Characterization of gastric cancer-stimulated signaling pathways and function of CTGF in cancer-associated fibroblasts.

BACKGROUND: Cancer-associated fibroblasts (CAFs) are key components of the tumor microenvironment (TME) that play an important role in cancer progression. Although the mechanism by which CAFs promote tumorigenesis has been well investigated, the underlying mechanism of CAFs activation by neighboring cancer cells remains elusive. In this study, we aim to investigate the signaling pathways involved in CAFs activation by gastric cancer cells (GC) and to provide insights into the therapeutic targeting of CAFs for overcoming GC. METHODS: Alteration of receptor tyrosine kinase (RTK) activity in CAFs was analyzed using phospho-RTK array. The expression of CAFs effector genes was determined by RT-qPCR or ELISA. The migration and invasion of GC cells co-cultured with CAFs were examined by transwell migration/invasion assay. RESULTS: We found that conditioned media (CM) from GC cells could activate multiple receptor tyrosine kinase signaling pathways, including ERK, AKT, and STAT3. Phospho-RTK array analysis showed that CM from GC cells activated PDGFR tyrosine phosphorylation, but only AKT activation was PDGFR-dependent. Furthermore, we found that connective tissue growth factor (CTGF), a member of the CCN family, was the most pronouncedly induced CAFs effector gene by GC cells. Knockdown of CTGF impaired the ability of CAFs to promote GC cell migration and invasion. Although the PDGFR-AKT pathway was pronouncedly activated in CAFs stimulated by GC cells, its pharmacological inhibition affected neither CTGF induction nor CAFs-induced GC cell migration. Unexpectedly, the knockdown of SRC and SRC-family kinase inhibitors, dasatinib and saracatinib, significantly impaired CTGF induction in activated CAFs and the migration of GC cells co-cultured with CAFs. SRC inhibitors restored the reduced expression of epithelial markers, E-cadherin and Zonula Occludens-1 (ZO-1), in GC cells co-cultured with CAFs, as well as CAFs-induced aggregate formation in a 3D tumor spheroid model. CONCLUSIONS: This study provides a characterization of the signaling pathways and effector genes involved in CAFs activation, and strategies that could effectively inhibit it in the context of GC. Video Abstract.

Elucidating molecular mechanisms and therapeutic synergy: irreversible HER2-TKI plus T-Dxd for enhanced anti-HER2 treatment of gastric cancer.

BACKGROUND: HER2-targeted therapies have improved the outcomes of HER2-positive gastric cancer (GC), yet resistance remains a challenge. We sought to explore the effects of reversible and irreversible HER2 tyrosine kinase inhibitors (TKIs) alone or in combination with the HER2-targeting antibody drug conjugate trastuzumab deruxtecan (T-Dxd). METHODS: The effects of HER2-TKIs on HER2 and downstream signaling were evaluated via Western blotting. Proteasomal inhibitors and co-immunoprecipitation assays were performed to explore the role of proteasomal degradation in HER2 expression modulation, and immunofluorescence assays were employed to explore mechanisms of HER2 internalization. The synergistic potential of the irreversible HER2-TKI pyrotinib in combination with T-Dxd was validated using growth and viability assays in anti-HER2-positive GC cell cultures and tumor growth and immunohistochemical staining assays in a mouse xenograft model. RESULTS: Our study revealed that reversible HER2-TKIs elevated HER2 protein levels, whereas irreversible HER2-TKIs decreased them. Pyrotinib triggered HER2 degradation within the proteasome by promoting ubiquitination and dissociation from HSP90. Furthermore, pyrotinib substantially induced HER2 internalization, which led to improved cellular uptake of T-Dxd. The increased T-Dxd uptake was accompanied by greater efficacy in suppressing the growth of GC cells and enhanced anti-tumor effects in an animal model. CONCLUSION: In summary, our research reveals the molecular mechanisms of irreversible HER2-TKIs in regulating HER2 protein expression by promoting HER2 internalization. These findings advance our comprehension of targeted therapy for GC and provide a promising therapeutic combination strategy with enhanced efficacy against HER2-positive GC.

ACTL8 Promotes the Progression of Gastric Cancer Through PI3K/AKT/mTOR Signaling Pathway.

BACKGROUND: Actin-like protein 8 (ACTL8) significantly correlates with tumor growth and prognosis across various cancer types. Nevertheless, the potential relationship between ACTL8 and gastric cancer (GC) remains uncertain. OBJECTIVE: This study aimed to elucidate the role of ACTL8 in human GC cells and to explore its mechanism. METHODS: Bioinformatics analysis tools, such as GEPIA2, Kaplan-Meier, and STRING, were utilized for a comprehensive investigation of the characteristics and functional roles of ACTL8 in GC, including differential expression, prognostic value, and related signaling pathways. Subsequently, gene expression analyses, cell function assays, and signaling pathway experiments were conducted to verify key findings. RESULTS: Bioinformatics analysis showed that ACTL8 was significantly elevated in GC and closely associated with poor prognosis. Gene expression experiments confirmed the bioinformatics results. Furthermore, ACTL8 knockdown markedly reduced GC cell proliferation and inhibited migration and invasion. Mechanistically, a significant increase in the phosphorylation levels of signaling proteins was observed in GC cells following ACTL8 overexpression, and PI3K/Akt/mTOR pathway inhibitors could reverse this effect. CONCLUSION: ACTL8 expression is significantly upregulated in GC cells and is closely correlated with poor patient prognosis. Further mechanistic studies revealed that ACTL8 may promote GC cell migration and proliferation through activation of the PI3K/Akt/mTOR signaling pathway. Consequently, ACTL8 emerges as a promising therapeutic target for GC.

Master Regulators of Causal Networks in Intestinal- and Diffuse-Type Gastric Cancer and the Relation to the RNA Virus Infection Pathway.

Causal networks are important for understanding disease signaling alterations. To reveal the network pathways affected in the epithelial-mesenchymal transition (EMT) and cancer stem cells (CSCs), which are related to the poor prognosis of cancer, the molecular networks and gene expression in diffuse- and intestinal-type gastric cancer (GC) were analyzed. The network pathways in GC were analyzed using Ingenuity Pathway Analysis (IPA). The analysis of the probe sets in which the gene expression had significant differences between diffuse- and intestinal-type GC in RNA sequencing of the publicly available data identified 1099 causal networks in diffuse- and intestinal-type GC. Master regulators of the causal networks included lenvatinib, pyrotinib, histone deacetylase 1 (HDAC1), mir-196, and erb-b2 receptor tyrosine kinase 2 (ERBB2). The analysis of the HDAC1-interacting network identified the involvement of EMT regulation via the growth factors pathway, the coronavirus pathogenesis pathway, and vorinostat. The network had RNA-RNA interactions with microRNAs such as mir-10, mir-15, mir-17, mir-19, mir-21, mir-223, mir-25, mir-27, mir-29, and mir-34. The molecular networks revealed in the study may lead to identifying drug targets for GC.

Robotic subtotal D2-gastrectomy for gastric cancer after right hemiliver transplantation: case report and literature review.

BACKGROUND: With the progress achieved in transplant surgeries an improved long-term survival of patients is obtained due to more effective immunosuppressant therapy. De novo malignancy (DNM) has gained interest in this group of patients. DNM is a major cause of late mortality after liver transplantation. METHODS: We report the case of a patient who underwent orthotopic liver transplantation with right hemiliver (right split) 18 years ago who came to our attention for gastric cancer. We performed a robotic subtotal gastrectomy D2 lymphadenectomy with manual latero lateral trans mesocolic BII gastro jejunal anastomosis using da Vinci robotic surgery system at our hospital. RESULTS: The operation was successful, the operative time was 230 min, the intraoperative blood loss was 100 ml. The patient was discharged on day 8 after surgery, and no complications occurred. Postoperative pathological stages were pT2 N0 (0/25). During the follow-up period, the patient was in good health without long-term complications. CONCLUSION: Robotic approach is feasible in patients after liver transplantation.

USP14-mediated deubiquitination of SIRT1 in macrophage promotes fatty acid oxidation amplification and M2 phenotype polarization.

There is a trend of increasing young cases with gastric cancer globally. Sensitive early diagnosis methods and new therapeutic approaches are still the focus of clinical diagnosis and therapy of gastric cancer. USP14 plays an extensive role in tumor malignancy and fat metabolism regulation. However, researchers still have gaps in their knowledge of its substrates, which makes it difficult for deubiquitinases to become clinical targets. TAMs were isolated from tumor or polarized from primary THP1 cells by tumors cell lines under the control of IU1 and FAO inhibitor therapy. Cytokines controlled macrophages were compared to evaluate the capability to induce USP14 expression. Fatty acid uptake assay and OCR measurement were used to analyze macrophage metabolism. USP14 is found the correlation with tumor poor prognosis and poor immunophenotype in gastric cancer patients and mouse tumor models. Activation of USP14 determines elevated protein stability of SIRT1 and is required for activation of macrophage fatty acid oxidation and immunosuppressive phenotype. Although overexpression of USP14 is not sufficient to polarize macrophages to the M2 phenotype, inhibition of USP14 by IU1 in tumor-bearing mice disrupts the suppressive activity of cancer-promoting macrophages and effectively reshapes immune microenvironment characteristics. Our study provides evidence that a novel therapeutic strategy that targets to lipid metabolism of macrophages in tumors could be a potential option for emerging treatments for gastric cancer.

Investigating the prognostic and predictive value of the type II cystatin genes in gastric cancer.

BACKGROUND: Accumulating evidence indicates that type II cystatin (CST) genes play a pivotal role in several tumor pathological processes, thereby affecting all stages of tumorigenesis and tumor development. However, the prognostic and predictive value of type II CST genes in GC has not yet been investigated. METHODS: The present study evaluated the expression and prognostic value of type II CST genes in GC by using The Cancer Genome Atlas (TCGA) database and the Kaplan-Meier plotter (KM plotter) online database. The type II CST genes related to the prognosis of GC were then screened out. We then validated the expression and prognostic value of these genes by immunohistochemistry. We also used Database for Annotation, Visualization, and Integrated Discovery (DAVID), Gene Multiple Association Network Integration Algorithm (GeneMANIA), Search Tool for the Retrieval of Interacting Genes/Proteins (STRING), nomogram, genome-wide co-expression analysis, and other bioinformatics tools to analyze the value of type II CST genes in GC and the underlying mechanism. RESULTS: The data from the TCGA database and the KM plotter online database showed that high expression of CST2 and CST4 was associated with the overall survival (OS) of patients with GC. The immunohistochemical expression analysis showed that patients with high expression of CST4 in GC tissues have a shorter OS than those with low expression of CST4 (HR = 1.85,95%CI: 1.13-3.03, P = 0.015). Multivariate Cox regression analysis confirmed that the high expression level of CST4 was an independent prognostic risk factor for OS. CONCLUSIONS: Our findings suggest that CST4 could serve as a tumor marker that affects the prognosis of GC and could be considered as a potential therapeutic target for GC.

Microvesicles from bone marrow-derived mesenchymal stem cells promote Helicobacter pylori-associated gastric cancer progression by transferring thrombospondin-2.

BACKGROUND: Our previous study found that bone marrow-derived mesenchymal stem cells (BMSCs) promote Helicobacter pylori (H pylori)-associated gastric cancer (GC) progression by secreting thrombospondin-2 (THBS2). Extracellular vesicles (EVs) are important carriers for intercellular communication, and EVs secreted by BMSCs have been shown to be closely related to tumor development. The aim of this study was to investigate whether BMSC-derived microvesicles (MVs, a main type of EV) play a role in H. pylori-associated GC by transferring THBS2. METHODS: BMSCs and THBS2-deficient BMSCs were treated with or without the supernatant of H. pylori for 12 h at a multiplicity of infection of 50, and their EVs were collected. Then, the effects of BMSC-derived MVs and THBS2-deficient BMSC-derived MVs on the GC cell line MGC-803 were assessed by in vitro proliferation, migration, and invasion assays. In addition, a subcutaneous xenograft tumor model, a nude mouse intraperitoneal metastasis model, and a tail vein injection metastasis model were constructed to evaluate the effects of BMSC-derived MVs and THBS2-deficient BMSC-derived MVs on GC development and metastasis in vivo. RESULTS: BMSC-derived MVs could be readily internalized by MGC-803 cells. BMSC-derived MVs after H. pylori treatment significantly promoted their proliferation, migration and invasion in vitro (all P < 0.05) and promoted tumor development and metastasis in a subcutaneous xenograft tumor model, a nude mouse intraperitoneal metastasis model, and a tail vein injection metastasis model in vivo (all P < 0.05). The protein expression of THBS2 was significantly upregulated after H. pylori treatment in BMSC-derived MVs (P < 0.05). Depletion of the THBS2 gene reduces the tumor-promoting ability of BMSC-MVs in an H. pylori infection microenvironment both in vitro and in vivo. CONCLUSION: Overall, these findings indicate that MVs derived from BMSCs can promote H. pylori-associated GC development and metastasis by delivering the THBS2 protein. Video Abstract.

Comprehensive transcriptomic profiling and mutational landscape of primary gastric linitis plastica.

BACKGROUND: Primary gastric linitis plastica (GLP) is a distinct phenotype of gastric cancer with poor survival. Comprehensive molecular profiles and putative therapeutic targets of GLP remain undetermined. METHODS: We subjected 10 tumor-normal tissue pairs to whole exome sequencing (WES) and whole transcriptome sequencing (WTS). 10 tumor samples were all GLP which involves 100% of the gastric wall macroscopically. TCGA data were compared to generate the top mutated genes and the overexpressed genes in GLP. RESULTS: Our results reveal that GLP has distinctive genomic and transcriptomic features, dysfunction in the Hippo pathway is likely to be a key step during GLP development. 6 genes were identified as significantly highly mutated genes in GLP, including AOX1, ANKRD36C, CPXM1, PTPN14, RPAP1, and DCDC1). MUC6, as a previously identified gastric cancer driver gene, has a high mutation rate (20%) in GLP. 20% of patients in our GLP cohort had CDH1 mutations, while none had RHOA mutations. GLP exhibits high immunodeficiency and low AMPK pathway activity. Our WTS results showed that 3 PI3K-AKT pathway-related genes (PIK3R2, AKT3, and IGF1) were significantly up-regulated in GLP. Two genes were identified using immunohistochemistry (IHC), IGF2BP3 and MUC16, which specifically expressed in diffuse-type-related gastric cancer cell lines, and its knockdown inhibits PI3K-AKT pathway activity. CONCLUSIONS: We provide the first integrative genomic and transcriptomic profiles of GLP, which may facilitate its diagnosis, prognosis, and treatment.

Long Non-Coding RNAs (lncRNAs) as Regulators of the PI3K/AKT/mTOR Pathway in Gastric Carcinoma.

Gastric cancer (GC) represents ~10% of the global cancer-related deaths, increasingly affecting the younger population in active stages of life. The high mortality of GC is due to late diagnosis, the presence of metastasis and drug resistance development. Additionally, current clinical markers do not guide the patient management adequately, thereby new and more reliable biomarkers and therapeutic targets are still needed for this disease. RNA-seq technology has allowed the discovery of new types of RNA transcripts including long non-coding RNAs (lncRNAs), which are able to regulate the gene/protein expression of many signaling pathways (e.g., the PI3K/AKT/mTOR pathway) in cancer cells by diverse molecular mechanisms. In addition, these lncRNAs might also be proposed as promising diagnostic or prognostic biomarkers or as potential therapeutic targets in GC. This review describes important topics about some lncRNAs that have been described as regulators of the PI3K/AKT/mTOR signaling pathway, and hence, their potential oncogenic role in the development of this malignancy.

An artificial intelligence method to assess the tumor microenvironment with treatment outcomes for gastric cancer patients after gastrectomy.

BACKGROUND: The tumor microenvironment (TME) plays an important role in the occurrence and development of gastric cancer (GC) and is widely used to assess the treatment outcomes of GC patients. Immunohistochemistry (IHC) and gene sequencing are the main analysis methods for the TME but are limited due to the subjectivity of observers, the high cost of equipment and the need for professional analysts. METHODS: The ImmunoScore (IS) was developed in the TCGA cohort and validated in GEO cohorts. The Radiomic ImmunoScore (RIS) was developed in the TCGA cohort and validated in the Nanfang cohort. A nomogram was developed and validated in the Nanfang cohort based on RIS and clinical features. RESULTS: For IS, the area under the curves (AUCs) were 0.798 for 2-year overall survival (OS) and 0.873 for 4-year overall survival. For RIS, in the TCGA cohort, the AUCs distinguishing High-IS or Low-IS and predicting prognosis were 0.85 and 0.81, respectively; in the Nanfang cohort, the AUC predicting prognosis was 0.72. The nomogram performed better than the TNM staging system according to the ROC curve (all P < 0.01). Patients with TNM stage II and III in the High-nomogram group were more likely to benefit from adjuvant chemotherapy than Low-nomogram group patients. CONCLUSIONS: The RIS and the nomogram can be used to assess the TME, prognosis and adjuvant chemotherapy benefit of GC patients after radical gastrectomy and are valuable additions to the current TNM staging system. High-nomogram GC patients may benefit more from adjuvant chemotherapy than Low-nomogram GC patients.

Elucidated tumorigenic role of MAML1 and TWIST1 in gastric cancer is associated with Helicobacter pylori infection.

BACKGROUND: Epithelial-mesenchymal transition (EMT) has a fundamental role in tumor initiation, progression, and metastasis. Helicobacter pylori (HP) induces EMT and thus causes gastric cancer (GC) by deregulating multiple signaling pathways involved in EMT. TWIST1 and MAML1 have been confirmed to be critical inducers of EMT via diverse signaling pathways such as Notch signaling. This study aimed to investigate for the first time possible associations between TWIST1/MAML1 mRNA expression levels, HP infection, and clinicopathological characteristics in GC patients. METHOD: TWIST1 and MAML1 mRNA expression levels were evaluated in tumoral and adjacent normal tissues in 73 GC patients using the quantitative reverse transcription PCR (RT-qPCR) method. PCR technique was also applied to examine the infection with HP in GC samples. RESULTS: Upregulation of TWIST1 and MAML1 expression was observed in 35 (48%) and 34 (46.6%) of 73 tumor samples, respectively. Co-overexpression of these genes was found in 26 of 73 (35.6%) tumor samples; meanwhile, there was a significant positive correlation between MAML1 and TWIST1 mRNA expression levels (P < 0.001). MAML1 overexpression exhibited meaningful associations with advanced tumor stages (P = 0.006) and nodal metastases (P ˂ 0.001). 34 of 73 (46.6%) tumors tested positive for HP, and meanwhile, MAML1 expression was positively related with T (P = 0.05) and grade (P = 0.0001) in these HP-positive samples. Increased TWIST1 expression was correlated with patient sex (P = 0.035) and advanced tumor grade (P = 0.017) in HP-infected tumors. Furthermore, TWIST1 and MAML1 expression levels were inversely linked with histologic grade in HP-negative tumor samples (P = 0.021 and P = 0.048, respectively). CONCLUSION: We propose TWIST1 and MAML1 as potential biomarkers of advanced-stage GC that determine the characteristics and aggressiveness of the disease. Based on accumulating evidence and our findings, they can be introduced as promising therapeutic targets to modify functional abnormalities in cells that promote GC progression. Moreover, HP may enhance GC growth and metastasis by disrupting TWIS1/MAML1 expression patterns and related pathways.

Glaucocalyxin a prevents hypoxia-induced epithelial-mesenchymal transition in human gastric cancer cells through the PI3K/Akt signaling pathway.

Hypoxia is a frequent occurrence in most solid tumors and associated with multiple cancer progression. Glaucocalyxin A (GLA) has been found to exhibit anti-tumor effect in several types of cancer, except gastric cancer (GC). The present study aimed to evaluate the function of GLA in GC and explore the underlying mechanism under hypoxia condition. Our results showed that GLA suppressed cell viability of MGC-803 cells in both normoxic or hypoxic conditions. MGC-803 cells were more sensitive to GLA in hypoxic condition. GLA attenuated hypoxia-induced migration and invasion of GC cells. Western blot assay proved that GLA elevated E-cadherin expression, as well reduced N-cadherin and vimentin expressions in hypoxia-induced GC cells. Moreover, we also found that GLA suppressed the expression of HIF-1α in both mRNA and protein levels. Furthermore, GLA blocked hypoxia-induced activation of PI3K/Akt pathway in GC cells. Notably, insulin like growth factor 1 (IGF-1), an activator of PI3K/Akt pathway, reversed the effects of GLA on cell migration, invasion and EMT in hypoxia-treated MGC-803 cells. In conclusion, these findings demonstrated that GLA exerted inhibitory effects on cell migration, invasion and epithelial to mesenchymal transition (EMT) via the PI3K/Akt signaling pathway in GC cells.

LRG1 mediated by ATF3 promotes growth and angiogenesis of gastric cancer by regulating the SRC/STAT3/VEGFA pathway.

BACKGROUND: Increasing evidence indicates that leucine-rich-alpha-2-glycoprotein 1 (LRG1) is associated with multiple malignancies, but whether it participates in gastric cancer (GC) angiogenesis remains unclear. METHODS: The expression levels of LRG1 were assessed in GC samples. Endothelial tube formation analysis, HUVEC migration assay, chorioallantoic membrane assay (CAM), and xenograft tumor model were used to investigate the effect of LRG1 on angiogenesis in gastric cancer. The involvement of activating transcription factor 3 (ATF3) was analyzed by chromatin immunoprecipitation (ChIP) and dual-luciferase reporter assay. Western blot and enzyme-linked immunosorbent assay were performed to measure the SRC/STAT3/VEGFA pathway. RESULTS: LRG1 was overexpressed in GC tissues and associated with cancer angiogenesis. In addition, LRG1 markedly promoted GC cell proliferation in vitro and in vivo. Moreover, overexpression of LRG1 could stimulate GC angiogenesis in vitro and in vivo. Then, we identified ATF3 promotes the transcription of LRG1 and is a positive regulator of angiogenesis. Additionally, LRG1 could activate VEGFA expression via the SRC/STAT3/ VEGFA pathway in GC cells, thus contributing to the angiogenesis of GC. CONCLUSIONS: The present study suggests LRG1 plays a crucial role in the regulation of angiogenesis in GC and could be a potential therapeutic target for GC.

Knockdown of LncRNA SBF2-AS1 Inhibited Gastric Cancer Tumorigenesis via the Wnt/LRP5 Signaling Pathway.

This investigation aimed to uncover the impact of a long noncoding RNA, SET-binding factor 2 antisense RNA1 (SBF2-AS1) on the malignant progression of gastric cancer (GC) and to further explore its underlying mechanism. SBF2-AS1 expression was quantified by qRT-PCR in GC cell lines and GC tissues. In vitro loss-of-function studies of SBF2-AS1, accompanied by flow cytometry, CCK-8, and cell invasion tests, were applied to elucidate the impact of SBF2-AS1 on the tumor progression of GC cells. Finally, Western blotting and a luciferase assay were used to detect WNT/LRP5 signaling pathway activation. SBF2-AS1 was aberrantly expressed in GC cell lines (p<0.05) and GC tissues (p<0.05). Cell invasive and proliferative capabilities were inhibited via SBF2-AS1 knockdown, resulting in apoptosis of NCI-N87 and MKN74 cells. Additionally, online database analysis uncovered a positive correlation between SBF2-AS1 and the Wnt/LRP5 signaling pathway (p<0.05). SBF2-AS1 knockdown blocked the Wnt/LRP5 signaling pathway, whereas the effects of SBF2-AS1 knockdown on the malignant genotype of MKN74 as well as NCI-N87 cells were partially restored by triggering the Wnt/ LRP5 signaling pathway. High expression of SBF2-AS1 was found in GC, the malignant progression of which was repressed via SBF2-AS1 knockdown by inhibiting the Wnt/LRP5 signaling pathway.

LncRNA FGD5-AS1 drives the malignant development of gastric cancer by negatively interacting with FZD3.

We aimed to detect the expression pattern of long non-coding RNA (lncRNA) FGD5-AS1 in gastric cancer (GC) samples and its impact on driving the development of GC. FGD5-AS1 levels in 66 cases of GC tissues and paracancerous ones were detected. Its influences on clinical features and prognosis in GC patients were analyzed. In AGS and SGC-7901 cells with FGD5-AS1 knockdown, phenotype changes were assessed through cell counting kit-8 (CCK-8), Transwell and wound healing assay. The downstream target of FGD5-AS1 was searched by a bioinformatics tool and confirmed by dual-luciferase reporter assay. Their interaction in regulating the malignant development of GC was finally explored. FGD5-AS1 was upregulated in GC tissues compared to paracancerous ones. GC patients expressing a high level of FGD5-AS1 had higher risk of lymphatic metastasis or distant metastasis and worse prognosis than those with a low level. Knockdown of FGD5-AS1 weakened proliferative and metastatic abilities in AGS and SGC-7901 cells. FZD3 was the downstream target of FGD5-AS1. Protein levels of FZD3 and FZD5 were upregulated, while b-catenin, TGF-b and MMP9 were downregulated in GC cells with FGD5-AS1 knockdown. Knockdown of FZD3 abolished the regulatory effects of FGD5-AS1 on malignant phenotypes of GC cells. FGD5-AS1 is upregulated in GC samples, which is linked to metastasis and prognosis in GC. It drives proliferative and metastatic abilities in GC cells via negatively interacting with FZD3.

Influence of the Microbiome Metagenomics and Epigenomics on Gastric Cancer.

Gastric cancer (GC) is one of the major causes of cancer deaths worldwide. The disease is seldomly detected early and this limits treatment options. Because of its heterogeneous and complex nature, the disease remains poorly understood. The literature supports the contribution of the gut microbiome in the carcinogenesis and chemoresistance of GC. Drug resistance is the major challenge in GC therapy, occurring as a result of rewired metabolism. Metabolic rewiring stems from recurring genetic and epigenetic factors affecting cell development. The gut microbiome consists of pathogens such as H. pylori, which can foster both epigenetic alterations and mutagenesis on the host genome. Most of the bacteria implicated in GC development are Gram-negative, which makes it challenging to eradicate the disease. Gram-negative bacterium co-infections with viruses such as EBV are known as risk factors for GC. In this review, we discuss the role of microbiome-induced GC carcinogenesis. The disease risk factors associated with the presence of microorganisms and microbial dysbiosis are also discussed. In doing so, we aim to emphasize the critical role of the microbiome on cancer pathological phenotypes, and how microbiomics could serve as a potential breakthrough in determining effective GC therapeutic targets. Additionally, consideration of microbial dysbiosis in the GC classification system might aid in diagnosis and treatment decision-making, taking the specific pathogen/s involved into account.

The m6A Methyltransferase METTL3-Mediated N6-Methyladenosine Modification of DEK mRNA to Promote Gastric Cancer Cell Growth and Metastasis.

Gastric cancer (GC) is the fifth most common cancer and the third deadliest cancer in the world, and the occurrence and development of GC are influenced by epigenetics. Methyltransferase-like 3 (METTL3) is a prominent RNA n6-adenosine methyltransferase (m6A) that plays an important role in tumor growth by controlling the work of RNA. This study aimed to reveal the biological function and molecular mechanism of METTL3 in GC. The expression level of METTL3 in GC tissues and cells was detected by qPCR, Western blot and immunohistochemistry, and the expression level and prognosis of METTL3 were predicted in public databases. CCK-8, colony formation, transwell and wound healing assays were used to study the effect of METTL3 on GC cell proliferation and migration. In addition, the enrichment effect of METTL3 on DEK mRNA was detected by the RIP experiment, the m6A modification effect of METTL3 on DEK was verified by the MeRIP experiment and the mRNA half-life of DEK when METTL3 was overexpressed was detected. The dot blot assay detects m6A modification at the mRNA level. The effect of METTL3 on cell migration ability in vivo was examined by tail vein injection of luciferase-labeled cells. The experimental results showed that METTL3 was highly expressed in GC tissues and cells, and the high expression of METTL3 was associated with a poor prognosis. In addition, the m6A modification level of mRNA was higher in GC tissues and GC cell lines. Overexpression of METTL3 in MGC80-3 cells and AGS promoted cell proliferation and migration, while the knockdown of METTL3 inhibited cell proliferation and migration. The results of in vitro rescue experiments showed that the knockdown of DEK reversed the promoting effects of METTL3 on cell proliferation and migration. In vivo experiments showed that the knockdown of DEK reversed the increase in lung metastases caused by the overexpression of METTL3 in mice. Mechanistically, the results of the RIP experiment showed that METTL3 could enrich DEK mRNA, and the results of the MePIP and RNA half-life experiments indicated that METTL3 binds to the 3'UTR of DEK, participates in the m6A modification of DEK and promotes the stability of DEK mRNA. Ultimately, we concluded that METTL3 promotes GC cell proliferation and migration by stabilizing DEK mRNA expression. Therefore, METTL3 is a potential biomarker for GC prognosis and a therapeutic target.

RNF168 promotes RHOC degradation by ubiquitination to restrain gastric cancer progression via decreasing HDAC1 expression.

Gastric cancer (GC) is the most common cancer worldwide. Although advances in the treatments, the oncogenic mechanisms are still largely unknown. RNF168 (ring-finger nuclear factor 168) is an important regulator of DNA double-strand break (DSB) repair, and its defects have been involved in the pathogenesis of a number of human diseases including cancer. However, its effects on GC are still unclear. In the study, we demonstrated that RNF168 expression was remarkably down-regulated in human GC tissues, and its low expression showed worse overall survival rate in GC patients. Importantly, we here reported that RNF168 directly interacted with Ras homolog gene family member C (RHOC) and induced its ubiquitination to promote RHOC degradation. RHOC exhibited higher expression in human GC tissues, and its knockdown significantly restrained cell proliferation, migration and invasion in GC cell lines. Moreover, RHOC knockdown led to a significant reduction in GC tumor growth in a xenograft mouse model. Additionally, histone deacetylase 1 (HDAC1) was found to be markedly decreased in GC cells with RHOC knockdown. Intriguingly, RHOC suppression-ameliorated proliferative and migratory ability in GC cells were significantly diminished by HDAC1 over-expression. Our in vivo studies finally confirmed that RHOC inhibition dramatically reduced the lung metastasis in nude mice. Collectively, all our results demonstrated that RNF168 directly interacted with RHOC to induce its degradation via promoting its ubiquitination, contributing to the inhibition of cell proliferation and metastasis in GC through decreasing HDAC1. Thus, targeting RNF168/RHOC/HDAC1 axis might be promising to develop effective therapies for GC treatment.

International cost-effectiveness analysis evaluating endoscopic screening for gastric cancer for populations with low and high risk.

BACKGROUND: Gastric cancer remains one of the 3 most common causes of cancer death worldwide. Understanding the health and economic factors that affect screening cost-effectiveness in different countries will help address when and where it makes most sense to screen for gastric cancer. METHODS: We performed a cost-effectiveness analysis using a Markov model to compare screening and surveillance strategies for gastric cancer in Brazil, France, Japan, Nigeria, and the United States. Primary outcome was the incremental cost-effectiveness ratio. We then performed a sensitivity analysis to determine how each variable affected the overall model. RESULTS: In all countries, the most cost-effective strategies, measured by incremental cost-effectiveness ratio relative to no screening, were screening every 10 years, surveillance of high- and low-risk patients every 5 and 10 years, respectively, and screening every 5 years. Only Japan had at least one cost-effective screening strategy. The most important variables across different screening strategies and countries were starting age of screening, cost of endoscopy, and baseline probability of local gastric cancer at time of diagnosis. CONCLUSIONS: Our model suggests that screening for gastric cancer is cost-effective in countries with higher incidence and lower costs of screening, but screening may still be a viable option in high-risk populations within low incidence countries.