Alterations of tumor suppressor and tumor-related genes in the development and progression of gastric cancer

Analytical Validation of Loss of Heterozygosity and Mutation Detection in Pancreatic Fine-Needle Aspirates by Capillary Electrophoresis and Sanger Sequencing

Pancreatic cystic disease, including duct dilation, represents precursor states towards the development of pancreatic cancer, a form of malignancy with relatively low incidence but high mortality. While most of these cysts (>85%) are benign, the remainder can progress over time, leading to malignant transformation, invasion, and metastasis. Cytologic diagnosis is challenging, limited by the paucity or complete absence of cells representative of cystic lesions and fibrosis. Molecular analysis of fluids collected from endoscopic-guided fine-needle aspiration of pancreatic cysts and dilated duct lesions can be used to evaluate the risk of progression to malignancy. The basis for the enhanced diagnostic utility of molecular approaches is the ability to interrogate cell-free nucleic acid of the cyst/duct and/or extracellular fluid. The allelic imbalances at tumor suppressor loci and the selective oncogenic drivers are used clinically to help differentiate benign stable pancreatic cysts from those progressing toward high-grade dysplasia. Methods are discussed and used to determine the efficacy for diagnostic implementation. Here, we report the analytical validation of methods to detect causally associated molecular changes integral to the pathogenesis of pancreatic cancer from pancreatic cyst fluids.

Mutational landscape of TP53 and CDH1 in gastric cancer

In this editorial we comment on an article published in a recent issue of the World J Gastrointest Surg. A common gene mutation in gastric cancer (GC) is the TP53 mutation. As a tumor suppressor gene, TP53 is implicated in more than half of all tumor occurrences. TP53 gene mutations in GC tissue may be related with clinical pathological aspects. The TP53 mutation arose late in the progression of GC and aided in the final switch to malignancy. CDH1 encodes E-cadherin, which is involved in cell-to-cell adhesion, epithelial structure maintenance, cell polarity, differentiation, and intracellular signaling pathway modulation. CDH1 mutations and functional loss can result in diffuse GC, and CDH1 mutations can serve as independent prognostic indicators for poor prognosis. GC patients can benefit from genetic counseling and testing for CDH1 mutations. Demethylation therapy may assist to postpone the onset and progression of GC. The investigation of TP53 and CDH1 gene mutations in GC allows for the investigation of the relationship between these two gene mutations, as well as providing some basis for evaluating the prognosis of GC patients.

Predictive value of DNA methylation in the efficacy of chemotherapy for gastric cancer

Background

Gastric cancer (GC) is one of the most common causes of cancer-related death. Drug resistance in chemotherapy often occurs in patients with GC, leading to tumor recurrence and poor survival. DNA methylation is closely related to the development of cancer.

Methods

To investigate the role of DNA methylation in chemotherapy resistance in GC patients, we conducted a comprehensive analysis using DNA methylation data and survival information obtained from The Cancer Genome Atlas. Univariate Cox analysis was performed to screen for differential DNA methylation of chemotherapy response in patients who did and did not receive chemotherapy. Multivariate Cox analysis was then performed to identify the independent prognostic genes. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses were used to explore the biological function of the signature genes.

Results

Patients receiving adjuvant chemotherapy for GC survived longer. 308 differentially methylated genes were demonstrated to be associated with prognosis. Six genes were optimally chosed for establisehing the risk model, including C6orf222, CCNL1, CREBZF, GCKR, TFCP2, and VIPR2. It was constructed based on the DNA methylation levels of these six genes: risk score = 0.47123374*C6orf222 + 9.53554803*CCNL1 + 10.40234138* CREBZF + 0.07611856* GCKR + 18.87661557*TFCP2 - 0.46396254* VIPR2. According to the risk score, patients receiving chemotherapy were divided into high- and low-risk groups, and the prognosis of the two groups was compared. The high-risk group had a shorter survival; however, this association was not present in patients without chemotherapy. The accuracy and predictive efficacy of the risk score in predicting the 1-, 3-, and 5-year survival of patients was evaluated with the receiver operating characteristic curve. In patients receiving chemotherapy, the area under the curve of the risk score for 1-, 3-, and 5-year survival was 0.841, 0.72, and 0.734, respectively. In patients who did not receive chemotherapy, the area under the curve was 0.406, 0.585, and 0.585, respectively. A nomogram model was constructed based on the risk score and clinical indicators. The model showed good consistency in the predicted probabilities and actual probabilities. Gene Ontology functional enrichment of these candidate methylated genes showed the following molecular functions: RNA binding, protein binding, mRNA binding, and nucleic acid binding; that they were mediated mainly through the following cell components: nuclear speck, nucleoplasm, nucleus, catalytic step 2 spliceosome, and the transcription factor AP-1 complex; and that they were involved in the following biological processes: mRNA processing, mRNA splicing, and RNA polymerase II promoter transcription. The Kyoto Encyclopedia of Genes and Genomes pathway enrichment results revealed that the signaling pathways mainly enriched were transcriptional misregulation in cancer, spliceosome, and the IL-17 signaling pathway.

Conclusion

Our work identifies a six DNA methylated expression signature as a promising biomarker of chemo-resistance in GC, which provides new insights into the development of new strategies to overcome chemo-resistance in GC.

Evaluating the Magnolol Anticancer Potential in MKN-45 Gastric Cancer Cells

Background and Objectives: Combination therapy improves the effect of chemotherapy on tumor cells. Magnolol, used in treating gastrointestinal disorders, has been shown to have anti-cancer properties. We investigated the synergistic effect of cisplatin and magnolol on the viability and maintenance of MKN-45 gastric cancer cells. Materials and Methods: The toxicity of magnolol and/or cisplatin was determined using the MTT technique. The trypan blue method was used to test magnolol and/or cisplatin's effect on MKN-45 cell growth. Crystal violet staining was used to assess the treated cells' tendency for colony formation. The expression of genes linked to apoptosis, cell cycle arrest, and cell migration was examined using the qPCR method. Results: According to MTT data, using magnolol and/or cisplatin significantly reduced cell viability. The ability of the treated cells to proliferate and form colonies was also reduced considerably. Magnolol and/or cisplatin treatment resulted in a considerable elevation in Bax expression. However, the level of Bcl2 expression was dramatically reduced. p21 and p53 expression levels were significantly increased in the treated cells, while MMP-9 expression was significantly reduced. Conclusions: These findings show that magnolol has a remarkable anti-tumor effect on MKN-45 cells. In combination with cisplatin, magnolol may be utilized to overcome cisplatin resistance in gastric cancer cells.

Association between multiple gene promoter hypermethylation and the risk of gastric cancer: A systematic review and meta-analysis

BACKGROUND

Several studies have demonstrated an association between multiple gene hypermethylation and gastric cancer. However, the intrinsic mechanisms remain elusive and highly debatable. To this end, our study aims to investigate the correlation between the methylation status of multiple gene promoters and gastric cancer.

METHODS

PubMed, EMBASE, CNKI, WanFang, Cqvip, and Cochrane Library were queried from inception to May 2021, and the relationship between the methylation status of the CpG islands and gastric cancer risk was systematically assessed under the inclusion and exclusion criteria. The incidence of DNA methylation between tumor and non-tumor tissues was compared, and the clinicopathological significance of DNA methylation in gastric carcinoma was further evaluated. The odds ratio (OR) was estimated with a 95% confidence interval (CI), and forest plots were generated using the fixed-effects or random-effects model.

RESULTS

In total, 201 studies were enrolled, and a higher frequency of CpG islands methylation was identified in gastric cancer tissues than in non-neoplastic tissues. This suggests that aberrant polygene methylation might be associated with the initial onset and progression of gastric cancer.

CONCLUSION

This study sheds light on the significance of polygene methylation status in gastric cancer. The DNA methylation of these genes may serve as underlying epigenetic biomarkers, providing a promising molecular diagnostic approach for human gastric cancer clinical diagnosis. More large randomized trials are needed to confirm the findings.

Deciphering cervical cancer-associated biomarkers by integrated multi-omics approach

OBJECTIVES

Cervical Squamous Cell Carcinoma (CESC) is one of the most fatal female malignancies, and the underlying molecular mechanisms governing this disease have not been fully explored. In this research, we planned to conduct the analysis of Gene Expression Omnibus (GEO) cervical squamous cell carcinoma microarray datasets by a detailed in silico approach and to explore some novel biomarkers of CESC.

METHODS

The top commonly differentially expressed genes (DEGs) from the GSE138080 and GSE113942 datasets were analyzed by Limma package-based GEO2R tool. The protein-protein interaction (PPI) network of the DEGs was drawn through Search Tool for the Retrieval of Interacting Genes (STRING), and top 6 hub genes were obtained from Cytoscape. Expression analysis and validation of hub genes expression in CESC samples and cell lines were done using UALCAN, OncoDB, GENT2, and HPA. Additionally, cBioPortal, Gene set enrichment analysis (GSEA) tool, Kaplan-Meier (KM) plotter, ShinyGO, and DGIdb databases were also used to check some important values of hub genes in CESC.

RESULTS

Out of 79 DEGs, the minichromosome maintenance complex component 4 (MCM4), nucleolar and spindle-associated protein 1 (NUSAP1), cell division cycle associated 5 (CDCA5), cell division cycle 45 (CDC45), denticleless E3 ubiquitin protein ligase homolog (DTL), and chromatin licensing and DNA replication factor 1 (CDT1) genes were regarded as hub genes in CESC. Further analysis revealed that the expressions of all these hub genes were significantly elevated in CESC cell lines and samples of diverse clinical attributes. In this study, we also documented some important correlations between hub genes and some other diverse measures, including DNA methylation, genetic alterations, and Overall Survival (OS). Last, we also identify hub genes associated ceRNA network and 31 important chemotherapeutic drugs.

CONCLUSION

Through detailed in silico methodology, we identified 6 hub genes, including MCM4, NUSAP1, CDCA5, CDC45, DTL, and CDT1, which are likely to be associated with CESC development and diagnosis.

A Rare MSH2 Variant as a Candidate Marker for Lynch Syndrome II Screening in Tunisia: A Case of Diffuse Gastric Carcinoma

Several syndromic forms of digestive cancers are known to predispose to early-onset gastric tumors such as Hereditary Diffuse Gastric Cancer (HDGC) and Lynch Syndrome (LS). LSII is an extracolonic cancer syndrome characterized by a tumor spectrum including gastric cancer (GC). In the current work, our main aim was to identify the mutational spectrum underlying the genetic predisposition to diffuse gastric tumors occurring in a Tunisian family suspected of both HDGC and LS II syndromes. We selected the index case “JI-021”, which was a woman diagnosed with a Diffuse Gastric Carcinoma and fulfilling the international guidelines for both HDGC and LSII syndromes. For DNA repair, a custom panel targeting 87 candidate genes recovering the four DNA repair pathways was used. Structural bioinformatics analysis was conducted to predict the effect of the revealed variants on the functional properties of the proteins. DNA repair genes panel screening identified two variants: a rare MSH2 c.728G>A classified as a variant with uncertain significance (VUS) and a novel FANCD2 variant c.1879G>T. The structural prediction model of the MSH2 variant and electrostatic potential calculation showed for the first time that MSH2 c.728G>A is likely pathogenic and is involved in the MSH2-MLH1 complex stability. It appears to affect the MSH2-MLH1 complex as well as DNA-complex stability. The c.1879G>T FANCD2 variant was predicted to destabilize the protein structure. Our results showed that the MSH2 p.R243Q variant is likely pathogenic and is involved in the MSH2-MLH1 complex stability, and molecular modeling analysis highlights a putative impact on the binding with MLH1 by disrupting the electrostatic potential, suggesting the revision of its status from VUS to likely pathogenic. This variant seems to be a shared variant in the Mediterranean region. These findings emphasize the importance of testing DNA repair genes for patients diagnosed with diffuse GC with suspicion of LSII and colorectal cancer allowing better clinical surveillance for more personalized medicine.

The HIF-1α as a Potent Inducer of the Hallmarks in Gastric Cancer

Simple Summary

Gastric cancer is one of the most aggressive tumors in the clinic that is resistant to chemotherapy. Gastric tumors are rich in hypoxic niches, and high expression of hypoxia-inducible factor-1α is associated with poor prognosis. Therefore, strategies that target hypoxia-inducible factor-1α signaling may be highly effective in gastric cancer treatment. However, the precise mechanisms by which hypoxia-inducible factor-1α induces tumor hallmarks in gastric cancer are yet unrevealed. Here, we review the role of hypoxia-inducible factor-1α as a potent inducer of the cancer hallmarks in gastric cancer to provide a broad perspective and reveal missing links investigating which may offer new strategies to target hypoxia-inducible factor-1α signaling in gastric cancer.

Abstract

Hypoxia is the principal architect of the topographic heterogeneity in tumors. Hypoxia-inducible factor-1α (HIF-1α) reinforces all hallmarks of cancer and donates cancer cells with more aggressive characteristics at hypoxic niches. HIF-1α potently induces sustained growth factor signaling, angiogenesis, epithelial–mesenchymal transition, and replicative immortality. Hypoxia leads to the selection of cancer cells that evade growth suppressors or apoptotic triggers and deregulates cellular energetics. HIF-1α is also associated with genetic instability, tumor-promoting inflammation, and escape from immunity. Therefore, HIF-1α may be an important therapeutic target in cancer. Despite that, the drug market lacks safe and efficacious anti-HIF-1α molecules, raising the quest for fully unveiling the complex interactome of HIF-1α in cancer to discover more effective strategies. The knowledge gap is even wider in gastric cancer, where the number of studies on hypoxia is relatively low compared to other well-dissected cancers. A comprehensive review of the molecular mechanisms by which HIF-1α induces gastric cancer hallmarks could provide a broad perspective to the investigators and reveal missing links to explore in future studies. Thus, here we review the impact of HIF-1α on the cancer hallmarks with a specific focus on gastric cancer.

Neuronal pentraxin II (NPTX2) hypermethylation promotes cell proliferation but inhibits cell cycle arrest and apoptosis in gastric cancer cells by suppressing the p53 signaling pathway

Gastric cancer is a considerable health burden worldwide. DNA methylation, a major epigenetic phenomenon, is closely related to the pathogenesis of cancer. Neuronal pentraxin II (NPTX2) has been found to be hypermethylated in several cancers such as glioblastoma and pancreatic cancer. However, the roles of NPTX2 in gastric cancer have not been reported. To explore this issue, NPTX2 expression in gastric cancer cells was assessed by western blot and quantitative real-time polymerase chain reaction (qRT-PCR). The methylation analysis of NPTX2 was performed by qRT-PCR as well as methylation-specific PCR (MS-PCR). The effects of NPTX2 on gastric cancer cell proliferation, apoptosis and cell cycle were detected by colony formation, CCK-8 and flow cytometry assays, respectively. The interaction of NPTX2 with the p53 signaling pathway was evaluated by western blot. Our study found the down-regulated expression of NPTX2 in gastric cancer cells compared with human gastric mucosal cells. In addition, the hypermethylation of NPTX2 was observed in gastric cancer cells, which was correlated with the low expression of NPTX2. Moreover, NPTX2 inhibited gastric cancer cell proliferation, inhibited apoptosis and induced cell cycle arrest. Furthermore, NPTX2 enhanced the protein expression of p53, p21 and PTEN to activate the p53 signaling pathway. Therefore, NPTX2 hypermethylation caused the downregulation of NPTX2 expression, which could promote cell proliferation, inhibit apoptosis and cause cell cycle arrest in gastric cancer cells by suppressing the p53 signaling pathway. Therefore, NPTX2 may be crucial for the progression of gastric cancer.

Netrin-1 expression and targeting in multiple myeloma

Deleted in colorectal cancer (DCC) and uncoordinated-5 (UNC5) receptors, play a key role in tumor progression of several solid tumors by inducing apoptosis when unbound to their ligand netrin-1. Netrin 1 is currently being evaluated as a therapeutic target. These receptors, known as dependence receptors, and their ligands, have not yet been extensively explored in hematological malignancies. Here, we performed a screening of various human myeloma cell lines and bone marrow samples from multiple myeloma patients for netrin-1 and its receptors to determine the expression of netrin 1 and its receptors in multiple myeloma as well as to assess the potential anti-myeloma activity of a novel anti-netrin-1 treatment (NP137). Our results showed heterogeneous expression of netrin-1 and its receptors DCC and UNC5H2(B) in six human myeloma lines. Additionally, immunohistochemistry and flow cytometry showed expression of these molecules in a majority of myeloma patient samples. In vitro NP137 did not induce apoptosis of myeloma cell lines yet enhanced the cytotoxicity of bortezomib and dexamethasone. In vivo, NP137 treatment of SCID mice with established RPMI8226 myeloma tumors led to a reduction of tumor size compared to controls. Ex vivo, NP137 lowered the plasma cells percentage in bone marrow aspirates in a fraction of the patient samples analyzed. These results suggest that netrin signaling could constitute a novel therapeutic target in multiple myeloma.

Determination of a six-gene prognostic model for cervical cancer based on WGCNA combined with LASSO and Cox-PH analysis

AIM

This study aimed to establish a risk model of hub genes to evaluate the prognosis of patients with cervical cancer.

METHODS

Based on TCGA and GTEx databases, the differentially expressed genes (DEGs) were screened and then analyzed using GO and KEGG analyses. The weighted gene co-expression network (WGCNA) was then used to perform modular analysis of DEGs. Univariate Cox regression analysis combined with LASSO and Cox-pH was used to select the prognostic genes. Then, multivariate Cox regression analysis was used to screen the hub genes. The risk model was established based on hub genes and evaluated by risk curve, survival state, Kaplan-Meier curve, and receiver operating characteristic (ROC) curve.

RESULTS

We screened 1265 DEGs between cervical cancer and normal samples, of which 620 were downregulated and 645 were upregulated. GO and KEGG analyses revealed that most of the upregulated genes were related to the metastasis of cancer cells, while the downregulated genes mostly acted on the cell cycle. Then, WGCNA mined six modules (red, blue, green, brown, yellow, and gray), and the brown module with the most DEGs and related to multiple cancers was selected for the follow-up study. Eight genes were identified by univariate Cox regression analysis combined with the LASSO Cox-pH model. Then, six hub genes (SLC25A5, ENO1, ANLN, RIBC2, PTTG1, and MCM5) were screened by multivariate Cox regression analysis, and SLC25A5, ANLN, RIBC2, and PTTG1 could be used as independent prognostic factors. Finally, we determined that the risk model established by the six hub genes was effective and stable.

CONCLUSIONS

This study supplies the prognostic value of the risk model and the new promising targets for the cervical cancer treatment, and their biological functions need to be further explored.

MicroRNA-1297 inhibits proliferation and promotes apoptosis in gastric cancer cells by downregulating CDC6 expression

Gastric cancer (GC), one of the most common malignant tumors and the second most common leading cause of cancer-related death worldwide, is a biologically heterogeneous disease accompanied by various genetic and epigenetic alterations. However, the molecular mechanisms underlying this disease are complex and not completely understood. Increasing studies have shown that aberrant microRNA (miRNA) expression is associated with GC tumorigenesis and growth. MiR-1297 has been confirmed to be a cancer suppressor in diverse tumors in humans. However, to date, the function and mechanism of miR-1297 in GC have not been determined. Here, we found that the expression of miR-1297 was significantly reduced in GC tissues or GC cell lines compared with paracarcinoma normal tissue or normal cell lines. Exogenic overexpression of miR-1297 in GC cell lines can inhibit cell proliferation and colony formation and induce apoptosis, and inhibition of miR-1297 in GC cell lines can promote cell proliferation and colony formation, and reduce apoptosis in vitro. We further confirmed that miR-1297 acted as a tumor suppressor through targeting cell division control protein 6 (CDC6) in GC. Moreover, the inverse relationship between miR-1297 and CDC6 was verified in GC cell lines. Our results indicated that miR-1297 is a potent tumor suppressor in GC, and its antiproliferative and gene-regulatory effects are, in part, mediated through its downstream target gene, CDC6. These findings implied that miR-1297 might be used as a novel therapeutic target of GC.

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

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

An Overview of Promising Biomarkers in Cancer Screening and Detection

Applications of biomarkers have been proved in oncology screening, diagnosis, predicting response to treatment as well as monitoring the progress of the disease. Considering the crucial role played by them during different disease stages, it is extremely important to evaluate, validate, and assess them to incorporate them into routine clinical care. In this review, the role of few most promising and successfully used biomarkers in cancer detection, i.e. PD-L1, E-Cadherin, TP53, Exosomes, cfDNA, EGFR, mTOR with regard to their structure, mode of action, and reports signifying their pathological significance, are addressed. Also, an overview of some successfully used biomarkers for cancer medicine has been presented. The study also summarizes biomarker-driven personalized cancer therapy i.e., approved targets and indications, as per the US FDA. The review also highlights the increasingly prominent role of biomarkers in drug development at all stages, with particular reference to clinical trials. The increasing utility of biomarkers in clinical trials is clearly evident from the trend shown, wherein ~55 percent of all oncology clinical trials in 2019 were seen to involve biomarkers, as opposed to ~ 15 percent in 2001, which clearly proves the essence and applicability of biomarkers for synergizing clinical information with tumor progression. Still, there are significant challenges in the implementation of these possibilities with strong evidence in cost-- effective manner.

Precision medicine in gastric cancer

Gastric cancer (GC) is a complex disease linked to a series of environmental factors and unhealthy lifestyle habits, and especially to genetic alterations. GC represents the second leading cause of cancer-related deaths worldwide. Its onset is subtle, and the majority of patients are diagnosed once the cancer is already advanced. In recent years, there have been innovations in the management of advanced GC including the introduction of new classifications based on its molecular characteristics. Thanks to new technologies such as next-generation sequencing and microarray, the Cancer Genome Atlas and Asian Cancer Research Group classifications have also paved the way for precision medicine in GC, making it possible to integrate diagnostic and therapeutic methods. Among the objectives of the subdivision of GC into subtypes is to select patients in whom molecular targeted drugs can achieve the best results; many lines of research have been initiated to this end. After phase III clinical trials, trastuzumab, anti-Erb-B2 receptor tyrosine kinase 2 (commonly known as ERBB2) and ramucirumab, anti-vascular endothelial growth factor receptor 2 (commonly known as VEGFR2) monoclonal antibodies, were approved and introduced into first- and second-line therapies for patients with advanced/metastatic GC. However, the heterogeneity of this neoplasia makes the practical application of such approaches difficult. Unfortunately, scientific progress has not been matched by progress in clinical practice in terms of significant improvements in prognosis. Survival continues to be low in contrast to the reduction in deaths from many common cancers such as colorectal, lung, breast, and prostate cancers. Although several target molecules have been identified on which targeted drugs can act and novel products have been introduced into experimental therapeutic protocols, the overall approach to treating advanced stage GC has not substantially changed. Currently, surgical resection with adjuvant or neoadjuvant radiotherapy and chemotherapy are the most effective treatments for this disease. Future research should not underestimate the heterogeneity of GC when developing diagnostic and therapeutic strategies aimed toward improving patient survival.

IGSF1: A novel oncogene regulates the thyroid cancer progression

Thyroid cancer has been continuously increasing and extraordinarily prevalent worldwide. The genetic diagnosis has been widely used in fine needle aspiration. IGSF1, an immunoglobulin superfamily member 1, has been shown to be associated with the regulation of thyroid hormone. But the function of IGSF1 in thyroid cancer has not been explored yet. In this article, we will illuminate the correlation between IGSF1 expression and thyroid cancer. We analysed the level of IGSF1 expression in 55 pairs of tissue samples by real-time polymerase chain reaction (PCR) and The Cancer Genome Atlas (TCGA) data portal. After that, we transfected small interfering RNA to silence IGSF1 in thyroid cancer cell lines (KTC-1 and BCPAP) and confirmed the function of IGSF1 by performed colony formation, migration, invasion, cell counting kit-8, and apoptosis assays. IGSF1 was upregulated in thyroid cancer tissues compared with the adjacent normal tissues (t = 5.783, df = 54; P < .0001) and TCGA (T: N = 65.91 ± 3.998, n = 501: 2.824 ± 0.273, n = 58; P < .0001). In thyroid cell lines, experiments showed that downregulated IGSF1 inhibited proliferation, metastasis, and promoted cell apoptosis. Meanwhile, inhibited IGSF1 expression could downregulate N-cadherin, vimentin, and EZH2, which is associated with metastasis. Thyroid cancer cells IGSF1 expression levels are a correlation with its ability to growth, metastasis, and apoptosis.

Crosstalk Between DNA Damage and Inflammation in the Multiple Steps of Gastric Carcinogenesis

Over the last years, intensive investigations in molecular biology and cell physiology extended tremendously the knowledge about the association of inflammation and cancer. In frame of this paradigm, the human pathogen Helicobacter pylori triggers gastritis and gastric ulcer disease, and contributes to the development of gastric cancer. Mechanisms, by which the bacteria-induced inflammation in gastric mucosa leads to intestinal metaplasia and carcinoma, are represented in this review. An altered cell-signaling response and increased production of free radicals by epithelial and immune cells account for the accumulation of DNA damage in gastric mucosa, if infection stays untreated. Host genetics and environmental factors, especially diet, can accelerate the process, which offers the opportunity of intervention based on a balanced nutrition. It is supposed that inflammation might influence stem- or progenitor cells in gastric tissue predisposing for metaplasia or tumor relapse. Herein, DNA is strongly mutated and labile, which restricts therapy options. Thus, the understanding of the mechanisms that underlie gastric carcinogenesis will be of preeminent importance for the development of strategies for screening and early detection. As most gastric cancer patients face late-stage disease with a poor overall survival, the development of multi-targeted therapeutic intervention strategies is a major challenge for the future.

Activation of LXRβ inhibits proliferation, promotes apoptosis, and increases chemosensitivity of gastric cancer cells by upregulating the expression of ATF4

Recently, great advances have been achieved in both surgery and chemotherapy for the treatment of gastric cancer, but there is still poor prognosis for this disease. The aim of this study is to investigate the role of liver X receptor β (LXRβ) in chemosensitivity of gastric cancer SGC7901 cells. From 171 patients with gastric cancer, the gastric cancer and paracancerous tissues were selected to measure the expression of LXRβ and ATF4. Gastric cancer cell lines were cultured and screened to figure out the proliferation and apoptosis of gastric cancer SGC7901 cells with the treatment of LXRβ agonist (GW3965), ATF4 short hairpin RNA (shRNA), and chemotherapy drug paclitaxel. The expression of apoptosis-related gene cleaved caspase-3 was detected by Western blot analysis. First, we found that the expressions of LXRβ and ATF4 in gastric cancer tissues and cells were significantly lower than those in their paracancerous tissues and gastric mucosal epithelial cells. In addition, activation of LXRβ and paclitaxel treatment suppressed proliferation of SGC7901 cells, and the expression of ATF4 was upregulated in a concentration-dependent manner. Furthermore, shRNA significantly inhibited the expression of ATF4 and blocked the chemosensitivity of SGC7901 cells to LXRβ activation. Our study demonstrates that the expression of LXRβ was low in gastric cancer. In addition, activation of LXRβ may inhibit the proliferation of gastric cancer cells, promote apoptosis, and increase chemosensitivity by upregulating the expression of ATF4.

Loss of LLGL1 Expression Correlates with Diffuse Gastric Cancer and Distant Peritoneal Metastases

BACKGROUND

Loss of LLGL1 has been associated with loss of cellular adhesion and dissemination of cells from colorectal cancer and malignant melanoma. Regulation and relevance of LLGL1 were analyzed in gastric cancer patients with lymphatic and distant dissemination. Furthermore, LLGL1 expression was analyzed in relation to the cellular adhesion protein E-cadherin.

METHODS

LLGL1 and E-cadherin transcription levels were evaluated in 56 gastric cancer patients and five gastric cancer cell lines. IHC staining for LLGL1 was performed on 39 gastric cancer specimens. LLGL1 was stably transfected into LLGL1 negative gastric cancer cell line SNU16 (del(17) (p11.2)) for functional in vitro assays and a xenograft bioassay.

RESULTS

Gastric cancer specimens and cell lines displayed LLGL1 and E-cadherin expression levels with variable intensity. In gastric mucosa, LLGL1 exhibited weak cytoplasmic and strong cortical staining. Loss of LLGL1 expression occurred in 65% of gastric cancers and significantly correlated with loss of E-cadherin expression (P=0.00009). Loss of LLGL1 expression was associated with the diffuse type of gastric cancer (P=0.029) with peritoneal carcinomatosis (M1; P=0.006) and with female gender (P=0.017). Stable reexpression of LLGL1 in SNU16 cells significantly increased both plastic surface adhesion and extracellular matrix proteins laminin and fibronectin, but had no impact on in vitro proliferation, apoptosis, or invasion or on in vivo proliferation or differentiation in our xenograft bioassay.

CONCLUSION

LLGL1 is coexpressed with E-cadherin. Loss of expression of either protein is associated with diffuse gastric cancer and peritoneal metastases. LLGL1 does not impact on proliferation or epithelial-mesenchymal transition (EMT) rather increasing cellular adhesion.

Genomic alterations in gastric cancers discovered via whole-exome sequencing

Background

Gastric cancer (GC) ranks the second in mortality rate among all cancers. Metastases account for most of the deaths in GC patients. Yet our understanding of GC and its metastasis mechanism is still very limited.

Methods

We performed 20 whole-exome sequencing (WES) on 5 typical metastatic gastric adenocarcinoma (GAC) patients with lymph node metastasis. We compared both the primary tumors to their metastatic lymph nodes, and a specific analysis pipeline was used to detect single nucleotide variants (SNVs), small insertions/deletions (indels) and copy number variants (CNVs).

Results

(1) We confirmed 30 candidate mutations in both primary and lymph nodes tissues, and other 7 only in primary tumors. (2) Copy number gains were observed in a large section of 17q12–21, as well as copy number losses in regions containing CDKN2A and CDKN2B in both primary and lymph nodes tissues.

Conclusions

Our results provide preliminary insights in the molecular mechanisms of GC initiation, development, and metastatic progression. These results need to be validated through large-scale studies.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-5097-8) contains supplementary material, which is available to authorized users.

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

Gastric cancer is the third leading cause of cancer-related deaths and ranks as the fifth most common cancer worldwide. Incidence and mortality differ depending on the geographical region and gastric cancer ranks first in East Asian countries. Although genetic factors, gastric environment, and Helicobacter pylori infection have been associated with the pathogenicity and development of intestinal-type gastric cancer that follows the Correa’s cascade, the pathogenicity of diffuse-type gastric cancer remains mostly unknown and undefined. However, genetic abnormalities in the cell adherence factors, such as E-cadherin and cellular activities that cause impaired cell integrity and physiology, have been documented as contributing factors. In recent years, H. pylori infection has been also associated with the development of diffuse-type gastric cancer. Therefore, in this report, we discuss the host factors as well as the bacterial factors that have been reported as associated factors contributing to the development of diffuse-type gastric cancer.

DNA methylation as an epigenetic regulator of gallbladder cancer: An overview

Gallbladder cancer (GBC) is a lethal health issue affecting mostly the women in their middle-age. High incidence of GBC has been reported across the world specifically in Asian countries, India and Pakistan. The exact etiology remains unknown, although several risk factors and genetic aberrations involving mutations or epigenetic changes may be involved in gallbladder carcinogenesis. This article presents a review of the published literature mainly from the year 2003 onwards. The topic of main concerns was epigenetic regulation of GBC. All relevant studies identified were included and are described according to the aforementioned subheadings. In this review, we have discussed the role of DNA methylation in GBC, clinical implication and future prospects of biomarker development for early diagnosis and therapeutic interventions.

Expression of gremlin1 in gastric cancer and its clinical significance

As an antagonist of bone morphogenetic proteins (BMPs), 2, 4 and 7, gremlin1 plays a role in regulating organogenesis, tissue differentiation and angiogenesis. However, there is little information regarding gremlin1 in gastrointestinal cancer. We attempted to clarify how gremlin1 expression affects the clinical features and biological properties of gastric cancer. A total of 232 gastric cancer patients who received R0 gastrectomy at Kagoshima University Hospital were enrolled. Gremlin1 expression in gastric cancer was detected by immunohistochemical and western blotting methods. Correlations between clinicopathological parameters and gremlin1 expression were analyzed. Gremlin1 was identified in the cytoplasm and nucleus of all gastric cancer cell lines and some regions of surgical specimens of gastric cancer. One hundred and seventeen of the 232 patients (50.4%) were classified as gremlin1-positive based on gremlin1 expression. Gremlin1 positivity was correlated with shallower tumor depth, smaller tumor size, less nodal involvement and vessel invasion (p < 0.05). The 5-year survival rate of the gremlin1-positive group was 81%, which was significantly higher than the gremlin1-negative group (p < 0.01). Multivariate analysis revealed that gremlin1 was not selected as an independent prognostic marker. Gremlin1 expression in gastric cancer may be a useful prognostic marker that is involved with the BMP signaling pathway. Furthermore, gremlin1 may have clinical use as a diagnostic and treatment tool.

MicroRNA-937 inhibits cell proliferation and metastasis in gastric cancer cells by downregulating FOXL2

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An increase in galectin-3 causes cellular unresponsiveness to IFN-γ-induced signal transduction and growth inhibition in gastric cancer cells

Glycogen synthase kinase (GSK)-3β facilitates interferon (IFN)-γ signaling by inhibiting Src homology-2 domain-containing phosphatase (SHP) 2. Mutated phosphoinositide 3-kinase (PI3K) and phosphatase and tensin homolog (PTEN) cause AKT activation and GSK-3β inactivation to induce SHP2-activated cellular unresponsiveness to IFN-γ in human gastric cancer AGS cells. This study investigated the potential role of galectin-3, which acts upstream of AKT/GSK-3β/SHP2, in gastric cancer cells. Increasing or decreasing galectin-3 altered IFN-γ signaling. Following cisplatin-induced galectin-3 upregulation, surviving cells showed cellular unresponsiveness to IFN-γ. Galectin-3 induced IFN-γ resistance independent of its extracellular β-galactoside-binding activity. Galectin-3 expression was not regulated by PI3K activation or by a decrease in PTEN. Increased galectin-3 may cause GSK-3β inactivation and SHP2 activation by promoting PDK1-induced AKT phosphorylation at a threonine residue. Overexpression of AKT, inactive GSK-3β^R96A, SHP2, or active SHP2^D61A caused cellular unresponsiveness to IFN-γ in IFN-γ-sensitive MKN45 cells. IFN-γ-induced growth inhibition and apoptosis in AGS cells were observed until galectin-3 expression was downregulated. These results demonstrate that an increase in galectin-3 facilitates AKT/GSK-3β/SHP2 signaling, causing cellular unresponsiveness to IFN-γ.

Microsatellite Alterations and Protein Expression of 5 Major Tumor Suppressor Genes in Gastric Adenocarcinomas

PURPOSE: In gastric adenocarcinoma (GC), the major tumor suppressor genes (TSGs) such as p16, PTEN, Rb, E-cadherin, and p53, may play important roles in various regulatory pathways and in tumor suppression. This study evaluated the loss of heterozygosity (LOH) of microsatellite and protein expression of 5 TSGs and the results were examined for their correlation with clinicopathological factors. METHODS: LOH analysis was carried out using polymerase chain reactions with 15 polymorphic microsatellite markers of 5 chromosomes containing TSGs in 100 surgically resected tumors. Protein expression was evaluated by immunohistochemistry (IHC). RESULTS: LOH was detected in 83% of GCs. LOH of 9p21, 10q23, 13q14, 16q22, and 17p13 were detected in 26%, 31%, 24%, 22%, and 35% of cases, respectively. Protein expression of p16, PTEN, Rb, E-cadherin, and p53 were found to be 31%, 39%, 28%, 32%, and 46% of cases. Advanced GCs showed significantly higher rates of 17p13 LOH and p53 expression. 9p21 LOH and E-cadherin IHC were correlated with higher tumor grade. Lymph node metastasis was correlated with the LOH of 9p21, 16q22, and 17p13 and IHC of the Rb and p53. A higher stage was correlated with 10q23 and 17p13 in LOH and p53 for IHC. CONCLUSION: These results suggest that LOH and protein expression of various TSGs are important in carcinogenesis and tumor invasion. Additionally, LOH and IHC may be useful clinical indicators for determining the prognosis of patients with GCs. In particular, the 17p13 LOH and p53 for IHC can be applied as simple evaluations in the clinic.

Diagnostic, Predictive, Prognostic, and Therapeutic Molecular Biomarkers in Third Millennium: A Breakthrough in Gastric Cancer

Introduction

Gastric cancer is the fifth most common cancer and the third cause of cancer death. The clinical outcomes of the patients are still not encouraging with a low rate of 5 years' survival. Often the disease is diagnosed at advanced stages and this obviously negatively affects patients outcomes. A deep understanding of molecular basis of gastric cancer can lead to the identification of diagnostic, predictive, prognostic, and therapeutic biomarkers.

Main Body

This paper aims to give a global view on the molecular classification and mechanisms involved in the development of the tumour and on the biomarkers for gastric cancer. We discuss the role of E-cadherin, HER2, fibroblast growth factor receptor (FGFR), MET, human epidermal growth factor receptor (EGFR), hepatocyte growth factor receptor (HGFR), mammalian target of rapamycin (mTOR), microsatellite instability (MSI), PD-L1, and TP53. We have also considered in this manuscript new emerging biomarkers as matrix metalloproteases (MMPs), microRNAs, and long noncoding RNAs (lncRNAs).

Conclusions

Identifying and validating diagnostic, prognostic, predictive, and therapeutic biomarkers will have a huge impact on patients outcomes as they will allow early detection of tumours and also guide the choice of a targeted therapy based on specific molecular features of the cancer.

Down-regulation of KLF5 in cancer-associated fibroblasts inhibit gastric cancer cells progression by CCL5/CCR5 axis

It was well known that cancer-associated fibroblasts (CAFs) were an essential factor in tumor progression. However, the actual mechanism of stromal fibroblasts activation and tumor promoting effects remain unclear. Here, we showed that KLF5 expression was more frequently observed in gastric cancer-associated fibroblasts compared with normal mucosal fibroblasts. Moreover, KLF5 expression in tumor stroma was closely associated with clinicopathological features such as tumor size, invasion depth, cell grade and lymph node metastasis, as well as poor prognosis in patients with gastric cancer. In addition, we further demonstrated that KLF5-regulating CAFs affect gastric cancer cells progression by CCL5 secretion and activation of CCR5. Taken together, we concluded that KLF5 expression in gastric cancer-associated fibroblasts contribute to poor survival and promote cancer cells progression by activation of CCL5/CCR5 axis, which suggesting that KLF5 in CAFs might be considered as a promising target for the treatment of gastric cancer.

Mutational analysis of driver genes with tumor suppressive and oncogenic roles in gastric cancer

Gastric cancer (GC) is a complex disease with heterogeneous genetic mechanisms. Genomic mutational profiling of gastric cancer not only expands our knowledge about cancer progression at a fundamental genetic level, but also could provide guidance on new treatment decisions, currently based on tumor histology. The fact that precise medicine-based treatment is successful in a subset of tumors indicates the need for better identification of clinically related molecular tumor phenotypes, especially with regard to those driver mutations on tumor suppressor genes (TSGs) and oncogenes (ONGs). We surveyed 313 TSGs and 160 ONGs associated with 48 protein coding and 19 miRNA genes with both TSG and ONG roles. Using public cancer mutational profiles, we confirmed the dual roles of CDKN1A and CDKN1B. In addition to the widely recognized alterations, we identified another 82 frequently mutated genes in public gastric cancer cohort. In summary, these driver mutation profiles of individual GC will form the basis of personalized treatment of gastric cancer, leading to substantial therapeutic improvements.

Roles of p38 and JNK protein kinase pathways activated by compound cantharidin capsules containing serum on proliferation inhibition and apoptosis of human gastric cancer cell line

The aim of the present study was to investigate the inhibitory effect of compound cantharides capsules (CCCs) on the viability and apoptosis of human gastric cancer cell lines, BGC-823 and SGC-7901, and to detect its regulation of gene expression levels, as well as its inhibition mechanisms. Each cell line was grouped into a control group, CCC serum group, 5-fluorouracil (5-FU) group, combination therapy group (CCC serum + 5-FU) and serum control group. Growth curves were measured and flow cytometry was used to detect cell apoptosis and cell viability. The mRNA expression level of proliferation-related C-MYC and p53 genes were assayed by reverse transcription-quantitative polymerase chain reaction. Protein phosphorylation levels of proliferating cell nuclear antigen, p38 mitogen-activated protein kinase, extracellular signal-related kinase 1/2, c-Jun N-terminal kinase (JNK) and IκB were assayed by western blotting. The combined CCC serum and 5-FU group exhibited a higher inhibition rate in both cell lines and CCC serum therapy demonstrated a similar effect to 5-FU treatment, as demonstrated in the MTT and cell growth assay. Combined therapy significantly decreased the C-MYC mRNA expression levels and increased p53 mRNA expression levels (P<0.05). Combined therapy of 5-FU and CCC was more significant compared with CCC serum or 5-FU only (P<0.05). P38 and JNK-related protein phosphorylation are involved in apoptosis initiated by CCC combined 5-FU therapy. Combined therapy was able to significantly inhibit human gastric cancer cell growth (P<0.05), and advance cell apoptosis compared with CCC serum only. CCC serum resulted in downregulation of the c-Myc gene and upregulation of the p53 gene. p38 and JNK-related protein phosphorylation is involved in the inhibition of cell viability and apoptosis of human gastric cancer cell lines.

Effect of histone modifications on hMLH1 alternative splicing in gastric cancer

hMLH1 is one of the mismatch genes closely related to the occurrence of gastric cancer. Epigenetic regulation may play more important roles than gene mutations in DNA damage repair genes to drive carcinogenesis. In this article, we discuss the role of epigenetic changes, especially histone modifications in the regulation of hMLH1 alternative splicing. Our results showed that hMLH1 delEx10, delEx11, delEx10-11, delEx16 and delEx17 transcripts were ubiquitous in sporadic Chinese gastric cancer patients and gastric cancer cell lines. Lower level of H4K16ac and H3ac was detected in hMLH1 exon 10-11 region in gastric cancer cell lines when compared with human gastric mucosal epithelial cell line GES-1. A significant decrease of hMLH1 delEx11 and delEx10-11 was observed in gastric cancer cell lines after trichostatin A treatment. H3K36me3 and H3K4me2 levels were lower in hMLH1 exon 10-11 and exon 16-17 regions in gastric cancer lines when compared with GES-1. Aberrant transcripts such as hMLH1 delEx11 and delEx10-11 were significantly higher in gastric cancer cell lines after small interfering RNA-mediated knockdown of SETD2 (the specific methyltransferase of H3K36). The hMLH1 delEx10 and delEx10-11 transcripts were increased after interference of SRSF2. Taken together, our study demonstrates that lower level of histone acetylation and specific histone methylation such as H3K36me3 correlate with aberrant transcripts in hMLH1 exon 10-11 region. SRSF2 may be involved in these specific exons skipping as well.

MicroRNA-216b is Down-Regulated in Human Gastric Adenocarcinoma and Inhibits Proliferation and Cell Cycle Progression by Targeting Oncogene HDAC8

PURPOSE

Accumulating evidence indicates that micro (mi)RNAs play a critical role in carcinogenesis and cancer progression; however, their role in the tumorigenesis of gastric adenocarcinoma remains unclear so the present study investigated this in gastric cancer (GC) tissues and cell lines.

METHODS

Human GC specimens (n = 57) and patient-paired non-cancerous specimens were obtained from patients at the First Affiliated Hospital, Henan University of Science and Technology. The AGS and GC9811 gastric cancer cell lines were also used. Expression levels of miR-216b and HDAC8 were examined by quantitative real-time PCR and the expression of HDAC8 was also examined by Western blotting and immunohistochemistry assay. The cell cycle progression was determined by FACS. MiR-216b inhibitor, mimics, and siRNA-HDAC8 transfections were performed to study the loss and gain of function.

RESULTS

We reported a significantly decreased expression of miR-216b in GC clinical specimens compared with paired non-cancerous tissues. We also observed a significant down-regulation of miR-216b expression in GC cell lines AGS and GC9811 (p < 0.0001). The introduction of miR-216b suppressed GC cell proliferation and cell cycle progression by targeting HDAC8, an oncogene shown to promote malignant tumor development with a potential miR-216b binding site in its 3' untranslated region. HDAC8 expression was shown to be significantly increased in AGS and GC9811 cell lines (p < 0.0001) and GC tissues compared with controls. Moreover, HDAC8 inhibition suppressed cell cycle progression compared with control groups (22 % ± 1.6 % vs 34 % ± 2.1), indicating that HDAC8 may function as an oncogene in the development of GC. Furthermore, HDAC8 expression was negatively correlated (p < 0.0001), while miR-216b expression was positively correlated with the clinical outcome of GC patients (p < 0.0001).

DISCUSSION

Our data suggest that miR-216b functions as a tumor suppressor in human GC by, at least partially, targeting HDAC8.

Association between CHFR gene hypermethylation and gastric cancer risk: a meta-analysis

BACKGROUND

The association between the hypermethylation of CHFR gene and gastric cancer risk has been investigated by a number of studies. However, the sample size of the majority of these studies was very small. To get a more a convincing conclusion, here we performed a meta-analysis of the previously published studies to assess the association between CHFR methylation and the risk of gastric cancer.

METHODS

Eligible studies were identified by searching the MEDLINE/PubMed, Embase, and Web of Science databases before May 2016 without any language restriction. The strength of the association was estimated by odds ratio with its 95% confidence interval (CI).

RESULTS

Totally 1,399 samples, including 758 gastric cancer cases and 641 controls, from 13 studies were included in the present meta-analysis. Compared with non-cancer controls, the pooled OR of CHFR methylation in gastric cancer patients was 9.08 (95% CI: 6.40-12.88, P<0.001), suggesting that the methylation of CHFR was significantly associated with increased risk of gastric cancer. Similar results were observed when subgroup analyses were performed stratified by country, ethnicity, and methylation testing methods.

CONCLUSION

Our meta-analysis showed a strong positive correlation between CHFR methylation and risk of gastric cancer, suggesting that CHFR methylation might be a promising biomarker for the diagnosis of gastric cancer.

Clinical effect of DAPK promoter methylation in gastric cancer: A systematic meta-analysis

BACKGROUND

The loss of death-associated protein kinase (DAPK) gene expression through promoter methylation is involved in many tumors. However, the relationship between DAPK promoter methylation and clinicopathological features of gastric cancer (GC) remains to be done. Therefore, we performed a meta-analysis to assess the role of DAPK promoter methylation in GC.

METHODS

Literature databases were searched to retrieve eligible studies. The pooled odds ratios (ORs) with its 95% confidence intervals (CIs) were calculated using the Stata 12.0 software.

RESULTS

Final 22 available studies with 1606 GC patients and 1508 nonmalignant controls were analyzed. A significant correlation was found between DAPK promoter methylation and GC (OR = 3.23, 95% CI = 1.70-6.14, P < 0.001), but we did not find any significant association in Caucasian population, and in blood samples in subgroup analyses. DAPK promoter methylation was associated with tumor stage and lymph node status (OR = 0.69, 95% CI = 0.49-0.96, P = 0.03; OR = 1.50, 95% CI = 1.12-2.01, P = 0.007; respectively). However, we did not find that DAPK promoter methylation was associated with gender status and tumor histology.

CONCLUSION

Our findings suggested that DAPK promoter methylation may play a key role in the carcinogenesis and progression of GC. In addition, methylated DAPK was a susceptible gene for Asian population. However, more studies with larger subjects should be done to further evaluate the effect of DAPK promoter methylation in GC patients, especially in blood and Caucasian population subgroup.

Lysine-specific demethylase 1 promotes tumorigenesis and predicts prognosis in gallbladder cancer

Gallbladder Cancer (GBC), characterized by invasive growth and infiltrative dissemination, is difficult to diagnose and has poor prognosis. Emerging evidence demonstrates that Lysine-Specific Demethylase 1 (LSD1) has important roles in carcinogenesis, proliferation and metastasis. We studied the roles and molecular mechanisms of LSD1 in GBC. We examined LSD1 expression in 109 paired samples of GBC and normal gallbladder tissues. We found GBC tissues had upregulated LSD1 compared with normal gallbladder tissues (P = 0.003), and its high expression was associated with tumor-node-metastasis stage (P < 0.0001), Nevin's stage (P = 0.0093) and distant metastases (P = 0.0070). We found positive correlations between LSD1 expression and other proteins: epithelial-mesenchymal transition markers, C-myc and cyclin-related proteins. Inhibiting LSD1 expression in vitro impaired the proliferation and invasiveness of GBC cells and also downregulated c-myc expression and consequently inhibited GBC cell proliferation. LSD1 overexpression promotes GBC development and may be a predictor for a worsened prognosis. LSD1 may be a novel therapeutic target and prognostic tool for gallbladder cancer.

Silencing NKD2 by promoter region hypermethylation promotes gastric cancer invasion and metastasis by up-regulating SOX18 in human gastric cancer

Naked cuticle homolog2 (NKD2) is located in chromosome 5p15.3, which is frequently loss of heterozygosity in human colorectal and gastric cancers. In order to understand the mechanism of NKD2 in gastric cancer development, 6 gastric cancer cell lines and 196 cases of human primary gastric cancer samples were involved. Methylation specific PCR (MSP), gene expression array, flow cytometry, transwell assay and xenograft mice model were employed in this study. The expression of NKD1 and NKD2 was silenced by promoter region hypermethylation. NKD1 and NKD2 were methylated in 11.7% (23/196) and 53.1% (104/196) in human primary gastric cancer samples. NKD2 methylation is associated with cell differentiation, TNM stage and distant metastasis significantly (all P < 0.05), and the overall survival time is longer in NKD2 unmethylated group compared to NKD2 methylated group (P < 0.05). Restoration of NKD2 expression suppressed cell proliferation, colony formation, cell invasion and migration, induced G2/M phase arrest, and sensitized cancer cells to docetaxel. NKD2 inhibits SOX18 and MMP-2,7,9 expression and suppresses BGC823 cell xenograft growth. In conclusion, NKD2 methylation may serve as a poor prognostic and chemo-sensitive marker in human gastric cancer. NKD2 impedes gastric cancer metastasis by inhibiting SOX18.

Gastric biomarkers: a global review

BACKGROUND

Gastric cancer is an aggressive disease with a poor 5-year survival and large global burden of disease. The disease is biologically and genetically heterogeneous with a poorly understood carcinogenesis at the molecular level. Despite the many prognostic, predictive, and therapeutic biomarkers investigated to date, gastric cancer continues to be detected at an advanced stage with resultant poor clinical outcomes.

MAIN BODY

This is a global review of gastric biomarkers with an emphasis on HER2, E-cadherin, fibroblast growth factor receptor, mammalian target of rapamycin, and hepatocyte growth factor receptor as well as sections on microRNAs, long noncoding RNAs, matrix metalloproteinases, PD-L1, TP53, and microsatellite instability.

CONCLUSION

A deeper understanding of the pathogenesis and biological features of gastric cancer, including the identification and characterization of diagnostic, prognostic, predictive, and therapeutic biomarkers, hopefully will provide improved clinical outcomes.

c-Jun N-terminal kinase activation has a prognostic implication and is negatively associated with FOXO1 activation in gastric cancer

Background

Since the biological function of c-Jun N-terminal kinase (JNK) in gastric cancer remains unclear, we investigated the clinical significance of JNK activation and its association with FOXO1 activation.

Methods

Immunohistochemical tissue array analysis of 483 human gastric cancer specimens was performed, and the results of the immunostaining were quantified. The correlation between JNK activation (nuclear staining for pJNK) and clinicopathological features, the proliferation index, prognosis or FOXO1 inactivation (cytoplasmic staining for pFOXO1) was analyzed. The SNU-638 gastric cancer cell line was used for in vitro analysis.

Results

Nuclear staining of pJNK was found in 38 % of the gastric carcinomas and was higher in the early stages of pTNM (P < 0.001). pJNK staining negatively correlated with lymphatic invasion (P = 0.034) and positively correlated with intestinal type by Lauren’s classification (P = 0.037), Ki-67-labeling index (P < 0.001), cyclin D1 (P = 0.045), cyclin E (P < 0.001) and pFOXO1 (P < 0.001). JNK activation correlated with a longer patients survival (P =0.008) and patients with a JNK-active and FOXO1-inactive tumor had a higher survival rate than the remainder of the population (P = 0.004). In vitro analysis showed that JNK inhibition by SP600125 in SNU-638 cells decreased cyclin D1 protein expression and increased FOXO1 activation. Further, JNK inhibition markedly suppressed colony formation, which was partially restored by FOXO1 shRNA expression.

Conclusions

Our results indicate that JNK activation may serve as a valuable prognostic factor in gastric cancer, and that it is implicated in gastric tumorigenesis, at least in part, through FOXO1 inhibition.

The effect of antisense inhibitor of miRNA 106b∼25 on the proliferation, invasion, migration, and apoptosis of gastric cancer cell

Accumulating data has demonstrated that miRNA 106b∼25, which are composed of the highly conserved miRNA 106b, miRNA 93, and miRNA 25, play carcinogenic roles in cancers. We investigated the expression of miRNA 106b∼25 in gastric cancer cells (SGC 7901, MGC 803, BGC 823) and normal gastric epithelial cell then inhibited miRNA 106b∼25 expression via transiently transfecting their antisense inhibitor. After miRNA 106b∼25 cluster was inhibited, MTT, Scratch test, Transwell invasion test, and flow cytometry were applied to investigate the proliferation, invasion, migration, cell cycle, and apoptosis of gastric cancer cell. The expression of miRNA 106b, miRNA 93, and miRNA 25 in gastric cancer cells SGC 7901, MGC 803, and BGC 823 was significantly higher than in gastric epithelial cell GES-1. The most significant suppression of miRNA 106b∼25 expressions can be detected in MGC 803 cell after transiently transfecting their antisense inhibitors. So, MGC 803 cell was selected as our research object. After inhibiting miRNA 106b and miRNA 93 respectively and combined, the proliferation, migration, and invasion of gastric cancer cell MGC 803 were significantly suppressed. The most significant suppression was observed in combined inhibiting group. After miRNA 106b∼25 cluster was inhibited respectively or combined, more gastric cancer cells were arrested in the G0G1 phase. However, there was no statistical difference in comparing with control groups. While the percentages of apoptotic cells increased after miRNA 106b∼25 cluster was inhibited, the statistical difference was detected only in combined inhibiting group. Inhibiting miRNA 106b∼25 cluster via transfecting antisense inhibitor can influence biological behavior of gastric cancer cell.

Different patterns of allelic imbalance in sporadic tumors and tumors associated with long-term exposure to gamma-radiation

The study aimed to reveal cancer related mutations in DNA repair and cell cycle genes associated with chronic occupational exposure to gamma-radiation in personnel of the Siberian Group of Chemical Enterprises (SGCE). Mutations were analyzed by comparing genotypes of malignant tumors and matched normal tissues of 255 cancer patients including 98 exposed to external gamma-radiation (mean dose 128.1±150.5mSv). Also a genetic association analysis was carried out in a sample of 149 cancer patients and 908 healthy controls occupationally exposed to gamma-radiation (153.2±204.6mSv and 150.5±211.2mSv, respectively). Eight SNPs of genes of DNA excision repair were genotyped (rs13181, rs1052133, rs1042522, rs2305427, rs4244285, rs1045642, rs1805419 and rs1801133). The mutation profiles in heterozygous loci for selected SNP were different between sporadic tumors and tumors in patients exposed to radiation. In sporadic tumors, heterozygous genotype Arg/Pro of the rs1042522 SNP mutated into Arg/0 in 15 cases (9.6%) and 0/Pro in 14 cases (8.9%). The genotype Lys/Gln of the rs13181 SNP mutated into Lys/0 and 0/Gln in 9 and 4 cases, respectively. In tumors of patients exposed to low-level radiation, the rs1042522 Arg/0 mutated genotype was found in 12 cases (12.1%), while in 2 cases (2%) 0/Pro mutation was observed. Finally, the rs13181 0/Gln mutated genotype was observed in 15 cases (16,5%) . Thus, our study showed the difference in patterns of allelic imbalance in tumors appeared under low-level radiation exposure and spontaneous tumors for selected SNPs. This suggests different mechanisms of inactivation of heterozygous genotypes in sporadic and radiation-induced tumors.

Effects of PTEN gene alteration in patients with gallbladder cancer

Gallbladder cancer (GBC) is an aggressive malignancy usually diagnosed in an advanced stage. We investigated the effects of alterations of the phosphatase and tensin homologue (PTEN) gene on the occurrence and development of GBC, which has not been previously reported. A total 141 cases of GBC were analyzed for mutation, expression, and methylation across the nine exons of the PTEN gene. DNA sequencing methods were applied for mutation detection, whereas protein expression and methylation status were evaluated by immunohistochemical and methylation-specific PCR analysis, respectively. Novel PTEN mutations were observed in 6.3% of cases (9/141), and they included two silent mutations. In mutant cases, according to changes in codons, the respective amino acid sequences were also changed, which caused of proteins. A high percentage (72%) of loss of protein expression was observed more often in cases than in control samples. Interestingly, all nine cases with mutations showed loss of PTEN expression, whereas four of these nine cases showed positive promoter methylation. Hypermethylation was significantly more common in older patients than in younger ones (P<0.02). These findings suggest that PTEN mutations and inactivation may play an important role in the development and progression of gallbladder carcinoma.

Implications for chronic toxicity of benzo[a]pyrene in sea bream cultured hepatocytes: Cytotoxicity, inflammation, and cancerogenesis

Benzo[a]pyrene (B[a]P) is the most studied dangerous polycyclic aromatic hydrocarbon for its hepatotoxic, carcinogenic, mutagenic, teratogenic, and immunosuppressant effects, which can affect both wild and farmed marine fish through the trophic chain. This study investigated, for the first time, the chronic effects induced in vitro by B[a]P prolonged exposure on gilthead sea bream (Sparus aurata L.) hepatocytes, evaluating the cellular and nuclear latent damage. The purpose was to characterize the kind of B[a]P cyto- and genotoxic damage by morphological and immunocytochemical parameters applied in combination with the use of multiple assay endpoints. In light of our results, the short-term effects at higher B[a]P doses were linked to higher cytotoxicities and necrotic lysis, whereas a sustained inflammatory response at medium-low doses was perceived as a mitochondria-mediated apoptosis, both by surface and nuclear morphological changes. The strong immunoreactivity for the cleaved caspase-3 showed that the labeled cells committed suicide by apoptosis. B[a]P involvement on carcinogenesis comes from prolonged exposure at lower doses, establishing the connection between the escape from apoptosis and the selection of a tumoral phenotype. Cells colabeled with proliferating cell nuclear antigen/caspase-3 within the proliferative foci, were proliferating transformed oval stem cells, which escaped the suicide by apoptosis allowing cancer development. Finally, it was established that sea bream cultured hepatocytes are highly sensitive to chronic B[a]P exposure, as serious genotoxic effects were found even at the lowest doses.

AID, p53 and MLH1 expression in early gastric neoplasms and the correlation with the background mucosa

A number of tumor-associated genes have been associated with gastric cancer development. The present study evaluated differences in tumor-associated protein expression and phenotype among early gastric neoplasms, and correlated these data with those of the background mucosa. The expression of activation-induced cytidine deaminase (AID), p53 and MLH1 in 151 early gastric neoplasms [22 gastric adenomas, 92 intramucosal carcinomas (MCs), and 37 submucosal carcinomas (SMCs)] was examined immunohistochemically and compared with that of the corresponding background mucosal condition. The cellular phenotypes of the neoplasms and the corresponding background intestinal metaplasia were also determined. Aberrant AID, p53 and MLH1 expression was detected in 36.4, 0 and 0% of the adenomas, in 35.9, 32.6 and 16.3% of the MCs, and in 56.8, 62.2 and 21.6% of the SMCs, respectively. The frequency of aberrant AID and p53 expression in the SMCs was significantly increased compared with that in the MCs (AID, P<0.05; p53, P<0.01). Aberrant AID expression was significantly associated with p53 overexpression in the SMCs (P<0.01), but not in the adenomas or MCs. In addition, AID expression was associated with the severity of mononuclear cell activity in the non-cancerous mucosa adjacent to the tumor (P<0.05), particularly in the SMC cases. The percentage of MCs (34.8%) and SMCs (24.3%) that were of the gastric phenotype was higher compared with the percentage of adenomas (18.2%). These results indicated that p53 and MLH1 expression and a gastric phenotype may be important for carcinogenesis, and that chronic inflammation and AID and p53 expression are associated with submucosal progression.

Clinicopathological significance and potential drug target of RUNX3 in non-small cell lung cancer: a meta-analysis

BACKGROUND

Emerging evidence indicates that RUNX3 is a candidate tumor suppressor in several types of human tumors, including non-small cell lung cancer (NSCLC). However, the correlation between RUNX3 hypermethylation and clinicopathological characteristics of NSCLC remains unclear. Here, we conducted a systematic review and meta-analysis to quantitatively evaluate the effects of RUNX3 hypermethylation on the incidence of NSCLC and clinicopathological characteristics.

METHODS

A detailed literature search was made using Medline, Embase and Web of Science for related research publications written in English. The methodological quality of the studies was evaluated. The data were extracted and assessed independently by two reviewers. Analysis of pooled data was performed. The odds ratio (OR) and hazard ratio were calculated and summarized.

RESULTS

Final analysis of 911 NSCLC patients from 13 eligible studies was performed. We observed that RUNX3 hypermethylation was significantly higher in NSCLC than in normal lung tissue; the pooled OR from seven studies including 361 NSCLC and 345 normal lung tissue (OR 7.08, confidence interval 4.12-12.17, P<0.00001). RUNX3 hypermethylation may also be associated with pathological types. The pooled OR was obtained from eleven studies including 271 squamous cell carcinoma and 389 adenocarcinoma (OR 0.41, confidence interval 0.19-0.89, P=0.02), which indicated that RUNX3 hypermethylation is significantly higher in adenocarcinoma that in squamous cell carcinoma. We did not find that RUNX3 hypermethylation was correlated with clinical stage or differentiated status. However, NSCLC patients with RUNX3 hypermethylation had a lower survival rate than those without RUNX3 hypermethylation.

CONCLUSION

The results of this meta-analysis suggest that RUNX3 hypermethylation is associated with an increased risk and worse survival in NSCLC. RUNX3 hypermethylation, which induces inactivation of the RUNX3 gene, plays an important role in lung carcinogenesis and clinical outcome.

Increased DNA methyltransferase 1 protein expression correlates significantly with intestinal histological type and gender in gastric carcinomas

PURPOSE

Promoter hypermethylation and reduced expression of many genes have been found in gastric cancer. DNA methyltransferases are enzymes potentially affecting promoter hypermethylation.

MATERIAL AND METHODS

We analyzed proteins expression of DNA methyltransferase 1 and 3b by immunohistochemistry in 47 surgically resected gastric cancer samples for which clinicopathological characteristics, patient's outcome and methylation status of 11 selected tumor-related genes have been determined. Promoter methylation status of genes was assessed by methylation specific PCR.

RESULTS

We found that DNMT1 and 3b were up-regulated in gastric cancer and were detected in 51.1% and 57.4% of cases, respectively. Co-expression of DNMT1 and 3b was detected in 44.7%. Correlations analysis have showed that DNMT1 overexpression was significantly correlated with gastric cancer of intestinal histological type (P=0.01) and with gender of patient (P=0.01). However, there was no correlation between DNMT1 and DNMT3b overexpression in cancer and patients outcome. Moreover, there were no clear relations between the proteins expression of DNMT1 and 3b and DNA methylation status of genes. But co-expression of DNMT1 and DNMT3b was significantly associated with promoter hypermethylation of RAR-β2 (P=0.04).

CONCLUSIONS

Results from our study indicate that DNMT1 and 3b were overexpressed and could be involved in gastric tumorigenesis of intestinal histological type in the case of Tunisian patients.

Interaction of sonic hedgehog (SHH) pathway with cancer stem cell genes in gastric cancer

Gastric cancer may appear by frequent genetic or epigenetic changes in oncogenes, tumor suppressor or DNA mismatch repair genes. Molecular studies show the possibility of involvement of certain cancer pathways in gastric cancer. In this respect, DNA methylation is one of the most important epigenetic alterations in gastric cancer and identifying the signaling mechanism and also methylation of some genes that are involved in gastric cancer can help to improve treatment strategies. Relatively, there are many reported methylation alteration of genes in stem cells in all kinds of tumors with some of these genes having a key role in tumor development. Correspondingly, KLF5, CDX1/2, WNT1 and FEM1A are considerable genes in gastric cancer, although many researches and studies have illustrated that sonic hedgehog and expression of its signaling cascade proteins are related in gastric cancer. Relatively, modification in these genes causes many eclectic cancers such as rhabdomyosarcoma and diverse kinds of digestive system tumor development. Conspicuously, these master genes have a noticeable role in stem cell's growth regulation as well as other kinds of cancer such as breast cancer and leukemia. Hence, we concluded that research and studies on methylation and expression of these genes and also the investigation of molecular signaling in gastric cancer can acquire impressive conclusions in order to control and treat this common place and serious problem.