Gastric cancer: Basic aspects

Long Non-Coding RNAs in Drug Resistance of Gastric Cancer: Complex Mechanisms and Potential Clinical Applications

Gastric cancer (GC) ranks as the third most prevalent malignancy and a leading cause of cancer-related mortality worldwide. However, the majority of patients with GC are diagnosed at an advanced stage, highlighting the urgent need for effective perioperative and postoperative chemotherapy to prevent relapse and metastasis. The current treatment strategies have limited overall efficacy because of intrinsic or acquired drug resistance. Recent evidence suggests that dysregulated long non-coding RNAs (lncRNAs) play a significant role in mediating drug resistance in GC. Therefore, there is an imperative to explore novel molecular mechanisms underlying drug resistance in order to overcome this challenging issue. With advancements in deep transcriptome sequencing technology, lncRNAs-once considered transcriptional noise-have garnered widespread attention as potential regulators of carcinogenesis, including tumor cell proliferation, metastasis, and sensitivity to chemo- or radiotherapy through multiple regulatory mechanisms. In light of these findings, we aim to review the mechanisms by which lncRNAs contribute to drug therapy resistance in GC with the goal of providing new insights and breakthroughs toward overcoming this formidable obstacle.

RAE1 promotes gastric carcinogenesis and epithelial-mesenchymal transition

AIMS

The purpose of this study was to explore the role of RAE1 in the invasion and metastasis of gastric cancer (GC) cells.

MATERIALS AND METHODS

RAE1 expression in GC cells was determined by reverse-transcription polymerase chain reaction (qRT-PCR) and Western blotting (WB). Cell models featuring RAE1 gene silencing and overexpression were constructed by lentiviral transfection; The proliferation, migration, and invasion ability of cells were detected by cell counting, colony formation assay, would healing assay, and transwell invasion and migration test. WB analysis of ERK/MAPK signaling pathway (ERK1/2, p-ERK1/2, c-Myc) and EMT-related molecules (ZEB1, E-cadherin, N-cadherin, and Vimentin).

RESULTS

The expression level of RAE1 in GC was notably higher than in adjacent tissues. Elevated RAE1 expression correlated with an unfavorable prognosis for GC patients. Knockdown of RAE1, as compared to the control group, resulted in a significant inhibition of proliferation, migration, and invasion abilities in GC cell lines. Furthermore, RAE1 knockdown led to a substantial decrease in the expression of N-cadherin, vimentin, ZEB1, p-ERK1/2, and c-Myc proteins, coupled with a marked increase in E-cadherin expression. The biological effects of RAE1 in GC cells were effectively reversed by the inhibition of the ERK/MAPK signaling pathway using SCH772984. Additionally, RAE1 knockdown demonstrated a suppressive effect on GC tumor size in vivo. Immunohistochemistry (IHC) results revealed significantly lower expression of Ki-67 in RAE1 knockout mice compared to the control group.

CONCLUSIONS

RAE1 promotes GC cell migration and invasion through the ERK/MAPK pathway and is a potential therapeutic target for GC therapy.

CircNRD1 elevates THAP domain containing 11 through sequestering microRNA-421 to inhibit gastric cancer growth and tumorigenesis

We explored the role and mechanism of circular RNAcircNRD1 in gastric cancer (GC) progression, aiming to identify new bio-markers for the treatment and prognosis of GC patients. The RNA expression was examined by reverse transcription-quantitative polymerase chain reaction. Cell proliferation, migration and invasion were analyzed by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, 5-ethynyl-2'-deoxyuridine (EdU) incorporation assay, scratch assay and transwell assay. Western blot assay was conducted for protein expression measurement. Dual-luciferase reporter, RNA immunoprecipitation, and RNA pull-down assays were conducted to verify the interaction between microRNA-421 (miR-421) and circNRD1 or THAP domain containing 11 (THAP11). Xenograft tumor model was established to perform in vivo experiments. CircNRD1 was notably downregulated in GC tissues and cell lines. Additionally, decreased circNRD1 level was closely associated with advanced tumor stage and dismal prognosis in GC patients. CircNRD1 overexpression suppressed the proliferation and metastasis of GC cells. CircNRD1 acted as a molecular sponge for miR-421 in GC cells, and the antitumor impacts of circNRD1 overexpression in GC cells could be alleviated by miR-421 overexpression. miR-421 directly targeted THAP11, and circNRD1 could up-regulate THAP11 expression in GC cells through sponging miR-421. THAP11 knockdown reversed circNRD1 overexpression-induced tumor suppressing effects in GC cells. CircNRD1 overexpression significantly blocked tumor growth in vivo. CircNRD1 suppressed the proliferation and metastasis of GC cells in vitro and blocked tumor growth in vivo via modulating miR-421/THAP11 axis.

Extraction, Characterization, and Evaluation of the Cytotoxic Activity of Piperine in Its Isolated form and in Combination with Chemotherapeutics against Gastric Cancer

Gastric cancer is one of the most frequent types of neoplasms worldwide, usually presenting as aggressive and difficult-to-manage tumors. The search for new structures with anticancer potential encompasses a vast research field in which natural products arise as promising alternatives. In this scenario, piperine, an alkaloid of the Piper species, has received attention due to its biological activity, including anticancer attributes. The present work proposes three heating-independent, reliable, low-cost, and selective methods for obtaining piperine from Piper nigrum L. (Black pepper). Electronic (SEM) and optical microscopies, X-ray diffraction, nuclear magnetic resonance spectroscopies (¹³C and ¹H NMR), and optical spectroscopies (UV-Vis, photoluminescence, and FTIR) confirm the obtention of piperine crystals. The MTT assay reveals that the piperine samples exhibit good cytotoxic activity against primary and metastasis models of gastric cancer cell lines from the Brazilian Amazon. The samples showed selective cytotoxicity on the evaluated models, revealing higher effectiveness in cells bearing a higher degree of aggressiveness. Moreover, the investigated piperine crystals demonstrated the ability to act as a good cytotoxicity enhancer when combined with traditional chemotherapeutics (5-FU and GEM), allowing the drugs to achieve the same cytotoxic effect in cells employing lower concentrations. These results establish piperine as a promising molecule for therapy investigations in aggressive gastric cancer, both in its isolated form or as a bioenhancer.

Novel prognostic indicator combining inflammatory indicators and tumor markers for gastric cancer

BACKGROUND

Gastric cancer (GC) is one of the most common malignant tumors worldwide, and we hope to identify an economical but practical prognostic indicator. It has been reported that inflammatory indicators and tumor markers are associated with GC progression and are widely used to predict prognosis. However, existing prognostic models do not comprehensively analyze these predictors.

METHODS

This study retrospectively reviewed 893 consecutive patients who underwent curative gastrectomy from January 1, 2012, to December 31, 2015, in the Second Hospital of Anhui Medical University. Prognostic factors predicting overall survival (OS) were analyzed using univariate and multivariate Cox regression analyses. Nomograms including independent prognostic factors were plotted for predicting survival.

RESULTS

Ultimately, 425 patients were enrolled in this study. Multivariate analyses demonstrated that the neutrophil-to-lymphocyte ratio (NLR, total neutrophil count/lymphocyte count × 100%) and CA19-9 were independent prognostic factors for OS (p=0.001, p=0.016). The NLR-CA19-9 score (NCS) is constructed as the combination of the NLR and CA19-9. We defined NLR<2.46 and CA19-9≤37 U/ml as an NCS of 0, NLR≥2.46 or CA19-9>37 U/ml as an NCS 1, and NLR≥2.46 and CA19-9>37 U/ml as an NCS of 2. The results showed that higher NCS was significantly associated with worse clinicopathological characteristics and OS (p<0.05). Multivariate analyses revealed that the NCS was an independent prognostic factor for OS (NCS1: p<0.001, HR=3.172, 95% CI=2.120-4.745; NCS2: p<0.001, HR=3.052, 95% CI=1.928-4.832). Compared with traditional predictive indices, the NCS had the highest AUC for a 12-month survival, a 36-month survival, a 60-month survival, and OS (AUC= 0.654, 0.730, 0.811, 0.803, respectively). The nomogram had a higher Harrell's C-index than the TNM stage alone (0.788 vs. 0.743).

CONCLUSIONS

The NCS provides more accurate predictions of the prognosis of GC patients, and its predictive value is significantly better than that of traditional inflammatory indicators or tumor markers. It is an effective complement to existing GC assessment systems.

Girdin acts as an oncogene in gastric cancer by regulating AKT/GSK3β/β-catenin signaling

ThE present work focused on exploring Girdin expression within gastric cancer (GC), examining the effect of Girdin on the cell phenotype of GC, and clarifying the underlying mechanisms. Girdin expression in GC samples was identified by immunohistochemistry (IHC) and quantitative real-time PCR (qRT-PCR) assays. Girdin-targeting siRNAs were transfected into GC cells; later, we examined GC cell proliferation, migration, invasion, and apoptosis, respectively. Additionally, the protein expression was examined through Western blotting assay. Moreover, the tumor implantation experiment was conducted for examining Girdin knockdown in vivo. The results showed that Girdin expression elevated within GC samples, which was associated with the dismal prognostic outcome. Girdin knockdown suppressed GC cell proliferation, migration, and invasion, and enhanced apoptosis and cell cycle arrest. Girdin promoted the phosphorylation of AKT, GSK3β, and β-catenin. Moreover, Girdin inhibited the phosphorylation of β-catenin. Girdin suppressed cell apoptosis and stimulated cell migration and invasion, while AKT inhibitor (MK2206) treatment reversed the effect of Girdin overexpression, and GSK3β inhibitor (CHIR99021) treatment enhanced the effect of Girdin overexpression on GC cells. Besides, Girdin delayed tumor growth in vivo. In conclusion, Girdin was abnormally expressed in GC samples, which promoted the development of GC by regulating AKT/GSK3β/β-catenin signaling.

A novel signature based on CeRNA and immune status predicts prognostic risk and drug sensitivity in gastric cancer patients

Background

At present, there is increasing evidence that both competitive endogenous RNAs (ceRNAs) and immune status in the tumor microenvironment (TME) can affect the progression of gastric cancer (GC), and are closely related to the prognosis of patients. However, few studies have linked the two to jointly determine the prognosis of patients with GC. This study aimed to develop a combined prognostic model based on ceRNAs and immune biomarkers.

Methods

First, the gene expression profiles and clinical information were downloaded from TCGA and GEO databases. Then two ceRNA networks were constructed on the basis of circRNA. Afterwards, the key genes were screened by univariate Cox regression analysis and Lasso regression analysis, and the ceRNA-related prognostic model was constructed by multivariate Cox regression analysis. Next, CIBERSORT and ESTIMATE algorithms were utilized to obtain the immune cell infiltration abundance and stromal/immune score in TME. Furthermore, the correlation between ceRNAs and immunity was found out through co-expression analysis, and another immune-related prognosis model was established. Finally, combining these two models, a comprehensive prognostic model was built and visualized with a nomogram.

Results

The (circRNA, lncRNA)-miRNA-mRNA regulatory network of GC was constructed. The predictive power of ceRNA-related and immune-related prognosis models was moderate. Co-expression analysis showed that the ceRNA network was correlated with immunity. The integrated model of combined ceRNAs and immunity in the TCGA training set, the AUC values of 1, 3, and 5-year survival rates were 0.78, 0.76, and 0.78, respectively; in the independent external validation set GSE62254, they were 0.81, 0.79, and 0.78 respectively; in GSE15459, they were 0.84, 0.88 and 0.89 respectively. Besides, the prognostic score of the comprehensive model can predict chemotherapeutic drug resistance. Moreover, we found that plasma variant translocation 1 (PVT1) and infiltrating immune cells (mast cells) are worthy of further investigation as independent prognostic factors.

Conclusions

Two ceRNA regulatory networks were constructed based on circRNA. At the same time, a comprehensive prognosis model was established, which has a high clinical significance for prognosis prediction and chemotherapy drug selection of GC patients.

A DCS-related lncRNA signature predicts the prognosis and chemotherapeutic response of patients with gastric cancer

The combination of docetaxel, cisplatin, and S-1 (DCS) is a common chemotherapy regimen for patients with gastric cancer (GC). However, studies on long noncoding RNAs (lncRNAs) associated with the chemotherapeutic response to and prognosis after DCS remain lacking. The aim of the present study was to identify DCS mRNAs-lncRNAs associated with chemotherapy response and prognosis in GC patients. In the present study, we identified 548 lncRNAs associated with these 16 mRNAs in the TCGA and GSE31811 datasets. Eleven lncRNAs were used to construct a prognostic signature by least absolute shrinkage and selection operator (LASSO) regression. A model including the 11 lncRNAs (LINC02532, AC007277.1, AC005324.4, AL512506.1, AC068790.7, AC022509.2, AC113139.1, LINC00106, AC005165.1, MIR100HG, and UBE2R2-AS1) associated with the prognosis of GC was constructed. The signature was validated in the TCGA database, model comparison, and qRT-PCR experiments. The results showed that the risk signature was a more effective prognostic factor for GC patients. Furthermore, the results showed that this model can well predicting chemotherapy drug response and immune infiltration of GC patients. In addition, our experimental results indicated that lower expression levels of LINC00106 and UBE2R2-AS1 predicted worse drug resistance in AGS/DDP cells. The experimental results agreed with the predictions. Furthermore, knockdown of LINC00106 or UBE2R2-AS1 can significantly enhanced the proliferation and migration of GC AGS cells in vitro. In conclusion, a novel DCS therapy-related lncRNA signature may become a new strategy to predict chemotherapy response and prognosis in GC patients. LINC00106 and UBE2R2-AS1 may exhibit a tumor suppressive function in GC.

Proteomics and Metabolomics Unveil Codonopsis pilosula (Franch.) Nannf. Ameliorates Gastric Precancerous Lesions via Regulating Energy Metabolism

Objective: This study aimed to systematically evaluate the efficacy of Codonopsis pilosula (Franch.) Nannf. (Codonopsis Radix, CR) and reveal the mechanism of its effects on suppressing Gastric Precancerous Lesions. Methods: First, we established the GPL rat model which was induced by N-methyl-N'-nitro-N-nitrosoguanidine, a disordered diet, and 40% ethanol. The CR's anti-Gastric Precancerous Lesions effect was comprehensively evaluated by body weight, pathological section, and serum biochemical indexes. Then, quantitative proteomics and metabolomics were conducted to unveil the disturbed protein-network and pharmacodynamic mechanism. Furthermore, serum pharmacology was employed to confirm that CR's anti-gastritis and anti-cancer phenotype in cell models. Results: In animal models, CR had been shown to control inflammation and ameliorate Gastric Precancerous Lesions. Considering the combination of proteomics and metabolomics, we found that CR could significantly reverse the biological pathways related to energy metabolism which were disturbed by the Gastric Precancerous Lesions model. Furthermore, the results of serum pharmacology indicated that the Codonopsis Radix containing serum could ameliorate gastritis injury and selectively inhibit the proliferation of gastric cancer cells rather than normal cells, which was closely related to ATP production in the above mentioned cells. Conclusion: In summary, CR exerted anti-Gastric Precancerous Lesions effects by ameliorating gastritis injury and selectively inhibiting the proliferation of gastric cancer cells rather than normal cells. Proteomics and metabolomics unveiled that its efficacy was closely related to its regulation of the energy-metabolism pathway. This research not only provided new ideas for exploring the mechanism of complex systems such as Chinese herbals but also benefited the treatment strategy of Gastric Precancerous Lesions via regulating energy metabolism.

Engagement of CEACAM1 by Helicobacterpylori HopQ Is Important for the Activation of Non-Canonical NF-κB in Gastric Epithelial Cells

The gastric pathogen Helicobacter pylori infects half of the world's population and is a major risk factor for gastric cancer development. In order to attach to human gastric epithelial cells and inject the oncoprotein CagA into host cells, H. pylori utilizes the outer membrane protein HopQ that binds to the cell surface protein CEACAM, which can be expressed on the gastric mucosa. Once bound, H. pylori activates a number of signaling pathways, including canonical and non-canonical NF-κB. We investigated whether HopQ-CEACAM interaction is involved in activating the non-canonical NF-κB signaling pathway. Different gastric cancer cells were infected with the H. pylori wild type, or HopQ mutant strains, and the activation of non-canonical NF-κB was related to CEACAM expression levels. The correlation between CEACAM levels and the activation of non-canonical NF-κB was confirmed in human gastric tissue samples. Taken together, our findings show that the HopQ-CEACAM interaction is important for activation of the non-canonical NF-κB pathway in gastric epithelial cells.

The role of long noncoding RNAs in regulating invasion and metastasis of malignant tumors

Long noncoding RNAs (lncRNAs) are a group of non-protein-coding transcripts exceeding 200 nucleotides in length, which are emerging as key players in various fundamental biological processes. Furthermore, it is increasingly recognized that mutation and dysregulation of lncRNAs contribute importantly to a variety of human diseases, particularly human cancers. Previous studies have revealed that altered lncRNAs have a close association with tumorigenesis, metastasis, prognosis and diagnosis of cancers. The present review aims to exhibit a brief overview of the associated reports of lncRNAs in cancers, including colorectal cancer, gastric cancer, lung adenocarcinoma, nasopharyngeal carcinoma, cervical cancer and esophageal cancer. Altogether, we argue that lncRNAs have potential as new biomarkers in cancer prognosis and diagnosis, and as promising therapeutic targets for the prevention and treatment of human cancers.

Comparison of CellSearch and Circulating Tumor Cells (CTC)-Biopsy Systems in Detecting Peripheral Blood Circulating Tumor Cells in Patients with Gastric Cancer

Background

The purpose of this study was to compare circulating tumor cells (CTCs)/circulating tumor microemboli (CTM) detection rates of the CellSearch and CTC-Biopsy systems in patients with gastric cancer (GC). We also investigated potential correlations between clinicopathological characteristics and prognosis in patients with GC.

Material/Methods

This prospective study was conducted at the Shandong Institute of Cancer Prevention and Control in China. Fifty-nine patients with GC and 22 healthy volunteers were recruited and their peripheral blood samples were examined by the CTC-Biopsy system and CellSearch system for CTC.

Results

The rate of detection of CTCs/CTM was significantly higher with the CTC-Biopsy system than with the CellSearch system (59.32% vs. 27.12%, P<0.001). The Kappa value was 0.179, indicating poor consistency. CTCs detected with the CellSearch system in patients with stage III/IV GC was significantly correlated with neutrophil count (P=0.020), neutrophil/lymphocyte ratio (N/L ratio) (P=0.009), CA19-9 (P=0.049), tumor size (P=0.026), and the extent of vascular invasion (P=0.007). CTCs detected with the CTC-Biopsy system correlated with tumor differentiation (P=0.010). CTM in patients with stage I/II GC and stage II/IV GC correlated with CEA (P=0.004) and tumor differentiation (P=0.030), respectively. A CTC count >3 detected with the CellSearch system, and not the CTC-Biopsy system, correlated with reduced progression-free survival and overall survival.

Conclusions

The CTC-Biopsy system was superior to the CellSearch system for detecting CTCs in GC patients. CTM were detected with the CTC-Biopsy system but not with the CellSearch system. CTCs detected with the CellSearch system correlated with various clinicopathological factors and long-term survival outcomes.

ST6Gal1 targets the ectodomain of ErbB2 in a site-specific manner and regulates gastric cancer cell sensitivity to trastuzumab

The clinical performance of the therapeutic monoclonal antibody trastuzumab in the treatment of ErbB2-positive unresectable gastric cancer (GC) is severely hampered by the emergence of molecular resistance. Trastuzumab's target epitope is localized within the extracellular domain of the oncogenic cell surface receptor tyrosine kinase (RTK) ErbB2, which is known to undergo extensive N-linked glycosylation. However, the site-specific glycan repertoire of ErbB2, as well as the detailed molecular mechanisms through which specific aberrant glycan signatures functionally impact the malignant features of ErbB2-addicted GC cells, including the acquisition of trastuzumab resistance, remain elusive. Here, we demonstrate that ErbB2 is modified with both α2,6- and α2,3-sialylated glycan structures in GC clinical specimens. In-depth mass spectrometry-based glycomic and glycoproteomic analysis of ErbB2's ectodomain disclosed a site-specific glycosylation profile in GC cells, in which the ST6Gal1 sialyltransferase specifically targets ErbB2 N-glycosylation sites occurring within the receptor's trastuzumab-binding domain. Abrogation of ST6Gal1 expression reshaped the cellular and ErbB2-specific glycomes, expanded the cellular half-life of the ErbB2 receptor, and sensitized ErbB2-dependent GC cells to trastuzumab-induced cytotoxicity through the stabilization of ErbB dimers at the cell membrane, and the decreased activation of both ErbB2 and EGFR RTKs. Overall, our data demonstrates that ST6Gal1-mediated aberrant α2,6-sialylation actively tunes the resistance of ErbB2-driven GC cells to trastuzumab.

miR-6838-5p Affects Cell Growth, Migration, and Invasion by Targeting GPRIN3 via the Wnt/β-Catenin Signaling Pathway in Gastric Cancer

Gastric cancer (GC) is a highly prevalent digestive malignant tumor, ranking second in the tumor-related mortality globally. The microRNAs have been confirmed to be connected with GC progression. Accumulative evidence has suggested that miR-6838-5p exerts a suppressive effect on human cancers. Nonetheless, whether miR-6838-5p is involved in the regulation of GC remains to be investigated. During our research, miR-6838-5p was downregulated in GC cells. Upregulated miR-6838-5p repressed GC cell cycle progression, proliferation, migration, and invasion. Furthermore, miR-6838-5p overexpression repressed the nuclear import of β-catenin, thus inactivating Wnt/β-catenin pathway. Moreover, we observed that GPRIN3 was targeted by miR-6838-5p in GC with luciferase reporter and RIP assays. GPRIN3 upregulation reversed the suppression of miR-6838-5p in GC cellular processes. These findings suggest miR-6838-5p restrains the malignant behaviors of GC cells via targeting GPRIN3 to repress Wnt/β-catenin signaling pathway, which may provide novel targets for GC treatment.

BCYRN1 is correlated with progression and prognosis in gastric cancer

Long non-coding RNA brain cytoplasmic RNA 1 (BCYRN1) has been found to play an important role in tumorigenesis of a variety of tumors including gastric cancer (GC). However, the prognostic significance and molecular mechanism of BCYRN1 was still unknown in GC. In the present study, we found BCYRN1 expression was dramatically elevated in GC tissues and cell lines, and positively associated with tumor depth, lymph node metastasis and clinical stage in patients with GC. Moreover, univariate and multivariate Cox regression analyses demonstrated that high BCYRN1 expression was independent prognostic factor for overall survival in GC patients. In lncRNA-microRNA interactome database, we found that there were putative binding sites between BCYRN1 and miR-204-5p. Furthermore, we confirmed that down-regulation of BCYRN1 inhibited GC cell proliferation, migration and invasion through directly up-regulated miR-204-5p expression. In conclusion, BCYRN1 acts as a promising prognostic predictor in GC patients and regulated GC cell proliferation, cell cycle, migration and invasion through targeting miR-204-5p.

Genomics Score Based on Genome-Wide Network Analysis for Prediction of Survival in Gastric Cancer: A Novel Prognostic Signature

Purpose

Gastric cancer (GC) is a product of multiple genetic abnormalities, including genetic and epigenetic modifications. This study aimed to integrate various biomolecules, such as miRNAs, mRNA, and DNA methylation, into a genome-wide network and develop a nomogram for predicting the overall survival (OS) of GC.

Materials and Methods

A total of 329 GC cases, as a training cohort with a random of 150 examples included as a validation cohort, were screened from The Cancer Genome Atlas database. A genome-wide network was constructed based on a combination of univariate Cox regression and least absolute shrinkage and selection operator analyses, and a nomogram was established to predict 1-, 3-, and 5-year OS in the training cohort. The nomogram was then assessed in terms of calibration, discrimination, and clinical usefulness in the validation cohort. Afterward, in order to confirm the superiority of the whole gene network model and further reduce the biomarkers for the improvement of clinical usefulness, we also constructed eight other models according to the different combinations of miRNAs, mRNA, and DNA methylation sites and made corresponding comparisons. Finally, Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were also performed to describe the function of this genome-wide network.

Results

A multivariate analysis revealed a novel prognostic factor, a genomics score (GS) comprising seven miRNAs, eight mRNA, and 19 DNA methylation sites. In the validation cohort, comparing to patients with low GS, high-GS patients (HR, 12.886; P < 0.001) were significantly associated with increased all-cause mortality. Furthermore, after stratification of the TNM stage (I, II, III, and IV), there were significant differences revealed in the survival rates between the high-GS and low-GS groups as well (P < 0.001). The 1-, 3-, and 5-year C-index of whole genomics-based nomogram were 0.868, 0.895, and 0.928, respectively. The other models have comparable or relatively poor comprehensive performance, while they had fewer biomarkers. Besides that, DAVID 6.8 further revealed multiple molecules and pathways related to the genome-wide network, such as cytomembranes, cell cycle, and adipocytokine signaling.

Conclusion

We successfully developed a GS based on genome-wide network, which may represent a novel prognostic factor for GC. A combination of GS and TNM staging provides additional precision in stratifying patients with different OS prognoses, constituting a more comprehensive sub-typing system. This could potentially play an important role in future clinical practice.

High plasma levels of COL10A1 are associated with advanced tumor stage in gastric cancer patients

BACKGROUND

Gastric cancer (GC) remains an aggressive malignancy with a high rate of mortality, being the third leading cause of cancer-related death. More than one million newly diagnosed cases and 782685 deaths due to GC were reported in 2018. GC is characterized by limited effective treatment options and the lack of consistent biomarkers for the diagnosis and prognosis of these patients. The discovery of new biomarkers useful in the early diagnosis of GC is mandatory.

AIM

To evaluate the potential of COL10A1 as a circulating biomarker for the diagnosis and prognosis of gastric adenocarcinoma patients.

METHODS

Plasma and tissue obtained from 49 patients with gastric adenocarcinoma have been used in exploring the expression of COL10A1. Real-time PCR and western blot techniques were used to evaluate COL10A1 level in gastric tumor tissue compared to normal adjacent tissue. The circulating level of COL10A1 was also evaluated by ELISA in plasma of gastric adenocarcinoma patients. Survival analysis was made in order to evaluate the potential of COL10A1 as a biomarker for the diagnosis and prognosis of gastric adenocarcinoma patients.

RESULTS

Our results showed a significant increase in COL10A1 gene expression and protein levels in gastric tumor tissue compared to adjacent normal tissue (P < 0.05). COL10A1 seems to show an elevated expression from the beginning of carcinogenesis, in the early stages, and its increased level remains elevated during cancer progression. A significant increase of COL10A1 plasma level in gastric adenocarcinoma patients was also identified. Moreover, increased COL10A1 plasma level was associated with poor survival of the patients. Plasma COL10A1 performed a diagnostic value in GC with area under the receiver operating characteristic curve (AUC) of 0.9171 (P = 0.0002), sensitivity of 87.76%, and specificity of 100.0%. Furthermore, this study demonstrated the potential role of plasma COL10A1 in the early detection of GC, as in the early stage, we obtained an AUC of 0.8789 (P = 0.0030), sensitivity of 81.25%, and specificity of 100.0%.

CONCLUSION

Circulating expression level of COL10A1 is significantly increased in gastric adenocarcinoma patients being associated with poor survival and is a potential biomarker for early detection of GC.

MiR-129-5p induces cell cycle arrest through modulating HOXC10/Cyclin D1 to inhibit gastric cancer progression

MicroRNAs (miRNAs) play important roles in posttranscriptional regulation and may serve as targets for the diagnosis and treatment of cancers. Nevertheless, a comprehensive understanding of miRNAs profiles in gastric cancer progression is still lacking. Here, we report that miR-129-5p is downregulated in gastric cancer by analyzing TCGA database (n = 41) and clinical tumor samples (n = 60). MiR-129-5p transfection suppressed gastric cancer cell proliferation through inducing G1 phase arrest in vitro and inhibit xenograft tumor growth in vivo. MiR-129-5p directly targeted the 3' untranslated regions (3' UTR) of HOXC10 mRNA and downregulated its expression. Importantly, miR-129-5p could reverse the oncogenic effect induced by HOXC10. We systemically screened the downstream target of HOXC10 by ChIP sequencing, and found that HOXC10 could transcriptionally regulate the expression of Cyclin D1 and facilitate G1/S cell cycle transition. Notably, high levels of HOXC10 and Cyclin D1 were related with poor prognosis of gastric cancer patients (n = 90). These findings reveal a novel role of miR-129-5p/HOXC10/Cyclin D1 axis in modulating cell cycle and gastric tumorigenesis, which might provide potential prognostic biomarkers and therapeutic targets for gastric cancer patients.

Long Noncoding RNA DLGAP1-AS1 Promotes the Aggressive Behavior of Gastric Cancer by Acting as a ceRNA for microRNA-628-5p and Raising Astrocyte Elevated Gene 1 Expression

Purpose

The long noncoding RNA DLGAP1 antisense RNA 1 (DLGAP1-AS1) plays well-defined roles in the malignant progression of hepatocellular carcinoma. The purpose of this study was to determine whether DLGAP1-AS1 affects the aggressive behavior of gastric cancer (GC).

Methods

DLGAP1-AS1 expression in GC tissue samples and cell lines was determined by reverse-transcription quantitative PCR. GC cell proliferation, apoptosis, migration, invasion, and tumor growth in vitro as well as in vivo were examined by the Cell Counting Kit-8 assay, flow-cytometric analysis, transwell migration and invasion assays, and xenograft model experiments, respectively.

Results

DLGAP1-AS1 was overexpressed in GC tissue samples and cell lines. Among patients with GC, the increased level of DLGAP1-AS1 correlated with tumor size, TNM stage, lymph node metastasis, distant metastasis, and shorter overall survival. The knockdown of DLGAP1-AS1 suppressed GC cell proliferation, migration, and invasion in vitro, as well as promoted cell apoptosis and hindered tumor growth in vivo. Mechanistically, DLGAP1-AS1 functioned as a competing endogenous RNA for microRNA-628-5p (miR-628-5p) in GC cells, thereby increasing the expression of the miR-628-5p target astrocyte elevated gene 1 (AEG-1). Functionally, the recovery of the miR-628-5p/AEG-1 axis output attenuated the effects of DLGAP1-AS1 knockdown in GC cells.

Conclusion

DLGAP1-AS1 is a pleiotropic oncogenic lncRNA in GC. DLGAP1-AS1 plays a pivotal part in the oncogenicity of GC in vitro and in vivo by regulating the miR-628-5p/AEG-1 axis. DLGAP1-AS1, miR-628-5p, and AEG-1 form a regulatory pathway to facilitate GC progression, suggesting this pathway as an effective target for the treatment of GC.

Development and validation of a novel nomogram to predict overall survival in gastric cancer with lymph node metastasis

Gastric cancer (GC) with lymph node metastasis (LNM) at diagnosis is associated with a unstable prognosis and indefinite survival times. The aim of the present study was to construct and validate a model for the Overall survival (OS) estimation for patients with LNM. The nomogram was constructed to predict the OS for LNM-positive GC using the primary group of 836 patients and validated using an independent cohort of 411 patients. Factors in the nomogram were identified by multivariate Cox hazard analysis. The predictive capability of nomogram was evaluated by calibration analysis and decision curve analysis. Multivariate analysis suggested that eight pre-treatment characteristics were used for developing the nomogram. In the primary cohort, the C-index for OS prediction was 0.788 (95% CI: 0.753-0.823), while in validation cohort, the C-index for OS prediction was 0.769 (95% CI: 0. 720-0.818). The calibration plot for the probability of OS and decision curve analyses showed an optimal agreement. Based on the nomogram, we could divided patients into three groups: low-risk group, middle-risk group and a high-risk group(p <0.001).Taken together, we have provided an easy-to-used and accurate tool for predicting OS, furthermore could be used for risk stratification of OS of LNM-positive GC patients.

PAK1 silencing is synthetic lethal with CDK4/6 inhibition in gastric cancer cells via regulating PDK1 expression

Gastric cancer (GC) is one of the most common malignancies worldwide. The prognosis of GC is unsatisfied owning to widespread metastasis. P21-activated kinase 1 (PAK1), a member of serine/threonine kinases, is associated with the progression of multiple types of human cancers. Here, we demonstrated that CDK4/6 inhibitor reduced GC cell viability and decreased PAK1 expression. Consistently, PAK1 ablation increased GC cell sensitivity exposed to CDK4/6 inhibitor and promoted DNA damage. We also revealed PAK1 depletion notably affected PDK1-AKT pathway, and PDK1 overexpression totally abrogated the effect of PAK1 deletion on DNA damage in GC cells. Additionally, PDK1 overexpression also rescued the increased GC cell sensitivity towards CDK4/6 inhibitor and the cell cycle arrest caused by PAK1 depletion. Our findings, therefore, suggested that PAK1 silencing increased sensitivity to CDK4/6 inhibition in gastric cancer cells via PDK1-AKT pathway. We, therefore, thought PAK1 as a promising therapeutic target for the treatment of CDK4/6 inhibitor-resistant gastric cancer.

Curcumin micelles suppress gastric tumor cell growth by upregulating ROS generation, disrupting redox equilibrium and affecting mitochondrial bioenergetics

A proposed novel mechanism of anticancer activity of curcumin micelles through redox equilibrium in gastric cancer.

Circular RNA hsa-circ-0007766 modulates the progression of Gastric Carcinoma via miR-1233-3p/GDF15 axis

Circular RNAs (circRNAs), a new kind of non-coding RNAs, have gradually been proved to be critical regulators of gene expression; however, the underlying mechanisms still need to be elaborated. In the present study, we investigated the role of hsa-circ-0007766 in gastric carcinoma (GC). Quantitative real-time PCR was applied to detect the differential expression levels of circRNA, miRNAs, and mRNAs in human tissues and specific cell lines. GC cell lines were transiently transfected with siRNA. Then the proliferation, migration, and invasion assays were performed to evaluate the effect of hsa-circ-0007766 in GC cell lines. Fluorescence in situ hybridization, RNA pulldown assay was used to confirm the location of hsa-circ-0007766 and its relationship with miR-1233-3p. Luciferase reporter assay was then conducted to verify the interaction between miR-1233-3p and GDF15. Interestingly, we found that hsa-circ-0007766 was highly expressed in human GC tissues and GC cell lines. Knock-down of hsa-circ-0007766 inhibited cell proliferation, migration, invasion, and down-regulated the expression of GDF15. Moreover, hsa-circ-0007766 was identified as a sponge of miR-1233-3p, which could target gene GDF15 to regulate the progression of GC. Finally, hsa-circ-0007766 was evaluated to be a valuable diagnostic marker with a sensitivity of 53.33% and specificity of 83.33% by ROC analysis. This study unveils a mechanism by which hsa-circ-0007766 regulates GDF15 via hsa-circ-0007766/miR-1233-3p/GDF15 axis, which may provide new insight for GC therapeutic strategies.

LOXL1-AS1 Drives The Progression Of Gastric Cancer Via Regulating miR-142-5p/PIK3CA Axis

Background

Gastric cancer (GC) is a deadly disease, and its incidence is especially high in East Asia including China. Recently, some long non-coding RNA (lncRNAs) have been identified as oncogenes or tumor suppressors. This study aimed to determine the function and mechanism of lncRNA LOXL1-AS1 on the progression of GC.

Methods

RT-PCR was done to measure the expression levels of LOXL1-AS1 and miR-142-5p in GC tissues. The association between pathological indexes and LOXL1-AS1 expression was also analyzed. Human GC cell lines AGS and BGC823 were used as cell models. CCK-8 and colony formation assays were conducted to assess the effect of LOXL1-AS1 on the proliferation of GC cell lines. Transwell assay was conducted to determine the influence of LOXL1-AS1 on cell migration and invasion. Furthermore, luciferase reporter assay was carried out to confirm the relationship of miR-142-5p with LOXL1-AS1. Additionally, Western blot was done to detect the regulatory function of LOXL1-AS1 on PIK3CA, a target of miR-142-5p. In vivo experiment was also performed to validate the roles and mechanism of LOXL1-AS1 on the growth and metastasis of GC cells.

Results

LOXL1-AS1 expression in GC samples was significantly increased, which was correlated with unfavorable pathological indexes. Highly expressed LOXL1-AS1 was closely linked to shorter overall survival time and post-progression survival time of the patients. LOXL1-AS1 markedly modulated the malignant phenotypes of GC cells. Additionally, overexpressed LOXL1-AS1 notably reduced the expression of miR-142-5p, but enhanced the expression level of PIK3CA. In vivo experiments further validated that knockdown of LOXL1-AS1 inhibited the growth and metastasis of GC cells via regulating miR-142-5p and PIK3CA.

Conclusion

LOXL1-AS1 was a sponge of tumor suppressor miR-142-5p in GC, enhanced the expression of PIK3CA indirectly and functioned as an oncogenic lncRNA.

The regulatory roles and potential prognosis implications of long non-coding RNAs in gastric cancer

Accumulating dysregulated lncRNAs have been demonstrated to execute vital functions in the pathogenesis and progress of gastric cancer (GC) through versatile molecular mechanisms. In this review, we classify the mechanisms of dysregulated lncRNAs in GC into several governing types according to their roles at molecular level. For each regulatory role, we illustrate several instructive examples and introduce significant effects of lncRNAs on cellular biological properties of GC. Besides, we summarize a group of lncRNA-signatures that are potential biomarkers in the prediction of prognosis for GC patients.

Down-regulated hsa_circ_0067934 facilitated the progression of gastric cancer by sponging hsa-mir-4705 to downgrade the expression of BMPR1B

Background

Gastric cancer is the third most lethal cancer worldwide. Finding a novel marker is essential to targeted therapy and the diagnosis of gastric cancer. As newly discovered markers, circRNAs have aroused widespread attention on a global scale. Our research aims to understand the role of circRNAs in gastric cancer and to explore the underlying pathogenesis.

Methods

Raw expression data of circRNAs were obtained from the GEO database. Integrated bioinformatics analysis was used to screen differentially expressed circRNAs (DECs) by RobustRankAggreg package. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were performed to predict the functions of DECs. Then, the miRNAs and mRNAs at the downstream of DECs were predicted. Expression data of miRNAs and mRNAs were downloaded from The Cancer Genome Atlas (TCGA). The aberrantly expressed miRNAs and mRNAs were selected using the edgeR package.

Results

Four datasets (GSE78092, GSE83521, GSE89143, and GSE93541) were downloaded from the GEO database. Among them, two DECs (hsa_circ_0007991 and hsa_circ_0067934) were screened. The functional analyses of DECs confirmed that they were cancer-related circRNAs. Furthermore, hsa-mir-4705 (miRNA) and BMPR1B (mRNA) at the downstream of hsa_circ_0067934 were found differentially expressed in gastric cancer by expression data from TCGA database.

Conclusions

Our study discovered the critical roles of hsa_circ_0007991 and hsa_circ_0067934 in the development of gastric cancer, and they could be novel markers for targeted therapy and assist the diagnosis of early-stage gastric cancer. Moreover, we discovered that the hsa_circ_0067934/hsa-mir-4705/BMPR1B axis might be involved in the carcinogenesis of gastric cancer.

Identification of Potentially Functional CircRNA-miRNA-mRNA Regulatory Network in Gastric Carcinoma using Bioinformatics Analysis

Background

As all we know, gastric cancer (GC) is a highly aggressive disease. Recently, circular RNA (circRNA) was found to play a vital role in regulation of GC. Some circRNAs could regulate messenger RNA (mRNA) expression by functioning as a microRNA (miRNA) sponge. Nevertheless, the circRNA-miRNA-mRNA regulatory network involved GC rarely has been explored and researched.

Material/Methods

All the differentially expressed circRNAs, miRNAs, and mRNA were derived from Gene Expression Omnibus (GEO) microarray data (GSE78092, GSE89143, GSE93415, and GSE54129). GC level 3 miRNA-sequencing data and clinical information were downloaded from The Cancer Genome Atlas (TCGA) database. Furthermore, a circRNA-miRNA-mRNA regulatory network was constructed by Cytoscape (version 3.6.1). Gene Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway revealed the functions and signaling pathways associated with these target genes. Hub genes of protein-protein interaction (PPI) network were identified by STRING database and cytoHubba.

Results

The regulatory network consists of 3 circRNAs, 22 miRNAs, and 128 mRNAs. Only 3 miRNAs of the network were consistent with the expression of TCGA and were associated with some clinical features. The results of the functional analysis of 128 mRNAs showed that GO analysis and KEGG pathways of inclusion criteria were 49 and 24, respectively. PPI network and Cytoscape showed that the top 10 hub genes were MYC, CTGF, TGFBR2, TGFBR1, SERPINE1, KRAS, ZEB1, THBS1, CDK6, and TNS1; 4 of which were verified by GEPIA based on TCGA. Highly expressed SERPINE1 had a poor OS (over survival) and DFS (disease-free survival), and TGFBR1 expression increased along with the increase of clinical stages.

Conclusions

This study looked at a circRNA-miRNA-mRNA regulatory network associated with GC and explored the potential functions of mRNA in the network, then identified a new molecular marker for prediction, prognosis, and therapeutic targets for clinical patients.

Spondin 2 promotes the proliferation, migration and invasion of gastric cancer cells

Spondin 2 (SPON2), a member of the Mindin F‐Spondin family, identifies pathogens, activates congenital immunity and promotes the growth and adhesion of neurons as well as binding to their receptors, but its role in promoting or inhibiting tumour metastasis is controversial. Here, we investigated its expression levels and mechanism of action in gastric cancer (GC). Western blotting and GC tissue arrays were used to determine the expression levels of SPON2. ELISAs were performed to measure the serum levels of SPON2 in patients with GC. Two GC cell lines expressing low levels of SPON2 were used to analyse the effects of regulating SPON2 expression on proliferation, migration, invasion, the cell cycle and apoptosis. The results revealed that SPON2 was highly expressed in GC tissues from patients with relapse or metastasis. The levels of SPON2 in sera of patients with GC were significantly higher compared with those of healthy individuals and patients with atrophic gastritis. Knockdown of SPON2 expression significantly inhibited the proliferation, migration and invasion of GC cells in vitro and in vivo. Down‐regulation of SPON2 arrested the cell cycle in G1/S, accelerated apoptosis through the mitochondrial pathway and inhibited the epithelial‐mesenchymal transition by blocking activation of the ERK1/2 pathway. In summary, this study suggests that SPON2 acts as an oncogene in the development of GC and may serve as a marker for the diagnosing GC as well as a new therapeutic target for GC.

MiR-203 acts as a radiosensitizer of gastric cancer cells by directly targeting ZEB1

Objective: Gastric cancer (GC) is a common tumor malignancy with high incidence and poor prognosis. Radiotherapy is one of the main strategies for GC treatment, while development of radioresistance limits the effectiveness. microRNA-203 (miR-203) has been reported to participate in progression of GC, whereas its interaction with radiosensitivity of GC and the related mechanism remain largely unclear. Methods: The expressions of miR-203 and zinc finger E-box binding homeobox 1 (ZEB1) were measured in GC tissues and cells by quantitative real-time polymerase chain reaction or western blot. Survival fraction, cell viability and apoptosis were measured in GC cells after treatment of radiation by colony formation, 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay or flow cytometry, respectively. Tumor volume and weight were detected in murine xenograft model after radiation treatment. The interaction between miR-203 and ZEB1 was explored by bioinformatics analysis and luciferase activity assay. Results: miR-203 expression was down-regulated and ZEB1 mRNA level was up-regulated in GC. The expression of miR-203 was associated with radiosensitivity of GC cells. Moreover, overexpression of miR-203 decreased survival fraction, cell viability and tumor growth but promoted cell apoptosis in radiation-treated GC cells. However, knockdown of miR-203 played an opposite effect. ZEB1 was validated as a target of miR-203, and it was involved in miR-203-mediated radiosensitivity of GC cells in vitro and in vivo. Conclusion: miR-203 promoted radiosensitivity of GC cells by targeting ZEB1, indicating miR-203 as a promising radiosensitizer for GC treatment.

Helicobacter pylori infection and gastric cancer biology: tempering a double-edged sword

Helicobacter pylori (H. pylori) infection affects an estimated 4.4 billion people globally. Moreover, H. pylori presents the most significant risk factor for gastric cancer and low-grade mucosa-associated lymphoid tissue (MALT) lymphoma, and it is the first example of bacterial infection linked to carcinogenesis. Here, we contend that H. pylori research, which focuses on a cancer-causing pathogen resident in a relatively accessible organ, the stomach, could constitute an exemplar for microbial-related carcinogenesis in less tractable organs, such as the pancreas and lung. In this context, molecular biological approaches that could reap rewards are reviewed, including: (1) gastric cancer dynamics, particularly the role of stem cells and the heterogeneity of neoplastic cells, which are currently being investigated at the single-cell sequencing level; (2) mechanobiology, and the role of three-dimensional organoids and matrix metalloproteases; and (3) the connection between H. pylori and host pathophysiology and the gut microbiome. In the context of H. pylori's contribution to gastric cancer, several important conundrums remain to be fully elucidated. From among them, this article discusses (1) why H. pylori infection, which causes both gastric and duodenal inflammation, is only linked to gastric cancer; (2) whether a "precision oncomicrobiology" approach could enable a fine-tuning of the expression of only cancer-implicated H. pylori genes while maintaining beneficial H. pylori-mediated factors in extra-gastric tissues; and (3) the feasibility of using antibiotics targeting the microbial DNA damage system, which shares commonalities with mechanisms for human cell replication, as chemopreventives. Additional therapeutic perspectives are also discussed.

Development and validation of a prognostic nomogram in gastric cancer with hepatitis B virus infection

Background

Patients with HBsAg-positive gastric cancer (GC) are a heterogeneous group, and it is not possible to accurately predict the overall survival (OS) in these patients.

Methods

We developed and validated a nomogram to help improve prediction of OS in patients with HBsAg-positive GC. The nomogram was established by a development cohort (n = 245), and the validation cohort included 84 patients. Factors in the nomogram were identified by univariate and multivariate Cox hazard analysis. We tested the accuracy of the nomograms by discrimination and calibration, and plotted decision curves to assess the benefits of nomogram-assisted decisions in a clinical context. Then we evaluated the risk in the two cohort.

Results

Significant predictors were age, tumor stage, distant metastases, gamma-glutamyl transpeptidase (GGT) and alkaline phosphatase (ALP). The proportional-hazards model (nomogram) was based on pre-treatment characteristics. The nomogram had a concordance index (C-index) of 0.812 (95% CI 0.762–0.862), which was superior than the C-index of AJCC TNM Stage (0.755, 95% CI 0.702–0.808). The calibration plot in the validation cohort based on 5 predictors suggested good agreement between actual and nomogram-predicted OS probabilities. The decision curve showed that the nomogram in predicting OS is better than that of TNM staging system in all range. Moreover, patients were divided into three distinct risk groups for OS by the nomogram: low risk group, middle risk group and high risk group, respectively.

Conclusion

This nomogram, using five pre-treatment characteristics, improves prediction of OS in patients with HBsAg-positive gastric cancer. It represents an improvement in prognostication over the current TNM stage. To generalize the use of this nomogram in other groups, additional validation with data from other institutions is required.