Frequent epigenetic inactivation of SFRP genes and constitutive activation of Wnt signaling in gastric cancer

SFRP2 mediates Epstein-Barr virus and bladder cancer risk: a Mendelian randomization study and colocalization analysis

Studies suggest a possible association between Epstein-Barr virus (EBV) infection and bladder cancer (BCa) risk, though this remains unclear. Secreted frizzled-related protein (sFRP) is also linked to BCa, with some DNA viruses potentially regulating its expression. This study used Mendelian randomization (MR) and colocalization analysis to explore the causal relationship between EBV infection, BCa risk, and the mediating role of sFRP. We first performed a two-sample MR study to assess the causal relationship between 5 EBV-related antibodies (AEB-IgG, EA-D, EBNA-1, VCA-p18, ZEBRA) and BCa using the Finnish Consortium's R11 dataset, validated with R10. Reverse MR analysis followed. For significant results, multivariable MR (MVMR) was applied to adjust for confounding risk factors. A two-step MR explored the potential mediating role of 3 sFRPs (sFRP1, sFRP2, sFRP3) between positive exposures and BCa. Colocalization analysis were conducted for positive exposures, mediators, and BCa, with multiple sensitivity analyses confirming the robustness of the results. The two-sample Mendelian randomization study found that EBNA-1 (OR = 1.15, 95% CI: 1.01-1.30; p = 0.039) and VCA-p18 (OR = 1.36, 95% CI: 1.13-1.64; p = 0.001) may increase BCa risk, with only VCA-p18 (P_fdr = 0.006) showing a significant effect after False Discovery Rate (FDR) correction. The Finnish Consortium R10 replication study yielded similar results, and reverse MR analysis did not suggest reverse causality. After MVMR adjusted for relevant confounders, VCA-p18 (OR = 1.40, 95% CI: 1.13-1.74; p = 0.002) still significantly increased BCa risk. Two-step MR identified sFRP2 as a mediator, with VCA-p18 down-regulating sFRP2 expression to elevate BCa risk. Colocalization analysis suggested a shared causal variant (nearby gene HLA-DQA1) between VCA-p18 and BCa (PPH4 = 65.44%). Multiple sensitivity analyses confirmed the robustness of the results. Our study suggests that EBV infection (VCA-p18 antibody) may increase the risk of BCa by lowering sFRP2 levels. Additionally, EBNA-1 antibodies may also contribute to an elevated risk of BCa. We hope these findings will provide new insights for future research on the association between EBV and BCa.

Deciphering Aflatoxin B1 affected critical molecular pathways governing cancer: A bioinformatics study using CTD and PANTHER databases

Aflatoxin B1 (AFB1) is a fungal toxin consistently found as a contaminant in food products such as cereals, nuts, spices, and oilseeds. AFB1 exposure can lead to hepatotoxicity, cancer, immune suppression, reproductive deficiency, nutritional dysfunction, and growth impairment. AFB1 has also been listed as one of the most potent human carcinogens by the International Agency for Research on Cancer. Although the correlation between AFB1 exposure and cancer initiation and progression is already reported in the literature, very little information is available about what molecular pathways are affected during cancer development. Considering this, we first selected AFB1-responsive genes involved in five deadliest cancer types including lung, colorectal, liver, stomach, and breast cancers from the Comparative Toxicogenomics Database (CTD). Then, using the PANTHER database, a statistical overrepresentation test was performed to identify the significantly affected pathways in each cancer type. The gonadotropin-releasing hormone receptor (GnRHR) pathway, the CCKR signaling pathway, and angiogenesis were found to be the most affected pathways in lung, breast, liver, and stomach cancers. In addition, AFB1 toxicity majorly impacted apoptosis and Wnt signaling pathways in liver and stomach cancers, respectively. Moreover, the most affected pathways in colorectal cancer were the Wnt, CCKR, and GnRHR pathways. Furthermore, gene analysis was also performed for the most affected pathways associated with each cancer and identified thirteen key genes (e.g., FOS, AKT1) that may serve as biological markers for a particular type of AFB1-induced cancer as well as for in vitro AFB1 toxicological studies using specific cancer cell lines.

Wnt Pathway-Targeted Therapy in Gastrointestinal Cancers: Integrating Benchside Insights with Bedside Applications

The Wnt signaling pathway is critical in the onset and progression of gastrointestinal (GI) cancers. Anomalies in this pathway, often stemming from mutations in critical components such as adenomatous polyposis coli (APC) or β-catenin, lead to uncontrolled cell proliferation and survival. In the case of colorectal cancer, dysregulation of the Wnt pathway drives tumor initiation and growth. Similarly, aberrant Wnt signaling contributes to tumor development, metastasis, and resistance to therapy in other GI cancers, such as gastric, pancreatic, and hepatocellular carcinomas. Targeting the Wnt pathway or its downstream effectors has emerged as a promising therapeutic strategy for combating these highly aggressive GI malignancies. Here, we review the dysregulation of the Wnt signaling pathway in the pathogenesis of GI cancers and further explore the therapeutic potential of targeting the various components of the Wnt pathway. Furthermore, we summarize and integrate the preclinical evidence supporting the therapeutic efficacy of potent Wnt pathway inhibitors with completed and ongoing clinical trials in GI cancers. Additionally, we discuss the challenges of Wnt pathway-targeted therapies in GI cancers to overcome these concerns for effective clinical translation.

Combining methylated RNF180 and SFRP2 plasma biomarkers for noninvasive diagnosis of gastric cancer

INTRODUCTION

Gastric cancer (GC) is a common malignant tumor, and early diagnosis significantly improves patient survival rates. This study aimed to investigate the diagnostic value of ring finger protein 180 (RNF180) and secreted frizzled protein 2 (SFRP2) in GC.

MATERIALS & METHODS

A total of 165 healthy individuals, 34 patients with precancerous gastric lesions, and 104 patients with confirmed GC were divided into training and validation sets; methylated RNF180 and SFRP2 were detected in circulating DNA from blood samples. Six models, including those based on logistic regression, Naive Bayes, K-nearest neighbor algorithm, glmnet, neural network, and random forest (RF) were built and validated. Area under the curve (AUC), sensitivity, specificity, positive predictive value, and negative predictive value were determined.

RESULTS

In the training set, the RF model with RNF180 and SFRP2 (R + S) had an AUC of 0.839 (95 % CI: 0.727-0.951), sensitivity of 60.3 %, and specificity of 85.5 % for diagnosing GC. The RF model with R + S+ Tumor markers had an AUC of 0.849 (95 % CI: 0.717-0.981), sensitivity of 62.8 %, and specificity of 87.1 %. In the validation set, the RF model with R + S had an AUC of 0.844 (95 % CI: 0.774-0.923), sensitivity of 87.8 %, and specificity of 69.2 %. The RF model with R + S + Tumor markers had an AUC of 0.858 (95 % CI: 0.781-0.939), sensitivity of 85.4 %, and specificity of 76.9 %.

CONCLUSION

Our results suggest that RNF180 and SFRP2 could serve as diagnostic biomarkers for GC when using the RF model.

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

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

Epigenetic control of cell signalling in cancer stem cells

The self-renewing cancer stem cells (CSCs) represent one of the distinct cell populations occurring in a tumour that can differentiate into multiple lineages. This group of sparsely abundant cells play a vital role in tumour survival and resistance to different treatments during cancer. The lack of exclusive markers associated with CSCs makes diagnosis and prognosis in cancer patients extremely difficult. This calls for the identification of unique regulators and markers for CSCs. Various signalling pathways like the Wnt/β-catenin pathway, Hedgehog pathway, Notch pathway, and TGFβ/BMP play a major role in the regulation and maintenance of CSCs. Epigenetic regulatory mechanisms add another layer of complexity to control these signalling pathways. In this chapter, we discuss about the role of epigenetic mechanisms in regulating the cellular signalling pathways in CSCs. The epigenetic regulatory mechanisms such as DNA methylation, histone modification and microRNAs can modulate the diverse effectors of signalling pathways and consequently the growth, differentiation and tumorigenicity of CSCs. In the end, we briefly discuss the therapeutic potential of targeting these epigenetic regulators and their target genes in CSCs.

The Role of WNT Pathway Mutations in Cancer Development and an Overview of Therapeutic Options

It is well established that mutations in the canonical WNT-signalling pathway play a major role in various cancers. Critical to developing new therapeutic strategies is understanding which cancers are driven by WNT pathway activation and at what level these mutations occur within the pathway. Some cancers harbour mutations in genes whose protein products operate at the receptor level of the WNT pathway. For instance, tumours with RNF43 or RSPO mutations, still require exogenous WNT ligands to drive WNT signalling (ligand-dependent mutations). Conversely, mutations within the cytoplasmic segment of the Wnt pathway, such as in APC and CTNNB1, lead to constitutive WNT pathway activation even in the absence of WNT ligands (ligand-independent). Here, we review the predominant driving mutations found in cancer that lead to WNT pathway activation, as well as explore some of the therapeutic interventions currently available against tumours harbouring either ligand-dependent or ligand-independent mutations. Finally, we discuss a potentially new therapeutic avenue by targeting the translational apparatus downstream from WNT signalling.

The regulatory role of N6-methyladenosine RNA modification in gastric cancer: Molecular mechanisms and potential therapeutic targets

N6-methyladenosinen (m⁶A) methylation is a frequent RNA methylation modification that is regulated by three proteins: "writers", "erasers", and "readers". The m⁶A modification regulates RNA stability and other mechanisms, including translation, cleavage, and degradation. Interestingly, recent research has linked m⁶A RNA modification to the occurrence and development of cancers, such as hepatocellular carcinoma and non-small cell lung cancer. This review summarizes the regulatory role of m⁶A RNA modification in gastric cancer (GC), including targets, the mechanisms of action, and the potential signaling pathways. Our present findings can facilitate our understanding of the significance of m⁶A RNA modification in GC.

Autoimmune gastritis induces aberrant DNA methylation reflecting its carcinogenic potential

BACKGROUND

Autoimmune gastritis (AIG) is a chronic inflammatory condition in gastric mucosa and is associated with increased cancer risk, though not as high as that by Helicobacter pylori (H. pylori)-associated gastritis (HPG). Although aberrant DNA methylation is induced by HPG and the level correlates with the risk of gastric cancer, DNA methylation induction by AIG is unknown.

METHODS

Gastric mucosa samples from the corpus were collected from 12 people with AIG without H. pylori infection, 10 people with HPG, and eight healthy volunteers. Genome-wide DNA methylation analysis was conducted using Infinium Methylation EPIC array. Gene expression was analyzed by quantitative RT-PCR.

RESULTS

The AIG samples had extensive aberrant DNA methylation but presented unique methylation profiles against the HPG samples after correction of leucocyte fractions. Comparison between the AIG and HPG samples showed that AIG induced methylation, but less than HPG, in overall CpG sites and also in promoter CpG islands. Promoter CpG islands of tumor-suppressor genes in the pathway of cell cycle, cell adhesion, p53, and WNT were highly methylated in the AIG samples, but more so in the HPG samples. The expression levels of IL1B and IL8, secreted by macrophage, were significantly lower in the AIG samples than in the HPG samples, suggesting that a difference in inflammatory response affected the degree and patterns of aberrant DNA methylation.

CONCLUSIONS

AIG induced aberrant DNA methylation in gastric mucosa. However, the degree of DNA methylation was less than that by HPG, which reflected carcinogenic risk.

Delineation of gastric tumors with activated ERK/MAPK signaling cascades for the development of targeted therapeutics

The ERK/MAPK signaling pathway is activated in various cancers including gastric cancer. Targeting the ERK/MAPK/MEK pathway has been considered as a promising strategy for cancer therapy. However, MEK inhibition leads to a series of resistance mechanisms due to mutations in MEK, elevated expression of RAS or RAF proteins and activation of the associated signaling pathways. In the present study, ERK/MAPK pathway specific gene signatures were identified to be highly activated in intestinal subtype gastric tumors. Inhibition of ERK/MAPK pathway with the inhibitor PD98059 in gastric cancer cell lines by in vitro signaling pathway and genome-wide expression profiling revealed the associated signaling pathways. Functional genomic investigation of the ERK/MAPK regulated genes reveals the association of ERK/MAPK pathway with E2F, Myc, SOX-2, TGF-β, OCT4 and Notch pathways in gastric cancer cells. Of these, E2F, Myc and SOX-2 pathways are activated in intestinal subtype gastric tumors and TGF-β, OCT4, Notch pathways are activated in diffuse subtype gastric tumors. Further, the mutational load of gastric tumors was found to have association and correlation with the activation pattern of ERK/MAPK pathways across gastric tumors. ERK/MAPK activation was also found to represent the EBV and MSI activated subtypes of gastric tumors. Identification of potent drug candidates inhibiting the ERK/MAPK and associated pathways would pave a way for developing the targeted therapeutics for a subset of gastric tumors with activated ERK/MAPK signaling cascade.

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

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

Value of Plasma Methylated SFRP2 in Prognosis of Gastric Cancer

BACKGROUND

Secreted frizzled-related protein 2 (SFRP2) in circulating tumor DNA (ctDNA) is related to gastric cancer (GC) proliferation. However, whether methylated SFRP2 in ctDNA serves as the biomarker in GC patients remains unknown.

AIMS

To investigate the relationship between methylated SFRP2 and the clinical outcomes of GC patients.

METHODS

One hundred and forty-eight GC patients receiving systemic chemotherapy were collected during 2015-2017. Aberrant SFRP2 methylation was detected before and after chemotherapy by digital PCR-based technologies.

RESULTS

Baseline SFRP2 methylation positively correlated with lymph node status (P < 0.001), distant metastasis (P < 0.001) and TNM stage (P = 0.005). The top 50% methylated SFRP2 had shorter progression-free survival (PFS) and overall survival (OS) than those with bottom 50% in stage III GC patients (median PFS, 11.0 vs. NR months; HR 13.05; 95% CI 3.05-55.95; median OS 17.0 vs. NR months; HR 7.80; 95% CI 1.81-33.60) and stage IV GC patients (median PFS, 4.0 vs. 7.0 months; HR 2.74; 95% CI 1.58-4.78; median OS 12.0 vs. 16.0 months; HR 3.14; 95% CI 1.67-5.92). Besides, the increased methylated SFPR2 from baseline to post-treatment was related to the worse PFS and OS among stage IV patients (median PFS, 5.0 vs. 7.0 months; HR 2.17; 95% CI 1.25-3.76; median OS 12.0 vs. 15.5 months; HR 3.51; 95% CI 1.94-6.35), but not to stage III patients.

CONCLUSIONS

SFRP2 methylation and dynamic change are associated with GC prognosis. Our findings provide potential biomarker detection approach in ctDNA for prognosis prediction and dynamic monitoring among GC patients.

Epigenetic Regulation of the Wnt/β-Catenin Signaling Pathway in Cancer

Studies over the past four decades have elucidated the role of Wnt/β-catenin mediated regulation in cell proliferation, differentiation and migration. These processes are fundamental to embryonic development, regeneration potential of tissues, as well as cancer initiation and progression. In this review, we focus on the epigenetic players which influence the Wnt/β-catenin pathway via modulation of its components and coordinated regulation of the Wnt target genes. The role played by crosstalk with other signaling pathways mediating tumorigenesis is also elaborated. The Hippo/YAP pathway is particularly emphasized due to its extensive crosstalk via the Wnt destruction complex. Further, we highlight the recent advances in developing potential therapeutic interventions targeting the epigenetic machinery based on the characterization of these regulatory networks for effective treatment of various cancers and also for regenerative therapies.

MicroRNA-135a-induced formation of CD133+ subpopulation with cancer stem cell properties in cervical cancer

Cancer stem cells (CSCs) play significant roles in tumor initiation. MicroRNA-135a (miR-135a) induced the formation of a CD133+ subpopulation from a human papillomavirus-immortalized cervical epithelial cell line. Compared with the CD133- cells, the CD133+ cells expressed higher levels of miR-135a and OCT4, exhibited significantly higher tumorsphere forming capacity and the time required for tumorsphere formation was shortened in the second generation. Serum induction suppressed the expression of CD133, OCT4 and miR-135a, but increased expression of involucrin in the miR-135a-induced CD133+ cells. The miR-135a-induced CD133+ cells were tumorigenic in a limiting dilution approach in vivo. The cells expressed significantly higher level of active β-catenin and OCT4 than the CD133- counterpart. Wnt3a enhanced the expression of OCT4 and CD133 in cervical cancer cells but failed to enhance CD133 transcription in normal cervical cells. Wnt3a stimulation also increased tumorsphere size and self-renewal of miR-135a-induced CD133+ subpopulation. Wnt/β-catenin inhibition suppressed tumorsphere formation while Wnt3a partially nullified the inhibitory effect. Taken together, miR-135a induced the formation of a subpopulation of cells with CSC properties both in vitro and in vivo and the Wnt/β-catenin signaling pathway is essential to maintain its tumorigenicity.

Demethylation of the SFRP4 Promoter Drives Gastric Cancer Progression via the Wnt Pathway

Wnt signaling is believed to be an important contributor to tumor development and has been reported to be modulated by secreted frizzled-related proteins (SFRP). Nevertheless, the role of secreted frizzled-related protein 4 (SFRP4) in tumorigenesis remains controversial. We aim to explore its biological function in gastric cancer. Genomes analysis based on the Gene Expression Omnibus (GEO) dataset was used to find the differential gene expression between different tumor-node-metastasis (TNM) stages of gastric cancer. IHC was used to determine the relationship between SFRP4 expression and clinicopathologic characteristics in patients with gastric cancer. The influence of SFRP4 on tumor progression was evaluated by CCK-8, colony formation, cell apoptosis, and cell cycle in vitro, as well as xenograft model in vivo. The methylation status of SFRPs was examined in gastric cancer specimens by quantitative methylation analysis. SFRP4 was most upregulated in advanced gastric cancer. High intratumoral SFRP4 expression, which was associated with tumor invasion and metastasis, was also a poor prognostic indicator for patients with gastric cancer. In vitro and in vivo studies revealed that SFRP4 could promote tumor growth; however, IWR-1 could suppress tumor growth mediated by SFRP4 overexpression. Mechanistic exploration found that SFRP4 was overexpressed by the decrease of promoter methylation and thus could competitively antagonize the inhibitory effect of SFRP1 on Wnt pathway activation and tumor progression in gastric cancer. IMPLICATIONS: In gastric cancer, the expression of SFRP4 was upregulated by decreased methylation. High intratumoral SFRP4 expression could activate the Wnt pathway to promote tumor progression and predict poor survival of patients with gastric cancer.

Feasibility of Plasma-Methylated SFRP2 for Early Detection of Gastric Cancer

Gastric cancer (GC) is fifth most frequently diagnosed cancer and second leading cause of cancer in China. More than 80% of GC are diagnosed at an advanced stage due to low uptake rate of invasive screening method. The performance of methylated SFRP2 test was evaluated in 236 plasma samples, including 92 patients with GC, 16 intestinal metaplasia patients, 26 gastric fundic gland polyp patients, 13 small adenoma patients, 39 hyperplastic polyp patients, and 50 control patients. The sensitivity of plasma methylated SFRP2 was compared to serum CEA, CA72-4, CA19-9, and CA242 results in 79 patients with GC. The sensitivities for detecting GC and gastric intestinal metaplasia by methylated SFRP2 test were 60.9% and 56.3% with a specificity of 86.0%. Methylated SFRP2 test had significantly higher positive detection rate for patients with GC than gastric fundic gland polyp, small adenoma, and hyperplastic polyp patients. In 79 patients with GC, the sensitivities of CEA, CA72-4, CA19-9, and CA242 for detecting GC were 22.8%, 16.5%, 12.7%, and 11.4%. In comparison, the sensitivity of methylated SFRP2 test for detecting GC was 58.2%. Plasma methylated SFRP2 test may become a valuable tool for the noninvasive detection of GC and precursor lesions and showed higher sensitivity than serum tumor markers.

High-risk HPV infection modulates the promoter hypermethylation of APC, SFRP1, and PTEN in cervical cancer patients of North India

Persistent infection with oncogenic HPV and downregulation of tumor suppressor genes play an essential role in the development and progression of cervical cancer. The present study aimed to identify the promoter methylation status of APC, SFRP1, and PTEN which are important regulators of Wnt pathway and their association with high-risk HPV infection and gene expression. Methylation Specific PCR (MSP) and quantitative reverse transcription PCR (RT-qPCR) were used to detect methylation status and gene expression levels of APC, SFRP1, and PTEN in cervical cancer biopsies (110) and paired non-cancerous biopsies (28). APC promoter was methylated in 38%, SFRP1 in 95%, and PTEN in 55% of the cervical cancer biopsies. Our data showed a trend of a higher rate of methylation of the gene promoters in cervical cancer biopsies while; they were majorly un-methylated in non-cancerous biopsies. Corresponding to a higher rate of methylation in cancer biopsies, the gene expression levels of APC, SFRP1, and PTEN were reduced in cervical cancer samples in comparison to normal cervix tissues. Further, we observed that 97% cancer biopsies were HPV infected and high-risk type HPV16 and 18 infections were significantly positively associated with APC (p = 0.008 and p = 0.007), SFRP1 (p = 0.003 and p = 0.0067), and PTEN (p = 0.049 and p = 0.008) promoter methylation. APC, SFRP1, and PTEN promoter hyper-methylation is positively associated with high-risk HPV infection and inversely associated with gene expression. Our findings show that high-risk HPV infection promotes methylation of these genes and further promotes their silencing.

Loss of SFRP1 expression is a key progression event in gastrointestinal stromal tumor pathogenesis

The mechanism of high-grade transformation in gastrointestinal stromal tumors (GISTs) remains to be clarified. We aim to discover the key progression events by studying biphasic GISTs. The study group included 101 GISTs. Nineteen of these had been screened from 263 GISTs to represent the early stage of GIST high-grade transformation, characterized by juxtaposed low-grade and high-grade regions in the same tumor (so-called biphasic GISTs). Mutational analyses, fluorescence in situ hybridization (FISH), NanoString analyses, telomere analysis, and gene expression profiling were carried out, followed by in silico analyses, cell line study, and immunohistochemical validation. Using gene expression analysis, downregulation of SFRP1 was revealed to be the main event in GIST high-grade transformation (p = 0.013), accompanied by upregulation of EZH2. In silico analyses revealed that downregulation of SFRP1 was a common feature in GIST progression across several different series. Immunohistochemically, the expression of SFRP1 was validated to be significantly lower in high-grade GISTs (WHO risk group 3a or higher) than in low-grade GISTs (p < 0.001), and attenuation/loss of SFRP1 was associated with GIST tumor progression (p < 0.001). By NanoString and FISH analyses, chromosomal 9/9p loss was the only recurrent large-scale chromosome aberration in biphasic GISTs, with a correlation with SFRP1 downregulation. Subclones containing chromosome 9/9p loss could be appreciated in the low-grade parts of biphasic GISTs. TP53 mutation, RB1 loss, KIT/PDGFRA mutation, and alternative lengthening of telomeres did not play a significant role in GIST high-grade transformation. In conclusion, high-grade transformation of GISTs features SFRP1 downregulation and chromosome 9/9p loss.

Klotho and the Treatment of Human Malignancies

Klotho was first discovered as an anti-ageing protein linked to a number of age-related disease processes, including cardiovascular, renal, musculoskeletal, and neurodegenerative conditions. Emerging research has also demonstrated a potential therapeutic role for Klotho in cancer biology, which is perhaps unsurprising given that cancer and ageing share similar molecular hallmarks. In addition to functioning as a tumour suppressor in numerous solid tumours and haematological malignancies, Klotho represents a candidate therapeutic target for patients with these diseases, the majority of whom have limited treatment options. Here, we examine contemporary evidence evaluating the anti-neoplastic effects of Klotho and describe the modulation of downstream oncogenic signalling pathways, including Wnt/β-catenin, FGF, IGF1, PIK3K/AKT, TGFβ, and the Unfolded Protein Response. We also discuss possible approaches to developing therapeutic Klotho and consider technological advances that may facilitate the delivery of Klotho through gene therapy.

Targeting Wnt Signaling for the Treatment of Gastric Cancer

The Wnt signaling pathway is evolutionarily conserved, regulating both embryonic development and maintaining adult tissue homeostasis. Wnt signaling controls several fundamental cell functions, including proliferation, differentiation, migration, and stemness. It therefore plays an important role in the epithelial homeostasis and regeneration of the gastrointestinal tract. Often, both hypo- or hyper-activation of the pathway due to genetic, epigenetic, or receptor/ligand alterations are seen in many solid cancers, such as breast, colorectal, gastric, and prostate. Gastric cancer (GC) is the fourth commonest cause of cancer worldwide and is the second leading cause of cancer-related death annually. Although the number of new diagnoses has declined over recent decades, prognosis remains poor, with only 15% surviving to five years. Geographical differences in clinicopathological features are also apparent, with epidemiological and genetic studies revealing GC to be a highly heterogeneous disease with phenotypic diversity as a result of etiological factors. The molecular heterogeneity associated with GC dictates that a single 'one size fits all' approach to management is unlikely to be successful. Wnt pathway dysregulation has been observed in approximately 50% of GC tumors and may offer a novel therapeutic target for patients who would otherwise have a poor outcome. This mini review will highlight some recent discoveries involving Wnt signaling in GC.

Hypermethylated promoters of tumor suppressor genes were identified in Crohn's disease patients

BACKGROUND/AIMS

Overwhelming evidence suggests that inflammatory bowel disease (IBD) is caused by a complicated interplay between the multiple genes and abnormal epigenetic regulation in response to environmental factors. It is becoming apparent that epigenetic factors are significantly associated with the development of the disease. DNA methylation remains the most studied epigenetic modification, and hypermethylation of gene promoters is associated with gene silencing.

METHODS

DNA methylation alterations may contribute to the many complex diseases development by regulating the interplay between external and internal environmental factors and gene transcriptional expression. In this study, we used 15 tumor suppressor genes (TSGs), originally identified in colon cancer, to detect promoter methylation in patients with Crohn's disease (CD). Methylation specific polymerase chain reaction and bisulfite sequencing analyses were performed to assess methylation level of TSGs in CD patients.

RESULTS

We found 6 TSGs (sFRP1, sFRP2, sFRP5, TFPI2, Sox17, and GATA4) are robustly hypermethylated in CD patient samples. Bisulfite sequencing analysis confirmed the methylation levels of the sFRP1, sFRP2, sFRP5, TFPI2, Sox17, and GATA4 promoters in the representative CD patient samples.

CONCLUSIONS

In this study, the promoter hypermethylation of the TSGs observed indicates that CD exhibits specific DNA methylation signatures with potential clinical applications for the noninvasive diagnosis of IBD and the prognosis for patients with IBD.

Effects of Exposure to Mild Hyperbaric Oxygen on DSS-Induced Colonic Inflammation and Diarrhea in Rats

Purpose

In rodents, dextran sulfate sodium (DSS)-induced diarrhea and colonic inflammation have similar symptoms to those of ulcerative colitis in humans. We examined the effects of exposure to mild hyperbaric oxygen (MHO) at an atmospheric pressure of 1317 hPa with 40% oxygen on DSS-induced diarrhea and colonic inflammation in rats.

Methods

Five-week-old male Kyoto Apc Delta (KAD) rats (n = 12) were administered 2% DSS through drinking water for 1 week. Subsequently, DSS-treated male rats were not subjected to any further treatment (n = 6) or exposed to MHO (n = 6) for 2 weeks. Age-matched KAD rats not subjected to DSS treatment or exposed to MHO were used as the control group (n = 6).

Results

Control rats did not exhibit diarrhea and colonic inflammation. However, DSS-treated rats exhibited diarrhea and colonic inflammation, regardless of exposure to MHO. Exposure to MHO for 2 weeks led to decreased incidence of diarrhea in DSS-treated rats (p < 0.05). Exposure to MHO had no effect on colonic inflammation in DSS-treated rats (p = 0.12).

Conclusion

Exposure to MHO for 2 weeks can improve diarrhea but cannot attenuate colonic inflammation, possibly due to the short exposure duration (2 weeks) used in this study.

Comprehensive Analysis of the Canonical and Non-canonical Wnt Signaling Pathways in Gastric Cancer

BACKGROUND

Previous studies showed that dysregulation of Wnt signaling by gene mutation and abnormal gene expression is one of the causative factors for gastric cancer (GC). So far, a systematic and comprehensive analysis of gene mutation, gene expression, and DNA methylation profiles of the Wnt pathway associated with gastric carcinogenesis, however, has not yet been reported.

AIMS

To this end, we investigated all the above-mentioned genetic alterations associated with the canonical and non-canonical Wnt pathways in GC tumors, in order to understand the molecular mechanism underlying gastric carcinogenesis.

METHODS

The information on gene mutations and expression was obtained from data resources, such as TCGA, GSEA, and TCGA-STAD, and was analyzed with the cBioPortal platform. We also performed in vitro analysis on DDK2 gene, a Wnt inhibitor, to characterize its role in GC tumor cells.

RESULTS

We found that gene mutations of 43 Wnt genes and abnormal expression of 13 Wnt genes occurred at a high frequency in GC tumors, and gene amplification and deletion are the major mutation types. Clusters of DNA methylation associated with Wnt signaling genes and GC tumors were also revealed, and a significant increase in β-catenin activity was found in the hypermethylated group of GC tumors. In addition, overexpression of DKK2 gene significantly inhibited multiple biological processes of the GC cells, including their growth, clonal forming, migration, and invasion ability, and induced apoptosis of the GC cells.

CONCLUSIONS

Our current study suggested that gene mutation, abnormal gene expression, and altered DNA methylation profiles associated with the Wnt signaling may play an important role in gastric carcinogenesis, and DKK2 gene may act as a tumor suppressor in gastric cells.

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

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

The Silencing of SFRP2 Expression in ESCC Is Due to Methylation of the Gene Promoter

OBJECTIVE

Our aim of the study was to investigate the expression level and methylation status of the secreted frizzled-related protein 2 in esophageal squamous cell carcinoma and to evaluate the clinical utility of the marker.

MATERIAL AND METHODS

We first used Immunohistochemistry (ICH) to explore the expression level of secreted frizzled-related protein 2 protein in esophageal squamous cell carcinoma tissues and adjacent normal tissues and then used methylation-specific polymerase chain reaction and bisulfite sequencing polymerase chain reaction to detect methylation status of secreted frizzled-related protein 2.

RESULTS

Secreted frizzled-related protein 2 expression was notably reduced in patients with esophageal squamous cell carcinoma, whereas methylation of secreted frizzled-related protein 2 was increased in the majority of esophageal squamous cell carcinoma specimens.

CONCLUSION

Sum up, we have demonstrated the abnormal DNA hypermethylation, causing reduced or absent gene expression. Methylation testing of secreted frizzled-related protein 2 using epigenetic marker may be a significative screening method for patients with esophageal squamous cell carcinoma.

WNT Signaling in Cancer Immunosurveillance

Deregulated WNT signaling has been shown to favor malignant transformation, tumor progression, and resistance to conventional cancer therapy in a variety of preclinical and clinical settings. Accumulating evidence suggests that aberrant WNT signaling may also subvert cancer immunosurveillance, hence promoting immunoevasion and resistance to multiple immunotherapeutics, including immune checkpoint blockers. Here, we discuss the molecular and cellular mechanisms through which WNT signaling influences cancer immunosurveillance and present potential therapeutic avenues to harness currently available WNT modulators for cancer immunotherapy.

Bioinformatics analysis to identify action targets in NCI-N87 gastric cancer cells exposed to quercetin

CONTEXT

Quercetin exerts antiproliferative effects on gastric cancer. However, its mechanisms of action on gastric cancer have not been comprehensively revealed.

OBJECTIVE

We investigated the mechanisms of action of quercetin against gastric cancer cells.

MATERIALS AND METHODS

Human NCI-N87 gastric cancer cells were treated with 15 μM quercetin or dimethyl sulfoxide (as a control) for 48 h. DNA isolated from cells was sequenced on a HiSeq 2500, and the data were used to identify differentially expressed genes (DEGs) between groups. Then, enrichment analyses were performed for DEGs and a protein-protein interaction (PPI) network was constructed. Finally, the transcription factors (TFs)-DEGs regulatory network was visualized by Cytoscape software.

RESULTS

A total of 121 DEGs were identified in the quercetin group. In the PPI network, Fos proto-oncogene (FOS, degree = 12), aryl hydrocarbon receptor (AHR, degree = 12), Jun proto-oncogene (JUN, degree = 11), and cytochrome P450 family 1 subfamily A member 1 (CYP1A1, degree = 11) with higher degrees highly interconnected with other proteins. Of the 5 TF-DEGs, early growth response 1 (EGR1), FOS like 1 (FOSL1), FOS, and JUN were upregulated, while AHR was downregulated. Moreover, FOSL1, JUN, and Wnt family member 7B (WNT7B) were enriched in the Wnt signaling pathway.

DISCUSSION AND CONCLUSIONS

CYP1A1 highly interconnected with AHR in the PPI network. Therefore, FOS, AHR, JUN, CYP1A1, EGR1, FOSL1, and WNT7B might be targets of quercetin in gastric cancer.

Hypermethylation of multiple Wnt antagonist genes in gastric neoplasia: Is H pylori infection blasting fuse?

Wnt antagonist genes hypermethylation has been found in several tumors. Accordingly, the events that occur during the progression of adenoma to carcinoma have been characterized and include activation of the Wnt-pathway. Further, gastric adenoma (GA) is a premalignant lesion of gastric adenocarcinoma (GAC). In this paper, we focused our interesting on Wnt signaling path function in the pathogenesis of GAC.We compared the differences between low grade adenoma (LGA), high grade adenoma (HGA), GACs and corresponding normal gastric tissue (NGT). Specific indexes include the pathological characteristics of gastric neoplasia, Helicobacter pylori infection, β-catenin mutation status, and methylation status of Wnt antagonist genes.There was significant difference of β-catenin expression in patient with NGT, LGA, HGA, and GAC, the results respectively were 4.2%, 41.7%, 83.3%, and 91.7%. Only 1 GACs was detected exon 3 of β-catenin mutation. Wnt antagonist genes mRNA expression levels, such as APC, sFRP-1, Wif-1, and Dkk-1, were significantly reduced in GAC. Promoter methylation levels of the 4 genes were significantly elevated in GAC and HGA compared to NGT and LGA. However, there was no significant difference between HGAs and GACs. The β-catenin abnormal expression was correlated with hypermethylation of these 4 genes. Multiple gene concurrent methylation phenomenon was increased from NGTs to GACs; the amount of methylation genes in GACs and HGAs was more than NGTs and LGAs. The more methylation of the above-mentioned genes, the more severity of local inflammation. The infection rate of H pylori was significantly higher in patient with HGA (66.7%, 16/24) and GAC (58.5%, 14/24) than in LGAs (16.7%,4/24) (PHGA-LGA = .024, PGAC-LGA = .032). In addition, the present of H pylori also correlated with the β-catenin abnormal expression and the hypermethylation status of Wnt antagonist genes (P < .001). But other parameters in adenoma cases had no significantly related with infection of H pylori.Hypermethylation of Wnt antagonist genes may have a tight relationship with gastric tumorigenesis. And these genes may increase the incidence of GAC. Additionally, H pylori may have promotion function in GA formation.

Oncogenic role of SFRP2 in p53-mutant osteosarcoma development via autocrine and paracrine mechanism

Osteosarcoma (OS), the most common primary bone tumor, is highly metastatic with high chemotherapeutic resistance and poor survival rates. Using induced pluripotent stem cells (iPSCs) generated from Li-Fraumeni syndrome (LFS) patients, we investigate an oncogenic role of secreted frizzled-related protein 2 (SFRP2) in p53 mutation-associated OS development. Interestingly, we find that high SFRP2 expression in OS patient samples correlates with poor survival. Systems-level analyses identified that expression of SFRP2 increases during LFS OS development and can induce angiogenesis. Ectopic SFRP2 overexpression in normal osteoblast precursors is sufficient to suppress normal osteoblast differentiation and to promote OS phenotypes through induction of oncogenic molecules such as FOXM1 and CYR61 in a β-catenin-independent manner. Conversely, inhibition of SFRP2, FOXM1, or CYR61 represses the tumorigenic potential. In summary, these findings demonstrate the oncogenic role of SFRP2 in the development of p53 mutation-associated OS and that inhibition of SFRP2 is a potential therapeutic strategy.

Targeting histone methyltransferase G9a inhibits growth and Wnt signaling pathway by epigenetically regulating HP1α and APC2 gene expression in non-small cell lung cancer

BACKGROUND

Dysregulated histone methyltransferase G9a may represent a potential cancer therapeutic target. The roles of G9a in tumorigenesis and therapeutics are not well understood in non-small cell lung cancer (NSCLC). Here we investigated the impact of G9a on tumor growth and signaling pathways in NSCLC.

METHODS

Immunohistochemistry analyzed G9a expression in NSCLC tissues. Both siRNA and selective inhibitor were used to target G9a. The impact of targeting G9a on key genes, signaling pathways and growth were investigated in NSCLC cells by RNA sequencing analysis, rescue experiments, and xenograft models.

RESULTS

Overexpression of G9a (≥ 5% of cancer cells showing positive staining) was found in 43.2% of 213 NSCLC tissues. Multiple tumor-associated genes including HP1α, APC2 are differentially expressed; and signaling pathways involved in cellular growth, adhesion, angiogenesis, hypoxia, apoptosis, and canonical Wnt signaling pathways are significantly altered in A549, H1299, and H1975 cells upon G9a knockdown. Additionally, targeting G9a by siRNA-mediated knockdown or by a selective G9a inhibitor UNC0638 significantly inhibited tumor growth, and dramatically suppressed Wnt signaling pathway in vitro and in vivo. Furthermore, we showed that treatment with UNC0638 restores the expression of APC2 expression in these cells through promoter demethylation. Restoring HP1α and silencing APC2 respectively attenuated the inhibitory effects on cell proliferation and Wnt signaling pathway in cancer cells in which G9a was silenced or suppressed.

CONCLUSIONS

These findings demonstrate that overexpressed G9a represents a promising therapeutic target, and targeting G9a potentially suppresses growth and Wnt signaling pathway partially through down-regulating HP1α and epigenetically restoring these tumor suppressors such as APC2 that are silenced in NSCLC.

Therapeutic potency of Wnt signaling antagonists in the pathogenesis of prostate cancer, current status and perspectives

Prostate cancer is a major cause of cancer-related death in males. Wnt/β-catenin signaling plays a critical role in the pathogenesis of this disease by regulating angiogenesis, drug resistance, cell proliferation, and apoptosis. Suppression of Wnt canonical or noncanonical signaling pathways via Wnt biological or pharmacological antagonists is a potentially novel therapeutic approach for patients with prostate cancer. This review summarizes the role of Wnt signaling inhibitors in the pathogenesis of prostate cancer for a better understanding and hence a better management of this disease.

DNA Methylation Profiling of Breast Cancer Cell Lines along the Epithelial Mesenchymal Spectrum-Implications for the Choice of Circulating Tumour DNA Methylation Markers

(1) Background: Epithelial–mesenchymal plasticity (EMP) is a dynamic process whereby epithelial carcinoma cells reversibly acquire morphological and invasive characteristics typical of mesenchymal cells. Identifying the methylation differences between epithelial and mesenchymal states may assist in the identification of optimal DNA methylation biomarkers for the blood-based monitoring of cancer. (2) Methods: Methylation-sensitive high-resolution melting (MS-HRM) was used to examine the promoter methylation status of a panel of established and novel markers in a range of breast cancer cell lines spanning the epithelial–mesenchymal spectrum. Pyrosequencing was used to validate the MS-HRM results. (3) Results: VIM, DKK3, and CRABP1 were methylated in the majority of epithelial breast cancer cell lines, while methylation of GRHL2, MIR200C, and CDH1 was restricted to mesenchymal cell lines. Some markers that have been used to assess minimal residual disease such as AKR1B1 and APC methylation proved to be specific for epithelial breast cell lines. However, RASSF1A, RARβ, TWIST1, and SFRP2 methylation was seen in both epithelial and mesenchymal cell lines, supporting their suitability for a multimarker panel. (4) Conclusions: Profiling DNA methylation shows a distinction between epithelial and mesenchymal phenotypes. Understanding how DNA methylation varies between epithelial and mesenchymal phenotypes may lead to more rational selection of methylation-based biomarkers for circulating tumour DNA analysis.

Molecular Signaling in Tumorigenesis of Gastric Cancer

Gastric cancer (GC) is regarded as the fifth most common cancer and the third cause of cancer-related deaths worldwide. Mechanism of GC pathogenesis is still unclear and relies on multiple factors, including environmental and genetic characteristics. One of the most important environmental factors of GC occurrence is infection with Helicobacter pylori that is classified as class one carcinogens. Dysregulation of several genes and pathways play an essential role during gastric carcinogenesis. Dysregulation of developmental pathways such as Wnt/β-catenin signaling, Hedgehog signaling, Hippo pathway, Notch signaling, nuclear factor-kB, and epidermal growth factor receptor have been found in GC. Epithelial-mesenchymal transition, as an important process during embryogenesis and tumorigenesis, is supposed to play a role in initiation, invasion, metastasis, and progression of GC. Although surgery is the main therapeutic modality of the disease, the understanding of biological processes of cell signaling pathways may help to develop new therapeutic targets for GC.

Clinical and genomic landscape of gastric cancer with a mesenchymal phenotype

Gastric cancer is a heterogeneous cancer, making treatment responses difficult to predict. Here we show that we identify two distinct molecular subtypes, mesenchymal phenotype (MP) and epithelial phenotype (EP), by analyzing genomic and proteomic data. Molecularly, MP subtype tumors show high genomic integrity characterized by low mutation rates and microsatellite stability, whereas EP subtype tumors show low genomic integrity. Clinically, the MP subtype is associated with markedly poor survival and resistance to standard chemotherapy, whereas the EP subtype is associated with better survival rates and sensitivity to chemotherapy. Integrative analysis shows that signaling pathways driving epithelial-to-mesenchymal transition and insulin-like growth factor 1 (IGF1)/IGF1 receptor (IGF1R) pathway are highly activated in MP subtype tumors. Importantly, MP subtype cancer cells are more sensitive to inhibition of IGF1/IGF1R pathway than EP subtype. Detailed characterization of these two subtypes could identify novel therapeutic targets and useful biomarkers for prognosis and therapy response.

The prognosis and treatment of gastric cancer is complicated by heterogeneity. Here, the authors reveal two molecular subtypes, the mesenchymal subtype associated with poor survival and chemoresistance, and the epithelial phenotype associated with better survival and sensitivity to chemotherapy.

Clinicopathological Characteristics and Mutations Driving Development of Early Lung Adenocarcinoma: Tumor Initiation and Progression

Lung cancer is the leading cause of cancer-related deaths worldwide, with lung adenocarcinoma representing the most common lung cancer subtype. Among all lung adenocarcinomas, the most prevalent subset develops via tumorigenesis and progression from atypical adenomatous hyperplasia (AAH) to adenocarcinoma in situ (AIS), to minimally invasive adenocarcinoma (MIA), to overt invasive adenocarcinoma with a lepidic pattern. This stepwise development is supported by the clinicopathological and molecular characteristics of these tumors. In the 2015 World Health Organization classification, AAH and AIS are both defined as preinvasive lesions, whereas MIA is identified as an early invasive adenocarcinoma that is not expected to recur if removed completely. Recent studies have examined the molecular features of lung adenocarcinoma tumorigenesis and progression. EGFR-mutated adenocarcinoma frequently develops via the multistep progression. Oncogene-induced senescence appears to decrease the frequency of the multistep progression in KRAS- or BRAF-mutated adenocarcinoma, whose tumor evolution may be associated with epigenetic alterations and kinase-inactive mutations. This review summarizes the current knowledge of tumorigenesis and tumor progression in early lung adenocarcinoma, with special focus on its clinicopathological characteristics and their associations with driver mutations (EGFR, KRAS, and BRAF) as well as on its molecular pathogenesis and progression.

Decreased expression of SFRP2 promotes development of the pituitary corticotroph adenoma by upregulating Wnt signaling

Cushing's disease is primarily caused by pituitary adrenocorticotropin‑secreting adenoma. However, its pathogenesis has remained obscure. In the present study, whole transcriptome analysis was performed by RNA sequencing (RNA‑Seq) and expression of secreted frizzled‑related protein 2 (SFRP2) was decreased in corticotroph tumors compared with normal pituitary glands. Furthermore, the RNA‑Seq results were validated and the expression of SFRP2 in tumor tissues was analyzed by comparing another cohort of 23 patients with Cushing's disease and 3 normal human pituitary samples using reverse transcription‑quantitative polymerase chain reaction, western blot and immunohistochemistry staining. Clinically, there was an association between lower SFRP2 expression and aggressive adenoma characteristics, including larger size and invasiveness. Conversely, SFRP2 overexpression reduced the ability of AtT20 cells to proliferate and migrate, and reduced production of the adrenocorticotrophic hormone in vitro. Mechanistically, overexpressed SFRP2 reduced the level of β‑catenin in the cytoplasm and nucleus, and decreased Wnt signaling activity in AtT20 cells. Therefore, SFRP2 appears to act as a tumor suppressor in Cushing's disease by regulating the activity of the Wnt signaling pathway.

Secreted Wnt antagonists in leukemia: A road yet to be paved

Wnt signaling has been a topic of research for many years for its diverse and fundamental functions in physiological (such as embryogenesis, organogenesis, proliferation, tissue repair and cellular differentiation) and pathological (carcinogenesis, congenital/genetic diseases, and tissue degeneration) processes. Wnt signaling pathway aberrations are associated with both solid tumors and hematological malignancies. Unregulated Wnt signaling observed in malignancies may be due to a wide spectrum of abnormalities, from mutations in the genes of key players to epigenetic modifications of Wnt antagonists. Of these, Wnt antagonists are gaining significant attention for their potential of being targets for treatment and inhibition of Wnt signaling. In this review, we discuss and summarize the significance of Wnt signaling antagonists in the pathogenesis and treatment of hematological malignancies.

Wnt Signalling in Gastrointestinal Epithelial Stem Cells

Wnt signalling regulates several cellular functions including proliferation, differentiation, apoptosis and migration, and is critical for embryonic development. Stem cells are defined by their ability for self-renewal and the ability to be able to give rise to differentiated progeny. Consequently, they are essential for the homeostasis of many organs including the gastrointestinal tract. This review will describe the huge advances in our understanding of how stem cell functions in the gastrointestinal tract are regulated by Wnt signalling, including how deregulated Wnt signalling can hijack these functions to transform cells and lead to cancer.

Downregulation of Frizzled-7 induces the apoptosis of hepatocellular carcinoma cells through inhibition of NF-κB

The aim of the present study was to investigate the functional role of Frizzled-7 (FZD7) in the apoptosis of hepatoma cells. HepG2 and Huh-7 hepatocellular carcinoma (HCC) cell lines with FZD7 expression were selected for use in the present study. The small hairpin RNA (shRNA) eukaryotic expression vector specific to FZD7 was constructed using gene recombination, and was then transfected into HepG2 and Huh-7 hepatoma cell lines using Lipofectamine 2000 to assess whether the downregulation of FZD7 could affect the proliferative ability of these cells. The results demonstrated that the downregulation of FZD7 expression significantly inhibited the proliferative ability of both cell types through the induction of cell apoptosis, as evidenced using Cell Counting kit-8 assays and flow cytometry. Furthermore, the western blotting results demonstrated that silencing of FZD7 increased the activities of caspase-3 and caspase-9. These increases were also associated with the downregulation of the inhibitor of the apoptosis protein family. Additionally, it was revealed that silencing of FZD7 expression caused the downregulation of apoptosis regulator Bcl-2 and Bcl-XL in HepG2, and Huh-7 cells, as determined through western blot analysis and reverse transcription-quantitative polymerase chain reaction. In the following work, ELISA and western blot analysis revealed that the knockdown of FZD7 inhibited the expression and activities of nuclear factor-κB (NF-κB) p65. Furthermore, it was demonstrated that the expression levels of phosphylated-Smad2/3 were markedly upregulated in sh-FZD7-transfected HepG2 and Huh-7 cells. Then, shRNA eukaryotic expression vector specific to transforming growth factor (TGF)-β receptor II was transfected into both cell lines to investigate the association between the TGF-β/Smad signaling pathway and NF-κB p65. Notably, when the TGF-β/Smad signaling pathway was inhibited, no significant differences in the cell apoptosis rate and NF-κB expression levels were identified in HCC cells. Overall, the results of the present study suggest that the shRNA-mediated knockdown of FZD7 induces apoptosis of hepatoma cell lines through the inhibition of NF-κB. In addition, the TGF-β/Smad signaling pathway appeared to partially participate in the underlying molecular mechanism of FZD7 in HCC.

Epigenetic Mechanisms and Events in Gastric Cancer-Emerging Novel Biomarkers

Gastric cancer is one of the most common malignancy worldwide. The various genetic and epigenetic events have been found to be associated with its carcinogenesis. The epigenetic is a heritable and transient/reversible change in the gene expression that is not accompanied by modification in the DNA sequence. This event is characterized by the alteration in the promoter CpG island of the gene or histone modification. These events are associated with silencing of critical tumor suppressor gene and activation of oncogenes leading to carcinogenesis. The DNA methylation is a chemical change in the DNA sequence that most commonly occurs at cytosine moiety of CpG dinucleotide and histone, primarily on N- terminal tail that ultimately effect the interaction of DNA with chromatin modifying protein.Hypermethylation of tumor suppressor genes and global hypomethylation of oncogenes are widely studied epigenetic modifications. There are large number of publish reports regarding epigenetic events involving gastric cancer. These changes are potentially useful in identifying markers for early diagnosis and management of this lethal malignancy. Also, role of specific miRNAs and long non coding RNAs in regulation of gene expression is gaining interest and is a matter of further investigation. In this review, we aimed to summarize major epigenetic events (DNA methylation) in gastric cancer along with alteration in miRNAs and long non coding RNAs which plays an important role in pathology of this poorly understood malignancy.

Downregulation of HP1α suppresses proliferation of cholangiocarcinoma by restoring SFRP1 expression

Heterochromatin protein 1α (HP1α) is a gene that mediates chromatin conformation, gene silencing and cancer progression. However, little is known regarding the impact of HP1α in the pathogenesis of cholangiocarcinoma (CCA). In the present study, we demonstrate that HP1α is significantly upregulated in CCA tissues and cell lines, while downregulation of HP1α leads to suppression of cell proliferation. Then we find that downregulation of HP1α can decrease H3K9me3 enrichment and DNA methylation rate of secreted frizzled-related protein 1 (SFRP1) promoter, resulting in restoring the expression of SFRP1. Moreover, restoration of SFRP1 expression can suppress CCA cells proliferation. These results provide a mechanistic understanding of the role of HP1α in the pathogenesis of CCA and may offer a novel therapeutic target in this disease.

Helicobacter pylori-induced modulation of the promoter methylation of Wnt antagonist genes in gastric carcinogenesis

BACKGROUND

This study aimed to investigate the changes in the promoter methylation and gene expression of multiple Wnt antagonists between the chronic infection and eradication of Helicobacter pylori (H. pylori) in gastric carcinogenesis.

METHODS

The levels of methylation and corresponding mRNA expression of seven Wnt antagonist genes (SFRP1, -2, -5, DKK1, -2, -3, WIF1) were compared among the patients with H. pylori-positive gastric cancers (GCs), and H. pylori-positive and H. pylori-negative controls, by quantitative MethyLight assay and real-time reverse transcription (RT)-polymerase chain reaction (PCR), respectively. The changes of the methylation and expression levels of the genes were also compared between the H. pylori eradication and H. pylori-persistent groups 1 year after endoscopic resection of GCs.

RESULTS

The methylation levels of SFRP and DKK family genes were significantly increased in the patients with H. pylori-positive GCs and followed by H. pylori-positive controls compared with H. pylori-negative controls (P < 0.001). SFRP1, -2, and DKK3 gene expression was stepwise downregulated from H. pylori-negative controls, H. pylori-positive controls, and to H. pylori-positive GCs (P < 0.05). Among the Wnt antagonists, only the degrees of methylation and downregulation of DKK3 were significantly reduced after H. pylori eradication (P < 0.05).

CONCLUSION

Epigenetic silencing of SFRP and DKK family genes may facilitate the formation of an epigenetic field during H. pylori-associated gastric carcinogenesis. The epigenetic field may not be reversed even after H. pylori eradication except by DKK3 methylation.

SPARC expression in gastric cancer predicts poor prognosis: Results from a clinical cohort, pooled analysis and GSEA assay

Background

The prognostic role of Secreted Protein Acidic and Rich in Cysteine (SPARC) in gastric cancer (GC) remains controversial. We investigated the clinical significance, the survival relevance, and potential function of SPARC in GC with resected samples, online gene set GSE62254, and cell line SGC7901.

Results

High immunostaining of SPARC significantly correlated with tumor differentiation (P = 0.004), and independently predicted shorter overall survival (OS) (HR = 1.446, P = 0.022), based on the current IHC evaluation. The accuracy of the results was further validated with 1000 times bootstrapping and the time-dependent receiver-operating characteristics (ROC) curves. The meta-analysis (pooled HR = 1.60, 95% CI: 1.01−2.53) confirmed SPARC as the predictor for reduced OS in GC. Moreover, the association between enhanced SPARC expression and Adriamycin (Adr) sensitivity was revealed by GSEA, and then confirmed by comparative cellular experiments, such as the protein level analysis of SGC7901and SGC7901/Adr cell line.

Materials and Methods

Immunohistochemistry (IHC) method was used to detect SPARC expression in 137 GC cases. Meta-analysis was performed based on 5 studies published in English on PubMed up to March 2016. GSEA was performed using online data set GSE62254 and GC-related functional gene sets derived from molecular signatures database (MSigDB). Western Blot was carried out to compare protein-level differences between gastric carcinoma SGC7901 cell line and Adr resistant SGC7901/Adr cell line. MTT assay was done to confirm the induction of SPARC on Adr sensitivity

Conclusions

Increased SPARC expression in GC led to a worse clinical outcome of patients and might induce Adr sensitivity of GC cells.

SFRP1 Promoter Methylation and Renal Carcinoma Risk: A Systematic Review and Meta-Analysis

BACKGROUND/AIM

Epigenetic inactivation of tumor suppressor genes is an important molecular mechanism in the formation and development of human tumors. The purpose of our study was to evaluate the correlation between the methylation level of the secreted frizzled-related protein 1 (SFRP1) gene and the risk of renal cell carcinoma (RCC).

METHODS

The relevant literature was searched in detail in several electronic databases. The methodological heterogeneity was analyzed by meta-regression and subgroup analyses. The odds ratios (ORs) and their corresponding 95% confidence intervals (CIs) were calculated to summarize the dichotomous outcomes of our meta-analysis.

RESULTS

The ten included articles contained 535 RCC samples and 475 normal controls. The results demonstrated that the methylation level of the SFRP1 promoter region was significantly correlated with an increased incidence of RCC (OR=13.72; 95% CI: 6.01-31.28; P=0.000). Furthermore, the eligible studies that had sufficient clinical data about the RCC cases were included in the analysis, and the results indicated that the frequency of SFRP1 promoter methylation was associated with a higher histological grade (P=0.000), tumor stage (P=0.033), tumor size (≥5 cm; P=0.029), and distant metastasis (P=0.047).

CONCLUSION

Our results indicate that the methylation level of the SFRP1 promoter region is increased in patients with RCC compared to normal controls and might be involved in the occurrence and development of RCC. Additional well-designed studies are needed to further verify our conclusions.

SFRP Tumour Suppressor Genes Are Potential Plasma-Based Epigenetic Biomarkers for Malignant Pleural Mesothelioma

Malignant pleural mesothelioma (MPM) is associated with asbestos exposure. Asbestos can induce chronic inflammation which in turn can lead to silencing of tumour suppressor genes. Wnt signaling pathway can be affected by chronic inflammation and is aberrantly activated in many cancers including colon and MPM. SFRP genes are antagonists of Wnt pathway, and SFRPs are potential tumour suppressors in colon, gastric, breast, ovarian, and lung cancers and mesothelioma. This study investigated the expression and DNA methylation of SFRP genes in MPM cells lines with and without demethylation treatment. Sixty-six patient FFPE samples were analysed and have showed methylation of SFRP2 (56%) and SFRP5 (70%) in MPM. SFRP2 and SFRP5 tumour-suppressive activity in eleven MPM lines was confirmed, and long-term asbestos exposure led to reduced expression of the SFRP1 and SFRP2 genes in the mesothelium (MeT-5A) via epigenetic alterations. Finally, DNA methylation of SFRPs is detectable in MPM patient plasma samples, with methylated SFRP2 and SFRP5 showing a tendency towards greater abundance in patients. These data suggested that SFRP genes have tumour-suppresive activity in MPM and that methylated DNA from SFRP gene promoters has the potential to serve as a biomarker for MPM patient plasma.

Chronic Cigarette Smoke-Induced Epigenomic Changes Precede Sensitization of Bronchial Epithelial Cells to Single-Step Transformation by KRAS Mutations

We define how chronic cigarette smoke-induced time-dependent epigenetic alterations can sensitize human bronchial epithelial cells for transformation by a single oncogene. The smoke-induced chromatin changes include initial repressive polycomb marking of genes, later manifesting abnormal DNA methylation by 10 months. At this time, cells exhibit epithelial-to-mesenchymal changes, anchorage-independent growth, and upregulated RAS/MAPK signaling with silencing of hypermethylated genes, which normally inhibit these pathways and are associated with smoking-related non-small cell lung cancer. These cells, in the absence of any driver gene mutations, now transform by introducing a single KRAS mutation and form adenosquamous lung carcinomas in mice. Thus, epigenetic abnormalities may prime for changing oncogene senescence to addiction for a single key oncogene involved in lung cancer initiation.