Intestinal-type Gastric Cancer Research Articles

Prognostic value and association of Lauren classification with VEGF and VEGFR-2 expression in gastric cancer.

Gastric cancer (GC) is one of the most common malignant tumors in the world. As anti-angiogenic therapy shows efficacy in the treatment of GC, but only works in certain patients, the identification of potential beneficiaries are urgently required in order to apply appropriate treatments. The Lauren classification demonstrates numerous differences in etiology, epidemiology and pathology; however, the association between Lauren classification and pro-angiogenic factors remains unclear. The present study aimed to investigate the clinicopathological factors associated with Lauren classification and the prognostic significance of Lauren classification and vascular endothelial growth factor (VEGF) and VEGF receptor-2 (VEGFR-2) expression in GC. Paraffin-embedded GC tissues and clinical information of 255 patients with GC were collected. The clinicopathological factors associated with Lauren classification were evaluated by Logistic regression analysis. Kaplan-Meier survival and Cox regression analyses were used to examine the prognostic significance of Lauren classification and of VEGF and VEGFR-2 expression in patients with GC. The results demonstrated that there was no association between Lauren classification and VEGF and VEGFR-2 expression. Furthermore, results from survival analysis demonstrated that Lauren classification (P=0.001) and Tumor-Node-Metastasis stage (stage II, P=0.002; stage III, P<0.001) were independent prognostic factors in GC. Following subgroup analysis based on Tumor-Node-Metastasis stage, Lauren classification was demonstrated to be an independent prognostic factor in patients with stage III GC (P=0.010) but not in patients with stage I or II GC. Furthermore, VEGFR-2 overexpression was an independent predictor of survival in intestinal-type GC (P=0.040) but not in diffuse-type GC. Taken together, these results indicate that Lauren classification may serve as an independent prognostic factor for patients with GC. In addition, although the expression of VEGF and VEGFR-2 was not associated with Lauren classification, VEGFR-2 overexpression may be considered as an independent prognostic factor in intestinal-type GC.

Deep-learning based detection of gastric precancerous conditions

Conventional white-light endoscopy has high interobserver variability for the diagnosis of gastric precancerous conditions. Here we present a deep-learning (DL) approach for the diagnosis of atrophic gastritis developed and trained...

Role of Helicobacter pylori-induced Antralization in Gastric Carcinogenesis and its Implications in Clinical Practice

The aim of this article was to review the roles of Helicobacter pylori-induced antralization in gastric carcinogenesis and its implications in clinical practice. A search of PubMed/PubMed Central, Web of Science, and China National Knowledge Infrastructure was performed in December 2018 to retrieve all literature related to antralization (or antralisation), pyloric (or pseudopyloric) glands, pyloric (or pseudopyloric) metaplasia, or pyloric (or pseudopyloric) gland metaplasia, and spasmolytic polypeptide-expressing metaplasia (or SPEM). Among the synonyms, antralization and SPEM, which are derived in the same mechanisms at the molecular, cellular and tissue levels, are more commonly used in recent studies. Antralization (or SPEM) is associated with H. pylori infection, atrophic gastritis and intestinal metaplasia, while H. pylori eradication may reverse antralization. It is proposed that H. pylori infection leads to inflammation in the gastric mucosa and apoptosis of the epithelial cells of the proximal stomach, including gastric incisura, body and fundus. The stem cells proliferate and transform into mucous cells and form antral-type mucosa (i.e. antralization). Subsequently, H. pylori-induced antralization, if not controlled, may develop into atrophic gastritis, intestinal metaplasia, dysplasia, and early intestinal-type gastric cancer. Although many biomarkers, including the spasmolytic polypeptide and mucin 6, are specifically expressed in the gastric mucosa with antralization, none of them are evaluated for the clinical diagnosis of antralization. H. pylori-induced antralization (or SPEM) is believed to be an initiating and reversible stage of gastric carcinogenesis. Identification of antralization would help make an early intervention to cease or even reverse the process toward the development of gastric cancer. Currently, the “gold standard” for diagnosing antralization is pathology, which is invasive and time consuming. A non-invasive and convenient method that accurately and specifically diagnoses antralization is urgently required.

Correlations between Genetic Polymorphisms in Long Non-Coding RNA PRNCR1 and Gastric Cancer Risk in a Korean Population.

We evaluated the association between prostate cancer non-coding RNA 1 (PRNCR1) polymorphisms and the risk of developing gastric cancer (GC) and GC subgroups in Korea. A case–control study was conducted with 437 GC patients and 357 healthy controls using a TaqMan genotyping assay. A chi-squared test, binary logistic regression, and genetic models were used to explore the association between five PRNCR1 polymorphisms and GC risk. After adjusting for gender and age, overall analyses using the recessive model indicated that the rs13252298 GG genotype was significantly associated with increased risk of intestinal-type gastric cancer (IGC). In the stratification analyses, the recessive model indicated that the rs1016343 TT genotype was significantly associated with decreased GC risk in individuals aged <60 years showing lymph node metastasis (LNM)-negative results. The rs13252298 GG genotype in the recessive model showed increased GC risk in subjects aged ≥60 years showing LNM-positive results and those aged ≥60 years in tumor stage III. In the dominant model, the rs16901946 combined genotype (AG/GG) was significantly associated with increased GC risk in subjects aged <60 years with tumor stage III. In the recessive model, the rs16901946 GG genotype was associated with decreased risk of GC and IGC in males aged ≥60 years. Thus, genetic variations in PRNCR1 may contribute to susceptibility to GC.

IL-33-mediated mast cell activation promotes gastric cancer through macrophage mobilization

The contribution of mast cells in the microenvironment of solid malignancies remains controversial. Here we functionally assess the impact of tumor-adjacent, submucosal mast cell accumulation in murine and human intestinal-type gastric cancer. We find that genetic ablation or therapeutic inactivation of mast cells suppresses accumulation of tumor-associated macrophages, reduces tumor cell proliferation and angiogenesis, and diminishes tumor burden. Mast cells are activated by interleukin (IL)-33, an alarmin produced by the tumor epithelium in response to the inflammatory cytokine IL-11, which is required for the growth of gastric cancers in mice. Accordingly, ablation of the cognate IL-33 receptor St2 limits tumor growth, and reduces mast cell-dependent production and release of the macrophage-attracting factors Csf2, Ccl3, and Il6. Conversely, genetic or therapeutic macrophage depletion reduces tumor burden without affecting mast cell abundance. Therefore, tumor-derived IL-33 sustains a mast cell and macrophage-dependent signaling cascade that is amenable for the treatment of gastric cancer.

Mo1307 CLINICAL PREDICTORS AND SURVIVAL RATES OF DIFFUSE AND INTESTINAL TYPE OF GASTRIC CANCER PATIENTS: A 5-YEAR LONGITUDINAL STUDY

Histological classification of gastric cancer was largely used by Lauren’s criteria, dividing to intestinal and diffuse type. Some of previous studies have shown difference in clinical manifestation and prognosis between intestinal and diffuse type gastric cancer but limited studies were reported from Southeast Asian countries. The objective of this study was to compare clinical characteristic, endoscopic findings, and survival rate between diffuse and intestinal type gastric cancer in Thailand.

Differential gene expression in growth factors, epithelial mesenchymal transition and chemotaxis in the diffuse type compared with the intestinal type of gastric cancer.

Gastric cancer (GC) is a highly heterogeneous disease and one of the major causes of cancer-related mortality worldwide. Diffuse-type gastric adenocarcinoma (or poorly cohesive- with independent cells) is characterized by aggressive behavior (rapid invasion, chemoresistance and peritoneal metastasis), as compared with intestinal-subtype adenocarcinoma. Diffuse subtype GC additionally has a substantially increasing incidence rate in Europe and the USA, and was often associated with younger age. Our objective was to analyze the expression and clinical significance of genes involved in several signaling pathways in diffuse-type GC. Tumors samples and non-malignant gastric tissues were obtained from patients with GC (diffuse-type and intestinal-subtype adenocarcinoma). The expression of 33 genes coding for proteins involved in four categories, growth factors and receptors, epithelial-mesenchymal transition, cell proliferation and migration, and angiogenesis was determined by reverse transcription-quantitative polymerase chain reaction. The expression of 22 genes was significantly upregulated in diffuse-type GC and two were downregulated (including CDH1) compared with normal tissues. Among these genes, acompared with intestinal-subtype adenocarcinoma, diffuse-type GC revealed elevated levels of IGF1 and IGF1R, FGF7 and FGFR1, ZEB2, CXCR4, CXCL12 and RHOA, and decreased levels of CDH1, MMP9 and MKI67. The expression of selected genes was compared with other genes and according to clinical parameters. Furthermore, TGF-β expression was significantly increased in linitis, a sub-population of diffusely infiltrating type associated with extensive fibrosis and tumor invasion. Our study identified new target genes (IGF1, FGF7, CXCR4, TG-β and ZEB2) whose expression is associated with aggressive phenotype of diffuse-type GC.

TRPV2 Calcium Channel Gene Expression and Outcomes in Gastric Cancer Patients: A Clinically Relevant Association.

Gastric cancer (GC) is characterized by poor efficacy and the modest clinical impact of current therapies. Apoptosis evasion represents a causative factor for treatment failure in GC as in other cancers. Since intracellular calcium homeostasis regulation has been found to be associated with apoptosis resistance, the aberrant expression of intracellular calcium regulator genes (CaRGs) could have a prognostic value in GC patients. We analyzed the association of the expression levels of 98 CaRGs with prognosis by the log-rank test in a collection of 1524 GC samples from four gene expression profiling datasets. We also evaluated differential gene expression in comparison with normal stomach tissue, and then we crossed results with tissue microarrays from the Human Protein Atlas. Among the investigated CaRGs, patients with high levels of TRPV2 expression were characterized by a shorter overall survival. TRPV2 expression was found to increase according to tumor stage. Both mRNA and protein levels were significantly higher in tumor than normal stomach samples. TRPV2 was also associated with poor prognosis in the Lauren’s intestinal type GC and in patients treated with adjuvant therapy. Overall, we highlighted the relevance of TRPV2 not only as a prognostic biomarker but also as a potential therapeutic target to improve GC treatment efficacy.

Plasma Level of MicroRNAs, MiR-107, MiR-194 and MiR-210 as Potential Biomarkers for Diagnosis Intestinal-Type Gastric Cancer in Human

Background:Timely and sensitive diagnosis of gastric cancer is crucial for efficient treatment and survival of the patients. microRNAs have been considered as diagnostic biomarkers in different type of cancers including gastric cancer. In the present study, the expression profile of four microRNAs, miR-103, miR-107, miR-194 and miR-210 were evaluated in patients with intestinal-type of gastric cancer (IGC) in order to assess their diagnosis utility as noninvasive biomarkers.Methods:A total number of 100 plasma samples from patients with gastric cancer and healthy controls were obtained and total RNA was extracted using a commercial monophasic solution of phenol and guanidium thiocyanate. Reverse transcription (RT) reactions were performed by specific stem-loop RT primers and M-MuLV RT-enzyme. The expression patterns of microRNAs were assessed using reverse transcription quantitative real-time PCR (RT-qPCR) method and the expression of SNORD47 RNA was used as the reference for normalization.Results:The results indicate that the plasma levels of miR-107, miR-194, and miR-210 were significantly lower in patients. Receiver operating characteristic (ROC) curve analysis showed that the patients could be distinguished from healthy individuals at the cutoff levels of 0.504, 0.266, and 0.394 of miR-107, miR-194, and miR-210, respectively. On the other hand, the expression levels of these miRNAs were not significantly different in different clinicopathological stages of the disease.Conclusion:These findings suggest that the plasma levels of miR-107, miR-194 and miR-210 were downregulated in patients with ICG and propose these molecules as potential non-invasive biomarkers for detection of IGC.

Dissecting the Single-Cell Transcriptome Network Underlying Gastric Premalignant Lesions and Early Gastric Cancer

Intestinal-type gastric cancer is preceded by premalignant lesions, including chronic atrophic gastritis and intestinal metaplasia. In this study, we constructed a single-cell atlas for 32,332 high-quality cells from gastric antral mucosa biopsies of patients spanning a cascade of gastric premalignant lesions and early gastric cancer (EGC) using single-cell RNA sequencing. We then constructed a single-cell network underlying cellular and molecular characteristics of gastric epithelial cells across different lesions. We found that gland mucous cells tended to acquire an intestinal-like stem cell phenotype during metaplasia, and we identified OR51E1 as a marker for unique endocrine cells in the early-malignant lesion. We also found that HES6 might mark the pre-goblet cell cluster, potentially aiding identification of metaplasia at the early stage. Finally, we identified a panel of EGC-specific signatures, with clinical implications for the precise diagnosis of EGC. Our study offers unparalleled insights into the human gastric cellulome in premalignant and early-malignant lesions.

Molecular carcinogenesis of gastric cancer: Lauren classification, mucin phenotype expression, and cancer stem cells.

Gastric cancer (GC), one of the most common human cancers, is a heterogeneous disease with different phenotypes, prognoses, and responses to treatment. Understanding the pathogenesis of GC at the molecular level is important for prognosis prediction and determining treatments. Microsatellite instability (MSI), silencing of MLH1, MGMT, and CDKN2A genes by DNA hypermethylation, KRAS mutation, APC mutation, and ERBB2 amplification are frequently found in intestinal type GC. Inactivation of CDH1 and RARB by DNA hypermethylation, and amplification of FGFR and MET, are frequently detected in diffuse type GC. In addition, BST2 and PCDHB9 genes are overexpressed in intestinal type GC. Both genes are associated with GC progression. GC can be divided into gastric/intestinal mucin phenotypes according to mucin expression. MSI, alterations of TP73, CDH1 mutation, and DNA methylation of MLH are detected frequently in the gastric mucin phenotype. TP53 mutation, deletion of APC, and DNA methylation of MGMT are detected frequently in the intestinal mucin phenotype. FKTN is overexpressed in the intestinal mucin phenotype, and IQGAP3 is overexpressed in the gastric mucin phenotype. These genes are involved in GC progression. To characterize cancer stem cells, a useful method is spheroid colony formation. KIFC1 and KIF11 genes show more than twofold higher expression in spheroid-forming cells than that in parental cells. Both KIF genes are overexpressed in GC, and knockdown of these genes inhibits spheroid formation. Alterations of these molecules may be useful to understand gastric carcinogenesis. Specific inhibitors of these molecules may also be promising anticancer drugs.

MicroRNA-1224 Inhibits Tumor Metastasis in Intestinal-Type Gastric Cancer by Directly Targeting FAK.

Intestinal-type gastric cancer (GC) of the Lauren classification system has specific epidemiological characteristics and carcinogenesis patterns. MicroRNAs (miRNAs) have prognostic significance, and some can be used as prognostic biomarkers in GC. In this study, we identified miR-1224 as a potential survival-related miRNA in intestinal-type GC patients by The Cancer Genome Atlas (TCGA) analysis. Using quantitative real-time PCR (qRT-PCR), we showed that the relative expression of miR-1224 was significantly decreased in intestinal-type GC tissues compared to matched adjacent normal mucosa tissues (p < 0.01). We found that high miR-1224 expression was associated with no lymph-node metastasis (p < 0.05) and good prognosis (p = 0.028) in 90 intestinal-type GC tissues. Transfection of intestinal-type GC cells with miR-1224 mimics showed that miR-1224 suppressed cell migration in vitro (wound healing assay and Transwell migration assay), whereas the transfection of cells with miR-1224 inhibitor promoted cell migration in vitro. miR-1224 also suppressed intestinal-type GC cell metastasis in a xenograft mouse model. Furthermore, bioinformatics, luciferase reporter, Western blotting, and immunohistochemistry (IHC) studies demonstrated that miR-1224 directly bound to the focal adhesion kinase (FAK) gene, and downregulated its expression, which decreased STAT3 and NF-κB signaling and subsequent the epithelial-to-mesenchymal transition (EMT). Repression of FAK is required for the miR-1224-mediated inhibition of cell migration in intestinal-type GC. The present study demonstrated that miR-1224 is downregulated in intestinal-type GC. miR-1224 inhibits the metastasis of intestinal-type GC by suppressing FAK-mediated activation of the STAT3 and NF-κB pathways, and subsequent EMT. miR-1224 could represent an important prognostic factor in intestinal-type GC.

Immunistochemical Analysis of the Expression of TGFβ, Galectin-1, Vimentin, and Thrombospondin in Gastric Cancer Associated with Systemic Undifferentiated Connective Tissue Dysplasia.

We performed immunohistochemical analysis of the expression of TGFβ, galectin-1, vimentin, and thrombospondin in the mucosa in gastric cancer of diffuse and intestinal type associated with systemic undifferentiated connective tissue dysplasia. In diffuse gastric cancer, both with and without association with connective tissue dysplasia, a higher level of expression of TGFβ, galectin-1, vimentin, and thrombospondin in the tumor was detected in comparison with the perifocal and tumor zones in intestinal gastric cancer, which may reflect the pathogenetic peculiarities of the two histotypes of gastric cancer. Intestinal type of gastric cancer associated with connective tissue dysplasia is characterized by a high level of expression of galectin-1 and vimentin in the perifocal zone and TGFβ in the tumor zone. The pattern of expression of the studied markers can reflect both the pathogenetic peculiarities of the two histotypes of gastric cancer and peculiar expression of some growth factors, cytoskeleton proteins, and matrix-cell proteins associated with undifferentiated connective tissue dysplasia which may contribute to epithelial-mesenchymal transition.

The role of E-cadherin expression and E-cadherin gene promoter hypermethylation in gastric carcinoma

Background Gastric cancer is the third fatal cancers worldwide after lung cancer and liver cancer. Various studies have been launched to detect the markers helping predict the prognosis of different forms of this disease, thus, modifying the treatment regimen accordingly. The aim of this study was to define the role of the E-cadherin protein in such an important issue. Patients and methods Sixty-four patients with gastric carcinoma were included in this study. For each case, representative sections from the tumor tissue and the adjacent noncancerous tissue were assessed for E-cadherin protein expression by immunohistochemistry and promoter methylation by the methylation-specific PCR analysis technique. The results were correlated with Helicobacter pylori positivity and other clinicopathological variables. Result The frequencies of reduced E-cadherin expression and E-cadherin gene methylation were significantly higher in diffuse than intestinal-type gastric carcinoma. However, no significant relationship was found when being correlated to the T-stage and the N-stage of the corresponding lesions. Conclusion Reduced E-cadherin expression and E-cadherin methylation are common alterations in gastric cancer. These gene alternations facilitate cell invasion and metastatic spread with no significant correlation to the T-stage nor the N-stage of the tumor.

A subset of diffuse-type gastric cancer is susceptible to mTOR inhibitors and checkpoint inhibitors

BackgroundMechanistic target of rapamycin (mTOR) pathway is essential for the growth of gastric cancer (GC), but mTOR inhibitor everolimus was not effective for the treatment of GCs. The Cancer Genome Atlas (TCGA) researchers reported that most diffuse-type GCs were genomically stable (GS). Pathological analysis suggested that some diffuse-type GCs developed from intestinal-type GCs.MethodsWe established patient-derived xenograft (PDX) lines from diffuse-type GCs, and searched for drugs that suppressed their growth. Diffuse-type GCs were classified into subtypes by their gene expression profiles.ResultsmTOR inhibitor temsirolimus strongly suppressed the growth of PDX-derived diffuse-type GC-initiating cells, which was regulated via Wnt-mTOR axis. These cells were microsatellite unstable (MSI) or chromosomally unstable (CIN), inconsistent with TCGA report. Diffuse-type GCs in TCGA cohort could be classified into two clusters, and GS subtype was major in cluster I while CIN and MSI subtypes were predominant in cluster II where PDX-derived diffuse-type GC cells were included. We estimated that about 9 and 55% of the diffuse-type GCs in cluster II were responders to mTOR inhibitors and checkpoint inhibitors, respectively, by identifying PIK3CA mutations and MSI condition in TCGA cohort. These ratios were far greater than those of diffuse-type GCs in cluster I or intestinal-type GCs. Further analysis suggested that diffuse-type GCs in cluster II developed from intestinal-type GCs while those in cluster I from normal gastric epithelial cells.ConclusionmTOR inhibitors and checkpoint inhibitors might be useful for the treatment of a subset of diffuse-type GCs which may develop from intestinal-type GCs.

Frizzled-7 Is Required for Wnt Signaling in Gastric Tumors with and Without Apc Mutations.

A subset of patients with gastric cancer have mutations in genes that participate in or regulate Wnt signaling at the level of ligand (Wnt) receptor (Fzd) binding. Moreover, increased Fzd expression is associated with poor clinical outcome. Despite these findings, there are no in vivo studies investigating the potential of targeting Wnt receptors for treating gastric cancer, and the specific Wnt receptor transmitting oncogenic Wnt signaling in gastric cancer is unknown. Here, we use inhibitors of Wnt/Fzd (OMP-18R5/vantictumab) and conditional gene deletion to test the therapeutic potential of targeting Wnt signaling in preclinical models of intestinal-type gastric cancer and ex vivo organoid cultures. Pharmacologic targeting of Fzd inhibited the growth of gastric adenomas in vivo. We identified Fzd7 to be the predominant Wnt receptor responsible for transmitting Wnt signaling in human gastric cancer cells and mouse models of gastric cancer, whereby Fzd7-deficient cells were retained in gastric adenomas but were unable to respond to Wnt signals and consequently failed to proliferate. Genetic deletion of Fzd7 or treatment with vantictumab was sufficient to inhibit the growth of gastric adenomas with or without mutations to Apc. Vantictumab is currently in phase Ib clinical trials for advanced pancreatic, lung, and breast cancer. Our data extend the scope of patients that may benefit from this therapeutic approach as we demonstrate that this drug will be effective in treating patients with gastric cancer regardless of APC mutation status. SIGNIFICANCE: The Wnt receptor Fzd7 plays an essential role in gastric tumorigenesis irrespective of Apc mutation status, therefore targeting Wnt/Fzd7 may be of therapeutic benefit to patients with gastric cancer.

Identification of different gene expressions between diffuse- and intestinal-type spheroid-forming gastric cancer cells.

Three-dimensional in vitro spheroid models are unique because they are considered for enrichment of specific cell populations with self-renewal ability. In this study, we explored the different mechanisms of gastric cancer spheroid-forming cells according to the Lauren classification. We isolated and enriched cells with self-renewal ability using spheroid-forming methods from gastric cancer cell lines. The expression of candidate target genes was investigated using western blot and qRT-PCR analysis. Lentiviral shRNA knockdown of target gene expression was performed and the effects on spheroid, colony forming, and tumorigenic ability were analyzed. The SNU-638, SNU-484, MKN-28, and NCI-N87 successfully formed spheroid from single cell and enriched for self-renewal ability from 11 gastric cancer cell lines, including diffuse and intestinal types. The expression of SOX2 and E-cadherin increased in spheroid-forming cells in a diffuse-type cell line (SNU-638 and SNU-484), but not in the intestinal type (MKN-28 and NCI-N87). In contrast, ERBB3 expression was only increased in intestinal-type spheroid cells. The depletion of each candidate target gene expression suppressed self-renewal ability to grow as spheroids and colonies in a soft agar assay. In particular, down-regulated ERBB3 in the intestinal-type cell lines inhibited tumor growth in a mouse xenograft model. We found that high ERBB3 gene expression correlates with decreased survival in the intestinal type of gastric cancer. Our results suggest that diffuse- and intestinal-type spheroid-forming cells express genes differently. Our data suggest that these candidate genes from spheroid-forming cells can be used in applications in targeted therapy.

Characteristics and epidemiology of gastric cancer in Korea: Disparity in sex and age according to histologic classification.

21 Background: Gastric cancer (GC) is one of the most common cancers worldwide. The overall incidence of gastric cancer is higher in males, but signet ring cell carcinoma (SRC) is more common in younger females. However, the sex disparity according to the histological classification of GC in Korea has not studied much. The aim of this study is to analyze the difference of clinical manifestation between sex groups and to assess sex disparity to gastric cancer. Methods: We retrospectively analyzed 1488 patients (459 females (30.8%) and 2017 males (69.0%)) who diagnosed with gastric cancer at Korea University Ansan Hospital from 2009 to 2017. The patients were divided into three groups according to Lauren’s classification: Intestinal type GC (IGC), diffuse type GC (DGC), mixed type. The difference of clinicopathologic characteristics between these groups and sex groups were compared. Results: The age-group-specific annual incidence rates for intestinal and diffuse type GC were analyzed. The incidence of IGC increased from 40s in males. In females, the incidence of DGC was higher in young age and the proportion of IGC was increased rapidly after age 60 in females. Most of IGC appeared after age 60. (19.3% in below 60 vs. 80.7% in above 60 in females, 35.1% vs. 64.9% in males, p &lt; 0.001) IGC seemed to appear 10-20 years earlier in male than female. Female patients were associated with poorly differentiated adenocarcinoma, SRC and DGC. Diffuse and mixed type GC was more frequent with younger, female patients and associated with advanced GC and TNM stage. Kaplan-Meier analysis revealed that the patients with IGC had a higher cumulative survival rate than those with DGC (5-year survival rate 88.2% vs. 80.5%, p &lt; 0.001). Conclusions: Female patients with IGC were older than male patient and appeared about 10-20 years later. But this difference did not observed in DGC. Therefore, unlike DGC, sex hormones such as estrogen may act in development of IGC. This is supported by an increase of IGC in females after menopause. Further studies on role of estrogen in the development of gastric cancer are needed.

The association of novel recurrent in-frame gene fusions with prognosis of diffuse gastric cancer.

34 Background: Among the two histologic subtype of gastric cancer (GC), diffuse gastric cancer (DGC) is increasingly being considered distinct from intestinal type gastric cancer (IGC). Despite the relative importance of DGC, few whole transcriptomic analyses have been performed for this histological subtype. We therefore conducted an RNA-sequencing study to search for novel driver fusions in DGC. Methods: We conducted a whole transcriptomic and targeted RNA sequencing study of 384 Korean DGCs to identify gene fusions that may be novel prognostic markers or therapeutic targets. Targeted DNA sequencing and SNP6.0 array analyses were conducted in parallel. Results: Whole transcriptomic analyses were conducted in 80 discovery dataset tumors collected from young patients with DGC who had not been treated with chemotherapy or radiation. Twenty-five in-frame fusions were associated with DGC, four of which were recurrent in 384 DGCs based on targeted RNA sequencing and RT-PCR sequencing analyses. Three of the four recurrent fusions contained a RhoGAP domain in their 3’ partner genes. Patients with one of these three fusions have a significantly worse prognosis than those without (HR, 2.8 [95% CI, 1.5‒5.3]). The fusion that harbored a PAP2 domain in the 3’ partner gene was also identified as recurrent and poor prognostic in-frame fusions. Overall, RhoGAP and PAP2 domain-containing fusions were present in 7.5% of DGCs, but not in adjacent normal tissue, and clearly defined the worst prognosis subgroup. Their prognostic impact (adjusted HR 4.1 [95% CI, 2.1‒7.9]) was higher than, and independent of, chromosomal instability (CIN) and CDH1 mutation, which we previously identified as the strongest adverse prognostic genomic abnormalities in DGCs (adjusted HRs, 2.5 (1.5‒4.4) and 2.4 (1.3‒4.4), respectively). Our comprehensive in-frame fusion screen also identified several clinically-actionable fusions amenable to ALK or FGFR inhibition, which had not been previously associated with gastric cancer. Conclusions: Our findings may provide novel genomic insights guiding future personalized strategies for managing DGCs, given the strong prognostic impact of RhoGAP and PAP2 domain-containing gene fusions.

Initial and crucial genetic events in intestinal-type gastric intramucosal neoplasia.

Gastric cancer (GC) is one of the most common and life-threatening malignancies. The course of disease and tumor aggressiveness vary among GCs, although how early fate is determined and by what factors remains elusive. To solve this question, we collected 43 gastric intramucosal neoplasias (GINs), comprising dysplasia/intraepithelial neoplasia (D/IEN; a premalignant lesion) and minute GC (miGC; ≤10 mm) of intestinal histotype and performed targeted deep DNA sequencing of 67 GC-related genes derived from large-scale data. Gastric D/IEN was classified into low or high grade (LG-D/IEN or HG-D/IEN). The most frequent mutations in D/IENs included APC (19/25; 76%), ARID2 (6/25; 24%) and MUC6 (5/25; 20%). All LG-D/IENs had APC mutation (12/12) and APC hotspot mutations affecting R1450 and E1554 were noted in both LG-D/IEN and HG-D/IEN. ARID2 mutation always co-occurred with APC mutation, whose tumor variant allele frequency (TVAF) was higher than that of ARID2 in D/IEN. APC and TP53 mutations were mutually exclusive in D/IEN (p = 0.031 [main cohort], p = 0.025 [expanding cohort]) and TP53-mutated D/IEN was exclusively HG-D/IEN (4/4). TP53 mutations were highly recurrent (11/14; 79%) in MLH1-positive miGCs and were detected even in two microscopic lesions measuring 1 and 3 mm, respectively. Furthermore, TVAF analyses suggested that TP53 mutation is the initial event in the TP53-mutated miGCs. In contrast, TP53 mutation was absent (0/4) in MLH1-negative small intramucosal carcinoma (8-24 mm). Advanced GC data suggested that early mutations (APC and TP53) may affect the potential of cancerous progression from D/IEN. This study revealed somatic mutational landscape and initial mutations of GINs, and we report for the first time that TP53 mutations precede other mutations in intestinal-type GC. Our results also indicate that molecular subtyping based on APC/TP53 mutations would be a high-priority approach for determining and predicting the malignant potential of GIN, including D/IEN. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.