Diffuse Gastric Cancer: A Summary of Analogous Contributing Factors for Its Molecular Pathogenicity

Pathogenesis and potential reversibility of intestinal metaplasia - a milestone in gastric carcinogenesis

BACKGROUND

Non-cardia gastric cancer remains a major cause of cancer-related mortality worldwide, despite declining incidence rates in many industrialized countries. The development of intestinal-type gastric cancer occurs through a multistep process in which normal mucosa is sequentially transformed into hyperproliferative epithelium, followed by metaplastic processes leading to carcinogenesis. Chronic infection with Helicobacter pylori is the primary etiological agent that causes chronic inflammation of the gastric mucosa, induces atrophic gastritis, and can lead to intestinal metaplasia and dysplasia. Both intestinal metaplasia and dysplasia are precancerous lesions, in which gastric cancer is more likely to occur. Atrophic gastritis often improves after eradication of Helicobacter pylori; however, the occurrence of intestinal metaplasia has been traditionally regarded as "the point of no return" in the carcinogenesis sequence. Helicobacter pylori eradication heals non-atrophic chronic gastritis, may lead to regression of atrophic gastritis, and reduces the risk of gastric cancer in patients with these conditions. In this article, we discuss the pathogenesis, epigenomics, and reversibility of intestinal metaplasia and briefly touch upon potential treatment strategy.

CONCLUSIONS

Gastric intestinal metaplasia no longer appears to be an irreversible precancerous lesion. However, there are still many controversies regarding the improvement of intestinal metaplasia after Helicobacter pylori eradication.

[TSR2 overexpression inhibits proliferation and invasion of gastric cancer cells by downregulating the PI3K/AKT signaling pathway]

OBJECTIVE

To investigate the expression of TSR2 in gastric cancer and explore its correlation with progression of gastric cancer and the possible mechanism.

METHODS

We retrospectively analyzed TSR2 expression in clinical specimens from 105 gastric cancer patients and the impact of TSR2 expression level on disease progression and 5-year postoperative survival of the patients. GO and KEGG enrichment analyses were used to predict the biological functions and mechanisms of TSR2. In gastric cancer MGC-803 cells with lentivirus-mediated TSR2 overexpression or knockdown, the changes in cell proliferation, invasion, and migration were assessed with CCK-8 and Transwell assays, and the expressions of p-PI3K and p-AKT were detected using Western blotting.

RESULTS

TSR2 expression was significantly lower in gastric cancer tissues than in the adjacent tissues with significant correlations with CEA level, CA19-9 level, and T and N staging (P < 0.05). A low TSR2 expression, CEA≥5 μg/L, CA19-9≥37 kU/L, T3-T4 stages, and N2-N3 staged were identified as independent risk factors affecting 5-year survival rate of the patients following radical surgery (P < 0.05), and a high TSR2 expression was associated with a higher 5-year survival rate of the patients (P < 0.001). Bioinformatics analysis suggested the functional involvement of TSR2 with the PI3K/AKT signaling pathway. MGC-803 cells overexpressing TSR2 showed significantly lowered proliferation, migration, and invasion capacities (P < 0.05), while TSR2 knockdown produced the opposite effects (P < 0.05). Western blotting showed that TSR2 overexpression reduced the phosphorylation of PI3K and AKT, and TSR2 knockdown caused the opposite changes in MGC-803 cells (P < 0.05).

CONCLUSION

TSR2 is lowly expressed in gastric cancer tissues to adversely affect the patients' prognosis, and its overexpression inhibits gastric cancer cell proliferation, invasion, and migration possibly by downregulating the PI3K/AKT pathway.

RAC1-mediated integrin alpha-6 expression in E-cadherin-deficient gastric cancer cells promotes interactions with the stroma and peritoneal dissemination

Diffuse-type gastric cancer (DGC) is a subtype of gastric cancer that is prone to peritoneal dissemination, with poor patient prognosis. Although intercellular adhesion loss between cancer cells is a major characteristic of DGCs, the mechanism underlying the alteration in cell-to-extracellular matrix (ECM) adhesion is unclear. We investigated how DGCs progress and cause peritoneal dissemination through interactions between DGC cells and the tumour microenvironment (TME). P53 knockout and KRASG12V-expressing (GAN-KP) cells and Cdh1-deleted GAN-KP (GAN-KPC) cells were orthotopically transplanted into the gastric wall to mimic peritoneal dissemination. The GAN-KPC tumour morphology was similar to that of human DGCs containing abundant stroma. RNA sequencing revealed that pathways related to Rho GTPases and integrin-ECM interactions were specifically increased in GAN-KPC cells compared with GAN-KP cells. Notably, we found that Rac Family Small GTPase 1 (RAC1) induces Integrin Subunit Alpha 6 (ITGA6) trafficking, leading to its enrichment on the GC cell membrane. Fibroblasts activate the FAK/AKT pathway in GC cells by mediating extracellular matrix (ECM)-Itga6 interactions, exacerbating the malignant phenotype. In turn, GC cells induce abnormal expression of fibroblast collagen and its transformation into cancer-associated fibroblasts (CAFs), resulting in DGC-like subtypes. These findings indicate that Cdh1 gene loss leads to abnormal expression and changes in the subcellular localization of ITGA6 through RAC1 signalling. The latter, through interactions with CAFs, allows for peritoneal dissemination.

EBV-Associated Gastric Cancer; An In Situ Hybridization Assay on Tissue Microarray: A Multi-Region Study from Four Major Provinces of Iran

BACKGROUND

Gastric cancer is the fourth leading cause of cancer-related deaths in the world. The identification of gastric cancer subtypes related to recognizable microbial agents may play a pivotal role in the targeted prevention and treatment of this cancer. The current study is conducted to define the frequency of Epstein-Barr virus (EBV) infection in gastric cancers of four major provinces, with different incidence rates of gastric cancers, in Iran.

METHODS

Paraffin blocks of 682 cases of various types of gastric cancer from Tehran, South and North areas of Iran were collected. Twelve tissue microarray (TMA) blocks were constructed from these blocks. Localization of EBV in tumors was assessed by in situ hybridization (ISH) for EBV-encoded RNA (EBER). Chi-squared test was used to evaluate the statistical significance between EBV-associated gastric cancer (EBVaGC) and clinicopathologic tumor characteristics.

RESULTS

Fourteen out of 682 cases (2.1%) of gastric adenocarcinoma were EBER-positive. EBER was positive in 8 out of 22 (36.4%) of medullary carcinomas and 6 out of 660 (0.9%) of non-medullary type, which was a statistically significant difference (P<0.001). The EBVaGCs were more frequent in younger age (P=0.009) and also showed a trend toward the lower stage of the tumor (P=0.075).

CONCLUSION

EBV-associated gastric adenocarcinoma has a low prevalence in Iran. This finding can be due to epidemiologic differences in risk factors and exposures, and the low number of gastric medullary carcinomas in the population. It may also be related to gastric tumor heterogeneity not detected with the TMA technique.

The landscape of 8q24 cytoband in gastric cancer (Review)

Worldwide, gastric cancer (GC) is estimated to be the fifth most common type of cancer type in both sexes, ranking sixth for new cases, with >640,850 cases per year, and fourth in terms of mortality rate. Cancer presents numerical and structural alterations in chromosomes, often through gains and losses of regions. In GC, there are multiple genetic alterations, in which those located in cytoband 8q24 have been frequently described; essential genes are present in this cytoband, regulating the homeostasis of crucial biological processes, such as the MYC gene, which induces expression of selective genes to promote cell growth and proliferation. Conversely, DNA sequence variations can also occur when a single nucleotide in the genome sequence is altered, and this is termed a single nucleotide polymorphism (SNP). These alterations, which can serve as a biological marker, are present in at least 1% of the population and assist in identifying genes associated with GC. In the present review, 12 genes present in cytoband 8q24 related to GC (NSMCE2, PCAT1, CASC19, CASC8, CCAT2, PRNCR1, POU5F1B, PSCA, JRK, MYC, PVT1 and PTK2) are discussed. The PSCA gene was cited more frequently than others; it has four known SNPs associated with GC (rs2978980, rs2294008, rs2976392 and rs9297976). Thus, these SNPs should be further studied in different populations to determine their risk value in patients with GC.

The central role of gastrin in gastric cancer

The prevalence of gastric cancer has markedly declined, but due to the high mortality rates associated with gastric cancer, it is still a serious disease. The preferred classification of gastric cancer is according to Lauren into either the intestinal type, which has a glandular growth pattern, or the diffuse type, which does not have glandular structures. Both types have been classified as adenocarcinomas, with the latter type based on periodic acid-Schiff (PAS) positivity presumed to reflect mucin. However, the presence of mucin in the diffuse type, in contrast to neuroendocrine/enterochromaffin-like (ECL) cell markers, has not been confirmed by immunohistochemistry and in situ hybridization. The ECL cells are probably prone to becoming cancerous because they do not express E-cadherin. Gastric cancer is unique in that a bacterium, Helicobacter pylori, is thought to be its main cause. H. pylori predisposes infected individuals to cancer only after having caused oxyntic atrophy leading to gastric hypoacidity and hypergastrinemia. No single H. pylori factor has been convincingly proved to be carcinogenic. It is probable that gastrin is the pathogenetic factor for gastric cancer due to H. pylori, autoimmune gastritis, and long-term prolonged inhibition of gastric acid secretion. Hypergastrinemia induces ECL cell hyperplasia, which develops into neuroendocrine tumors (NETs) and then into neuroendocrine carcinomas in rodents, a sequence that has also been described in humans. During carcinogenesis, the tumor cells lose specific traits, requiring that sensitive methods be used to recognize their origin. Gastric cancer occurrence may hopefully be prevented by H. pylori eradication at a young age, and by the reduced use of inhibitors of acid secretion and use of a gastrin antagonist in those with previous long-term H. pylori infection and those with autoimmune gastritis.

Development of nomograms for predicting the survival of intestinal-type gastric adenocarcinoma patients after surgery

Intestinal-type gastric adenocarcinoma (IGA) is a common phenotype of gastric cancer. Currently, few studies have constructed nomograms that may predict overall (OS) and cancer-specific survival (CSS) probability after surgery. This study is to establish novel nomograms for predicting the survival of IGA patients who received surgery. A total of 1814 IGA patients who received surgery between 2000 and 2018 were selected from Surveillance, Epidemiology, and End Results database and randomly assigned to the training and validating sets at a ratio of 7:3. Then univariate and multivariate cox regression analyses were performed to screen significant indictors for the construction of nomograms. The calibration curve, the area under the receiver operating characteristic (receiver operating characteristic, ROC) curve (the area under curve, AUC), C-index, net reclassification index (NRI), integrated discrimination improvement (IDI) and decision curve analysis (DCA) curves were applied to assess the performance of the model. The significant outcomes of multivariate analysis revealed that ten variables (age, sex, race, surgery type, summary stage, grade, AJCC TNM stage, radiotherapy, number of regional nodes examined, number of regional nodes positive) were demonstrated to construct the nomogram for OS and ten variables (age, sex, race, surgery type, summary stage, grade, AJCC TNM stage, chemotherapy, number of regional nodes examined, number of regional nodes positive) for CSS. The calibration and AUC uncovered their favorable predictive performance. Subsequently, C-index, NRI, IDI and DCA curves further validated the predicative superiority of nomograms over 7th AJCC Stage System. The validated nomogram provides more reliable OS and CSS predictions for postoperative IGA patients with good accuracy, which can help surgeons in treatment decision-making and prognosis evaluation.

Aggressive Histology and Extensive Metastasis Characteristic of Very Young Gastric Cancer (Less Than 30 Years): A Retrospective Clinical Audit

Narendran KrishnamoorthiObjectives  Gastric cancer (GC) is an aggressive disease and remains one of the most common causes of cancer-related mortality worldwide. Incidence of gastric cancer in young (GCY) varies between 2 and 8%. GCY faces unique challenges such as biological variation, diagnosis at an advanced stage, issues related to fertility preservation, and psychosocial considerations. This study aimed to find the differences in clinical characteristics and treatment outcomes of GCY compared to gastric cancer in older adults (GCO). Material and Methods  This is a retrospective study from a tertiary care center. We screened records from 2015 to 2020, identified 33 records of GCY (less than 30 years), and compared the data with GCO (greater than 30 years) during 2015 and 2018. Results  We identified 33 patients with GCY with a median age of 28 years (21-30) and a female to male ratio of 2:1. In GCY, 60% of patients presented with metastatic disease. Diffuse-type histology was more common in the GCY than in GCO (66.7% vs. 41.7%, p  = 0.001). In patients with metastasis, multiple metastases were common in GCY compared to GCO (45% vs. 15%, p  = 0.003). The median duration of follow-up for all patients was 27 (24-29) months. In GCY, the median OS was not reached for patients treated with curative intent, and it was 13 months for those treated with palliative intent. Conclusion  The incidence of GCY in our study was like the western literature. Female patients with aggressive diffuse histology and multiple extensive metastases were characteristic of GCY. The survival outcomes were identical to GCO.

FTO-mediated m6A modification promotes malignant transformation of gastric mucosal epithelial cells in chronic Cag A+ Helicobacter pylori infection

OBJECTIVES

Cag A+ Helicobacter pylori chronic infection cause malignant transformation of the human gastric mucosa. N6-methyladenosine (m6A) modifications are the most common and abundant mRNA modifications and one of the pathways affecting tumorigenicity and tumor progression. However, the role of m6A modification in the process of chronic H. pylori infection leading to malignant transformation of gastric mucosa is unclear.

METHODS

In this study, we used Cag A- and Cag A+H. pylori chronic infection to establish cellular models in GES-1 cells and analyzed the cellular morphology, proliferation, apoptosis, invasiveness and tumorigenicity of gastric mucosal epithelial cells. The m6A expression levels of GES-1 cells after chronic infection with Cag A- and Cag A+H. pylori were examined, and modifying effect of FTO (the fat mass and obesity-associated protein) on CD44 was verified by MeRIP-qPCR. Finally, the FTO expression changes and m6A expression levels were further validated in clinical gastric cancer tissues.

RESULTS

Chronic Cag A+H. pylori-infected GES-1 cells exhibit altered cell morphology, apoptosis inhibition, abnormal proliferation, enhanced migration, colony formation, and increased stem cell-like properties. Meanwhile, FTO and CD44 expression was enhanced, and FTO may induce malignant transformation of gastric mucosa by regulating CD44 mRNA m6A methylation modifications.

CONCLUSIONS

We verified the effect of chronic stimulation of Cag A+H. pylori on malignant transformation of gastric mucosal epithelium. revealing the possibility of FTO in promoting malignant transformation of gastric mucosa by modifying CD44 mRNA methylation, suggesting that FTO expression is a potential molecule for malignant transformation of gastric mucosal epithelial cells.

Exploring the Genetic Diversity of Epstein-Barr Virus among Patients with Gastric Cancer in Southern Chile

The Epstein-Barr virus (EBV) has been associated with gastric cancer (GC), one of the deadliest malignancies in Chile and the world. Little is known about Chilean EBV strains. This study aims to investigate the frequency and genetic diversity of EBV in GC in patients in southern Chile. To evaluate the prevalence of EBV in GC patients from the Chilean population, we studied 54 GC samples using the gold standard detection method of EBV-encoded small RNA (EBER). The EBV-positive samples were subjected to amplification and sequencing of the Epstein-Barr virus nuclear protein 3A (EBNA3A) gene to evaluate the genetic diversity of EBV strains circulating in southern Chile. In total, 22.2% of the GC samples were EBV-positive and significantly associated with diffuse-type histology (p = 0.003). Phylogenetic analyses identified EBV-1 and EBV-2 in the GC samples, showing genetic diversity among Chilean isolates. This work provides important information for an epidemiological follow-up of the different EBV subtypes that may cause GC in southern Chile.

Machine learning models predict the mTOR signal pathway-related signature in the gastric cancer involving 2063 samples of 7 centers

Gastric cancer, as a tumor with poor prognosis, has been widely studied. Distinguishing the types of gastric cancer is helpful. Using the transcriptome data of gastric cancer in our study, relevant proteins of mTOR signaling pathway were screened to identify key genes by four machine learning models, and the models were validated in external datasets. Through correlation analysis, we explored the relationship between five key genes and immune cells and immunotherapy. By inducing cellular senescence in gastric cancer cells with bleomycin, we investigated changes in the expression levels of HRAS through western blot. By PCA clustering analysis, we used the five key genes for gastric cancer typing and explored differences in drug sensitivity and enrichment pathways between different clustering groups. We found that the SVM machine learning model was superior, and the five genes (PPARA, FNIP1, WNT5A, HRAS, HIF1A) were highly correlated with different immune cells in multiple databases. These five key genes have a significant impact on immunotherapy. Using the five genes for gastric cancer gene typing, four genes were expressed higher in group 1 and were more sensitive to drugs in group 2. These results suggest that subtype-specific markers can improve the treatment and provide precision drugs for gastric cancer patients.

Current advances in understanding the molecular profile of hereditary diffuse gastric cancer and its clinical implications

Hereditary diffuse gastric cancer (HDGC) is an autosomal dominant cancer syndrome attributed to germline CDH1 mutations that carries a high risk for early onset DGC. HDGC raises a significant health issue due to its high penetrance and mortality unless diagnosed early. The definitive treatment is to undergo prophylactic total gastrectomy which is associated with significant morbidity., highlighting the urgent need for alternative treatment methods. However, there is limited literature examining potential therapeutic strategies building on emerging insights into the molecular basis of progressive lesions in the context of HDGC. The aim of this review is to summarise the current understanding of HDGC in the context of CDH1 pathogenic variants followed by a review of the proposed mechanisms for progression. In addition, we discuss the development of novel therapeutic approaches and highlight pertinent areas for further research. A literature search was therefore performed for relevant studies examining CDH1 germline variants, second-hit mechanisms of CDH1, pathogenesis of HDGC and potential therapeutic strategies in databases, including PubMed, ScienceDirect and Scopus. Germline mutations are mostly truncating CDH1 variants affecting extracellular domains of E-cadherin, generally due to frameshift, single nucleotide variants or splice site mutations. A second somatic hit of CDH1 most commonly occurs via promoter methylation as shown in 3 studies, but studies are limited with a small sample size. The multi-focal development of indolent lesions in HDGC provide a unique opportunity to understand genetic events that drive the transition to the invasive phenotype. To date, a few signalling pathways have been shown to facilitate the progression of HDGC, including Notch and Wnt. In in-vitro studies, the ability to inhibit Notch signalling was lost in cells transfected with mutant forms of E-cadherin, and increased Notch-1 activity correlated with apoptosis resistance. Furthermore, in patient samples, overexpression of Wnt-2 was associated with cytoplasmic and nuclear β-catenin accumulation and increased metastatic potential. As loss-of-function mutations are challenging to target therapeutically, these findings pave the way towards a synthetic lethal approach in CDH1-deficient cells with some promising results in-vitro. In future, if we could better understand the molecular vulnerabilities in HDGC, there may be opportunities to offer alternative treatment pathways to avoid gastrectomy.

E-cadherin is a biomarker for ferroptosis sensitivity in diffuse gastric cancer

Gastric cancer is the third most common cause of cancer-related death worldwide. Diffuse-type gastric cancer (DGC) is a particularly aggressive subtype that is both difficult to detect and treat. DGC is distinguished by weak cell-cell cohesion, most often due to loss of the cell adhesion protein E-cadherin, a common occurrence in highly invasive, metastatic cancer cells. In this study, we demonstrate that loss-of-function mutation of E-cadherin in DGC cells results in their increased sensitivity to the non-apoptotic, iron-dependent form of cell death, ferroptosis. Homophilic contacts between E-cadherin molecules on adjacent cells suppress ferroptosis through activation of the Hippo pathway. Furthermore, single nucleotide mutations observed in DGC patients that ablate the homophilic binding capacity of E-cadherin reverse the ability of E-cadherin to suppress ferroptosis in both cell culture and xenograft models. Importantly, although E-cadherin loss in cancer cells is considered an essential event for epithelial-mesenchymal transition and subsequent metastasis, we found that circulating DGC cells lacking E-cadherin expression possess lower metastatic ability, due to their increased susceptibility to ferroptosis. Together, this study suggests that E-cadherin is a biomarker predicting the sensitivity to ferroptosis of DGC cells, both in primary tumor tissue and in circulation, thus guiding the usage of future ferroptosis-inducing therapeutics for the treatment of DGC.

The hypoxia-inducible factor-1α in stemness and resistance to chemotherapy in gastric cancer: Future directions for therapeutic targeting

Hypoxia-inducible factor-1α (HIF-1α) is a crucial mediator of intra-tumoral heterogeneity, tumor progression, and unresponsiveness to therapy in tumors with hypoxia. Gastric tumors, one of the most aggressive tumors in the clinic, are highly enriched in hypoxic niches, and the degree of hypoxia is strongly correlated with poor survival in gastric cancer patients. Stemness and chemoresistance in gastric cancer are the two root causes of poor patient outcomes. Based on the pivotal role of HIF-1α in stemness and chemoresistance in gastric cancer, the interest in identifying critical molecular targets and strategies for surpassing the action of HIF-1α is expanding. Despite that, the understanding of HIF-1α induced signaling in gastric cancer is far from complete, and the development of efficacious HIF-1α inhibitors bears various challenges. Hence, here we review the molecular mechanisms by which HIF-1α signaling stimulates stemness and chemoresistance in gastric cancer, with the clinical efforts and challenges to translate anti-HIF-1α strategies into the clinic.

Tissue factor-induced fibrinogenesis mediates cancer cell clustering and multiclonal peritoneal metastasis

Peritoneal metastasis is one of the most frequent causes of death in several types of advanced cancers; however, the underlying molecular mechanisms remain largely unknown. In this study, we exploited multicolor fluorescent lineage tracking to investigate the clonality of peritoneal metastasis in mouse xenograft models. When peritoneal metastasis was induced by intraperitoneal or orthotopic injection of multicolored cancer cells, each peritoneally metastasized tumor displayed multicolor fluorescence regardless of metastasis sites, indicating that it consists of multiclonal cancer cell populations. Multicolored cancer cell clusters form within the peritoneal cavity and collectively attach to the peritoneum. In vitro, peritoneal lavage fluid or cleared ascitic fluid derived from cancer patients induces cancer cell clustering, which is inhibited by anticoagulants. Cancer cell clusters formed in vitro and in vivo are associated with fibrin formation. Furthermore, tissue factor knockout in cancer cells abrogates cell clustering, peritoneal attachment, and peritoneal metastasis. Thus, we propose that cancer cells activate the coagulation cascade via tissue factor to form fibrin-mediated cell clusters and promote peritoneal attachment; these factors lead to the development of multiclonal peritoneal metastasis and may be therapeutic targets.

Gastric Cancer Risk and Pathogenesis in BRCA1 and BRCA2 Carriers

Carriers of a pathogenic germline variant (PV) in BRCA1 or BRCA2 are at increased risk for a number of malignancies, including breast, ovarian, pancreatic, and prostate cancer. In this review, we discuss emerging evidence that BRCA2 PV carriers, and likely also BRCA1 PV carriers, are also at increased risk for gastric cancer (GC), highlighting that GC may be part of the BRCA1/2 cancer risk spectrum. While the pathogenesis of GC among BRCA1/2 PV carriers remains unclear, increasing evidence reveals that GCs are often enriched with mutations in homologous recombination-associated genes such as BRCA1/2, and that GC prognosis and response to certain therapies can depend on BRCA1/2 expression. Given the strength of data published to date, a risk management strategy for GC among BRCA1/2 PV carriers is needed, and herein we also propose a potential strategy for GC risk management in this population. Moving forward, further study is clearly warranted to define the mechanistic relationship between BRCA1/2 PVs and development of GC as well as to determine how GC risk management should be factored into the clinical care of BRCA1/2 carriers.

Oncolytic virus: A catalyst for the treatment of gastric cancer

Gastric cancer (GC) is a leading contributor to global cancer incidence and mortality. According to the GLOBOCAN 2020 estimates of incidence and mortality for 36 cancers in 185 countries produced by the International Agency for Research on Cancer (IARC), GC ranks fifth and fourth, respectively, and seriously threatens the survival and health of people all over the world. Therefore, how to effectively treat GC has become an urgent problem for medical personnel and scientific workers at this stage. Due to the unobvious early symptoms and the influence of some adverse factors such as tumor heterogeneity and low immunogenicity, patients with advanced gastric cancer (AGC) cannot benefit significantly from treatments such as radical surgical resection, radiotherapy, chemotherapy, and targeted therapy. As an emerging cancer immunotherapy, oncolytic virotherapies (OVTs) can not only selectively lyse cancer cells, but also induce a systemic antitumor immune response. This unique ability to turn unresponsive 'cold' tumors into responsive 'hot' tumors gives them great potential in GC therapy. This review integrates most experimental studies and clinical trials of various oncolytic viruses (OVs) in the diagnosis and treatment of GC. It also exhaustively introduces the concrete mechanism of invading GC cells and the viral genome composition of adenovirus and herpes simplex virus type 1 (HSV-1). At the end of the article, some prospects are put forward to determine the developmental directions of OVTs for GC in the future.

Association between Body Mass Index and Risk of Gastric Cancer by Anatomic and Histologic Subtypes in Over 500,000 East and Southeast Asian Cohort Participants

BACKGROUND

This study was performed to investigate the association between body mass index (BMI) and gastric cancer in East and Southeast Asia where most of gastric cancer is non-cardia gastric cancer.

METHODS

On the basis of 8,997 gastric cancer cases among the Asia Cohort Consortium participants from China, Japan, Korea, and Singapore (N = 538,835), we assessed gastric cancer risk according to BMI by calculating hazard ratios (HR) and 95% confidence intervals (CI) using the Cox proportional hazard regression model.

RESULTS

A U-shaped associations between BMI and gastric cancer risk were observed. Gastric cancer risks in underweight group (&lt;18.5 kg/m2) and in obesity group (≥27.5 kg/m2) were higher than reference BMI group (23-24.9 kg/m2; HR, 1.15; 95% CI, 1.05-1.25 for underweight; HR, 1.12; 95% CI, 1.03-1.22 for obesity, respectively). The associations of underweight and obesity with gastric cancer risk were consistent in the analyses for non-cardia gastric cancer, intestinal-type gastric cancer, and late-onset gastric cancer. No significant association of underweight and obesity with the risk of cardia gastric cancer, diffuse-type gastric cancer, and early-onset gastric cancer was observed. In addition, we found that the U-shaped association between BMI and gastric cancer risk remained in nonsmokers, while only underweight was related to increased gastric cancer risk in smokers.

CONCLUSIONS

BMI has a U-shaped association with gastric cancer risk in East and Southeast Asian population, especially for the non-cardia gastric cancer, intestinal-type gastric cancer, and late-onset gastric cancer.

IMPACT

Future studies with consideration of anatomic location and histology of gastric cancer are needed to establish the association of underweight as well as obesity with gastric cancer risk.

Tumorigenic mechanisms of estrogen and Helicobacter pylori cytotoxin-associated gene A in estrogen receptor α-positive diffuse-type gastric adenocarcinoma

BACKGROUND

Diffuse-type gastric cancer (DGC), for which Helicobacter pylori infection is a causal factor, is associated with poor prognosis among young women, possibly due to female hormones such as estrogen. We aimed to identify the carcinogenesis induced by estrogen and H. pylori in DGC.

METHODS

We screened and selected estrogen receptor alpha (ERα)-positive (MKN45) and ERα-negative (SNU5) DGC cell lines. H. pylori strain 60190 and its isogenic mutant strain lacking cytotoxin-associated gene A (60190ΔCagA) were used to infect MKN45 cells. And the cytotoxin-related gene A (CagA) cDNA which was cloned into pSP65-SR-HA (cagA-pSP65SRa) vector was used to transfect MKN45 cells. Tumor samples were used for DGC organoid culture.

RESULTS

In MKN45 cells, we found that estradiol promotes epithelial-mesenchymal transition (EMT) and stemness phenotypes via HOTAIR expression. These effects were further enhanced by the addition of CagA secreted by H. pylori but were reversed by co-treatment with fulvestrant (ICI 182,780), a selective ER degrader. We also validated the effect of estrogen on DGC organoids. ERα expression was associated with tumor invasion and HOTAIR expression in DGC patients with overt H. pylori infection.

CONCLUSIONS

These findings may explain the rapid DGC progression in young women with physiologically high levels of estrogen and suggest that fulvestrant with ovarian function suppression could serve as a tumor-suppressive agent in premenopausal patients with DGC.

Accuracy evaluation of combining gastroscopy, multi-slice spiral CT, Her-2, and tumor markers in gastric cancer staging diagnosis

Background

To evaluate the diagnostic accuracy of single gastroscopy, multi-slice spiral CT, HER-2 or tumor markers, and their combination in the diagnosis of gastric cancer.

Methods

A total of 98 patients with gastric cancer were selected as the research subjects. All patients underwent preoperative gastroscopy, MSCT, and the expression levels of HER-2, CEA, CA199, CA724, and CA242 were detected. A control group of 98 normal adults was selected to compare the risk factors for gastric cancer and to analyze the data.

Results

There was statistical significance in the expression of the 5 markers in tumor size (P < 0.05), but no statistical significance in other clinical data (P > 0.05). The tumor marker CEA in gastric mucosal tissue of patients with gastric cancer had the highest positive detection rate for gastric cancer, and the difference was statistically significant (P < 0.05) compared with gastroscopy, MSCT and other markers. The combined diagnosis had higher sensitivity, specificity and accuracy compared with the single diagnosis of gastric cancer staging, and the difference was statistically significant (P < 0.05). Compared with normal adults, patients with gastric cancer had statistically significant differences in diet, body mass index, and family genetic history (P < 0.05), while there was no statistically significant difference in whether they had type A blood (P > 0.05).

Conclusion

The combined diagnosis of gastroscopy, MSCT, immunohistochemical marker Her-2, and tumor markers CEA, CA199, CA724, and CA242 can more accurately determine the clinical staging and lesion invasion depth of patients with gastric cancer and can significantly improve the sensitivity of diagnosis.

Diffuse-type Gastric Cancer

Gastric cancer is the most prevalent malignant tumor in Korea. Histologically, it is often classified into intestinal-type and diffuse-type. Intestinal-type gastric cancer is known to occur mainly from chronic gastritis caused by Helicobacter pylori (H. pylori) through atrophic gastritis and intestinal metaplasia, a precancerous change of the mucosa, whereas diffuse-type gastric cancer is caused by H. pylori infection, wherein active inflammation of the gastric mucosa occurs without precancerous changes in the mucosa. Compared with intestinal-type gastric cancer, it occurs at a young age, there is no difference in male to female ratio, or tends to occur more in women, and is more aggressive than intestinal-type gastric cancer. Intestinal-type gastric cancer is predominant in East Asian populations such as Koreans and Japanese, whereas diffuse-type gastric cancer has more uniform geographic distribution. In the present manuscript, I have reviewed diffuse-type gastric cancer, distinct from intestinal-type gastric cancer.

Sex-based differences in histology, staging, and prognosis among 2983 gastric cancer surgery patients

BACKGROUND

Few studies have been conducted on sex differences in the incidence, pathophysiology, and prognosis of gastric cancer (GC).

AIM

To analyze the differences in GC characteristics according to sex in patients who underwent surgical treatment for GC.

METHODS

A total of 2983 patients diagnosed with gastric adenocarcinoma who received surgical treatment at the Seoul National University Bundang Hospital between 2003 and 2017 were included. Baseline clinicopathological characteristics, histologic type of GC, overall and GC-specific survival rates, and associated risk factors were analyzed.

RESULTS

Among the 2983 patients, 2005 (67.2%) and 978 (32.8%) were males and females, respectively. The average age of the female group (59.36 years) was significantly younger than that of the male group (61.66 years; P < 0.001). Cancer of the gastric body (P < 0.001) and diffuse-type histology (P < 0.001) were more common in females than in males. This trend was more prominent in females younger than 60 years of age, with a significantly higher proportion of diffuse-type cancer than in the male group. Regardless of sex, diffuse-type GC was more common in younger patients, and the proportion of intestinal-type GC increased with age. The overall survival rate was significantly higher in females (P < 0.001). However, this difference disappeared for GC-specific survival (P = 0.168), except for the poor GC-specific survival rate in advanced-stage cancer (stage III or above) in females (P = 0.045). The risk factors for GC-related mortality were older age, upper location of GC, and diffuse- or mixed-type histology. In terms of comorbidities, more males died from diseases other than GC, including other malignancies such as lung cancer, hepatocellular carcinoma, and pancreatic cancer, and respiratory diseases such as interstitial lung disease and chronic obstructive pulmonary disease, while there were relatively more cardiovascular or cerebrovascular deaths in females.

CONCLUSION

Sex-based differences in GC were observed in clinicopathological features, including age at diagnosis, tumor location, histologic type, survival rate, and comorbidities.

E-Cadherin Modulation and Inter-Cellular Trafficking in Tubular Gastric Adenocarcinoma: A High-Resolution Microscopy Pilot Study

Despite the numerous advances in tumor molecular biology and chemotherapy options, gastric adenocarcinoma is still the most frequent form of gastric cancer. One of the core proteins that regulates inter-cellular adhesion, E-cadherin plays important roles in tumorigenesis as well as in tumor progression; however, the exact expression changes and modulation that occur in gastric cancer are not yet fully understood. In an attempt to estimate if the synthesis/degradation balance matches the final membrane expression of this adhesion molecule in cancer tissue, we assessed the proportion of E-cadherin that is found in the Golgi vesicles as well as in the lysosomal pathway We utilized archived tissue fragments from 18 patients with well and poorly differentiated intestinal types of gastric cancer and 5 samples of normal gastric mucosa, by using high-magnification multispectral microscopy and high-resolution fluorescence deconvolution microscopy. Our data showed that E-cadherin is not only expressed in the membrane, but also in the cytoplasm of normal and tumor gastric epithelia. E-cadherin colocalization with the Golgian vesicles seemed to be increasing with less differentiated tumors, while co-localization with the lysosomal system decreased in tumor tissue; however, the membrane expression of the adhesion molecule clearly dropped from well to poorly differentiated tumors. Thus E-cadherin seems to be more abundantly synthetized than eliminated via lysosomes/exosomes in less differentiated tumors, suggesting that post-translational modifications, such as cleavage, conformational inactivation, or exocytosis, are responsible for the net drop of E-cadherin at the level of the membrane in more anaplastic tumors. This behavior is in perfect accordance with the concept of partial epithelial-to-mesenchymal transition (P-EMT), when the E-cadherin expression of tumor cells is in fact not downregulated but redistributed away from the membrane in recycling vesicles. Moreover, our high-resolution deconvolution microscopy study showed for the first time, at the tissue level, the presence of Lysosome-associated membrane glycoprotein 1 (LAMP1)-positive exosomes/multivesicular bodies being trafficked across the membranes of tumor epithelial cells. Altogether, a myriad of putative modulatory pathways is available as a treatment turning point, even if we are to only consider the metabolism of membrane E-cadherin regulation. Future super-resolution microscopy studies are needed to clarify the extent of lysosome/exosome exchange between tumor cells and with the surrounding stroma, in histopathology samples or even in vivo.

An Insight into miR-1290: An Oncogenic miRNA with Diagnostic Potential

For more than two decades, the view of the roles of non-coding RNAs (ncRNAs) has been radically changing. These RNA molecules that are transcribed from our genome do not have the capacity to encode proteins, but are critical regulators of gene expression at different levels. Our knowledge is constantly enriched by new reports revealing the role of these new molecular players in the development of many pathological conditions, including cancer. One of the ncRNA classes includes short RNA molecules called microRNAs (miRNAs), which are involved in the post-transcriptional control of gene expression affecting various cellular processes. The aberrant expression of miRNAs with oncogenic and tumor-suppressive function is associated with cancer initiation, promotion, malignant transformation, progression and metastasis. Oncogenic miRNAs, also known as oncomirs, mediate the downregulation of tumor-suppressor genes and their expression is upregulated in cancer. Nowadays, miRNAs show promising application in diagnosis, prediction, disease monitoring and therapy response. Our review presents a current view of the oncogenic role of miR-1290 with emphasis on its properties as a cancer biomarker in clinical medicine.

Single-cell RNA sequencing reveals a pro-invasive cancer-associated fibroblast subgroup associated with poor clinical outcomes in patients with gastric cancer

Background: The protumor activities of cancer-associated fibroblasts (CAFs) suggest that they are potential therapeutic targets for the treatment of cancer. The mechanism of CAF heterogeneity in gastric cancer (GC) remains unclear and has slowed translational advances in targeting CAFs. Therefore, a comprehensive understanding of the classification, function, activation stage, and spatial distribution of the CAF subsets in GC is urgently needed. Methods: In this study, the characteristics of the CAF subsets and the dynamic communication among the tumor microenvironment (TME) components regulated by the CAF subsets were analyzed by performing single-cell RNA sequencing of eight pairs of GC and adjacent mucosal (AM) samples. The spatial distribution of the CAF subsets in different Lauren subtypes of GC, as well as the neighborhood relations between these CAF subsets and the protumor immune cell subsets were evaluated by performing multistaining registration. Results: Tumor epithelial cells exhibited significant intratumor and intertumor variabilities, while CAFs mainly exhibited intratumor variability. Moreover, we identified four CAF subsets with different properties in GC. These four CAF subsets shared similar properties with their resident fibroblast counterparts in the adjacent mucosa but also exhibited enhanced protumor activities. Additionally, two CAF subsets, inflammatory CAFs (iCAFs) and extracellular matrix CAFs (eCAFs), communicated with adjacent immune cell subsets in the GC TME. iCAFs interacted with T cells by secreting interleukin (IL)-6 and C-X-C motif chemokine ligand 12 (CXCL12), while eCAFs correlated with M2 macrophages via the expression of periostin (POSTN). eCAFs, which function as a pro-invasive CAF subset, decreased the overall survival time of patients with GC. Conclusions: iCAFs and eCAFs not only exhibited enhanced pro-invasive activities but also mobilized the surrounding immune cells to construct a tumor-favorable microenvironment. Therefore, inhibiting their activation restrains the GC 'seed' and simultaneously improves the 'GC' soil, suggesting that it represents a promising therapeutic strategy for the treatment of GC.

Diagnosis of MALT Lymphoma from Surveillance Endoscopy of a Patient with a CDH1 Gene Germline Mutation

Carriers of the mutated CDH1 gene have an increased risk of developing early-onset signet-ring cell (diffuse) gastric cancer. We present a case of a young patient with a confirmed mutation of the CDH1 gene, who was diagnosed with a gastric marginal zone B-cell lymphoma (MZL) of mucosa-associated lymphoid tissue (MALT lymphoma) from surveillance endoscopy. He underwent Helicobacter pylori eradication treatment and was subsequently submitted to a total prophylactic gastrectomy. The surgical specimen only revealed foci of signet-ring cell carcinoma (SRCC) in situ without lymphoma signs. We highlight here the occurrence of other pathology in high-risk patients as well as its possible influence on the decision to perform gastrectomy.

Methylation and polymorphism in CDH1 gene promoter among patients with diffuse gastric cancer

Background:

The promoter methylation and single nucleotide polymorphisms (SNPs) affect the transcription activity of cancer-related genes in several cancers including diffuse gastric cancer (DGC). Here we aimed to evaluate the promoter methylation status and the rs16260 at the promoter region of the CDH1 gene in DGC.

Methods:

This case-control study was performed of 48 formalin-fixed paraffin-embedded (FFPE) blocks of DGC patients and 41 fresh frozen tissue samples of healthy individuals. Methylation status was evaluated using methylation-specific polymerase chain reaction (PCR) and the rs16260 at the promoter region of the CDH1 gene was assessed using PCR and sequencing method.

Results:

The occurrence of methylation at the promoter region of the CDH1 gene in DGC patients was significantly higher than control samples (P < 0.0001). The methylated status was significantly associated with the poor differentiated histological type of DGC (P = 0.0428). The frequency of AC genotype and the A allele in DGC patients was significantly higher than the control subjects (P = 0.006 and 0.003, respectively).

Conclusions:

Here we showed that methylation at the CDH1 promoter may contribute to the DGC development, and also the AC genotype was associated with the risk of DGC.

Integrin α5 mediates cancer cell-fibroblast adhesion and peritoneal dissemination of diffuse-type gastric carcinoma

Diffuse-type gastric carcinoma (DGC) has a poor prognosis due to its rapid diffusive infiltration and frequent peritoneal dissemination. DGC is associated with massive fibrosis caused by aberrant proliferation of cancer-associated fibroblasts (CAFs). Previously, we reported that direct heterocellular interaction between cancer cells and CAFs is important for the peritoneal dissemination of DGC. In this study, we aimed to identify and target the molecules that mediate such heterocellular interactions. Monoclonal antibodies (mAbs) against intact DGC cells were generated and subjected to high-throughput screening to obtain several mAbs that inhibit the adhesion of DGC cells to CAFs. Immunoprecipitation and mass spectrometry revealed that all mAbs recognized integrin α5 complexed with integrin β1. Blocking integrin α5 in DGC cells or fibronectin, a ligand of integrin α5β1, deposited on CAFs abrogated the heterocellular interaction. Administration of mAbs or knockout of integrin α5 in DGC cells suppressed their invasion led by CAFs in vitro and peritoneal dissemination in a mouse xenograft model. Altogether, these findings demonstrate that integrin α5 mediates the heterotypic cancer cell-fibroblast interaction during peritoneal dissemination of DGC and may thus be a therapeutic target.

Effects of Cynaroside on Cell Proliferation, Apoptosis, Migration and Invasion though the MET/AKT/mTOR Axis in Gastric Cancer

The Chinese medicine monomer cynaroside (Cy) is a flavonoid glycoside compound that widely exists in plants and has a variety of pharmacological effects, such as its important role in the respiratory system, cardiovascular system and central nervous system. Studies have reported that Cy has varying degrees of anticancer activity in non-small cell lung cancer, cervical cancer, liver cancer, esophageal cancer and other cancers. However, there are no relevant reports about its role in gastric cancer. The MET/AKT/mTOR signaling pathway plays important roles in regulating various biological processes, including cell proliferation, apoptosis, autophagy, invasion and tumorigenesis. In this study, we confirmed that Cy can inhibit the cell growth, migration and invasion and tumorigenesis in gastric cancer. Our finding shows that Cy can block the MET/AKT/mTOR axis by decreasing the phosphorylation level of AKT, mTOR and P70S6K. Therefore, the MET/AKT/mTOR axis may be an important target for Cy. In summary, Cy has anti-cancer properties and is expected to be a potential drug for the treatment of gastric cancer.

Comparative effectiveness and tolerability of targeted agents combined with chemotherapy in patients with HER2-positive gastroesophageal cancer: A network meta-analysis

BACKGROUND

Gastric cancer (GC) or gastroesophageal junction (GEJ) cancer with HER2 overexpression is highly invasive, with a poor prognosis. With the development of new targeted agents, which agents have ideal therapeutic effects must be determined. This network meta-analysis analyzed the effectiveness and tolerability of targeted agents combined with chemotherapy in HER2-positive GC/GEJ cancer.

METHODS

Public databases were searched from the date of inception to October 22, 2020. Randomized controlled trials (RCTs) on targeted agent-related regimens for HER2-positive advanced GC or GEJ cancer were included. Subgroup analyses based on publication language, first-line treatment, second/third-line treatment, and HER2 staining intensity were performed.

RESULTS

In total, 13 articles were included. The trastuzumabderuxtecan (TraD) and pertuzumab plus trastuzumab and chemotherapy (PerTraChemo) regimens were considered to have high effectiveness but low tolerability. In the subgroup analysis, PerTraChemo still had high effectiveness with low tolerability as the first-line therapy. As the second- or third-line therapy, TraD and lapatinib plus chemotherapy (LapChemo) had high effectiveness and moderate tolerability. In terms of overall survival (OS) time, PerTraChemo had a relative advantage in the immunohistochemistry (IHC) 2+/in situ hybridization (ISH)+ population, whereas TraD, PerTraChemo, and trastuzumab plus chemotherapy (TraChemo) had a relative advantage in the IHC3+ population.

CONCLUSION

TraD had relative advantages as the second- or third-line therapy and in the IHC3 + population. PerTraChemo is a potential first-line therapy, but it requires further confirmation because the JACOB phase III clinical trial failed to confirm the superiority of PerTraChemo over TraChemo with regard to OS.

Aberrant expression of SFRP1, SFRP3, DVL2 and DVL3 Wnt signaling pathway components in diffuse gastric carcinoma

Diffuse gastric carcinoma (DGC) is characterized by poorly cohesive cells, highly invasive growth patterns, poor prognosis and resistance to the majority of available systemic therapeutic strategies. It has been previously reported that the Wnt/β-catenin signaling pathway serves a prominent role in the tumorigenesis of gastric carcinoma. However, the mechanism underlying the dysregulation of this pathway in DGC has not been fully elucidated. Therefore, the present study aimed to investigate the expression profiles of Wnt antagonists, secreted frizzled-related protein 1 (SFRP1) and secreted frizzled-related protein 3 (SFRP3), and dishevelled protein family members, dishevelled segment polarity protein 2 (DVL2) and dishevelled segment polarity protein 3 (DVL3), in DGC tissues. The association between the expression levels of these factors and the clinicopathological parameters of the patients was determined. Protein and mRNA expression levels in 62 DGC tumor tissues and 62 normal gastric mucosal tissues obtained from patients with non-malignant disease were measured using immunohistochemical and reverse transcription-quantitative PCR (RT-qPCR) analysis. Significantly lower protein expression levels of SFRP1 (P<0.001) and SFRP3 (P<0.001), but significantly higher protein expression levels of DVL2 (P<0.001) and DVL3 (P<0.001) were observed in DGC tissues compared with in control tissues by immunohistochemistry. In addition, significantly lower expression levels of SFRP1 (P<0.05) and higher expression levels of DVL3 (P<0.05) were found in in DGC tissues compared with those in normal gastric mucosal tissues using RT-qPCR. According to correlation analysis between the SFRP1, SFRP3, DVL2 and DVL3 protein expression levels and the clinicopathological characteristics of patients with DGC, a statistically significant correlation was found between the SFRP3 volume density and T stage (r=0.304; P=0.017) and between the SFRP3 volume density and clinical stage (r=0.336; P=0.008). In conclusion, the findings of the present study suggested that the Wnt signaling pathway components SFRP1, SFRP3, DVL2 and DVL3 may be aberrantly expressed in DGC tissues, implicating their possible role in the development of this malignant disease. The present data also revealed a positive relationship between SFRP3 protein expression and the clinical and T stage of DGC.

Expression of Four Autophagy-Related Genes Accurately Predicts the Prognosis of Gastrointestinal Cancer in Asian Patients

Gastrointestinal (GI) cancers are among the most fatal diseases in the world. Numerous studies have demonstrated the relationship between autophagy and development of gastrointestinal cancers. However, whether autophagy-related genes can predict prognosis of GI cancers in individuals of Asian ancestry has not been defined. This study, evaluated the prognostic value of autophagy-related genes in gastrointestinal cancer. Expression profile of autophagy-related genes for 296 gastrointestinal cancer patients of Asian ancestry was downloaded from the TCGA database (TCGA-LIHC, TCGA-STAD, TCGA-ESCA, TCGA-PAAD, TCGA-COAD, TCGA-CHOL, and TCGA-READ). The prognostic value of the autophagy-related genes was evaluated using univariate Cox, LASSO, and multivariate Cox regression analyses. The risk score of the autophagy-related gene signature was calculated to assess its predictive prognostic value for GI cancers. Forty-seven differentially expressed autophagy-related genes, in Asian patients with gastrointestinal cancers, were identified. Of the 47 genes, 4 were associated with prognosis of GI cancer (SQSTM1, BIRC5, NRG3, and CXCR4). A prognostic model for GI cancer, based on the expression of the above 4 genes in the training set, showed that cancer patients were stratified into high-risk and low-risk groups (P < 0.05). The utility of the model for overall survival (OS) of GI cancer patients was consistent across the entire set, training set, and test set (entire set: P = 4.568 × 10⁻⁴; train set: P = 5.718 × 10⁻³; test set: P = 3.516 × 10⁻²). The sensitivity and specificity of the ROC curve of the above prognostic model in predicting the 5-year prognosis of GI cancer was satisfactory (entire set: 0.728; train set: 0.727; test set: 0.733). Analysis of clinical samples validated the overexpression of the 4 genes (SQSTM1, BIRC5, NRG3, and CXCR4) in tumor tissues relative to paired normal tissues, consistent with bioinformatic findings. Expression of the 4 autophagy-related genes (SQSTM1, BIRC5, NRG3, and CXCR4) can accurately predict the prognosis of gastrointestinal tumors in Asian patients.

Knockdown of hsa_circ_0091994 constrains gastric cancer progression by suppressing the miR-324-5p/HMGA1 axis

CircRNAs have emerged as potential therapeutic targets for diseases such as gastric cancer (GC). We identified highly dysregulated circRNAs in GC tissue and further explored their potential mechanisms in the progression of GC. Hsa_circ_0091994 (cicrRNA_105040) was identified as a highly upregulated circRNA in GC tissues, whose host gene is negatively associated with the overall survival of patients. Using cell counting kit-8 and Annexin V assays, we observed that hsa_circ_0091994 knockdown inhibited the viability of AGS and HGC-27 cells by inducing apoptosis. Scratch wound healing assays showed that hsa_circ_0091994 knockdown also inhibited GC cell healing. Bioinformatics analysis and a luciferase assays revealed that hsa_circ_0091994 knockdown inhibits GC progression by suppressing miR-324-5p and HMGA1 expression. The antitumor effect of hsa_circ_0091994 knockdown was confirmed in vivo using a mouse xenograft model. Hsa_circ_0091994 knockdown inhibited the progression of GC by inhibiting the miR-324-5p/HMGA1 axis.

Sp1-Induced FNBP1 Drives Rigorous 3D Cell Motility in EMT-Type Gastric Cancer Cells

Cancer is heterogeneous among patients, requiring a thorough understanding of molecular subtypes and the establishment of therapeutic strategies based on its behavior. Gastric cancer (GC) is adenocarcinoma with marked heterogeneity leading to different prognoses. As an effort, we previously identified a stem-like subtype, which is prone to metastasis, with the worst prognosis. Here, we propose FNBP1 as a key to high-level cell motility, present only in aggressive GC cells. FNBP1 is also up-regulated in both the GS subtype from the TCGA project and the EMT subtype from the ACRG study, which include high portions of diffuse histologic type. Ablation of FNBP1 in the EMT-type GC cell line brought changes in the cell periphery in transcriptomic analysis. Indeed, loss of FNBP1 resulted in the loss of invasive ability, especially in a three-dimensional culture system. Live imaging indicated active movement of actin in FNBP1-overexpressed cells cultured in an extracellular matrix dome. To find the transcription factor which drives FNBP1 expression in an EMT-type GC cell line, the FNBP1 promoter region and DNA binding motifs were analyzed. Interestingly, the Sp1 motif was abundant in the promoter, and pharmacological inhibition and knockdown of Sp1 down-regulated FNBP1 promoter activity and the transcription level, respectively. Taken together, our results propose Sp1-driven FNBP1 as a key molecule explaining aggressiveness in EMT-type GC cells.

E-Cadherin expression in human tumors: a tissue microarray study on 10,851 tumors

BACKGROUND

The E-Cadherin gene (CDH1, Cadherin 1), located at 16q22.1 encodes for a calcium-dependent membranous glycoprotein with an important role in cellular adhesion and polarity maintenance.

METHODS

To systematically determine E-Cadherin protein expression in normal and cancerous tissues, 14,637 tumor samples from 112 different tumor types and subtypes as well as 608 samples of 76 different normal tissue types were analyzed by immunohistochemistry in a tissue microarray format.

RESULTS

E-Cadherin was strongly expressed in normal epithelial cells of most organs. From 77 tumor entities derived from cell types normally positive for E-Cadherin, 35 (45.5%) retained at least a weak E-Cadherin immunostaining in ≥99% of cases and 61 (79.2%) in ≥90% of cases. Tumors with the highest rates of E-Cadherin loss included Merkel cell carcinoma, anaplastic thyroid carcinoma, lobular carcinoma of the breast, and sarcomatoid and small cell neuroendocrine carcinomas of the urinary bladder. Reduced E-Cadherin expression was linked to higher grade (p = 0.0009), triple negative receptor status (p = 0.0336), and poor prognosis (p = 0.0466) in invasive breast carcinoma of no special type, triple negative receptor status in lobular carcinoma of the breast (p = 0.0454), advanced pT stage (p = 0.0047) and lymph node metastasis in colorectal cancer (p < 0.0001), and was more common in recurrent than in primary prostate cancer (p < 0.0001). Of 29 tumor entities derived from E-Cadherin negative normal tissues, a weak to strong E-Cadherin staining could be detected in at least 10% of cases in 15 different tumor entities (51.7%). Tumors with the highest frequency of E-Cadherin upregulation included various subtypes of testicular germ cell tumors and renal cell carcinomas (RCC). E-Cadherin upregulation was more commonly seen in malignant than in benign soft tissue tumors (p = 0.0104) and was associated with advanced tumor stage (p = 0.0276) and higher grade (p = 0.0035) in clear cell RCC, and linked to advanced tumor stage (p = 0.0424) and poor prognosis in papillary RCC (p ≤ 0.05).

CONCLUSION

E-Cadherin is consistently expressed in various epithelial cancers. Down-regulation or loss of E-Cadherin expression in cancers arising from E-Cadherin positive tissues as well as E-Cadherin neo-expression in cancers arising from E-Cadherin negative tissues is linked to cancer progression and may reflect tumor dedifferentiation.

Optimal care and survival for signet-ring cell and non-signet-ring cell gastric cancer are more achievable at academic cancer centers

BACKGROUND

Western literature lacks large-scale population studies comparing the influence of academic and high-volume (HV) versus low-volume (LV) cancer centers on gastric cancer oncologic outcomes.

METHODS

The National Cancer Database from 2004 to 2016 was used.

RESULTS

22871 patients were studied. Patients with stage III signet-ring cell gastric carcinoma (SRGC) received neoadjuvant treatment (NAT) more frequently at academic and HV comprehensive cancer centers (OR: 4.27 and 2.42; p < 0.0001 and 0.009) compared to community centers. Patients with stage III non-SRGC (NSRGC) had a 2.4 times higher odds of receiving NAT at academic centers. The R1 resection rate for NSRGC was lower at academic centers (OR: 0.67; p = 0.0018). Lymph node harvest ≥15 nodes was 1.6 and 1.9 times higher at academic centers for NSRGC and SRGC, respectively. Patients treated at academic centers had a significantly improved overall survival (OS).

CONCLUSIONS

Treatment at academic centers is associated with significant improvements in oncologic metrics and OS.

Partial Gastrectomy is Associated with Improved Overall Survival in Signet-Ring Cell Gastric Cancer

BACKGROUND

Signet-ring cell gastric cancer (SRGC) is a histological variant of gastric adenocarcinoma (GAC) with a worse prognosis compared to non-signet-ring cell gastric cancer (NSRGC). To our knowledge, the overall survival (OS) among patients with SRGC undergoing total/near-total (TG) versus partial gastrectomy (PG) has never been reported from a large-scale Western database.

METHODS

We performed a retrospective analysis of patients with both SRGC and NSRGC using The National Cancer Database.

RESULTS

In total, 17,086 patients were included. Patients who underwent TG versus PG were 25.5% (n = 770) versus 74.5% (n = 2246) for SRGC, and 20.9% (n = 2943) versus 79.1% (n = 11,127) for NSRGC, respectively. Patients who had SRGC were more likely to undergo TG (25.5% versus 20.9% P< 0.0001). Patients with distal gastric tumors were less likely to undergo TG (16.5% versus 25.4% P < 0.0001). Patients undergoing PG for the SRGC histological variant had better OS (HR = 0.68, CI=0.61-0.76; P < 0.0001) versus those who underwent TG. Similarly, NSRGC patients undergoing PG also had improved OS, but to a lesser extent (HR = 0.91, CI = 0.85-0.96; P= 0.002). Overall, PG for GAC was associated with improved OS compared to TG, although the OS benefit is more profound in the SRGC histological variant (P < 0.0001).

CONCLUSIONS

Our results show that TG is not associated with improved OS in patients who undergo gastrectomy for GAC, even when adjusted for tumor location. The survival differences are more pronounced in the SRGC histology variant. The worst survival is observed in patients with SRGC who undergo TG after adjusting for different covariates.

Helicobacter pylori Outer Membrane Vesicles and Extracellular Vesicles from Helicobacter pylori-Infected Cells in Gastric Disease Development

Extracellular vesicles (EVs) are cell-derived vesicles important in intercellular communication that play an essential role in host-pathogen interactions, spreading pathogen-derived as well as host-derived molecules during infection. Pathogens can induce changes in the composition of EVs derived from the infected cells and use them to manipulate their microenvironment and, for instance, modulate innate and adaptive inflammatory immune responses, both in a stimulatory or suppressive manner. Gastric cancer is one of the leading causes of cancer-related deaths worldwide and infection with Helicobacter pylori (H. pylori) is considered the main risk factor for developing this disease, which is characterized by a strong inflammatory component. EVs released by host cells infected with H. pylori contribute significantly to inflammation, and in doing so promote the development of disease. Additionally, H. pylori liberates vesicles, called outer membrane vesicles (H. pylori-OMVs), which contribute to atrophia and cell transformation in the gastric epithelium. In this review, the participation of both EVs from cells infected with H. pylori and H. pylori-OMVs associated with the development of gastric cancer will be discussed. By deciphering which functions of these external vesicles during H. pylori infection benefit the host or the pathogen, novel treatment strategies may become available to prevent disease.

Long noncoding RNA GAS8-AS1: A novel biomarker in human diseases

Long non-coding RNAs (lncRNAs) represent a group of ncRNAs with more than 200 nucleotides. These RNAs can specifically regulate gene expression at both the transcriptional and the post-transcriptional levels, and increasing evidence indicates that they play vital roles in a variety of disease-related cellular processes. The lncRNA GAS8 antisense RNA 1 (GAS8-AS1, also known as C16orf3) is located in the second intron of GAS8 and has been reported to be both abnormally expressed in several diseases and closely correlated with many clinical characteristics. GAS8-AS1 has been shown to affect many biological functions, including cell proliferation, migration, invasiveness, and autophagy using several signaling pathways. In this review, we have summarized current studies on GAS8-AS1 roles in disease and discuss its potential clinical utility. GAS8-AS1 may be a promising biomarker for both diagnoses and prognoses, and a novel target for many disease therapies.

Resolving pathogenicity classification for the CDH1 c.[715G>A] (p.Gly239Arg) Variant

Hereditary Diffuse Gastric Cancer (HDGC) syndrome is associated with CDH1 germline likely pathogenic/pathogenic variants. Carriers of CDH1 germline likely pathogenic/pathogenic variants are predisposed to diffuse gastric cancer and lobular breast cancer. This study aims to classify the CDH1 c.[715G>A] missense variant identified in a diffuse gastric cancer prone family by performing splicing studies. RT-PCR and subsequent cloning experiments were performed to investigate whether this variant completely disrupts normal splicing. This variant preferentially abolishes normal splicing through activation of a cryptic 3' acceptor splice site within exon 6 of CDH1, presumably leading to a premature protein truncation within first extracellular domain repeat of E-cadherin protein. Our results contributed to evidence necessary to resolve pathogenicity classification of this variant, indicating that this variant is to be classified as pathogenic.

Preoperatively Treated Diffuse-Type Gastric Adenocarcinoma: Glucose vs. Other Energy Sources Substantially Influence Prognosis and Therapy Response

Simple Summary

The diffuse type of gastric adenocarcinoma (dGAC) generally confers a poor prognosis compared to intestinal type. Some dGACs are not avid on fluorine-18 fluoro-2-deoxy-D-glucose PET (FDG-PET) while others seem to consume glucose avidly. We analyzed the outcomes based on the avidity of the primary on baseline FDG-PET. Our data suggest that if dGACs used glucose as an energy source then the prognosis was very poor while non-glucose sources improved prognosis. Multi-platform (including metabolomics) profiling of dGACs would yield useful biologic understanding.

Abstract

Diffuse type of gastric adenocarcinoma (dGAC) generally confers a poor prognosis compared to intestinal type. Some dGACs are not avid on fluorine-18 fluoro-2-deoxy-D-glucose PET (FDG-PET) while others seem to consume glucose avidly. We analyzed the outcomes based on the avidity (high with standardized uptake value (SUV) > 3.5 or low with SUV ≤ 3.5) of the primary on baseline FDG-PET. We retrospectively selected 111 localized dGAC patients who had baseline FDG-PET (all were treated with preoperative chemotherapy and chemoradiation). FDG-PET avidity was compared with overall survival (OS) and response to therapy. The mean age was 59.4 years and with many females (47.7%). The high-SUV group (58 (52.3%) patients) and the low-SUV group (53 (47.7%) patients) were equally divided. While the median OS for all patients was 49.5 months (95% CI: 38.5–98.8 months), it was 98.0 months (95% CI: 49.5–NE months) for the low-SUV group and 36.0 months for the high-SUV (p = 0.003). While the median DFS for all patients was 38.2 months (95% CI: 27.7–97.6 months), it was 98.0 (95% CI: 36.9–NE months) months for the low-SUV group was and only 27.0 months (95% CI: 15.2–63.2 months) for the high-SUV group (p = 0.005). Clinical responses before surgery were more common in the low-SUV group but overall we observed only 4 pathologic complete responses in 111 patients. Our unique data suggest that if dGACs used glucose as an energy source then the prognosis was very poor while non-glucose sources improved prognosis. Multi-platform (including metabolomics) profiling of dGACs would yield useful biologic understanding.

Treatment at an Academic Cancer Center Confers Better Survival by Stage for Signet-Ring Cell and Non-signet-Ring Cell Gastric Cancer

BACKGROUND

The literature lacks large-scale population studies comparing survival outcomes between signet-ring cell gastric carcinoma (SRGC) and non-SRGC (NSRGC) when treatment is delivered at academic versus community cancer centers.

METHODS

The National Cancer Database (NCDB) from 2004 to 2016 was queried to examine the association between treatment facility category and overall survival of patients who underwent gastrectomy for resectable gastric adenocarcinoma (GAC).

RESULTS

The study investigated 22,871 patients. Upstaging of resectable GAC to pathologic stage 4 was more evident at community centers (3.5%) than at academic centers (2.8%) for the NSRGC variant (p = 0.211), whereas it was comparable between the two facility categories for the SRGC variant (5.9% vs 6%, respectively). Patients with pathologic stage 1 or 3 NSRGC who underwent gastrectomy at academic programs had better overall survival (OS) (hazard ratio [HR], 0.68; p < 0.0001) than those who underwent gastrectomy at community centers (HR, 0.79; p < 0.0065). Similarly, patients with stage 2 SRGC had better OS when treated at academic versus community centers (HR, 0.54; p = 0.0019). No statistically significant improvement in OS was observed between patients with stage 2 NSRGC (HR, 0.84; p = 0.083) and those with stage 3 SRGC (HR, 0.78; p = 0.054) who were treated at academic centers. No survival benefit was demonstrated for stage 1 SRGC when academic and community centers were compared (p = 0.56).

CONCLUSIONS

This is the first study based on a large-scale database in the Western population that addressed the overall survival-by-stage of two distinct GAC histologic variants. Treatment at academic centers was associated with significant improvements in OS.

Novel somatic variants in CTNNA1 gene in Iranian patients with diffuse gastric cancer

AIM

we aimed to evaluate somatic mutations of CTNNA1 in DGC patients.

BACKGROUND

Diffuse gastric cancer (DGC) is a major type of gastric cancer where most cases are sporadic diffuse gastric cancer (SDGC). It has been shown that mutations in CTNNA1 are responsible for some cases of hereditary diffuse gastric cancer (HDGC).

METHODS

In the present work, 48 formalin-fixed paraffin-embedded tissues, including samples of 38 SDGC and 10 HDGC patients were examined through Sanger sequencing approach on PCR products amplified from 18 exons and boundaries of intron/exon of CTNNA1 gene.

RESULTS

We revealed 9 novel somatic mutations in CTNNA1 gene in patients with HDGC and SDGC, from which one variant was intronic. Eight patients had at least one disease-causing mutation (16.6%). Most of the patients were in the III stage of cancer (50%). Except for one patient, histological type of the rest of mutation-harboring patients was signet ring cell carcinoma, and only one HDGC patient had CTNNA1 mutation.

CONCLUSION

Our study showed several novel variants in the CTNNA1 gene in Iranian sporadic and hereditary DGC patients, and implies that the CTNNA1 gene mutations could be involved in the pathogenesis of DGC, either hereditary or in sporadic cases.

α-E-Catenin (CTNNA1) Inhibits Cell Proliferation, Invasion and EMT of Bladder Cancer

Aim

Bladder cancer (BLCA) is an urogenital system tumor with a high morbidity. We aimed to explore the function and potential mechanism of α-E-catenin (CTNNA1) in BLCA.

Methods

The CTNNA1 expression in BLCA tissues was detected using qRT-PCR and immunohistochemistry. QRT-PCR and Western blot were performed to measure the CTNNA1 expression in BLCA cell lines. CTNNA1 expression was up-regulated in T24 and UMUC-2 cells by CTNNA1 overexpression plasmid transfection. Cell proliferation, apoptosis, migration and invasion were respectively assessed by CCK-8 assay, flow cytometry, wound healing assay and transwell assay. The expression levels of epithelial–mesenchymal transition (EMT)-related factors were tested by qRT-PCR and Western blot. BLCA nude mice models were constructed to explore the effects of CTNNA1 on BLCA in vivo. Gene set enrichment analysis (GSEA) was proceeded to identify the CTNNA1-related pathways in BLCA.

Results

The expressions of CTNNA1 were down-regulated in BLCA tissues and cell lines, and its low expression indicated poor prognosis of BLCA patients. CTNNA1 inhibited cell proliferation, migration, invasion and EMT and promoted cell apoptosis in BLCA cells. CTNNA1 enhanced E-cadherin expression and suppressed N-cadherin, snail, MMP2 and MMP9 expressions in BLCA cells, which suggested that CTNNA1 repressed EMT in BLCA cells. Moreover, CTNNA1 could inhibit tumor growth in vivo. CTNNA1 was positively associated with P53 and apoptosis pathways in BLCA cells.

Conclusion

CTNNA1 inhibited cell proliferation, migration, invasion and EMT and promoted cell apoptosis in BLCA via activating P53 and apoptosis pathways. CTNNA1 might be a novel target in BLCA therapy.

Clinical Significance of CLDN18.2 Expression in Metastatic Diffuse-Type Gastric Cancer

Purpose

Isoform 2 of tight junction protein claudin-18 (CLDN18.2) is a potential target for gastric cancer treatment. A treatment targeting CLDN18.2 has shown promising results in gastric cancer. We investigated the clinical significance of CLDN18.2 and other cell-adherens junction molecules (Rho GTPase-activating protein [RhoGAP] and E-cadherin) in metastatic diffuse-type gastric cancer (mDGC).

Materials and Methods

We evaluated CLDN18.2, RhoGAP, and E-cadherin expression using two-plex immunofluorescence and quantitative data analysis of H-scores of 77 consecutive mDGC patients who received first-line platinum-based chemotherapy between March 2015 and February 2017.

Results

CLDN18.2 and E-cadherin expression was significantly lower in patients with peritoneal metastasis (PM) than those without PM at the time of diagnosis (P=0.010 and 0.013, respectively), whereas it was significantly higher in patients who never developed PM from diagnosis to death than in those who did (P=0.001 and 0.003, respectively). Meanwhile, CLDN18.2 and E-cadherin expression levels were significantly higher in patients with bone metastasis than in those without bone metastasis (P=0.010 and 0.001, respectively). Moreover, we identified a positive correlation between the expression of CLDN18.2 and E-cadherin (P<0.001), RhoGAP and CLDN18.2 (P=0.004), and RhoGAP and E-cadherin (P=0.001). Conversely, CLDN18.2, RhoGAP, and E-cadherin expression was not associated with chemotherapy response and survival.

Conclusions

CLDN18.2 expression was reduced in patients with PM but significantly intact in those with bone metastasis. Furthermore, CLDN18.2 expression was positively correlated with other adherens junction molecules, which is clinically associated with mDGC and PM pathogenesis.

Recent Advances of Functional Proteomics in Gastrointestinal Cancers- a Path towards the Identification of Candidate Diagnostic, Prognostic, and Therapeutic Molecular Biomarkers

Gastrointestinal (GI) cancer remains one of the common causes of morbidity and mortality. A high number of cases are diagnosed at an advanced stage, leading to a poor survival rate. This is primarily attributed to the lack of reliable diagnostic biomarkers and limited treatment options. Therefore, more sensitive, specific biomarkers and curative treatments are desirable. Functional proteomics as a research area in the proteomic field aims to elucidate the biological function of unknown proteins and unravel the cellular mechanisms at the molecular level. Phosphoproteomic and glycoproteomic studies have emerged as two efficient functional proteomics approaches used to identify diagnostic biomarkers, therapeutic targets, the molecular basis of disease and mechanisms underlying drug resistance in GI cancers. In this review, we present an overview on how functional proteomics may contribute to the understanding of GI cancers, namely colorectal, gastric, hepatocellular carcinoma and pancreatic cancers. Moreover, we have summarized recent methodological developments in phosphoproteomics and glycoproteomics for GI cancer studies.

The Potential Anticancer Activity of Phytoconstituents against Gastric Cancer-A Review on In Vitro, In Vivo, and Clinical Studies

Gastric cancer belongs to the heterogeneous malignancies and, according to the World Health Organization, it is the fifth most commonly diagnosed cancer in men. The aim of this review is to provide an overview on the role of natural products of plant origin in the therapy of gastric cancer and to present the potentially active metabolites which can be used in the natural therapeutical strategies as the support to the conventional treatment. Many of the naturally spread secondary metabolites have been proved to exhibit chemopreventive properties when tested on the cell lines or in vivo. This manuscript aims to discuss the pharmacological significance of both the total extracts and the single isolated metabolites in the stomach cancer prevention and to focus on their mechanisms of action. A wide variety of plant-derived anticancer metabolites from different groups presented in the manuscript that include polyphenols, terpenes, alkaloids, or sulphur-containing compounds, underlines the multidirectional nature of natural products.

Targeting DNA and mutant p53 by a naphthalimide derivative, NA20, exhibits selective inhibition in gastric tumorigenesis by blocking mutant p53-EGFR signaling pathway

Mutations of p53 in cancer cells not only subvert its antiproliferative properties but can also promote various oncogenic responses through a gain-of-function activity. Pharmacological manipulation of the mutant p53 pathway by specific compounds could be an effective strategy for cancer therapy. We show here that gain-of-function p53 mutation in gastric cancer cells promotes tumorigenesis by enhancing p53-EGFR (epidermal growth factor receptor) signaling pathway, and such process can be blocked by small molecule NA20, a naphthalimide derivative that exhibited selective inhibition in p53 mutant gastric cancer cell lines. We found that targeting DNA and blocking the mutant p53-drived carcinogenicity accounted for the primary antitumor effect of NA20 in gastric tumor models. NA20 bound to DNA and p53 identified by a combination of drug tracking, DNA relaxation assay and coimmunoprecipitation-mass spectrometry (CoIP-MS) detection, which led to the p21 activation and the suppression of EGFR signal cascading, thereby evoking cell cycle arrest and cell apoptosis, finally leading to cancer cell inhibition both in vitro and in vivo. Taken together, these results suggest that NA20 may be a potential candidate for gastric cancer therapy.