The role of Notch signaling in gastric carcinoma: molecular pathogenesis and novel therapeutic targets

GDF6 in gastric cancer upregulated by helicobacter pylori induces epithelial-mesenchymal translation via the TGF-β/SMAD3 signaling pathway

OBJECTIVE

To investigate the association between Helicobacter pylori infection and GDF6 expression in gastric cancer patients, and to determine its influence on prognosis and resistance to capecitabine.

METHODS

Tumor and adjacent non-tumor tissues were collected from 148 gastric cancer patients who underwent surgery in our department from October 2019 to June 2022. Of these patients, 78 tested positive for Helicobacter pylori and 70 tested negative. Hematoxylin-eosin (HE) and immunofluorescence staining were utilized to quantify GDF6 expression in cancerous and adjacent tissues. Patient prognosis was monitored via follow-up. Western blotting analyzed GDF6 expression in common gastric cancer cell lines. HGC27 cells exhibiting high GDF6 expression and BGC823 cells with low expression were used to create GDF6-silenced and overexpressed cell lines. The impact of GDF6 on the proliferation, migration, invasion, and cloning abilities of gastric cancer cells was evaluated using the CCK-8 assay, scratch test, Transwell assay, and plate colony formation assay. Fluorescent quantitative PCR and Western blotting assessed the effects of GDF6 levels on epithelial-mesenchymal transition (EMT) and tumor cell stemness.

RESULTS

GDF6 expression in gastric cancer tissues was significantly correlated with cancer grading and staging (P<0.05). Helicobacter pylori-positive tissues exhibited significantly higher GDF6 expression levels than negative samples (P<0.05). Kaplan-Meier survival analysis indicated that high GDF6 expression was associated with poor survival prognosis. Overexpressed GDF6 enhanced the proliferation, migration, and invasion abilities of gastric cancer cells, while silencing GDF6 yielded opposite results. Increased GDF6 expression upregulated TGF-β expression and the phosphorylation levels of SMAD3, leading to an elevation in mesenchymal cell markers N-cadherin, vimentin, and a reduction in epithelial cell markers cytokeratins, E-cadherin. Moreover, high GDF6 levels contributed to increased resistance to capecitabine and enhanced the expression of tumor stem cell markers Nanog, Sox-2, Oct-4, CD44, amplifying tumor cell stemness.

CONCLUSION

Helicobacter pylori infection is associated with increased GDF6 expression in gastric cancer tissue, correlating with poor survival prognosis. Elevated GDF6 expression promotes the proliferation, migration, and invasion abilities of gastric cancer cells, facilitates EMT via the TGF-β/SMAD3 pathway, and intensifies cell stemness and capecitabine resistance. Consequently, GDF6 presents itself as a potential new target for gastric cancer treatment.

DATA AVAILABILITY STATEMENT

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Importance of targeting various cell signaling pathways in solid cancers

Most adult human cancers are solid tumors prevailing in vital organs and lead to mortality all over the globe. Genetic and epigenetic alterations in cancer genes or genes of associated signaling pathways impart the most common characteristic of malignancy, that is, uncontrolled proliferation. Unless the mechanism of action of these cells signaling pathways (involved in cell proliferation, apoptosis, metastasis, and the maintenance of the stemness of cancer stem cells and cancer microenvironment) and their physiologic alteration are extensively studied, it is challenging to understand tumorigenesis as well as develop new treatments and precision medicines. Targeted therapy is one of the most promising strategies for treating various cancers. However, cancer is an evolving disease, and most patients develop resistance to these drugs by acquired mutations or mediation of microenvironmental factors or due to tumor heterogeneity. Researchers are striving to develop novel therapeutic options like combinatorial approaches targeting multiple responsible pathways effectively. Thus, in-depth knowledge of cell signaling and its components remains a critical topic of cancer research. This chapter summarized various extensively studied pathways in solid cancer and how they are targeted for therapeutic strategies.

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.

Delta/Notch-like Epidermal Growth Factor-Related Receptor (DNER), a Potential Prognostic Marker of Gastric Cancer Regulates Cell Survival and Cell Cycle Progression

Upregulation of the expression of Delta/notch-like epidermal growth factor-related receptor (DNER) and its oncogenic role have been reported in several cancers, including gastric, breast, and prostate cancers. This study aimed to investigate the oncogenic role of DNER and the mechanisms behind its oncogenic role in gastric cancer. Analysis of the RNASeq data of gastric cancer tissues obtained from the TCGA database revealed that the expression of DNER was associated with the pathology of advanced gastric cancer and the prognosis of patients. DNER expression was increased upon stem cell-enriching cancer spheroid culture. Knockdown of DNER expression inhibited cell proliferation and invasion, induced apoptosis, enhanced chemosensitivity, and decreased spheroid formation of SNU-638 gastric cancer cells. DNER silencing elevated the expression of p53, p21^cip/waf, and p27, and increased G₁ phase cells at the expense of S phase cells. Knockdown of p21^cip/waf expression in the DNER-silenced cells partially restored cell viability and S phase progression. DNER silencing also induced the apoptosis of SNU-638 cells. While both cleaved caspases-8 and 9 were detected in adherent cells, only cleaved caspase-8 was found to have increased in spheroid-cultured cells, suggesting a distinct activation pattern of caspase activation depending on the growth condition. Knockdown of p53 expression rescued the DNER-silenced cells from apoptosis and partially restored cell viability. In contrast, overexpression of the Notch intracellular domain (NICD) decreased the expression of p53, p21^cip/waf, and cleaved caspase-3 in DNER-silenced cells. Moreover, NICD expression fully reverted the cell viability reduction, arrest in the G₁ phase, and elevated apoptosis caused by DNER silencing, thereby suggesting activation of Notch signaling by DNER. Expression of a membrane-unbound mutant of mDNER also decreased cell viability and induced apoptosis. On the other hand, TGF-β signals were found to be involved in DNER expression in both adherent and spheroid-cultured cells. DNER could therefore be a link connecting TGF-β signaling to Notch signaling. Taken together, DNER regulates cell proliferation, survival, and invasive capacity of the gastric cancer cells through the activation of Notch signaling, which may facilitate tumor progression into an advanced stage. This study provides evidences suggesting that DNER could be a potential prognostic marker, a therapeutic target, and a drug candidate in the form of a cell-free mutant.

Identification of acquired Notch3 dependency in metastatic Head and Neck Cancer

During cancer development, tumor cells acquire changes that enable them to invade surrounding tissues and seed metastasis at distant sites. These changes contribute to the aggressiveness of metastatic cancer and interfere with success of therapy. Our comprehensive analysis of "matched" pairs of HNSCC lines derived from primary tumors and corresponding metastatic sites identified several components of Notch3 signaling that are differentially expressed and/or altered in metastatic lines and confer a dependency on this pathway. These components were also shown to be differentially expressed between early and late stages of tumors in a TMA constructed from over 200 HNSCC patients. Finally, we show that suppression of Notch3 improves survival in mice in both subcutaneous and orthotopic models of metastatic HNSCC. Novel treatments targeting components of this pathway may prove effective in targeting metastatic HNSCC cells alone or in combination with conventional therapies.

Molecular genetic and clinical characteristic analysis of primary signet ring cell carcinoma of urinary bladder identified by a novel OR2L5 mutation

To get a better understanding of the genetic basis of primary signet ring cell carcinoma (SRCC) of the bladder, which is highly rare and not yet explored. First, by using immunohistochemistry to find histological pathological characteristics. Second, a massively parallel whole-exome sequencing (WES) was performed on a 58-year-old male patient who had painless macroscopic hematuria and was pathologically diagnosed with primary SRCC of the bladder, followed by comparing with genes of ordinary urothelial cancer (UC) from TCGA. Furthermore, a population-based analysis using the SEER database was performed to investigate the prognosis (SRCC vs. UC). We identified 63 copy number variations (CNVs) with gain counts and 181 CNVs with loss counts. Totally 4515 mutations were discovered in C > T with a success rate of greater than 89%. The most frequently mutated pathway was RTK-RAS which has 85 genes involved in carcinogenic signaling. Final screening on predisposing genes is performed after filtering based on ACMG. Moreover, several driver genes, including NBN, KCTD18, SPATA13, ANKRD36, OR2L5, MALRD1, and LSMEM1, were detected. Sanger sequencing of germline DNA revealed the presence of a mutant base A/G of OR2L5 in the sequence, which was discovered for the first time in primary SRCC of the bladder. Furthermore, the immunohistochemical profile showed that primary SRCC of the bladder were positive for CK7, CK20, GATA-3, and expression of CK(AE1/AE2), EMA, and Ki67. In the SEER-based study, the patients with primary SRCC of the bladder got a worse prognosis compared to those with UC with median months overall survival (OS) 14 vs. 41, respectively, P = 0001, even after adjusting the variables in the Cox regression model, the SRCC of the bladder showed worse survival HR = 1.119, 95% CI = (1.081-1.328), P = 0.0001. These results imply that suppression of potential driver mutations may be a viable adjuvant treatment approach for primary SRCC in the bladder in place of standard chemotherapy, a possibility that warrants further clinical investigation.

The expression of long non-coding RNA LINC01389, LINC00365, RP11-138J23.1, and RP11-354K4.2 in gastric cancer and their impacts on EMT

BACKGROUND

Epithelial cancers acquire the epithelial to mesenchymal transition (EMT), which leads tumor cells to invade and metastasize to adjacent and distant tissues. The mechanisms involved in EMT phenotype are controlled by numerous markers as well as signalling pathways. Recently, long non-coding RNAs (lncRNAs) were introduced that play the regulatory role in EMT via crosstalk with EMT-related transcription factors and signalling pathways. The present study aimed to investigate the expression of four lncRNAs in human GC and elucidate their probable role in EMT procedure and the pathogenesis of gastric cancer (GC).

METHODS

The expression profile of lncRNAs (LINC01389, LINC00365, RP11-138J23.1, and RP11-354K4.2) and mRNAs (TWIST1, MMP13, MAML1, CD44s, and SALL4) between eighty-three GC and adjacent non-cancerous tissues were assessed by quantitative real-time PCR.

RESULTS

The significant downregulation of LINC00365 (66.3%) and RP11-354K4.2 (62.7%) were observed in GC samples; while the upregulation of LINC01389, RP11-138J23.1, TWIST1, MMP13, MAML1, CD44s, and SALL4 were found in 67.5%, 45.8%, 56.6%, 44.6%, 59%, 55.4%, and 62.7% tumors samples at the mRNA level, respectively. Dysregulation of these lncRNAs and EMT-related markers was significantly related to each other in a variety of clinicopathological features of patients (P < 0.05), indicating positive correlations between LINC01389, LINC00365, RP11-138J23.1, and RP11-354K4.2 with EMT status in GC.

CONCLUSION

These EMT-regulating lncRNAs may play a key role in transforming gastric epithelial to mesenchymal phenotype and can be novel therapeutic targets for GC. Our results highlight the importance of discovering new lncRNAs involved in gastric carcinogenesis. Detailed molecular mechanisms of these noncoding-coding markers in GC are urgently required.

Somatic Mutational Landscape in Mexican Patients: CDH1 Mutations and chr20q13.33 Amplifications Are Associated with Diffuse-Type Gastric Adenocarcinoma

The Hispanic population, compared with other ethnic groups, presents a more aggressive gastric cancer phenotype with higher frequency of diffuse-type gastric adenocarcinoma (GA); this could be related to the mutational landscape of GA in these patients. Using whole-exome sequencing, we sought to present the mutational landscape of GA from 50 Mexican patients who were treated at The Instituto Nacional de Cancerología from 2019 to 2020. We performed a comprehensive statistical analysis to explore the relationship of the genomic variants and clinical data such as tumor histology and presence of signet-ring cell, H. pylori, and EBV. We describe a potentially different mutational landscape between diffuse and intestinal GA in Mexican patients. Patients with intestinal-type GA tended to present a higher frequency of NOTCH1 mutations, copy number gains in cytobands 13.14, 10q23.33, and 12q25.1, and copy number losses in cytobands 7p12, 14q24.2, and 11q13.1; whereas patients with diffuse-type GA tended to present a high frequency of CDH1 mutations and CNV gains in cytobands 20q13.33 and 22q11.21. This is the first description of a mutational landscape of GA in Mexican patients to better understand tumorigenesis in Hispanic patients and lay the groundwork for discovering potential biomarkers and therapeutic targets.

Effects of the Wnt/β-Catenin Signaling Pathway on Proliferation and Apoptosis of Gastric Cancer Cells

Objective

To explore the effect of the Wnt/β-catenin signaling pathway on the proliferation and apoptosis of gastric cancer cells.

Methods

An MTT colorimetric assay was used to detect the inhibitory effect of the Wnt/β-catenin signaling pathway inhibitor FH535 on the proliferation of MKN45 gastric cancer cells. The cell proliferation index (PI) and apoptosis index (AI) were measured by flow cytometry. The expression levels of β-catenin, c-myc, and cleaved caspase-3 in MKN45 gastric cancer cells were detected.

Results

After using the Wnt/β-catenin signaling pathway inhibitor FH535, MKN45 gastric cancer cells showed obvious shrinkage, death, and cell density decrease. MTT showed that the A value of MKN45 gastric cancer cells in FH535 group was significantly lower than that in the control group (P < 0.05). The survival rate of MKN45 gastric cancer cells in FH535 group was significantly lower than that in the control group (P < 0.05). The cell cycle of gastric cancer was arrested in G0/G1 phase. The expression levels of β-catenin and c-myc protein in MKN45 gastric cancer cells in FH535 group decreased significantly (P < 0.05), while the expression level of cleaved caspase-3 protein increased significantly (P < 0.05).

Conclusion

The Wnt/β-catenin signal molecule can maintain the proliferation of gastric cancer cells. Inhibition of the Wnt/β-catenin signaling pathway can inhibit the proliferation of gastric cancer cells and promote the apoptosis of MKN45 gastric cancer cells.

Toll-like receptor 3 gene regulates cataract-related mechanisms via the Jagged-1/Notch signaling pathway

Epithelial-melancholy transition (EMT) is the main cause of organ fibrosis and a common pathogenetic mechanism in most cataracts. This study aimed to explore the molecular mechanism of Toll-like receptor (TLR)-3 in the occurrence and development of post-cataract EMT and to provide new ideas for the prevention and treatment of posterior capsule opacification (PCO). In the presence or absence of TLR3, the human lens epithelial cell (LEC) line, SRA01/04, was treated with the transforming growth factor (TGF)-β2. Cell counting kit-8 (CCK-8) and Transwell assays were used to analyze the cell proliferation, migration, and invasion. The expression levels of proteins and RNAs were detected by western blotting and quantitative polymerase chain reaction (qPCR) experiments. Functional gain and loss studies showed that TLR3 regulates the proliferation, migration, and invasion of LECs and EMT induced by TGF-β2. Moreover, TLR3 regulates the expression of Jagged-1, Notch-1, and Notch-3 These findings indicate that TLR3 prevents the progression of lens fibrosis by targeting the Jagged-1/Notch signaling pathway to regulate the proliferation, migration, and invasion of LECs, and TGF-β2-induced EMT. Therefore, the TLR3-Jagged-1/Notch signaling axis may be a potential therapeutic target for the treatment of fibrotic cataracts.

Morphogen Signals Shaping the Gastric Glands in Health and Disease

The adult gastric mucosa is characterised by deep invaginations of the epithelium called glands. These tissue architectural elements are maintained with the contribution of morphogen signals. Morphogens are expressed in specific areas of the tissue, and their diffusion generates gradients in the microenvironment. Cells at different positions in the gland sense a specific combination of signals that instruct them to differentiate, proliferate, regenerate, or migrate. Differentiated cells perform specific functions involved in digestion, such as the production of protective mucus and the secretion of digestive enzymes or gastric acid. Biopsies from gastric precancerous conditions usually display tissue aberrations and change the shape of the glands. Alteration of the morphogen signalling microenvironment is likely to underlie those conditions. Furthermore, genes involved in morphogen signalling pathways are found to be frequently mutated in gastric cancer. We summarise the most recent findings regarding alterations of morphogen signalling during gastric carcinogenesis, and we highlight the new stem cell technologies that are improving our understanding of the regulation of human tissue shape.

KMT2D loss drives aggressive tumor phenotypes in cutaneous squamous cell carcinoma

Cutaneous squamous cell carcinoma (cSCC) is the second most lethal skin cancer. Due to ultraviolet light-induced damage, cSCCs have a high mutation rate, but some genes are more frequently mutated in aggressive cSCCs. Lysine-specific histone methyltransferase 2D (KMT2D) has a two-fold higher mutation frequency in metastatic cSCCs relative to primary non-metastatic associated cSCCs. The role of KMT2D in more aggressive phenotypes in cSCC is uncharacterized. Studies of other tumor types suggest that KMT2D acts to suppress tumor development. To determine whether KMT2D loss has an impact on tumor characteristics, we disrupted KMT2D in a cSCC cell line using CRISPR-cas9 and performed phenotypic analyses. KMT2D loss modestly increased cell proliferation and colony formation (1.4- and 1.6-fold respectively). Cells lacking KMT2D showed increased rates of migration and faster cell cycle progression. In xenograft models, tumors with KMT2D loss showed slight increases in mitotic indices. Collectively, these findings suggest that KMT2D loss-of-function mutations may promote more aggressive and invasive behaviors in cSCC, suggesting that KMT2D-related pathways could be targets for cancer therapies. Future studies to determine the downstream genes and mechanism of phenotypic effect are needed.

Uncovering the dosage-dependent roles of Arid1a in gastric tumorigenesis for combinatorial drug therapy

Gastric cancer (GC) is one of the most common deadly cancers in the world. Although patient genomic data have identified AT-rich interaction domain 1A (ARID1A), a key chromatin remodeling complex subunit, as the second most frequently mutated gene after TP53, its in vivo role and relationship to TP53 in gastric tumorigenesis remains unclear. Establishing a novel mouse model that reflects the ARID1A heterozygous mutations found in the majority of human GC cases, we demonstrated that Arid1a heterozygosity facilitates tumor progression through a global loss of enhancers and subsequent suppression of the p53 and apoptosis pathways. Moreover, mouse genetic and single-cell analyses demonstrated that the homozygous deletion of Arid1a confers a competitive disadvantage through the activation of the p53 pathway, highlighting its distinct dosage-dependent roles. Using this unique vulnerability of Arid1a mutated GC cells, our combined treatment with the epigenetic inhibitor, TP064, and the p53 agonist, Nutlin-3, inhibited growth of Arid1a heterozygous tumor organoids, providing a novel therapeutic option for GC.

A Middle-Out Modeling Strategy to Extend a Colon Cancer Logical Model Improves Drug Synergy Predictions in Epithelial-Derived Cancer Cell Lines

Cancer is a heterogeneous and complex disease and one of the leading causes of death worldwide. The high tumor heterogeneity between individuals affected by the same cancer type is accompanied by distinct molecular and phenotypic tumor profiles and variation in drug treatment response. In silico modeling of cancer as an aberrantly regulated system of interacting signaling molecules provides a basis to enhance our biological understanding of disease progression, and it offers the means to use computer simulations to test and optimize drug therapy designs on particular cancer types and subtypes. This sets the stage for precision medicine: the design of treatments tailored to individuals or groups of patients based on their tumor-specific molecular cancer profiles. Here, we show how a relatively large manually curated logical model can be efficiently enhanced further by including components highlighted by a multi-omics data analysis of data from Consensus Molecular Subtypes covering colorectal cancer. The model expansion was performed in a pathway-centric manner, following a partitioning of the model into functional subsystems, named modules. The resulting approach constitutes a middle-out modeling strategy enabling a data-driven expansion of a model from a generic and intermediate level of molecular detail to a model better covering relevant processes that are affected in specific cancer subtypes, comprising 183 biological entities and 603 interactions between them, partitioned in 25 functional modules of varying size and structure. We tested this model for its ability to correctly predict drug combination synergies, against a dataset of experimentally determined cell growth responses with 18 drugs in all combinations, on eight cancer cell lines. The results indicate that the extended model had an improved accuracy for drug synergy prediction for the majority of the experimentally tested cancer cell lines, although significant improvements of the model's predictive performance are still needed. Our study demonstrates how a tumor-data driven middle-out approach toward refining a logical model of a biological system can further customize a computer model to represent specific cancer cell lines and provide a basis for identifying synergistic effects of drugs targeting specific regulatory proteins. This approach bridges between preclinical cancer model data and clinical patient data and may thereby ultimately be of help to develop patient-specific in silico models that can steer treatment decisions in the clinic.

SPON2 Is Upregulated through Notch Signaling Pathway and Promotes Tumor Progression in Gastric Cancer

Spondin-2 (SPON2) is involved in cancer progression and metastasis of many tumors; however, its role and underlying mechanism in gastric cancer are still obscure. In this study, we investigated the role of SPON2 and related signaling pathway in gastric cancer progression and metastasis. SPON2 expression levels were found to be upregulated in gastric cancer cell lines and patient tissues compared to normal gastric epithelial cells and normal controls. Furthermore, SPON2 silencing was observed to decrease cell proliferation and motility and reduce tumor growth in xenograft mice. Conversely, SPON2 overexpression was found to increase cell proliferation and motility. Subsequently, we focused on regulatory mechanism of SPON2 in gastric cancer. cDNA microarray and in vitro study showed that Notch signaling is significantly correlated to SPON2 expression. Therefore, we confirmed how Notch signaling pathway regulate SPON2 expression using Notch signaling-related transcription factor interaction and reporter gene assay. Additionally, activation of Notch signaling was observed to increase cell proliferation, migration, and invasion through SPON2 expression. Our study demonstrated that Notch signaling-mediated SPON2 upregulation is associated with aggressive progression of gastric cancer. In conclusion, we suggest upregulated SPON2 via Notch signaling as a potential target gene to inhibit gastric cancer progression.

Interaction of Long Noncoding RNAs and Notch Signaling: Implications for Tissue Homeostasis Loss

The Notch signaling is a crucial pathway involved in cellular development, progression, and differentiation. Deregulation of Notch signaling pathway commonly impacts tissue homeostasis, being highly associated with proliferative disorders. The long noncoding RNAs (lncRNAs), which are transcripts with more than 200 nucleotides that do not code for proteins, were already described as Notch signaling pathway-interacting molecules. Many of them act as important transcriptional and posttranscriptional regulators, affecting gene expression and targeting other regulatory molecules, such as miRNAs. Due to their strong impact on function and gene expression of Notch-related molecules, lncRNAs influence susceptibility to cancer and other diseases, and can be regarded as potential biomarkers and therapeutic targets. Along this chapter, we summarize the cross talk between the Notch signaling pathway and their most important modulating lncRNAs, as well as the pathological consequences of these interactions, in different tissues.

Establishment of novel long-term cultures from EpCAM positive and negative circulating tumour cells from patients with metastatic gastroesophageal cancer

Circulating tumour cell (CTC) enumeration and profiling has been established as a valuable clinical tool in many solid malignancies. A key challenge in CTC research is the limited number of cells available for study. Ex vivo CTC culture permits expansion of these rare cell populations for detailed characterisation, functional assays including drug sensitivity testing, and investigation of the pathobiology of metastases. We report for the first time the establishment and characterisation of two continuous CTC lines from patients with gastroesophageal cancer. The two cell lines (designated UWG01CTC and UWG02CTC) demonstrated rapid tumorigenic growth in immunodeficient mice and exhibit distinct genotypic and phenotypic profiles which are consistent with the tumours of origin. UWG02CTC exhibits an EpCAM+, cytokeratin+, CD44+ phenotype, while UWG01CTC, which was derived from a patient with metastatic neuroendocrine cancer, displays an EpCAM−, weak cytokeratin phenotype, with strong expression of neuroendocrine markers. Further, the two cell lines show distinct differences in drug and radiation sensitivity which match differential cancer-associated gene expression pathways. This is strong evidence implicating EpCAM negative CTCs in metastasis. These novel, well characterised, long-term CTC cell lines from gastroesophageal cancer will facilitate ongoing research into metastasis and the discovery of therapeutic targets.

Notch and mTOR Signaling Pathways Promote Human Gastric Cancer Cell Proliferation

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

Ubenimex Reverses MDR in Gastric Cancer Cells by Activating Caspase-3-Mediated Apoptosis and Suppressing the Expression of Membrane Transport Proteins

Gastric cancer (GC) is one of the most malignant tumors, accounting for 10% of deaths caused by all cancers. Chemotherapy is often necessary for treatment of GC; the FOLFOX regimen is extensively applied. However, multidrug resistance (MDR) of GC cells prevents wider application of this treatment. Ubenimex, an inhibitor of CD13, is used as an immune adjuvant to treat hematological malignancies. Here, we demonstrate that CD13 expression positively correlates with MDR development in GC cells. Moreover, Ubenimex reverses the MDR of SGC7901/X and MKN45/X cells and enhances their sensitivity to FOLFOX, in part by decreasing CD13 expression, which is accompanied by downregulation of Bcl-xl, Bcl-2, and survivin expression; increased expression of Bax; and activation of the caspase-3-mediated apoptotic cascade. In addition, Ubenimex downregulates expression of membrane transport proteins, such as P-gp and MRP1, by inhibiting phosphorylation in the PI3K/AKT/mTOR pathway to increase intracellular accumulations of 5-fluorouracil and oxaliplatin, a process for which downregulation of CD13 expression is essential. Therefore, the present results reveal a previously uncharacterized function of CD13 in promoting MDR development in GC cells and suggest that Ubenimex is a candidate for reversing the MDR of GC cells.

Cancer stem cells and fibroblast niche cross talk in an in-vitro oral dysplasia model

Understanding the cellular interactions during oral carcinogenesis has the potential to identify novel prognostic and therapeutic targets. This study aimed at investigating the cancer stem cell (CSC)-fibroblast niche interactions using in-vitro dysplastic cell line models developed from different stages of 4NQO-induced oral carcinogenic mice model. The spontaneously transformed epithelial cells (DysMSCTR6, 14 and 16) were developed from three time points (mild/moderate/severe), while two fibroblast cell lines (FibroMSCTR12, 16) were developed from moderate and severe dysplastic tissue. The epithelial (Epcam+/Ck+) and the fibroblast cell lines (Vimentin+/α-SMA+/Ck-) were authenticated and assessment of cells representing progressive grades of dysplastic severity indicated a significant increase in dysplastic marker profile (P < 0.05). Evaluation of the CSC characteristics showed that an increase in expression of Cd133, Cd44, Aldh1a1, Notch1, and Sox2 was accompanied by an increase in migratory (P > 0.05) and colony formation capacity (P > 0.005). Targeting Notch1 (GSI inhibitor PZ0187; 30 μM), showed a significant reduction in cell proliferation capacity (P < 0.05) and in the dysplastic marker profile. Further, Notch1 inhibition resulted in down regulation of Cd133 and Aldh1a 1 (P < 0.05) and a complete abrogation of colony formation ability (P < 0.0001). The effect of niche interactions evaluated using FibroMSCTR12-conditioned media studies, revealed an enrichment of ALDH1A1+ cells (P < 0.05), induction of spheroid formation ability (P < 0.0001) and increased proliferation capacity (3.7 fold; P < 0.005). Although PZ0187 reduced cell viability by ∼40%, was unable to abrogate the conditioned-media induced increase in proliferation capacity completely. This study reports a Notch-1 dependent enrichment of CSC properties during dysplastic progression and a Notch-1 independent dysplastic cell-fibroblast interaction during oral carcinogenesis.

MicroRNA-212 promotes the recovery function and vascular regeneration of endothelial progenitor cells in mice with ischemic stroke through inactivation of the notch signaling pathway via downregulating MMP9 expression

Ischemic stroke is a refractory disease caused by cerebral ischemic injury, which results in brain dysfunction. This study intends to investigate the effects of microRNA-212 (miR-212) on the recovery function and vascular regeneration of endothelial progenitor cells (EPCs) by inactivation of the Notch signaling pathway by binding to matrix metallopeptidase 9 (MMP9) in mice with ischemic stroke. According to the results of database retrieval systems and data analysis, MMP9 was predicted as a gene related to ischemic stroke and miR-212 is a potential regulating mRNA of MMP9. All 72 healthy adult C57BL6 mice were selected for middle cerebral artery occlusion (MCAO) establishment. Cerebral infarction was observed under triphenyltetrazolium chloride staining. A series of inhibitors, activators, and siRNAs were introduced to the verified regulatory functions for miR-212 governing MMP9 in ischemic stroke. Cell proliferation was detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and tube-forming ability by tubule formation test. Reverse transcription quantitative polymerase chain reaction and Western blot analysis were used to detect the expressions of miR-212, MMP9, Hes-1, and Notch-1. The corresponding results demonstrated that the area of cerebral infarction and the number of neuronal necrosis increased in the MCAO group in contrast to the sham group. Meanwhile, upregulation of miR-212 or downregulation of MMP9 decreases the expressions of MMP9, Hes-1 Notch-1, increases cell proliferation and tube-forming ability and improves the pathological conditions of EPCs. Our study suggests that miR-212 promotes recovery function and vascular regeneration of EPCs through negative regulation of the Notch signaling pathway via downregulating expression of MMP9, thus provides a clinical theoretical basis for ischemic stroke therapy.

High expression of the ANKRD49 protein is associated with progression and poor prognosis of gastric cancer

BACKGROUND

Gastric cancer is one of the most common malignant tumours. Identifying novel genes that govern the development of gastric cancer will help to elucidate its molecular mechanisms and find novel biomarkers.

METHODS

Expression of the ANKRD49 protein was assessed by immunohistochemical analysis of tissue microarrays containing 92 sets of human gastric cancer specimens with adjacent non-cancerous tissue. Associations between ANKRD49 levels and clinicopathological characteristics of the patient were investigated. The correlation between ANKRD49 expression and patient survival was analysed by the Kaplan-Meier method.

RESULTS

The results revealed that the expression level of the ANKRD49 protein in gastric cancer was significantly upregulated and correlated with the tumour size, tumour-node-metastasis (TNM) stage, histological grade, depth of invasion, vessel invasion, lymph node metastasis and distant metastasis. The mean survival time of patients with low expression levels of ANKRD49 was significantly longer than that of patients with high expression levels of ANKRD49. Multivariate Cox regression analysis demonstrated that the ANKRD49 protein expression level was an independent prognostic indicator for the survival rate of patients with gastric cancer.

CONCLUSION

The results of the present study highlighted an important role of the ANKRD49 protein in the progression of gastric cancer. The ANKRD49 protein could act as a potential biomarker for prognosis evaluation of gastric cancer and may be used as a molecular target for gastric cancer treatment.

DNA methyltransferases and gastric cancer: insight into targeted therapy

Gastric cancer is a major health problem worldwide occupying most frequent causes of cancer-related mortality. In addition to genetic modifications, epigenetic alterations catalyzed by DNA methyltransferases (DNMTs) are a well-characterized epigenetic hallmark in gastric cancer. The reversible nature of epigenetic alterations and central role of DNA methylation in diverse biological processes provides an opportunity for using DNMT inhibitors to enhance the efficacy of chemotherapeutics. In this review, we discussed key factors or mechanisms such as SNPs, infections and genetic modifications that trigger DNMTs level modification in gastric cancer, and their potential roles in cancer progression. Finally, we focused on how inhibitors of the DNMTs can most effectively be used for the treatment of gastric cancer with multidrug resistance.

MFAP2 promotes epithelial-mesenchymal transition in gastric cancer cells by activating TGF-β/SMAD2/3 signaling pathway

Introduction

Microfibril-associated protein 2 (MFAP2) is an extracellular matrix protein that interacts with fibrillin to modulate the function of microfibrils. MFAP2 has been reported to play a significant role in obesity, diabetes, and osteopenia, and has been shown to be upregulated in head and neck squamous cell carcinoma. However, the molecular function and prognostic value of MFAP2 have never been reported in gastric cancer (GC) or any other tumors.

Methods

The current study investigated the expression patterns, prognostic significance, functional role, and possible mechanisms of MFAP2 in GC.

Results

We demonstrated that MFAP2 was overexpressed in GC tissues, and its overexpression was significantly correlated with poor overall and disease-free survival in patients with GC. Moreover, we found that MFAP2 promoted the proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) phenotype in GC cells. MFAP2 might modulate EMT of GC cells by activating the TGF-β/SMAD2/3 signaling pathway.

Conclusion

These findings provide novel evidence that MFAP2 plays a crucial role in the progression of GC. Therefore, MFAP2 may be a promising prognostic marker and a potent anticancer agent.

Signalling mechanism(s) of epithelial-mesenchymal transition and cancer stem cells in tumour therapeutic resistance

Epithelial-mesenchymal transition (EMT) leads to tumour progression, including tumour metastasis, disease recurrence and therapy resistance. Cancer stem cells (CSCs) are a small group of cells that have the ability to undergo self-renewal and heterogeneous differentiation, which play a key role in the occurrence and development of cancer. EMT can promote tumour cells to develop stem cell characteristics, which makes tumours more difficult to treat. Therefore, exploring the role of EMT and CSCs in the metastasis of cancer is of great significance to guide tumour treatment and prognosis. In this review, we discuss EMT and CSCs in cancer progression and therapeutic resistance, with a special focus on the common characteristics and relationships between these processes, to explore the crucial relationships in the development of improved anti-tumour therapies.

AREAS COVERED

In this brief review article, the author has searched PubMed and Wikipedia for original research and reviewed articles to gather current information on the association of CSCs and EMT with therapeutic resistance characteristics, cancer growth and metastasis, which are believed to be regulated by the TGF-β, Wnt, Hedgehog (Hh), β-catenin, STAT3, Notch, and Nanog signalling pathways and other factors (miRNAs, microenvironment and additional cytokines).

New Perspectives on Diagnosis and Therapy of Malignant Pleural Mesothelioma

Malignant pleural mesothelioma (MPM) is a rare, but severe form of cancer, with an incidence that varies significantly within and among different countries around the world. It develops in about one to two persons per million of the general population, leading to thousands of deaths every year worldwide. To date, the MPM is mostly associated with occupational asbestos exposure. Asbestos represents the predominant etiological factor, with approximately 70% of cases of MPM with well-documented occupational exposure to asbestos, with the exposure time, on average greater than 40 years. Environmental exposure to asbestos is increasingly becoming recognized as a cause of mesothelioma, together with gene mutations. The possible roles of other cofactors, such as viral infection and radiation exposure, are still debated. MPM is a fatal tumor. This cancer arises during its early phase without clinical signs. Consequently, its diagnosis occurs at advanced stages. Standard clinical therapeutic approaches include surgery, chemo- and radiotherapies. Preclinical and clinical researches are making great strides in the field of this deadly disease, identifying new biomarkers and innovative therapeutic approaches. Among the newly identified markers and potential therapeutic targets, circulating microRNAs and the Notch pathway represent promising avenues that could result in the early detection of the tumor and novel therapeutic approaches.

Novel Insights on Notch signaling pathways in liver fibrosis

Liver fibrosis is characterized by an increased and altered deposition of extracellular matrix (ECM) proteins that make up excessive tissue scarring and promote chronic liver injury. Activation of hepatic stellate cells (HSCs) is a pivotal cellular event in the progression of liver fibrosis. However, the mechanisms involved in the development of liver fibrosis are only now beginning to be unveiled. The Notch pathway is a fundamental and highly conserved pathway able to control cell-fate, including cell proliferation, differentiation, apoptosis, regeneration and other cellular activities. Recently, the deregulation of Notch cascade has been found involved in many pathological processes, including liver fibrosis. These data give evidence for a role for Notch signaling in liver fibrosis. In addition，more and more date are available on the role of Notch pathways in the process. Therefore, this review focuses on the current knowledge about the Notch signaling pathway, which dramatically takes part in HSC activation and liver fibrosis, and look ahead on new perspectives of Notch signaling pathway research. Furthermore, we will summarize this new evidence on the different interactions in Notch signaling pathway-regulated liver fibrosis, and support the potentiality of putative biomarkers and unique therapeutic targets.

Sorcin induces gastric cancer cell migration and invasion contributing to STAT3 activation

Gastric cancer (GC) is a globally occurring malignancy that is characterized by a high mortality rate due to a high tendency to metastasize and poor prognoses. Sorcin, as known as SRI, a soluble resistance-related calcium-binding protein, plays a significant role in multidrug resistance. Sorcin is related to the migration and invasion of cancer cells. However, the mechanism remains unclear. Here, we used immunohistochemistry to confirm that the expression of sorcin in cancer tissues is higher than that in the adjacent normal tissues. The wound healing and transwell results indicate that sorcin can induce migration and invasion of GC cells. To explore the role of sorcin in GC metastasis, isobaric tags for relative and absolutely quantitation (iTRAQ) were used to examine cells with and without sorcin knockdown to identify the differentially expressed proteins (DEPs). The results were evaluated via RT-PCR and western blot to confirm the ITRAQ data. Inhibition of sorcin expression can down- regulate the expression of CTSZ, MMP2, MMP9 and p-STAT3 followed by suppression of tumor growth and metastasis. Together, we concluded that sorcin has a oncogenic activity via inducing tumor growth and metastasis, leading to development of therapeutic treatments for GC.