapy. Whereas, the proportion of CD4⁻CD8⁺MAIT cell subset in GC patients without chemotherapy was significantly lower than that in HC. Finally, the level of Granzyme-B (GrB), a molecule associated with MAIT cells was markedly lower in GC patients. But the correlation between the serum levels of GC-associated tumor antigens and the percentages of MAIT cells in GC patients was not observed. In conclusion, our study shows the decreased frequency, changed phenotypes and partial potentially impaired function of MAIT cells in GC patients, suggesting a possible MAIT cell-based immunological surveillance of GC.

TGFB1 polymorphisms and TGF-β1 plasma levels identify gastric adenocarcinoma patients with lower survival rate and disseminated disease

TGF‐β1 is involved in tumour growth. Four TGFB1 SNPs and TGF‐β1 production by stimulated PBMC were determined in seventy‐eight gastric adenocarcinoma patients. In addition, TGF‐β1 levels were measured in the plasma of further thirty patients. rs1800471‐G/C genotype was prevalent in patients (20.7%) compared to controls (8.4%), as it also was the rs1800468 SNP‐G/A genotype in stage IV patients (20.7%) compared to stage I, II and III patients, combined (10.3%). Conversely, the T/T rs1800469 SNP‐T/T genotype was absent in the former group and present in 19.0% in the latter. Furthermore, the rs1800469‐C/rs1800470‐T (CT) haplotype was found in 15.0% of stage IV patients as compared to 3.0% of the remaining patients (3.0%) and also identifies patients with worse five‐year life expectancy (P = .03). TGF‐β1 synthesis by stimulated PBMCs was significantly lower in patients with the risk SNPs or haplotype, compared to the alternative genotype. Finally, TGF‐β1 plasma levels were lower in patients with worse life expectancy. Analysis of TGFB1 SNPs and measurement of plasma TGF‐β1 levels serves to identify patients at risk of developing a more aggressive disease.

Non-coding RNAs underlying chemoresistance in gastric cancer

BACKGROUND

Gastric cancer (GC) is a major health issue in the Western world. Current clinical imperatives for this disease include the identification of more effective biomarkers to detect GC at early stages and enhance the prevention and treatment of metastatic and chemoresistant GC. The advent of non-coding RNAs (ncRNAs), particularly microRNAs (miRNAs) and long-non coding RNAs (lncRNAs), has led to a better understanding of the mechanisms by which GC cells acquire features of therapy resistance. ncRNAs play critical roles in normal physiology, but their dysregulation has been detected in a variety of cancers, including GC. A subset of ncRNAs is GC-specific, implying their potential application as biomarkers and/or therapeutic targets. Hence, evaluating the specific functions of ncRNAs will help to expand novel treatment options for GC.

CONCLUSIONS

In this review, we summarize some of the well-known ncRNAs that play a role in the development and progression of GC. We also review the application of such ncRNAs in clinical diagnostics and trials as potential biomarkers. Obviously, a deeper understanding of the biology and function of ncRNAs underlying chemoresistance can broaden horizons toward the development of personalized therapy against GC.

An insight into the roles of piRNAs and PIWI proteins in the diagnosis and pathogenesis of oral, esophageal, and gastric cancer

P-Element induced wimpy testis (PIWI)-interacting RNA (piRNA) is a member of the non-coding RNAs family. Four PIWI proteins are found to be expressed in humans. The number of studies focusing on the roles of piRNAs and PIWI proteins in the field of cancer is increasing. Oral, esophageal, and gastric cancers are considered as important causes of death. PIWI proteins and piRNAs are suggested to be involved in the pathogenesis of these diseases. Thus, studying these molecules may be beneficial for finding new therapeutics. Since it is shown that currently used biomarkers for these cancers have low sensitivity and specificity, there is a necessity for identifying novel non-invasive biomarkers which are highly sensitive and specific. This paper will provide an insight into current knowledge about the functions of PIWI proteins and piRNAs in the oral, esophageal, and gastric cancer. We discuss how PIWI proteins and piRNAs can be involved in the pathogenesis of these cancers. Moreover, we review the studies concerning with the roles of PIWI proteins and piRNAs as biomarkers which are used for diagnostic and prognostic purposes.

Aberrant Expression of NCAPG is Associated with Prognosis and Progression of Gastric Cancer

Introduction

Gastric cancer (GC), one of the most prevalent malignancies, is the third-leading cause of cancer-related deaths globally. The aim of this study is to investigate the involvement of non-structural maintenance of chromosomes condensin I complex subunit G (NCAPG) in the prognosis of GC.

Methods

Western blotting and immunostaining were employed to measure the NCAPG level in gastric tissues and cells. Kaplan–Meier analysis was applied to analyze the prognostic value of NCAPG in GC. RNA interference was applied to investigate the influence of the NCAPG silencing on GC cell growth and spread.

Results

NCAPG overexpression was associated with several clinicopathologic characteristics, including nodal status (P = 0.0378), distant metastasis (P = 0.0088), staging (P = 0.0230), vascular invasion (P = 0.0012), and disease-free survival (P = 0.004). Kaplan–Meier analysis revealed that NCAPG overexpression was positively correlated to poor GC patients disease-free and overall survival (P = 0.004 and P < 0.001, respectively). Univariate Cox regression analysis showed that the overexpression of NCAPG was a prognostic biomarker of GC (P = 0.005). In cultured GC cells, the knockdown of NCAPG suppressed cell proliferation, migration and invasion. Meanwhile, further studies revealed that the NCAPG silencing induces the G0/G1 cell cycle arrest and accordingly represses cell division. Finally, Western blotting showed that NCPAG knockdown dysregulated cell cycle- and epithelial–mesenchymal transition-related molecules.

Conclusion

Overall, the results reveal that NCAPG overexpression is a candidate prognostic biomarker and potential therapeutic target in GC.

Identification of a Tumor Microenvironment-relevant Gene set-based Prognostic Signature and Related Therapy Targets in Gastric Cancer

Rationale: The prognosis of gastric cancer (GC) patients is poor, and there is limited therapeutic efficacy due to genetic heterogeneity and difficulty in early-stage screening. Here, we developed and validated an individualized gene set-based prognostic signature for gastric cancer (GPSGC) and further explored survival-related regulatory mechanisms as well as therapeutic targets in GC. Methods: By implementing machine learning, a prognostic model was established based on gastric cancer gene expression datasets from 1699 patients from five independent cohorts with reported full clinical annotations. Analysis of the tumor microenvironment, including stromal and immune subcomponents, cell types, panimmune gene sets, and immunomodulatory genes, was carried out in 834 GC patients from three independent cohorts to explore regulatory survival mechanisms and therapeutic targets related to the GPSGC. To prove the stability and reliability of the GPSGC model and therapeutic targets, multiplex fluorescent immunohistochemistry was conducted with tissue microarrays representing 186 GC patients. Based on multivariate Cox analysis, a nomogram that integrated the GPSGC and other clinical risk factors was constructed with two training cohorts and was verified by two validation cohorts. Results: Through machine learning, we obtained an optimal risk assessment model, the GPSGC, which showed higher accuracy in predicting survival than individual prognostic factors. The impact of the GPSGC score on poor survival of GC patients was probably correlated with the remodeling of stromal components in the tumor microenvironment. Specifically, TGFβ and angiogenesis-related gene sets were significantly associated with the GPSGC risk score and poor outcome. Immunomodulatory gene analysis combined with experimental verification further revealed that TGFβ1 and VEGFB may be developed as potential therapeutic targets of GC patients with poor prognosis according to the GPSGC. Furthermore, we developed a nomogram based on the GPSGC and other clinical variables to predict the 3-year and 5-year overall survival for GC patients, which showed improved prognostic accuracy than clinical characteristics only. Conclusion: As a tumor microenvironment-relevant gene set-based prognostic signature, the GPSGC model provides an effective approach to evaluate GC patient survival outcomes and may prolong overall survival by enabling the selection of individualized targeted therapy.

The impact of DNA demethylation on the upregulation of the NRN1 and TNFAIP3 genes associated with advanced gastric cancer

Gastric cancer (GC) is the third leading cause of cancer-related death worldwide. Very few therapeutic options are currently available in this neoplasia. The use of 5-Aza-2'-deoxycytidine (5-AZAdC) was approved for the treatment of myelodysplastic syndromes, and this drug can treat solid tumours at low doses. Epigenetic manipulation of GC cell lines is a useful tool to better understand gene expression regulatory mechanisms for clinical applications. Therefore, we compared the gene expression profile of 5-AZAdC-treated and untreated GC cell lines by a microarray assay. Among the genes identified in this analysis, we selected NRN1 and TNFAIP3 to be evaluated for gene expression by RT-qPCR and DNA methylation by bisulfite DNA next-generation sequencing in 43 and 52 pairs of GC and adjacent non-neoplastic tissue samples, respectively. We identified 83 candidate genes modulated by DNA methylation in GC cell lines. Increased expression of NRN1 and TNFAIP3 was associated with advanced tumours (P < 0.05). We showed that increased NRN1 and TNFAIP3 expression seems to be regulated by DNA demethylation in GC samples: inverse correlations between the mRNA and DNA methylation levels in the promoter of NRN1 (P < 0.05) and the intron of TNFAIP3 (P < 0.05) were detected. Reduced NRN1 promoter methylation was associated with III/IV TNM stage tumours (P = 0.03) and the presence of Helicobacter pylori infection (P = 0.02). The identification of demethylated activated genes in GC may be useful in clinical practice, stratifying patients who are less likely to benefit from 5-AZAdC-based therapies. KEY MESSAGES: Higher expression of NRN1 and TNFAIP3 is associated with advanced gastric cancer (GC). NRN1 promoter hypomethylation contributes to gene upregulation in advanced GC. TNFAIP3 intronic-specific CpG site demethylation contributes to gene upregulation in GC. These findings may be useful to stratify GC patients who are less likely to benefit from DNA demethylating-based therapies.

Emerging Role of Circulating Tumor Cells in Gastric Cancer

With over 1 million incidence cases and more than 780,000 deaths in 2018, gastric cancer (GC) was ranked as the 5th most common cancer and the 3rd leading cause of cancer deaths worldwide. Though several biomarkers, including carcinoembryonic antigen (CEA), cancer antigen 19-9 (CA19-9), and cancer antigen 72-4 (CA72-4), have been identified, their diagnostic accuracies were modest. Circulating tumor cells (CTCs), cells derived from tumors and present in body fluids, have recently emerged as promising biomarkers, diagnostically and prognostically, of cancers, including GC. In this review, we present the landscape of CTCs from migration, to the presence in circulation, biologic properties, and morphologic heterogeneities. We evaluated clinical implications of CTCs in GC patients, including diagnosis, prognosis, and therapeutic management, as well as their application in immunotherapy. On the one hand, major challenges in using CTCs in GC were analyzed, from the differences of cut-off values of CTC positivity, to techniques used for sampling, storage conditions, and CTC molecular markers, as well as the unavailability of relevant enrichment and detection techniques. On the other hand, we discussed future perspectives of using CTCs in GC management and research, including the use of circulating tumor microembolies; of CTC checkpoint blockade in immunotherapy; and of organoid models. Despite the fact that there are remaining challenges in techniques, CTCs have potential as novel biomarkers and/or a non-invasive method for diagnostics, prognostics, and treatment monitoring of GC, particularly in the era of precision medicine.

Let-7a Could Serve as A Biomarker for Chemo-Responsiveness to Docetaxel in Gastric Cancer

BACKGROUND

MicroRNAs are noncoding RNAs which play critical roles in response to anti-cancer agents. Let-7a and miR-21 are well-known tumor-suppressor and oncomiR miRNAs, respectively. They are involved in tumorigenesis of gastric cancer and have potential to be used as markers in response to the therapy.

OBJECTIVE

We aimed to study alterations in the expression of Let-7a and miR-21, and their targets in gastric cancer cell lines after treatment with docetaxel.

METHODS

In order to determine the IC50 of docetaxel, MTT assay was performed in AGS, MKN45 and KATO III gastric cancer cell lines. The expression levels of Let-7a and miR-21 and their target genes, HMGA2 and PDCD4, were determined by reverse-transcription quantitative real-time PCR for both treated and untreated cell lines.

RESULTS

MTT assay showed higher IC50 concentration of docetaxel in KATO III in comparison with AGS and MKN45, indicating KATO III`s higher resistance to docetaxel. Following the treatment, the expression level of Let-7a was significantly increased in AGS and MKN45, while decreased in KATO III. Expression level of miR- 21 in the three treated cell lines was increased significantly. Not only Let-7a, but also expression level of HMGA2 and PDCD4 genes showed different patterns in KATO III in comparison with AGS and MKN45.

CONCLUSION

Down-regulation and up-regulation of Let-7a in docetaxel-resistant and sensitive cell lines, respectively indicates its potential usefulness as biomarker for responsiveness of gastric cancer to the therapy with docetaxel and also for predicting patient`s outcome.

Nesfatin-1 is a potential diagnostic biomarker for gastric cancer

The lack of reliable plasma biomarkers limits their use in the diagnosis of gastric cancer (GC). The current study aimed to determine whether plasma nesfatin-1 can be used as a novel non-invasive biomarker for the diagnosis of GC. The levels of nesfatin-1 in 40 patients with GC and 40 healthy individuals, who were selected from the Chaohu Hospital Affiliated to Anhui Medical University, were assessed. ELISA was used for the measurement of plasma nesfatin-1 levels, while immunohistochemistry was applied to determine Ki67 protein expression in GC and normal gastric tissues. The diagnostic value of plasma nesfatin-1 for GC was further assessed using receiver operating characteristic (ROC) curve analysis. The results revealed that, compared with the controls, the mean nesfatin-1 levels in patients with GC were significantly increased. Furthermore, the protein expression of Ki67 in GC tissue was significantly upregulated compared with that in normal gastric tissue. Plasma nesfatin-1 levels were also demonstrated to be correlated with Ki67 protein expression in GC tissues. Additionally, ROC curve analysis indicated the potential diagnostic value of nesfatin-1, and the area under the ROC curve (AUC) for nesfatin-1 was 0.857 (95% confidence interval, 0.769-0.946). At a threshold nesfatin-1 level of 1.075 ng/ml, the optimal sensitivity and specificity were 70.0 and 95.0%, respectively, in discriminating patients with GC from healthy controls. These results indicated that plasma nesfatin-1 may serve as a novel biomarker for the diagnosis of GC and determination of GC cell proliferation.

LncRNA PTCSC3 Is a Biomarker for the Treatment and Prognosis of Gastric Cancer

Background: Long noncoding RNA (lncRNA) papillary thyroid carcinoma susceptibility candidate 3 (PTCSC3) inhibits several types of cancer, whereas its role in gastric cancer is unknown. Materials and Methods: From May 2010 to May 2015, this study included 68 (36 males and 32 females, 35-69 years, 48.3 ± 7.1 years) gastric cancer patients and 60 healthy volunteers (32 males and 28 females, 34-67 years, 48.8 ± 6.5 years). Transient transfections, QPCR, CCK-8, transwell cell migration, and invasion assay were used for carrying out the research. Results: The authors found that plasma PTCSC3 was downregulated in gastric cancer patients. Downregulation of PTCSC3 distinguished early stage gastric cancer patients from healthy controls. LncRNA PTCSC3 expression levels were increased on the day of discharge in gastric cancer patients compared with pretreatment levels. During follow-up, patients with low plasma levels of PTCSC3 showed a significantly lower overall survival rate. PTCSC3 negatively regulated proliferation, invasion, and migration of gastric cancer cells. Conclusions: Therefore, lncRNA PTCSC3 may serve as a biomarker for the treatment and prognosis of gastric cancer.

Circular RNA hsa_circ_0006848 Related to Ribosomal Protein L6 Acts as a Novel Biomarker for Early Gastric Cancer

Objective

Circular RNAs (circRNAs) have been reported to be widely involved in pathological processes of various cancers. However, little is known about their diagnostic values in early gastric cancer (EGC). This study is aimed at exploring whether circulating circRNAs in plasma could act as biomarkers for EGC diagnosis.

Materials and Methods

Mass spectrometry (MS) was performed to identify the proteins that at significantly aberrantly levels in gastric cancer (GC) tissues. The target circRNA was identified by bioinformatics analysis. A receiver operating characteristic (ROC) curve was generated to evaluate the diagnostic utility.

Results

MS revealed that the ribosomal protein L6 (RPL6) expression was significantly downregulated only in EGC tissues vs. nontumorous tissues; this was validated by western blotting (n = 30, p = 0.0094). Bioinformatics analysis predicted that there is a hsa_circ_0006848/hsa_miR-329-5p/RPL6 axis in GC progression. The hsa_circ_0006848 expression was significantly downregulated in EGC tissues (vs. nontumorous tissues, n = 30, p = 0.0073) and plasma samples from EGC patients (vs. paired healthy volunteers, n = 30, p = 0.0089). In addition, the hsa_circ_0006848 plasma level in postoperative patients was significantly higher than that of preoperative patients (n = 30, p = 0.047). Furthermore, the decreased hsa_circ_0006848 expression in plasma was negatively correlated with poor differentiation (p = 0.037) and tumor size (p = 0.046). The area under the ROC curve (AUC) of hsa_circ_0006848 in plasma was 0.733, suggesting a good diagnostic value. The plasma hsa_circ_0006848 level combined with the carcinoembryonic antigen (CEA), carbohydrate-associated antigen 19-9 (CA19-9), and carbohydrate-associated antigen 72-4 (CA72-4) level increased the AUC to 0.825.

Conclusion

Our results indicated that plasma hsa_circ_0006848 may be a novel noninvasive biomarker in EGC diagnosis.

Current and future molecular diagnostics of gastric cancer

Introduction: Gastric cancer (GC) is the fifth most common cancer and confers the second-highest mortality among other cancers. Improving the survival rates of GC patients requires prompt and accurate diagnosis and effective treatment which is often preceded by the poorly understood pathogenic mechanisms. Area covered: This literature review aims to summarize current understanding of genetic and molecular alterations that promote carcinogenesis including (1) activation of oncogenes, (2) overexpression of growth factors, receptors and matrix metalloproteinases, (3) inactivation of tumor suppressor genes, DNA repair genes, and cell adhesion molecules and (4) alterations of cell-cycle regulators that regulate biological characteristics of cancer cells. Moreover, the significance of molecular biomarkers such as micro-RNAs (miRNAs) and long non-coding RNAs (lncRNAs) and advanced molecular techniques including droplet digital polymerase chain reaction (ddPCR), quantitative PCR (qPCR) and next-generation sequencing (NGS) are also discussed. Expert opinion: A GC-specific panel of biomarkers based on the NGS or ddPCR has the potential for diagnosis, prognosis, and monitoring treatment response in GC patients. Despite the requirements for validation in larger population in clinical studies, race-specific differences in the gene panel have also to be examined by performing the clinical trials in subjects with different races.

Association and in silico investigations of miR-302c insertion/deletion variant as a novel biomarker with susceptibility to gastric cancer

Gastric cancer (GC) is the fifth most prevalent malignant tumor and the third most frequent cause of cancer mortality worldwide. rs199971565 is an insertion/deletion (INDEL) located in microRNA-302c (miR-302c) seed site, which may affect its function and biogenesis. There is no genetic association study investigating this INDEL with any disease till now. Thus, the current study was conducted to investigate the association of rs199971565 with susceptibility to GC in an Iranian population. In addition, in silico studies were performed to reveal the possible functional significance of this INDEL. A total of 378 subjects were genotyped through amplification refractory mutation system PCR (ARMS-PCR) after DNA extraction from peripheral blood by the salting out procedure. Also, in silico analyses were performed through databases and web tools including MiRNASNP V2.0, miRWalk V2.0, miRTarBase, DAVID V6.8, RNAfold, PHDcleave, miRmap, and STarMir. Results revealed that there was an association between rs199971565 and the incidence risk of GC under a recessive (P = .04, odds ratio [OR] = 18.73; 95% confidence interval [CI] = 1.07-326.95) model of inheritance. Also, compared to the Ins allele, the Del allele significantly increased the risk of GC (P = .01, OR = 2.02; 95% CI = 1.11-3.66). Further analyses showed no significant association in age and sex between two study groups (P = .216 and P = .798, respectively). In conclusion, for the first time, this study indicated the association and in silico investigations of rs199971565 and suggested it as a novel INDEL biomarker located in the seed site of miR-302c, which may have crucial roles in the susceptibility to GC and its incidence risk.

Recent advances in gastric cancer early diagnosis

Gastric cancer (GC) remains an important cause of cancer death worldwide with a high mortality rate due to the fact that the majority of GC cases are diagnosed at an advanced stage when the prognosis is poor and the treatment options are limited. Unfortunately, the existing circulating biomarkers for GC diagnosis and prognosis display low sensitivity and specificity and the GC diagnosis is based only on the invasive procedures such as upper digestive endoscopy. There is a huge need for less invasive or non-invasive tests but also highly specific biomarkers in case of GC. Body fluids such as peripheral blood, urine or saliva, stomach wash/gastric juice could be a source of specific biomarkers, providing important data for screening and diagnosis in GC. This review summarized the recently discovered circulating molecules such as microRNAs, long non-coding RNAs, circular RNAs, which hold the promise to develop new strategies for early diagnosis of GC.

LncRNA GASL1 inhibits tumor growth in gastric carcinoma by inactivating the Wnt/β-catenin signaling pathway

Growth arrest associated lncRNA 1 (GASL1) is a newly discovered tumor suppressor long non-coding RNA (lncRNA) in osteosarcoma; however its role in other malignancies remains unknown. The aim of the present study was to investigate the involvement of GASL1 in gastric cancer. In the current study, gastric cancer tissue and adjacent healthy tissue samples were collected from patients with gastric carcinoma, and blood samples were collected from patients with gastric carcinoma and healthy controls to detect the expression of serum GASL1. All patients were followed up for 5 years and the diagnostic and prognostic value of GASL1 for gastric carcinoma was evaluated by ROC and survival curve analyses, respectively. The chi-square test was used to analyze the correlation between serum levels of GASL1 and the clinicopathological features of patients with gastric carcinoma. A GASL1 expression vector and GASL1 small interfering RNA were transfected into gastric cancer cell lines and the effects on β-catenin expression and cell proliferation were examined by western blot and cell proliferation assays, respectively. The expression level of lncRNA GASL1 was significantly downregulated in gastric cancer tissues compared with adjacent normal tissues from patients with gastric carcinoma. In addition, serum levels of GASL1 were significantly decreased in patients with gastric carcinoma when compared with healthy controls. Serum GASL1 levels distinguished patients with gastric carcinoma from healthy controls, and low expression levels of GASL1 were associated with decreased postoperative survival time. GASL1 overexpression downregulated, while GASL1 knockdown upregulated β-catenin expression. GASL1 overexpression inhibited, and GASL1 knockdown promoted gastric cancer cell proliferation. In addition, treatment with a Wnt agonist demonstrated no significant effect on GASL1 expression, however the inhibitory effect of GASL1 overexpression on cell proliferation was reduced following treatment with the Wnt agonist. In conclusion, the GASL1 lncRNA may inhibit tumor growth in patients with gastric carcinoma by inactivating the Wnt/β-catenin signaling pathway.

Role of histone acetylation in gastric cancer: implications of dietetic compounds and clinical perspectives

Histone modifications regulate the structural status of chromatin and thereby influence the transcriptional status of genes. These processes are controlled by the recruitment of different enzymes to a specific genomic site. Furthermore, obtaining an understanding of these mechanisms could help delineate alternative treatment and preventive strategies for cancer. For example, in gastric cancer, cholecalciferol, curcumin, resveratrol, quercetin, garcinol and sodium butyrate are natural regulators of acetylation and deacetylation enzyme activity that exert chemopreventive and anticancer effects. Here, we review the recent findings on histone acetylation in gastric cancer and discuss the effects of nutrients and bioactive compounds on histone acetylation and their potential role in the prevention and treatment of this type of cancer.

Diagnostic value of apolipoprotein C-I, transthyretin and apolipoprotein C-III in gastric cancer

Diagnostic value of apolipoprotein C-I (ApoC-I), transthyretin (TTR) and ApoC-III in gastric cancer were evaluated. Retrospective analysis methods were used to collect 60 patients with gastric cancer first diagnosed in The First Affiliated Hospital of Jiaxing University. There were 60 patients with chronic atrophic gastritis in the benign lesion group and 60 healthy individuals in the control group. The expression levels of serum ApoC-I, TTR and ApoC-III was detected by enzyme-linked immunosorbent assay. Differences existed in the expression levels of ApoC-I, TTR and ApoC-III in the gastric cancer group, benign lesion group and control group (P<0.001), with the expression levels of ApoC-I, TTR and ApoC-III in the gastric cancer group being lower than that of the benign lesion group (P<0.05), and the expression levels of ApoC-I, TTR and ApoC-III in the benign lesion group being lower than that of the control group (P<0.05). The expression levels of ApoC-I, TTR and ApoC-III in the gastric cancer group were to a certain degree correlated with the clinical stage, lymph node metastasis and differentiation of patients in the gastric cancer group (P<0.05). The specificity and negative predictive value of combined detection were proven to be higher than the separate detection of the three factors (P<0.05). The detection of serum ApoC-I, TTR and ApoC-III was of great significance in the diagnosis of gastric cancer and the estimation of its severity. The method of combined detection is worth a further in-depth study as it could improve the specificity of diagnosis and have a higher negative predictive value.

Traps and trumps from adjacent-to-tumor samples in gastric cancer research

The search for cancer biomarkers is frequently based on comparisons between tumors and adjacent-to-tumor samples. However, even after histological confirmation of been free of cancer cells, these adjacent-to-tumor samples might harbor molecular alterations which are not sufficient to cause them to look like cancer, but can differentiate these cells from normal cells. When comparing them, potential biomarkers are missed, and mainly the opportunity of finding initial aberrations presents in both tumors and adjacent samples, but not in true normal samples from non-cancer patients, resulting in misinterpretations about the carcinogenic process. Nevertheless, collecting adjacent-to-tumor samples brings trumps to be explored. The addition of samples from non-cancer patients opens an opportunity to increase the finds of the molecular cascade of events in the carcinogenic process. Differences between normal samples and adjacent samples might represent the first steps of the carcinogenic process. Adding samples of non-cancer patients to the analysis of molecular alterations relevant to the carcinogenic process opens a new window of opportunities to the discovery of cancer biomarkers and molecular targets.

SERUM CYTOKINE OF IL-2, IL-10 AND IL-12 LEVELS IN PATIENTS WITH STOMACH ADENOCARCINOMA

ABSTRACT BACKGROUND: Gastric adenocarcinoma is the fourth most common cause of cancer-associated death worldwide. OBJECTIVE: We evaluated the immunological status of patients with gastric cancer before surgery and circulating cytokines as potential diagnostic biomarkers for gastric cancer. METHODS: We included 90 healthy controls and 95 patients with distal Gastric adenocarcinoma in Mazandaran, Sari, Iran. We measured serum IL-2, IL-10 and IL-12 Levels by a sandwich enzyme-linked immunosorbent assay using the IBL international GMBH kit. RESULTS: The serum IL-10 levels in the patients with Gastric adenocarcinoma were significantly higher than those of the healthy controls (P=0.02). There were no significant differences in serum IL-2 and IL-12 levels between patients with gastric cancer and healthy controls. CONCLUSION: Increased levels of IL-10 might be useful as diagnostic biomarkers for Gastric adenocarcinoma; however, this needs to be confirmed with larger number of patients and with control groups other than blood donors, properly age paired. These results suggest that positive expression of IL-10 may be useful as a molecular marker to distinguish stage of gastric cancers which can be more readily controlled.

Novel prognostic biomarkers of gastric cancer based on gene expression microarray: COL12A1, GSTA3, FGA and FGG

Gastric cancer (GC) is the fifth most common malignancy and the third leading cause of cancer-associated mortality in the world. However, its mechanisms of occurrence and development have not been clearly elucidated. Furthermore, there is no effective tumor marker for GC. Using DNA microarray analysis, the present study revealed genetic alterations, screened out core genes as novel markers and discovered pathways for potential therapeutic targets. Differentially expressed genes (DEGs) between GC and adjacent normal tissues were identified, followed by pathway enrichment analysis of DEGs. Next, the protein-protein interaction (PPI) network of DEGs was built and visualized. Analyses of modules in the PPI network were then performed to identify the functional core genes. Finally, survival analysis of core genes was conducted. A total of 256 genes were identified as DEGs between the GC samples and normal samples, including 169 downregulated and 87 upregulated genes. Through Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis, the present study identified a total of 143 GO terms and 21 pathways. Six clusters of functional modules were identified, and the genes associated with these modules were screened out as the functional core genes. Certain core genes, including collagen type 12 α1 chain (COL12A1), glutathione S-transferase α3 (GSTA3), fibrinogen α chain (FGA) and fibrinogen γ chain (FGG), were the first reported to be associated with GC. Survival analysis suggested that these four genes, COL12A1 (P=0.002), GSTA3 (P=3.4×10⁻⁶), FGA (P=0.00075) and FGG (P=1.4×10-5), were significant poor prognostic factors and therefore, potential targets to improve diagnosis, optimize chemotherapy and predict prognostic outcomes.

The expansion of targetable biomarkers for CAR T cell therapy

Biomarkers are an integral part of cancer management due to their use in risk assessment, screening, differential diagnosis, prognosis, prediction of response to treatment, and monitoring progress of disease. Recently, with the advent of Chimeric Antigen Receptor (CAR) T cell therapy, a new category of targetable biomarkers has emerged. These biomarkers are associated with the surface of malignant cells and serve as targets for directing cytotoxic T cells. The first biomarker target used for CAR T cell therapy was CD19, a B cell marker expressed highly on malignant B cells. With the success of CD19, the last decade has shown an explosion of new targetable biomarkers on a range of human malignancies. These surface targets have made it possible to provide directed, specific therapy that reduces healthy tissue destruction and preserves the patient's immune system during treatment. As of May 2018, there are over 100 clinical trials underway that target over 25 different surface biomarkers in almost every human tissue. This expansion has led to not only promising results in terms of patient outcome, but has also led to an exponential growth in the investigation of new biomarkers that could potentially be utilized in CAR T cell therapy for treating patients. In this review, we discuss the biomarkers currently under investigation and point out several promising biomarkers in the preclinical stage of development that may be useful as targets.

HER2 Positive Gastric Carcinomas and Their Clinico-Pathological Characteristics

BACKGROUND:

HER2 protein expression in gastric carcinoma, in correlation with existing, acknowledged prognostic factors which include the parameters that determine the TNM stage of the disease, could become the basis for ongoing research in the field of molecular targeted and personalised therapy.

AIM:

To determine the expression of the HER2 protein in gastric carcinoma and to correlate the expression of a HER2 protein with clinicopathological characteristics of the disease.

MATERIAL AND METHODS:

The data of HER2 protein expression and the parameters of the TNM classification were obtained from the histopathological reports of the Institute of Pathology in Skopje, and for the clinical stage we used patient’s files from the University Clinic for Abdominal Surgery in Skopje.

RESULTS:

The analysis of the correlation of HER2 protein expression and TNM classification parameters pointed out a significant correlation between HER2 protein expression and intragastric localisation of gastric carcinoma (P = 0.005), and the tumour grade of differentiation (P = 0.034). There was also a positive correlation between HER2 protein expression pattern and positive lymph nodes in patients with gastric carcinoma (P = 0.03). The expression pattern of HER2 +++ was significantly more common registered in patients with positive lymph nodes (P = 0.03)

CONCLUSION:

The expression of HER2 protein could represent a biological marker with prognostic and predictive value in patients with gastric carcinoma. Considering the high mortality rate in patients with gastric carcinoma and lack of international standardised therapeutic approach, research of the role and significance of HER2 overexpression and Trastuzumab therapy may prove useful in the development of new therapeutic strategies.

Loss of cyclin-dependent kinase-like 2 predicts poor prognosis in gastric cancer, and its overexpression suppresses cells growth and invasion

Cyclin-dependent kinase-like 2 (CDKL2), a new member of the cyclin-dependent kinase family, may be involved in gastric cancer (GC) progression. Thus, we conducted this study to explore the clinical effect of CDKL2 in GC. Immunohistochemistry was used to measure CDKL2 levels in gastric tissues. The association of a high CDKL2 level with clinical and pathological characteristics, and the correlation between the CDKL2 level and disease-free and overall survival were analyzed. Transfection was employed to overexpress CDKL2 in GC cells and to investigate the effect of CDKL2 overexpression on cell proliferation and invasion. Loss of CDKL2 was positively correlated with several clinical and pathological characteristics, and patients with a low CDKL2 level had significantly poorer disease-free and overall survival than those with a high level (P = .005 and .001, respectively). Univariate analysis using the Cox proportional hazards model indicated that a low CDKL2 level was a prognosticator for inferior disease-free survival (P = .007). Based on immmunoblotting data, AGS and HGC-27 GC cells were chosen for CDKL2 overexpression. Cellular studies revealed that CDKL2 overexpression impaired cell proliferation and invasion. Loss of CDKL2 may serve as a biomarker for predicting GC patient outcomes and a potential therapeutic target for GC treatment.

Narrow line between benefit and harm: Additivity of hyperthermia to cisplatin cytotoxicity in different gastrointestinal cancer cells

AIM

To investigate the response to hyperthermia and chemotherapy, analyzing apoptosis, cytotoxicity, and cisplatin concentration in different digestive system cancer cells.

METHODS

AGS (gastric cancer cell line), Caco-2 (colon cancer cell line) and T3M4 (pancreatic cancer cell line) were treated by cisplatin and different temperature setting (37 °C to 45 °C) either in isolation, or in combination. Treatment lasted for one hour. 48 h after the treatment viability was evaluated by MTT, cell apoptosis by Annexin V-PE and 7ADD flow cytometry. Intracellular cisplatin concentration was measured immediately after the treatment, using mass spectrometry. Isobologram analysis was performed to evaluate the mathematical combined effect of temperature and cisplatin.

RESULTS

AGS cells were the most sensitive to isolated application of hyperthermia. Hyperthermia, in addition to cisplatin treatment, did not provoke a synergistic effect at intervals from 37 °C to 41 °C in neither cancer cell line. However, a temperature of 43 °C enhanced cisplatin cytotoxicity for Caco-2 cells. Moreover, isobologram analysis revealed mathematical antagonistic effects of cisplatin and temperature combined treatment in AGS cells; variations between synergistic, additive, and antagonistic effects in Caco-2 cells; and additive and antagonistic effects in T3M4 cells. Combined treatment enhanced initiation of cell apoptosis in AGS, Caco-2, and T3M4 cells by 61%, 20%, and 19% respectively. The increase of intracellular cisplatin concentration was observed at 43 °C by 30%, 20%, and 18% in AGS, Caco-2, and T3M4 cells, respectively.

CONCLUSION

In addition to cisplatin, hyperthermia up to 43 °C does not affect the viability of cancer cells in a synergistic manner.

Adjuvant chemoradiation for gastric carcinoma: State of the art and perspectives

An estimated 990,000 new cases of gastric cancer are diagnosed worldwide each year. Surgical excision, the only chance for prolonged survival, is feasible in about 20% of cases. Even after surgery, the median survival is limited to 12 to 20 months due to the frequency of locoregional and/or metastatic recurrences. This led to clinical trials associating surgery with neoadjuvant or adjuvant treatments to improve tumor control and patient survival. The most studied modalities are perioperative chemotherapy and adjuvant chemoradiotherapy. To date, evidence has shown a survival benefit for postoperative chemoradiotherapy and for perioperative chemotherapy. Phase III trials are ongoing to compare these two modalities. The aim of this review is to synthesize current knowledge about adjuvant chemoradiotherapy in the management of gastric adenocarcinoma, and to consider its prospects by integrating modern radiotherapy techniques.

LINE-1 hypomethylation is inversely correlated with UHRF1 overexpression in gastric cancer

DNA methylation is an important epigenetic modification that alters gene expression; DNA hypomethylation contributes to tumorigenesis through multiple processes. In the present study, the methylation of long interspersed element-1 (LINE-1) in 95 gastric cancer (GC) tissues and matched adjacent normal tissues was investigated by pyrosequencing. LINE-1 methylation was compared with the expression of ubiquitin-like with PHD and ring-finger protein 1 (UHRF1), an essential regulator of DNA methylation, using reverse transcription-quantitative polymerase chain reaction. Significant hypomethylation of LINE-1 and overexpression of UHRF1 were observed in GC tissues compared with the matched controls (P<0.001 and P=0.001, respectively). LINE-1 hypomethylation was inversely correlated with UHRF1 overexpression in GC tissues (r=-0.026, P=0.028). In addition, LINE-1 hypomethylation in GC was significantly associated with Lauren's histological classification, tumor differentiation and background intestinal metaplasia (P=0.014, P=0.042 and P=0.034, respectively). These results suggest that LINE-1 hypomethylation may be a potential biomarker for GC and it is indirectly regulated by UHRF1 overexpression.

Cancer sniffer dogs: how can we translate this peculiarity in laboratory medicine? Results of a pilot study on gastrointestinal cancers

BACKGROUND

Identification of cancer biomarkers to allow early diagnosis is an urgent need for many types of tumors, whose prognosis strongly depends on the stage of the disease. Canine olfactory testing for detecting cancer is an emerging field of investigation. As an alternative, here we propose to use GC-Olfactometry (GC/O), which enables the speeding up of targeted biomarker identification and analysis. A pilot study was conducted in order to determine odor-active compounds in urine that discriminate patients with gastrointestinal cancers from control samples (healthy people).

METHODS

Headspace solid phase microextraction (HS-SPME)-GC/MS and GC-olfactometry (GC/O) analysis were performed on urine samples obtained from gastrointestinal cancer patients and healthy controls.

RESULTS

In total, 91 key odor-active compounds were found in the urine samples. Although no odor-active biomarkers present were found in cancer carrier's urine, significant differences were discovered in the odor activities of 11 compounds in the urine of healthy and diseased people. Seven of above mentioned compounds were identified: thiophene, 2-methoxythiophene, dimethyl disulphide, 3-methyl-2-pentanone, 4-(or 5-)methyl-3-hexanone, 4-ethyl guaiacol and phenylacetic acid. The other four compounds remained unknown.

CONCLUSIONS

GC/O has a big potential to identify compounds not detectable using untargeted GC/MS approach. This paves the way for further research aimed at improving and validating the performance of this technique so that the identified cancer-associated compounds may be introduced as biomarkers in clinical practice to support early cancer diagnosis.

Diagnostic and prognostic value of CEA, CA19-9, AFP and CA125 for early gastric cancer

Background

The diagnostic and prognostic significance of carcinoembryonic antigen (CEA), carbohydrate associated antigen 19–9 (CA19–9), alpha-fetoprotein (AFP) and cancer antigen 125 (CA125) in early gastric cancer have not been investigated yet. Thus, the present study aimed to explore the diagnostic and prognostic significance of the four tumor markers for early gastric cancer.

Methods

From September 2008 to March 2015, 587 early gastric cancer patients were given radical gastrectomy in our center. The clinicopathological characteristics were recorded. The association between levels of CEA and CA19–9 and clinicopathological characteristics and prognosis of patients were analyzed.

Results

There were 444 men (75.6%) and 143 women (24.4%). The median age was 57 years (ranged 21–85). The 1-, 3- and 5-year overall survival rate was 99.1%, 96.8% and 93.1%, respectively. The positive rate of CEA, CA19–9, AFP and CA125 was 4.3%, 4.8%, 1.5% and 1.9%, respectively. The positive rate of all markers combined was 10.4%. The associations between the clinicopathological features and levels of CEA and CA19–9 were analyzed. No significant association was found between CEA level and clinicopathological features. However, elevated CA19–9 level was correlated with female gender and presence of lymph node metastasis. Age > 60 years old, presence of lymph node metastasis and elevation of CEA level were independent risk factors for poor prognosis of early gastric cancer.

Conclusions

The positive rates of CEA, CA19–9, APF and CA125 were relatively low for early gastric cancer. Elevation of CA19–9 level was associated with female gender and presence of lymph node metastasis. Elevation of CEA level was an independent risk factor for the poor prognosis of early gastric cancer.