Clinical Significance of NOTCH1 and NOTCH2 Expression in Gastric Carcinomas: An Immunohistochemical Study

High expression of NOTCH2 in gastric adenocarcinoma: A novel early diagnostic target

BACKGROUND AND AIM

NOTCH2 is overexpressed in gastric cancer (GC), and its enhanced activity is significantly correlated with worse tumor characteristics. We aim to analyze the clinicopathologic correlation between NOTCH2 and the molecular typing of GC by immunohistochemistry and by transcriptional sequencing.

METHODS

In this immunohistochemical study, we detected NOTCH2, EBER, P53, HER2, MLH1, MSH2, PMS2, and MSH6 and evaluated the association of NOTCH2 with clinical and histopathological features in a large single-institutional series of gastric adenocarcinomas (n = 488). The correlation was also investigated between immunohistochemical results and survival outcomes.

RESULTS

High NOTCH2 expression (2+/3+) was found in 139/488 (27.5%) samples analyzed. NOTCH2 expression was correlated with early stage T1 (P < 0.0001), GC in the fundus (P = 0.0364), and positive P53 status (P = 0.0019). We did not find an association between NOTCH2 and HER2, microsatellite instability, EBER, and overall survival. Through RNA sequencing, it was revealed that NOTCH2 plays an important biological function in the pathogenesis and development of GC.

CONCLUSIONS

Our findings suggested that NOTCH2 may be a potential diagnostic target for GC due to the fact that its high expression is closely associated with the early stages of cancer.

Helicobacter pylori-activated fibroblasts as a silent partner in gastric cancer development

The discovery of Helicobacter pylori (Hp) infection of gastric mucosa leading to active chronic gastritis, gastroduodenal ulcers, and MALT lymphoma laid the groundwork for understanding of the general relationship between chronic infection, inflammation, and cancer. Nevertheless, this sequence of events is still far from full understanding with new players and mediators being constantly identified. Originally, the Hp virulence factors affecting mainly gastric epithelium were proposed to contribute considerably to gastric inflammation, ulceration, and cancer. Furthermore, it has been shown that Hp possesses the ability to penetrate the mucus layer and directly interact with stroma components including fibroblasts and myofibroblasts. These cells, which are the source of biophysical and biochemical signals providing the proper balance between cell proliferation and differentiation within gastric epithelial stem cell compartment, when exposed to Hp, can convert into cancer-associated fibroblast (CAF) phenotype. The crosstalk between fibroblasts and myofibroblasts with gastric epithelial cells including stem/progenitor cell niche involves several pathways mediated by non-coding RNAs, Wnt, BMP, TGF-β, and Notch signaling ligands. The current review concentrates on the consequences of Hp-induced increase in gastric fibroblast and myofibroblast number, and their activation towards CAFs with the emphasis to the altered communication between mesenchymal and epithelial cell compartment, which may lead to inflammation, epithelial stem cell overproliferation, disturbed differentiation, and gradual gastric cancer development. Thus, Hp-activated fibroblasts may constitute the target for anti-cancer treatment and, importantly, for the pharmacotherapies diminishing their activation particularly at the early stages of Hp infection.

Pre-therapeutic molecular biomarkers of pathological response to neoadjuvant chemotherapy in gastric and esophago-gastric junction adenocarcinoma: A systematic review and meta-analysis

PURPOSE

Multimodal treatment is the standard of care in patients with locally advanced gastric cancer. Unfortunately, the response rate after neoadjuvant treatment remains limited. The ability to predict the response has a potential to improve patient outcomes by promoting a more individualized approach. We sought to describe the current state of research in pre-treatment molecular biomarkers of response to neoadjuvant therapy in gastric adenocarcinoma available for testing before the initiation of treatment and to perform a systematic review and meta-analysis in order to summarize and evaluate the potential methods.

METHODS

A systematic MEDLINE, EMBASE and CENTRAL literature search was conducted to extract articles on potentially predictive molecular biomarkers of pathological response to neoadjuvant therapy in patients with gastric- and esophago-gastric junction adenocarcinoma. Fixed and random effects models were used to undertake the meta-analysis when appropriate.

RESULTS

Data on predictive biomarkers was reported in 38 studies. These articles described 47 biomarkers showing statistical significance. After evaluation of all reported biomarkers, 3 of them met the inclusion criteria for meta-analysis. The meta-analysis results indicate that >5 ​ng/mL pre-therapeutic serum concentration of carcinoembryonic antigen (CEA; norm <5 ​ng/mL) is significantly associated with tumor response (RR ​= ​5.13, 95% CI 2.53-10.43, P ​= ​0.026).

CONCLUSION

Previous studies describe a large number of candidate biomarkers. Our meta-analysis indicated pre-therapeutic serum concentration of CEA >5 ​ng/mL as a potential and easy-accessible biomarker available for use before initiation of treatment. However, it could be only an additional tool for complex qualification for neoadjuvant therapy.

Elevated Notch-1 expression promotes the lymph node metastasis of gastric cancer and the Notch-1-PTEN-ERK1/2 signalling axis promotes the progression of gastric cancer

BACKGROUND

Gastric cancer (GC) is one of the most common malignant tumours and has a high fatality rate worldwide. This study investigated the role of the Notch-1 signalling pathway in the pathogenesis and progression of GC.

METHODS

A total of 64 patients with GC were included in this study. Immunohistochemistry staining was used to detect Notch-1 expression in tumour tissues and adjacent non-tumour tissues, and Notch-1 knockdown in GC cells was identified using short hairpin RNA. A cell scratch assay, transwell assay and flow cytometry analysis were used to analyse the effect of Notch-1 knockdown on cell proliferation, migration and cell cycle distribution. The expression of Notch-1, PTEN, Akt, ERK1/2, E-cadherin and other proteins was detected using Western blotting.

RESULTS

The expression level of Notch-1 in GC tissues was higher than that in adjacent non-tumour tissues (P < 0.05). High levels of Notch-1 were also found to be associated with sex (male) and lymph node metastasis (P < 0.05). Notch-1 knockdown in the AGS and BGC-823 GC cell lines inhibited the migration and proliferation of GC cells, and Notch-1 knockdown arrested the cell cycle in the G0/G1 phase. PTEN protein expression was elevated in the presence of Notch-1 knockdown, resulting in the inhibition of phosphorylated Akt protein expression. In addition, phosphorylated ERK protein levels decreased in the presence of Notch-1 knockdown. Further inhibition of ERK1/2 signalling by the MEK1/2 inhibitor U0126 decreased the proliferation of AGS cells. The results of in vivo experiments with xenotransplantation in nude mice are consistent with these results.

CONCLUSIONS

Notch-1 plays a key role in the development of GC and was found to promote the lymph node metastasis of GC. Notch-1 knockdown can effectively attenuate the progression of GC cells, which may function in part through the Notch-1-PTEN-ERK1/2 signalling axis.

A Comprehensive Bioinformatic Analysis of NOTCH Pathway Involvement in Stomach Adenocarcinoma

Background

Activation of NOTCH signaling pathways, which are key regulators of multiple cellular functions, has been frequently implicated in cancer pathogenesis, and NOTCH inhibitors have received much recent focus in the context of cancer therapeutics. However, the role and possible involvement of NOTCH pathways in stomach adenocarcinoma (STAD) are unclear. Here, putative regulatory mechanisms and functions of NOTCH pathways in STAD were investigated.

Methods

Publicly available data from the TCGA-STAD database were utilized to explore the involvement of canonical NOTCH pathways in STAD by analyzing RNA expression levels of NOTCH receptors, ligands, and downstream genes. Statistical analysis of the data pertaining to cancer and noncancerous samples was performed using R software packages and public databases/webservers.

Results

Significant differential gene expression between control and STAD samples was noted for all NOTCH receptors (NOTCH1, 2, 3, and 4), the delta-like NOTCH ligands (DLL-3 and 4), and typical downstream genes (HES1 and HEY1). Four genes (NOTCH1, NOTCH2, NOTCH3, and HEY1) presented prognostic values for the STAD outcome in terms of overall survival. Functional enrichment analysis indicated that NOTCH family genes-strongly correlated genes were mainly enriched in several KEGG signaling pathways such as the PI3K-Akt signaling pathway, human papillomavirus infection, focal adhesion, Rap1 signaling pathway, and ECM-receptor interaction. Gene set enrichment analysis (GSEA) results showed that NOTCH family genes-significantly correlated genes were mainly enriched in four signaling pathways, ECM (extracellular matrix), tumor angiogenesis, inflammatory response, and immune regulation.

Conclusions

NOTCH family genes may play an essential role in the progression of STAD by modulating immune cells and mediating ECM synthesis, angiogenesis, focal adhesion, and PI3K-Akt signaling. Multiple NOTCH family genes are valuable candidate biomarkers or therapeutic targets for the management of STAD.

Acupuncture Regulates Serum Differentially Expressed Proteins in Patients with Chronic Atrophic Gastritis: A Quantitative iTRAQ Proteomics Study

Objective

To identify differentially expressed proteins (DEPs) in sera of patients with chronic atrophic gastritis (CAG) using isobaric tags for relative and absolute quantitation (iTRAQ) and to explore acupuncture's mechanism in CAG.

Methods

Peripheral sera from 8 healthy volunteers (HC), 8 chronic nonatrophic gastritis (NAG) patients, 8 CAG patients, and 8 CAG patients who underwent acupuncture treatment (CAG + ACU) were collected followed by labeling with iTRAQ reagent for protein identification and quantification using two-dimensional liquid chromatography-tandem mass spectrometry (2D-LC-MS/MS). Representative DEPs were selected through bioinformatics, and proteins were verified by enzyme-linked immunosorbent assay (ELISA).

Results

A total of 4,448 unique peptides were identified, corresponding to 816 nonredundant proteins. A 1.4-fold difference was used as the threshold. Compared with the HC group, 75 and 106 DEPs were identified from CAG and NAG groups, respectively. Compared with the CAG group, 110 and 66 DEPs were identified from the NAG and CAG + ACU groups, respectively. The DEPs were mainly involved in protein binding and the Notch signaling pathway-related proteins, and the upregulated proteins included actin-binding proteins (thymosin beta-4, tropomyosin-4, profilin-1, transgelin-2), while the downregulated proteins included Notch2 and Notch3. After acupuncture, the expression of these proteins in CAG patients was less differentiated from that in healthy people. The level of the above 6 proteins were verified by ELISA, and the results were similar to the results of iTRAQ analysis.

Conclusions

Actin-binding proteins and Notch signaling pathway-related proteins were correlated with the development and progression of CAG and thus are potential diagnostic markers for CAG. Acupuncture may play a role in regulating actin-binding proteins and Notch signaling pathway-related proteins to play a therapeutic role in CAG.

Molecular Bases of Mechanisms Accounting for Drug Resistance in Gastric Adenocarcinoma

Gastric adenocarcinoma (GAC) is the most common histological type of gastric cancer, the fifth according to the frequency and the third among the deadliest cancers. GAC high mortality is due to a combination of factors, such as silent evolution, late clinical presentation, underlying genetic heterogeneity, and effective mechanisms of chemoresistance (MOCs) that make the available antitumor drugs scarcely useful. MOCs include reduced drug uptake (MOC-1a), enhanced drug efflux (MOC-1b), low proportion of active agents in tumor cells due to impaired pro-drug activation or active drug inactivation (MOC-2), changes in molecular targets sensitive to anticancer drugs (MOC-3), enhanced ability of cancer cells to repair drug-induced DNA damage (MOC-4), decreased function of pro-apoptotic factors versus up-regulation of anti-apoptotic genes (MOC-5), changes in tumor cell microenvironment altering the response to anticancer agents (MOC-6), and phenotypic transformations, including epithelial-mesenchymal transition (EMT) and the appearance of stemness characteristics (MOC-7). This review summarizes updated information regarding the molecular bases accounting for these mechanisms and their impact on the lack of clinical response to the pharmacological treatment currently used in GAC. This knowledge is required to identify novel biomarkers to predict treatment failure and druggable targets, and to develop sensitizing strategies to overcome drug refractoriness in GAC.

Elevated Expression of NOTCH1 Associates with Lymph Node Metastasis of Gastric Cancer and Knock-Down of NOTCH1 Attenuates Tumor Cell Progression

BACKGROUND Gastric cancer is the third leading cause of cancer-related death, while its molecular mechanism has not been fully clarified. This study aims to explore the role of Notch signaling in the pathogenesis of gastric cancer. MATERIAL AND METHODS A total of 64 patients with gastric cancer were enrolled. The expressions of NOTCH1 in tumor tissues and adjacent non-tumor tissues were detected by immunohistochemistry staining. The correlation between NOTCH1 expression and clinicopathological features of patients was analyzed. NOTCH1 was knocked down in gastric cancer cells. The effects of NOTCH1 blockade on cell proliferation, migration and cell cycle distribution were analyzed. The expressions of ERK1/2 and phospho-ERK1/2 (p-ERK1/2) were detected using western blotting. RESULTS Gastric cancer tissues expressed higher level of NOTCH1 than adjacent non-tumor tissues (P<0.05). The high level of NOTCH1 was found to be correlated with gender (male) and lymph node metastasis. However, the expression level of NOTCH1 did not affect the overall survival of patients with gastric cancer. NOTCH1 knock-down repressed the migration and proliferation of gastric cancer cells. Moreover, the cell cycle was arrested at G0/G1 phase by NOTCH1 blockade. The expressions of ERK1/2 and p-ERK1/2 decreased with NOTCH1 knock-down. Further inhibition of ERK1/2 signaling by a MEK1/2 inhibitor U0126 reduced the proliferation of AGS cells, which aggravated the inhibition effect of NOTCH1 knock-down on cell proliferation. CONCLUSIONS NOTCH1 may play an oncogenic role in gastric cancer. Inhibition of NOTCH1 can efficiently attenuate gastric cancer cell progression, probably in part through cross-talking with ERK1/2 signaling pathway.

A comparative study on the possible protective effect of esomeprazole, spirulina, wheatgrass on indomethacin-induced gastric ulcer in male albino rats

Gastric ulcer is a common problem affecting the gastrointestinal tract. Spirulina and wheatgrass are natural substances that have anti-inflammatory and antioxidant effects. The aim of the Work was to elucidate the possible protective role of spirulina and wheatgrass versus standard treatment esomeprazole on indomethacin-induced gastric ulcer in adult male albino rats. Eighty adult male albino rats were divided into eight groups: group I (the control group), group II that received indomethacin (100 mg/kg orally), group III that received esomeprazole (20 mg/kg orally), group IV that received spirulina (1000 mg/kg orally), group V that received wheatgrass (1000 mg/kg orally), group VI that received indomethacin (100 mg/kg) + esomeprazole (20 mg/kg), group VII that received indomethacin (100 mg/kg) + spirulina (1000 mg/kg) and group VIII that received indomethacin (100 mg/kg) + wheatgrass (1000 mg/kg). Six hours after indomethacin treatment, all rats were anesthetized and their stomachs obtained for measures of gastric acidity, pepsin activity, mucin content, gastrin, ulcer index, total antioxidant capacity (TAC), tumor necrosis factor -α (TNF-α), interleukin-8 (IL8), proapoptotic protein (Bax). Histological (using H&E stain, PAS reaction) and immunohistochemical (using anti Ki67 immunostain) techniques were performed. Western immunoblot analysis for heat shock protein 70 (HSP70) was also done. Moreover, a morphometric study was done for area% of positive immunoreactive cells for Ki67 and optical density and area% of PAS reaction. All performed measurements were followed by statistical analysis. Indomethacin induced loss of normal architecture of gastric mucosa with sloughing of surface epithelium and inflammatory cellular infiltration. It also led to a significant increase in gastric acidity, inflammatory mediators (TNF-α, IL-8), pro-apoptotic protein Bax and a significant decrease in TAC levels and HSP-70 expression. There was also a significant decrease in area% of Ki67 immunoreactivity and area% and optical density of PAS reaction as compared with the control group and other pre-treated rats. These disturbed parameters were associated with increased ulcer index. In pre-treatment groups, the structure of the mucosa was similar to control with marked improvement in the biochemical assay. In conclusion, Spirulina and wheatgrass can partly protect the gastric mucosa against indomethacin-induced damage to a degree similar to that of the classical treatment esomeprazole.

Downregulation of Notch Signaling in Kras-Induced Gastric Metaplasia

Activating mutations and amplification of Kras and, more frequently, signatures for Kras activation are noted in stomach cancer. Expression of mutant Kras^G12D in the mouse gastric mucosa has been shown to induce hyperplasia and metaplasia. However, the mechanisms by which Kras activation leads to gastric metaplasia are not fully understood. Here we report that Kras^LSL-G12D/+;Pdx1-cre, a mouse model known for pancreatic cancer, also mediates Kras^G12D expression in the stomach, causing gastric hyperplasia and metaplasia prior to the pathologic changes in the pancreas. These mice exhibit ectopic cell proliferation at the base of gastric glands, whereas wild-type mice contain proliferating cells primarily at the isthmus/neck of the gastric glands. Notch signaling is decreased in the Kras^LSL-G12D/+;Pdx1-cre gastric mucosa, as shown by lower levels of cleaved Notch intracellular domains and downregulation of Notch downstream target genes. Expression of a Notch ligand Jagged1 is downregulated at the base of the mutant gland, accompanied by loss of chief cell marker Mist1. We demonstrate that exogenous Jagged1 or overexpression of Notch intracellular domain stimulates Mist1 expression in gastric cancer cell lines, suggesting positive regulation of Mist1 by Notch signaling. Finally, deletion of Jagged1 or Notch3 in Kras^LSL-G12D/+;Pdx1-cre mice promoted development of squamous cell carcinoma in the forestomach, albeit short of invasive adenocarcinoma in the glandular stomach. Taken together, these results reveal downregulation of Notch signaling and Mist1 expression during the initiation of Kras-driven gastric tumorigenesis and suggest a tumor-suppressive role for Notch in this context.

Notch and mTOR Signaling Pathways Promote Human Gastric Cancer Cell Proliferation

Notch pathway signaling is known to promote gastric stem cell proliferation, and constitutive pathway activation induces gastric tumors via mTORC1 activation in mouse genetic models. The purpose of this study was to determine whether human gastric adenocarcinomas are similarly dependent on Notch and mTORC1 signaling for growth. Gene expression profiling of 415 human gastric adenocarcinomas in The Cancer Genome Atlas, and a small set of locally obtained gastric cancers showed enhanced expression of Notch pathway components, including Notch ligands, receptors and downstream target genes. Human gastric adenocarcinoma tissues and chemically induced mouse gastric tumors both exhibited heightened Notch and mTORC1 pathway signaling activity, as evidenced by increased expression of the NOTCH1 receptor signaling fragment NICD, the Notch target HES1, and the mTORC1 target phosphorylated S6 ribosomal protein. Pharmacologic inhibition of either Notch or mTORC1 signaling reduced growth of human gastric cancer cell lines, with combined pathway inhibition causing a further reduction in growth, suggesting that both pathways are activated to promote gastric cancer cell proliferation. Further, mTORC1 signaling was reduced after Notch inhibition suggesting that mTOR is downstream of Notch in gastric cancer cells. Analysis of human gastric organoids derived from paired control and gastric cancer tissues also exhibited reduced growth in culture after Notch or mTOR inhibition. Thus, our studies demonstrate that Notch and mTOR signaling pathways are commonly activated in human gastric cancer to promote cellular proliferation. Targeting these pathways in combination might be an effective therapeutic strategy for gastric cancer treatment.

The oncogenic effects of HES1 on salivary adenoid cystic carcinoma cell growth and metastasis

Background

Our previous study demonstrated a close relationship between NOTCH signaling pathway and salivary adenoid cystic carcinoma (SACC). HES1 is a well-known target gene of NOTCH signaling pathway. The purpose of the present study was to further explore the molecular mechanism of HES1 in SACC.

Methods

Comparative transcriptome analyses by RNA-Sequencing (RNA-Seq) were employed to reveal NOTCH1 downstream gene in SACC cells. Immunohistochemical staining was used to detect the expression of HES1 in clinical samples. After HES1-siRNA transfected into SACC LM cells, the cell proliferation and cell apoptosis were tested by suitable methods; animal model was established to detect the change of growth ability of tumor. Transwell and wound healing assays were used to evaluate cell metastasis and invasion.

Results

We found that HES1 was strongly linked to NOTCH signaling pathway in SACC cells. The immunohistochemical results implied the high expression of HES1 in cancerous tissues. The growth of SACC LM cells transfected with HES1-siRNAs was significantly suppressed in vitro and tumorigenicity in vivo by inducing cell apoptosis. After HES1 expression was silenced, the SACC LM cell metastasis and invasion ability was suppressed.

Conclusions

The results of this study demonstrate that HES1 is a specific downstream gene of NOTCH1 and that it contributes to SACC proliferation, apoptosis and metastasis. Our findings serve as evidence indicating that HES1 may be useful as a clinical target in the treatment of SACC.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4350-5) contains supplementary material, which is available to authorized users.

Annonaceous acetogenins mediated up-regulation of Notch2 exerts growth inhibition in human gastric cancer cells in vitro

Background

Gastric cancer (GC) is a global health problem because of limited treatments and poor prognosis. Annonaceous acetogenins (ACGs) has been reported to exert anti-tumorigenic effects in cancer, yet the mechanism underlying its effects on GC remains largely unknown. Notch signaling plays a critical role in cell proliferation, differentiation and apoptosis. Therefore, it may contribute to the development of GC. This study aims to explore the role of Notch2 in ACGs’ activities in GC cells.

Results

ACGs inhibited GC cells’ viability in a dose dependent manner and led to cell apoptosis and cell cycle arrest in G0/G1 phase with an increased Notch2 expression. Additionally, Notch2 siRNA reduced ACGs-induced cell growth inhibition while Notch2 cDNA transfection did the opposite.

Materials and Methods

ACGs were administrated in GC cells and cell proliferation was assayed by MTS, cell apoptosis and cell cycle were detected by flow cytometry. Additionally, the expression of Notch2 and the downstream target Hes1 were identified by Western blot. Furthermore, Notch2-siRNA transfection and Notch2-cDNA were performed to investigate the role of Notch2 in the antitumor effect of ACGs. Conclusions: Up-regulation of Notch2 by ACGs is a potential therapeutic strategy for GC.

Notch as a Driver of Gastric Epithelial Cell Proliferation

The gastric epithelium is sustained by a population of stem cells that replenish the various mature epithelial lineages throughout adulthood. Regulation of stem and progenitor cell proliferation occurs via basic developmental signaling pathways, including the Notch pathway, which recently was described to promote gastric stem cell proliferation in both mice and human beings. Current cancer theory proposes that adult stem cells that maintain gastrointestinal tissues accumulate mutations that promote cancerous growth, and that basic signaling pathways, such as Notch, which stimulate stem cell proliferation, can promote tumorigenesis. Accordingly, constitutive Notch activation leads to unchecked cellular proliferation and gastric tumors in genetic mouse models. Furthermore, there is emerging evidence suggesting that the Notch pathway may be activated in some human gastric cancers, supporting a potential role for Notch in gastric tumorigenesis. In this review, we first summarize the current understanding of gastric stem cells defined by genetic mouse studies, followed by discussion of the literature regarding Notch pathway regulation of gastric stem cell function in the mouse and human beings. Notch action to maintain gastric epithelial cell homeostasis and the cellular consequences of dysregulated signaling to promote tumorigenesis are discussed, including studies associating Notch activation with human gastric cancer. Finally, we compare and contrast Notch function in the stomach with other gastrointestinal tissues, including the intestine, to highlight the sensitivity of the stomach to Notch-induced tumors.

NOTCH1 and NOTCH2 regulate epithelial cell proliferation in mouse and human gastric corpus

The Notch signaling pathway is known to regulate stem cells and epithelial cell homeostasis in gastrointestinal tissues; however, Notch function in the corpus region of the stomach is poorly understood. In this study we examined the consequences of Notch inhibition and activation on cellular proliferation and differentiation and defined the specific Notch receptors functioning in the mouse and human corpus. Notch pathway activity was observed in the mouse corpus epithelium, and gene expression analysis revealed NOTCH1 and NOTCH2 to be the predominant Notch receptors in both mouse and human. Global Notch inhibition for 5 days reduced progenitor cell proliferation in the mouse corpus, as well as in organoids derived from mouse and human corpus tissue. Proliferation effects were mediated through both NOTCH1 and NOTCH2 receptors, as demonstrated by targeting each receptor alone or in combination with Notch receptor inhibitory antibodies. Analysis of differentiation by marker expression showed no change to the major cell lineages; however, there was a modest increase in the number of transitional cells coexpressing markers of mucous neck and chief cells. In contrast to reduced proliferation after pathway inhibition, Notch activation in the adult stomach resulted in increased proliferation coupled with reduced differentiation. These findings suggest that NOTCH1 and NOTCH2 signaling promotes progenitor cell proliferation in the mouse and human gastric corpus, which is consistent with previously defined roles for Notch in promoting stem and progenitor cell proliferation in the intestine and antral stomach.

NEW & NOTEWORTHY

Here we demonstrate that the Notch signaling pathway is essential for proliferation of stem cells in the mouse and human gastric corpus. We identify NOTCH1 and NOTCH2 as the predominant Notch receptors expressed in both mouse and human corpus and show that both receptors are required for corpus stem cell proliferation. We show that chronic Notch activation in corpus stem cells induces hyperproliferation and tissue hypertrophy, suggesting that Notch may drive gastric tumorigenesis.

Prognostic values of four Notch receptor mRNA expression in gastric cancer

Notch ligands and receptors are frequently deregulated in several human malignancies including gastric cancer. The activation of Notch signaling has been reported to contribute to gastric carcinogenesis and progression. However, the prognostic roles of individual Notch receptors in gastric cancer patients remain elusive. In the current study, we accessed the prognostic roles of four Notch receptors, Notch 1-4, in gastric cancer patients through "The Kaplan-Meier plotter" (KM plotter) database, in which updated gene expression data and survival information include a total of 876 gastric cancer patients. All four Notch receptors' high mRNA expression was found to be correlated to worsen overall survival (OS) for all gastric cancer patients followed for 20 years. We further accessed the prognostic roles of individual Notch receptors in different clinicopathological features using Lauren classification, pathological grades, clinical grades, HER2 status and different choices of treatments of gastric cancer patients. These results indicate that there are critical prognostic values of the four Notch receptors in gastric cancer. This information will be useful for better understanding of the heterogeneity and complexity in the molecular biology of gastric cancer and to develop tools to more accurately predict their prognosis.

Notch regulation of gastrointestinal stem cells

The gastrointestinal (GI) tract epithelium is continuously replenished by actively cycling stem and progenitor cells. These cell compartments are regulated to balance proliferation and stem cell renewal with differentiation into the various mature cell types to maintain tissue homeostasis. In this topical review we focus on the role of the Notch signalling pathway to regulate GI stem cell function in adult small intestine and stomach. We first present the current view of stem and progenitor cell populations in these tissues and then summarize the studies that have established the Notch pathway as a key regulator of gastric and intestinal stem cell function. Notch signalling has been shown to be a niche factor required for maintenance of GI stem cells in both tissues. In addition, Notch has been described to regulate epithelial cell differentiation. Recent studies have revealed key similarities and differences in how Notch regulates stem cell function in the stomach compared to intestine. We summarize the literature regarding Notch regulation of GI stem cell proliferation and differentiation, highlighting tissue-specific functions to compare and contrast Notch in the stomach and intestine.

Expression of APPL1 is correlated with clinicopathologic characteristics and poor prognosis in patients with gastric cancer

BACKGROUND

Although appl1 is overexpressed in many cancers, its status in gastric cancer (gc) is not known. In the present study, we used relevant pathologic and clinical data to investigate appl1 expression in patients with gc.

METHODS

In 47 gc and 27 non-gc surgical specimens, immunohistochemistry was used to detect the expression of appl1, and reverse-transcriptase polymerase chain reaction (rt-pcr) was used to detect messenger rna (mrna). A scatterplot visualized the relationship between survival time and mrna expression in gc patients. The log-rank test and other survival statistics were used to determine the association of appl1 expression with the pathologic features of the cancer and clinical outcomes.

RESULTS

In gc, appl1 was expressed in 28 of 47 specimens (59.6%), and in non-gc, it was expressed in 7 of 23 specimens (30.4%, p < 0.05). The expression of mrna in gc was 0.82 [95% confidence interval (ci): 0.78 to 0.86], and in non-gc, it was 0.73 (95% ci: 0.69 to 0.77; p < 0.05). Immunohistochemistry demonstrated that, in gc, appl1 expression was correlated with depth of infiltration (p = 0.005), lymph node metastasis (p = 0.017), and TNM stage (p = 0.022), but not with pathologic type (p = 0.41). Testing by rt-pcr demonstrated that, in gc, appl1 mrna expression was correlated with depth of infiltration (p = 0.042), lymph node metastasis (p = 0.031), and TNM stage (p = 0.04), but again, not with pathologic type (p = 0.98). The correlation coefficient between survival time and mrna expression was -0.83 (p < 0.01). Overexpression of appl1 protein (hazard ratio: 3.88; 95% ci: 1.07 to 14.09) and mrna (hazard ratio: 4.23; 95% ci: 3.09 to 15.11) was a risk factor for death in patients with gc.

CONCLUSIONS

Expression of appl1 is increased in gc. Overexpression is prognostic for a lethal outcome.

Tumor Suppressor Role of miR-363-3p in Gastric Cancer

Background

Gastric cancer (GC) is the most common cancer in the world. Despite the advancement of the treatment of GC, the 5-year overall survival rate is still very low. MicroRNAs (miRNAs) play important roles in the pathogenesis of GC. A recent study suggested that miR-363-3p plays a role in the development of GC. However, the function of miR-363-3p in GC is not fully understood.

Material/Methods

The network of NOTCH1 and the involved molecules was constructed by use of Cytoscape software. MiR-363-3p levels in GC tissues and cells were tested by qRT-PCR. Cells were miR-363-3p mimics or anti-miR-363-3p transfected by Lipofectamine. Bioinformatics algorithms from TargetScanHuman were used to predict the target genes of miR-363-3p. The NOTCH1 protein level was tested by Western blot. The interaction between miR-363-3p and NOTCH1 was confirmed by dual luciferase assays.

Results

MiR-363-3p showed low levels in GC tissues and cells. Enforced expression of miR-363-3p inhibited cell growth and migration of GC cells and vice versa. NOTCH1 is the targeted gene of miR-363-3p.

Conclusions

MiR-363-3p plays a tumor suppressor role in GC.