Gastric cancer stem cells

Fructose-bisphosphate Aldolase C Expression is Associated with Poor Prognosis and Stemness in Gastric Cancer

Gastric cancer (GC) is the third leading cause of cancer-related deaths in Japan, underscoring the urgent need for deeper insights into its pathogenesis. Spheroids provide a more realistic and versatile model for studying cancers and cancer stem cells (CSCs). While fructose-bisphosphate aldolase C (ALDOC) has been identified in colorectal cancer spheroids, its role in GC has remained largely unexplored. This study aimed to elucidate the role of ALDOC in GC by performing single-cell and functional analyses of GC spheroids and cell lines, along with immunohistochemistry of 127 GC samples to assess its correlation with CSC markers. Our single-cell analysis revealed upregulation of ALDOC in spheroids, with pseudotime analysis indicating that ALDOC-expressing cells were predominantly undifferentiated and co-expressed LGR5 and CD44. Further investigation into cell-cell interactions suggested that the stem cell state may be maintained by WNT, BMP, and EGF signaling. Functional assays demonstrated that ALDOC knockdown led to a marked reduction in the growth, invasiveness, and spheroid colony formation capacity of GC cell lines. Clinically, ALDOC was detected in the cytoplasm of 56.7% (72/127) of GC cases, and high ALDOC expression was significantly associated with poor overall survival (p < 0.01), and was an independent prognostic factor. Moreover, a significant association between ALDOC and CD44 expression in GC (p = 0.031). Conclusively, our findings identify ALDOC as a crucial prognostic marker and provide new insights into GC pathogenesis.

Emerging methods and techniques for cancer biomarker discovery

Modern cancer research depends heavily on the identification and validation of biomarkers because they provide important information about the diagnosis, prognosis, and response to treatment of the cancer. This review will provide a comprehensive overview of cancer biomarkers, including their development phases and recent breakthroughs in transcriptomics and computational techniques for detecting these biomarkers. Blood-based biomarkers have great potential for non-invasive tumor dynamics and treatment response monitoring. These include circulating tumor DNA, exosomes, and microRNAs. Comprehensive molecular profiles are provided by multi-omic technologies, which combine proteomics, metabolomics, and genomes to support the identification of biomarkers and the targeting of therapeutic interventions. Genetic changes are detected by next-generation sequencing, and patterns of protein expression are found by protein arrays and mass spectrometry. Tumor heterogeneity and clonal evolution can be understood using metabolic profiling and single-cell studies. It is projected that the use of several biomarkers-genetic, protein, mRNA, microRNA, and DNA profiles, among others-will rise, enabling multi-biomarker analysis and improving individualised treatment plans. Biomarker identification and patient outcome prediction are further improved by developments in AI algorithms and imaging techniques. Robust biomarker validation and reproducibility require cooperation between industry, academia, and doctors. Biomarkers can provide individualized care, meet unmet clinical needs, and enhance patient outcomes despite some obstacles. Precision medicine will continue to take shape as scientific research advances and the integration of biomarkers with cutting-edge technologies continues to offer a more promising future for personalized cancer care.

Discovering cancer stem-like molecule, nuclear factor I X, using spatial transcriptome in gastric cancer

Gastric cancer (GC) is characterized by significant intratumoral heterogeneity, and stem cells are promising therapeutic targets. Despite advancements in spatial transcriptome analyses, unexplored targets for addressing cancer stemness remain unknown. This study aimed to identify Nuclear Factor IX (NFIX) as a critical regulator of cancer stemness in GC and evaluate its clinicopathological significance and function. Spatial transcriptome analysis of GC was conducted. The correlation between NFIX expression, clinicopathological factors, and prognosis was assessed using immunostaining in 127 GC cases. Functional analyses of cancer cell lines validated these findings. Spatial transcriptome analysis stratified GC tissues based on genetic profiles, identified CSC-like cells, and further refined the classification to identify and highlight the significance of NFIX, as validated by Monocle 3 and CytoTRACE analyses. Knockdown experiments in cancer cell lines have demonstrated the involvement of NFIX in cancer cell proliferation and kinase activity. This study underscores the role of spatial transcriptome analysis in refining GC tissue classification and identifying therapeutic targets, highlighting NFIX as a pivotal factor. NFIX expression is correlated with poor prognosis and drives GC progression, suggesting its potential as a novel therapeutic target for personalized GC therapies.

POLQ inhibition attenuates the stemness and ferroptosis resistance in gastric cancer cells via downregulation of dihydroorotate dehydrogenase

Gastric cancer (GC) contains subpopulations of cancer stem cells (CSCs), which are described as the main contributors in tumor initiation and metastasis. It is necessary to clarify the molecular mechanism underlying CSCs phenotype and develop novel biomarkers and therapeutic targets for gastric cancer. Here, we show that POLQ positively regulates stem cell-like characteristics of gastric cancer cells, knockdown of POLQ suppressed the stemness of GC cells in vitro and in vivo. Further mechanistic studies revealed that POLQ knockdown could downregulate the expression of dihydroorotate dehydrogenase (DHODH). DHODH overexpression rescued the reduced stemness resulted by POLQ knockdown. Furthermore, we found that POLQ expression correlated with resistance to ferroptosis, and POLQ inhibition renders gastric cancer cells more vulnerable to ferroptosis. Further investigation revealed that POLQ regulated DHODH expression via the transcription factors E2F4, thereby regulating ferroptosis resistance and stemness of gastric cancer cells. Given the importance of POLQ in stemness and ferroptosis resistance of GC, we further evaluated the therapeutic potential of POLQ inhibitor novobiocin, the results show that novobiocin attenuates the stemness of GC cells and increased ferroptosis sensitivity. Moreover, the combination of POLQ inhibitor and ferroptosis inducer synergistically suppressed MGC-803 xenograft tumor growth and diminished metastasis. Our results identify a POLQ-mediated stemness and ferroptosis defense mechanism and provide a new therapeutic strategy for gastric cancer.

Morusin suppresses the stemness characteristics of gastric cancer cells induced by hypoxic microenvironment through inhibition of HIF-1α accumulation

Gastric cancer (GC) is a common, life-threatening malignancy that contributes to the global burden of cancer-related mortality, as conventional therapeutic modalities show limited effects on GC. Hence, it is critical to develop novel agents for GC therapy. Morusin, a typical prenylated flavonoid, possesses antitumor effects against various cancers. The present study aimed to demonstrate the inhibitory effect and mechanism of morusin on the stemness characteristics of human GC in vitro under hypoxia and to explore the potential molecular mechanisms. The effects of morusin on cell proliferation and cancer stem cell-like properties of the human GC cell lines SNU-1 and AGS were assessed by MTT assay, colony formation test, qRT-PCR, flow cytometry analysis, and sphere formation test under hypoxia or normoxia condition through in vitro assays. The potential molecular mechanisms underlying the effects of morusin on the stem-cell-like properties of human GC cells in vitro were investigated by qRT-PCR, western blotting assay, and immunofluorescence assay by evaluating the nuclear translocation and expression level of hypoxia-inducible factor-1α (HIF-1α). The results showed that morusin exerted growth inhibitory effects on SNU-1 and AGS cells under hypoxia in vitro. Moreover, the proportions of CD44+/CD24- cells and the sphere formation ability of SNU-1 and AGS reduced in a dose-dependent manner following morusin treatment. The expression levels of stem cell-related genes, namely Nanog, OCT4, SOX2, and HIF-1α, gradually decreased, and the nuclear translocation of the HIF-1α protein was apparently attenuated. HIF-1α overexpression partially reversed the abovementioned effects of morusin. Taken together, morusin could restrain stemness characteristics of GC cells by inhibiting HIF-1α accumulation and nuclear translocation and could serve as a promising compound for GC treatment.

Multifaceted role of microRNAs in gastric cancer stem cells: Mechanisms and potential biomarkers

MicroRNAs (miRNAs) have received much attention in the past decade as potential key epigenomic regulators of tumors and cancer stem cells (CSCs). The abnormal expression of miRNAs is responsible for different phenotypes of gastric cancer stem cells (GCSCs). Some specific miRNAs could be used as promising biomarkers and therapeutic targets for the identification of GCSCs. This review summarizes the coding process and biological functions of miRNAs and demonstrates their role and efficacy in gastric cancer (GC) metastasis, drug resistance, and apoptosis, especially in the regulatory mechanism of GCSCs. It shows that the overexpression of onco-miRNAs and silencing of tumor-suppressor miRNAs can play a role in promoting or inhibiting tumor metastasis, apart from the initial formation of GC. It also discusses the epigenetic regulation and potential clinical applications of miRNAs as well as the role of CSCs in the pathogenesis of GC. We believe that this review may help in designing novel therapeutic approaches for GC.

Biomarkers in Cancer Detection, Diagnosis, and Prognosis

Biomarkers are vital in healthcare as they provide valuable insights into disease diagnosis, prognosis, treatment response, and personalized medicine. They serve as objective indicators, enabling early detection and intervention, leading to improved patient outcomes and reduced costs. Biomarkers also guide treatment decisions by predicting disease outcomes and facilitating individualized treatment plans. They play a role in monitoring disease progression, adjusting treatments, and detecting early signs of recurrence. Furthermore, biomarkers enhance drug development and clinical trials by identifying suitable patients and accelerating the approval process. In this review paper, we described a variety of biomarkers applicable for cancer detection and diagnosis, such as imaging-based diagnosis (CT, SPECT, MRI, and PET), blood-based biomarkers (proteins, genes, mRNA, and peptides), cell imaging-based diagnosis (needle biopsy and CTC), tissue imaging-based diagnosis (IHC), and genetic-based biomarkers (RNAseq, scRNAseq, and spatial transcriptomics).

Kinesin Family Member B18 Is Related to Gastric Mucin Phenotype and Contributes to Gastric Cancer Progression by Regulating Epithelial-Mesenchymal Transition

INTRODUCTION

Gastric cancer (GC) remains a common health concern worldwide and is the third leading cause of death in Japan. It can be broadly classified into gastric and intestinal mucin phenotypes using immunohistochemistry. We previously reported numerous associations of kinesin family member (KIF) genes and mucin phenotypes with GC. However, no previous studies have reported on the importance of KIF18B in GC using immunostaining. Thus, in this study, we investigated the expression and functions of KIF18B, which is highly expressed in gastric mucin phenotype GC.

METHODS

We performed RNA-seq of gastric and intestinal mucin type GCs, and clinicopathological studies of the KIF18B we found were performed using 96 GC cases. We also performed functional analysis using GC-derived cell lines.

RESULT

RNA-seq showed the upregulation of matrisome-associated genes in gastric mucin phenotype GC and a high expression of KIF18B. KIF18B was detected in 52 of the 96 GC cases (54%) through immunohistochemistry. Low KIF18B expression was significantly associated with poor overall survival (p < 0.01). Other molecules that were significantly associated with KIF18B were MUC5AC and claudin 18; these were also significantly associated with the gastric mucin phenotype. KIF18B small interfering RNA (siRNA)-transfected GC cells showed greater growth and spheroid colony formation than the negative control siRNA-transfected cells. Furthermore, expression of snail family transcriptional repressor 1 and cadherin 2 was significantly increased and that of cadherin 1 was significantly decreased in KIF18B siRNA-transfected GC cells.

CONCLUSION

These findings not only suggest that KIF18B may be a useful prognostic marker, but also provide insight into the pathogenesis of the GC phenotype.

WNT2-SOX4 positive feedback loop promotes chemoresistance and tumorigenesis by inducing stem-cell like properties in gastric cancer

Gastric cancer (GC) is characterized by its vigorous chemoresistance to current therapies, which is attributed to the highly heterogeneous and immature phenotype of cancer stem cells (CSCs) during tumor initiation and progression. The secretory WNT2 ligand regulates multiple cancer pathways and has been demonstrated to be a potential therapeutic target for gastrointestinal tumors; however, its role involved in gastric CSCs (GCSCs) remains unclear. Here, we found that overexpression of WNT2 enhanced stemness properties to promote chemoresistance and tumorigenicity in GCSCs. Mechanistically, WNT2 was positively regulated by its transcription factor SOX4, and in turn, SOX4 was upregulated by the canonical WNT2/FZD8/β-catenin signaling pathway to form an auto-regulatory positive feedback loop, resulting in the maintenance of GCSCs self-renewal and tumorigenicity. Furthermore, simultaneous overexpression of both WNT2 and SOX4 was correlated with poor survival and reduced responsiveness to chemotherapy in clinical GC specimens. Blocking WNT2 using a specific monoclonal antibody significantly disrupted the WNT2-SOX4 positive feedback loop in GCSCs and enhanced the chemotherapeutic efficacy when synergized with the chemo-drugs 5-fluorouracil and oxaliplatin in a GCSC-derived mouse xenograft model. Overall, this study identified a novel WNT2-SOX4 positive feedback loop as a mechanism for GCSCs-induced chemo-drugs resistance and suggested that the WNT2-SOX4 axis may be a potential therapeutic target for gastric cancer treatment.

Emerging Role of Glioma Stem Cells in Mechanisms of Therapy Resistance

Since their discovery at the beginning of this millennium, glioma stem cells (GSCs) have sparked extensive research and an energetic scientific debate about their contribution to glioblastoma (GBM) initiation, progression, relapse, and resistance. Different molecular subtypes of GBM coexist within the same tumor, and they display differential sensitivity to chemotherapy. GSCs contribute to tumor heterogeneity and recapitulate pathway alterations described for the three GBM subtypes found in patients. GSCs show a high degree of plasticity, allowing for interconversion between different molecular GBM subtypes, with distinct proliferative potential, and different degrees of self-renewal and differentiation. This high degree of plasticity permits adaptation to the environmental changes introduced by chemo- and radiation therapy. Evidence from mouse models indicates that GSCs repopulate brain tumors after therapeutic intervention, and due to GSC plasticity, they reconstitute heterogeneity in recurrent tumors. GSCs are also inherently resilient to standard-of-care therapy, and mechanisms of resistance include enhanced DNA damage repair, MGMT promoter demethylation, autophagy, impaired induction of apoptosis, metabolic adaptation, chemoresistance, and immune evasion. The remarkable oncogenic properties of GSCs have inspired considerable interest in better understanding GSC biology and functions, as they might represent attractive targets to advance the currently limited therapeutic options for GBM patients. This has raised expectations for the development of novel targeted therapeutic approaches, including targeting GSC plasticity, chimeric antigen receptor T (CAR T) cells, and oncolytic viruses. In this review, we focus on the role of GSCs as drivers of GBM and therapy resistance, and we discuss how insights into GSC biology and plasticity might advance GSC-directed curative approaches.

The members of the miR-148/152 family inhibit cancer stem cell-like properties in gastric cancer via negative regulation of ITGA5

BACKGROUND

The role of microRNA (miRNA) in modulating the function of cancer stem cells through diverse signaling pathway has been evidenced. We here identified a role of microRNA (miRNA) family, specifically miR-148/152, in gastric cancer and delineated its functional effects on gastric cancer stem cells.

METHODS

Bioinformatics analysis was conducted to analyze expression of integrin α5 (ITGA5) which was verified through expression determination in clinical tissue samples. Next, the upstream regulatory factors of ITGA5 were determined. CD44⁺EpCAM (high) cells sorted from AGS cells subjected to gain-of-function experiments, followed by evaluation of their capacity of colony formation, generation of tumorosphere, cell migration and viability in vitro and xenograft tumor formation in vivo.

RESULTS

ITGA5 was elevated in gastric cancer tissues and confirmed as a target gene of the miR-148/152 family members. The miR-148/152 family members were downregulated in gastric cancer tissues and cells. Decreased expression of miR-148/152 family members was also detected in gastric cancer stem cells. However, the raised expression led to reduced colony formation, tumorosphere, cell migration, cell viability, and drug resistance of CD44+EpCAM (high) AGS cells in vitro, and tumorigenesis in vitro. ITGA5 overexpression reversed the effect of the miR-148/152 family members.

CONCLUSIONS

This study demonstrates that the miR-148/152 family members may prevent gastric cancer stem cell-like properties by targeting ITGA5, which can serve as an appealing target for gastric cancer treatment.

MiR-378a-3p acts as a tumor suppressor in gastric cancer via directly targeting RAB31 and inhibiting the Hedgehog pathway proteins GLI1/2

OBJECTIVE

To improve the prognosis of patients with gastric cancer (GC), more effective therapeutic targets are urgently needed. Increasing evidence indicates that miRNAs are involved in the progression of various tumors, and RAS-associated protein in the brain 31 (RAB31) is upregulated and promotes the progression of multiple malignant tumors. Here, we focused on identifying RAB31-targeted miRNAs and elucidating their potential mechanism in the progression of GC.

METHODS

RAB31 and miR-378a-3p expression levels were detected in paired fresh GC tissues and GC cell lines. Bioinformatics analysis was used to predict the miRNAs targeting RAB31 and the relationships between RAB31 and other genes. Dual-luciferase reporter assays were applied to verify the targeted interaction relationship. CCK-8, colony formation, flow cytometry, wound healing, and Transwell assays were performed to assess the proliferation, apoptosis, migration, and invasion of GC cells. Tumorsphere formation assays were performed to assess the stemness of gastric cancer stem cells. Related proteins were detected by Western blot. Xenograft assays in nude mice were performed to explore the effect of miR-378a-3p in vivo.

RESULTS

We report the first evidence that miR-378a-3p is downregulated in GC, whereas its overexpression inhibits proliferation, invasion, and migration as well as promotes apoptosis in GC cells. Mechanistically, miR-378a-3p inhibits the progression of GC by directly targeting RAB31. Restoring RAB31 expression partially offsets the inhibitory effect of miR-378a-3p. Further research revealed that miR-378a-3p inhibits GLI1/2 in the Hedgehog signaling pathway and attenuates the stemness of gastric cancer stem cells. Finally, xenograft assays showed that miR-378a-3p inhibits GC tumorigenesis in vivo.

CONCLUSIONS

MiR-378a-3p inhibits GC progression by directly targeting RAB31 and inhibiting the Hedgehog signaling pathway proteins GLI1/2.

Atranorin driven by nano materials SPION lead to ferroptosis of gastric cancer stem cells by weakening the mRNA 5-hydroxymethylcytidine modification of the Xc-/GPX4 axis and its expression

Gastric cancer is a highly malignant tumor. Gastric cancer stem cells (GCSCs) are the main causes of drug resistance, metastasis, recurrence, and poor prognosis. As a secondary metabolite of lichen, Atranorin has a variety of biological effects, such as antibacterial, anti-inflammatory, analgesic, and wound healing; however, its killing effect on GCSCs has not been reported. In this study, we constructed Atranorin complexes comprising superparamagnetic iron oxide nanoparticles (SPION) (Atranorin@SPION). In vitro and in vivo experiments confirmed that Atranorin@SPION could significantly inhibit the proliferation, invasion, angiogenesis, and tumorigenicity of CD44+/ CD24+ GCSCs, and induce oxidative stress injury, Fe2+ accumulation, and ferroptosis. Quantitative real-time reverse transcription PCR and western blotting results showed that Atranorin@SPION not only reduced the expression levels of GCSC stem cell markers and cell proliferation and division markers, but also significantly inhibited the expression levels of key molecules in the cystine/glutamate transporter (Xc-)/glutathione peroxidase 4 (GPX4) and Tet methylcytosine dioxygenase (TET) family proteins. The results of high performance liquid chromatography-mass spectrometry and Dot blotting showed that Atranorin@SPION significantly inhibited the mRNA 5‑hydroxymethylcytidine modification of GCSCs. Meanwhile, the results of RNA immunoprecipitation-PCR also indicated that Atranorin@SPIONs significantly reduced the 5-hydroxymethylcytidine modification level of GPX4 and SLC7A11 mRNA 3' untranslated region in GCSCs, resulting in a decrease in their stability, shortening their half-lives and reducing translation activity. Therefore, this study revealed that Atranorin@SPIONs induced ferroptosis of GCSCs by weakening the expression of the Xc-/GPX4 axis and the 5-hydroxymethylcytidine modification of mRNAs in the pathway, thereby achieving their therapeutic effect on gastric cancer.

The origin of gastric cancer stem cells and their effects on gastric cancer: Novel therapeutic targets for gastric cancer

Gastric cancer (GC) is one of the most prevalent malignancies and the most common causes of cancer-related mortality worldwide. Furthermore, the prognosis of advanced GC remains poor even after surgery combined with chemoradiotherapy. As a small group of cells with unlimited differentiation and self-renewal ability in GC, accumulating evidence shows that GC stem cells (GCSCs) are closely associated with the refractory characteristics of GC, such as drug resistance, recurrence, and metastasis. With the extensive development of research on GCSCs, GCSCs seem to be promising therapeutic targets for GC. However, the relationship between GCSCs and GC is profound and intricate, and its mechanism of action is still under exploration. In this review, we elaborate on the source and key concepts of GCSCs, systematically summarize the role of GCSCs in GC and their underlying mechanisms. Finally, we review the latest information available on the treatment of GC by targeting GCSCs. Thus, this article may provide a theoretical basis for the future development of the novel targets based on GCSCs for the treatment of GC.

Targeting Gastric Cancer Stem Cells to Enhance Treatment Response

Gastric cancer (GC) was the fourth deadliest cancer in the world in 2020, and about 770,000 people died from GC that year. The death of patients with GC is mainly caused by the metastasis, recurrence, and chemotherapy resistance of GC cells. The cancer stem cell theory defines cancer stem cells (CSCs) as a key factor in the metastasis, recurrence, and chemotherapy resistance of cancer. It considers targeting gastric cancer stem cells (GCSCs) to be an effective method for the treatment of GC. For GCSCs, genes or noncoding RNAs are important regulatory factors. Many experimental studies have found that some drugs can target the stemness of gastric cancer by regulating these genes or noncoding RNAs, which may bring new directions for the clinical treatment of gastric cancer. Therefore, this review mainly discusses related genes or noncoding RNAs in GCSCs and drugs that target its stemness, thereby providing some information for the treatment of GC.

Elevated Protein Kinase A Activity in Stomach Mesenchyme Disrupts Mesenchymal-epithelial Crosstalk and Induces Preneoplasia

BACKGROUND & AIMS

Mesenchymal-epithelial crosstalk (MEC) in the stomach is executed by pathways such as bone morphogenetic protein (BMP) and extracellular signal-regulated kinase (ERK). Mis-regulation of MEC disrupts gastric homeostasis and causes tumorigenesis. Protein Kinase A (PKA) crosstalks with BMP and ERK signaling; however, PKA function(s) in stomach development and homeostasis remains undefined.

METHODS

We generated a novel Six2-Cre^+/-PKAcαR^fl/wt (CA-PKA) mouse in which expression of constitutive-active PKAcαR was induced in gastric mesenchyme progenitors. Lineage tracing determined spatiotemporal activity of Six2-Cre in the stomach. For phenotyping CA-PKA mice histological, co-immunofluorescence, immunoblotting, mRNA sequencing, and bioinformatics analyses were performed.

RESULTS

Lineage tracing showed that Six2-Cre activity in the stomach is restricted to the mesenchymal compartment. CA-PKA mice showed disruption of gastric homeostasis characterized by aberrant mucosal development and epithelial hyperproliferation; ultimately developing multiple features of gastric corpus preneoplasia including decreased parietal cells, mucous cell hyperplasia, spasmolytic peptide expressing metaplasia with intestinal characteristics, and dysplastic and invasive cystic glands. Furthermore, mutant corpus showed marked chronic inflammation characterized by infiltration of lymphocytes and myeloid-derived suppressor cells along with the upregulation of innate and adaptive immune system components. Striking upregulation of inflammatory mediators and STAT3 activation was observed. Mechanistically, we determined there is an activation of ERK1/2 and downregulation of BMP/SMAD signaling characterized by marked upregulation of BMP inhibitor gremlin 1.

CONCLUSIONS

We report a novel role of PKA signaling in gastric MEC execution and show that PKA activation in the gastric mesenchyme drives preneoplasia by creating a proinflammatory and proproliferative microenvironment associated with the downregulation of BMP/SMAD signaling and activation of ERK1/2.

Helicobacter pylori infection induces stem cell-like properties in Correa cascade of gastric cancer

Gastric cancer (GC) is the fourth leading cause of cancer-related death. Its poor prognosis is attributed to unclear pathogenesis. Currently, the most widely accepted model for elucidating the mechanism of GC is the Correa cascade, which covers several histological lesions of the gastric mucosa. GC stem cells (CSCs) are crucial for oncogenesis in the Correa cascade and GC progression. As Helicobacter pylori (H. pylori) is the etiological factor in the Correa cascade, growing evidence suggests that enhancement of gastric stem cell-like properties and increase in CSCs correlate with H. pylori infection. In this paper, we review recent studies that present pathogenic mechanisms by which H. pylori induces gastric stem cell-like properties and CSCs, which may supplement the existing Correa model of GC. First, the dysfunction of developmental signaling pathways associated with H. pylori infection leads to the enhancement of gastric stemness. Second, H. pylori infection promotes alteration of the gastric mucosal microenvironment. In addition, epithelial-mesenchymal transition (EMT) may contribute to H. pylori-induced gastric stemness. Taken together, understanding these pathogeneses will provide potential therapeutic targets for the treatment of CSCs and malignant GC in H. pylori induced-Correa cascade of GC.

Protocadherin B9 Is Associated with Tumorigenesis and Cancer Progression in Colorectal Cancer

BACKGROUND

Genes encoding transmembrane proteins expressed specifically in cancer cells may be ideal therapeutic targets or biomarkers for diagnosis.

METHODS

In the present study, we investigated the expression and function of PCDHB9, which encodes transmembrane protein protocadherin B9 in colorectal cancer (CRC).

RESULTS

Immunohistochemical analysis showed that 39 (26%) of 148 CRC cases were positive for protocadherin B9. Expression of protocadherin B9 correlated with lymphatic invasion, venous invasion, and T classification and was weakly detected in adenomas by immunohistochemistry. Although PCDHB9 knockdown did not change cell growth and invasion activity in CRC cell lines, cell adhesion to fibronectin was significantly reduced by PCDHB9 knockdown. Expressions of ITGA3, ITGA4, ITGA5, ITGB1, and ITGB6 were significantly reduced by PCDHB9 knockdown. In addition, the number of spheres was significantly decreased by PCDHB9 knockdown.

CONCLUSION

These results suggest that protocadherin B9 might be associated with colorectal tumorigenesis and cancer progression in CRC.

Overexpression of aldolase, fructose-bisphosphate C and its association with spheroid formation in colorectal cancer

Colorectal cancer (CRC) is a leading cause of cancer-related death worldwide. The spheroid colony formation assay is a useful method to identify cancer stem cells (CSCs). Using the DLD-1 and WiDr CRC cell lines, we performed microarray analyses of spheroid body-forming and parental cells and demonstrated that aldolase, fructose-bisphosphate C (ALDOC) was overexpressed in the spheroid body-forming cells of both lines. Cells transfected with small interfering RNA against ALDOC demonstrated lower proliferation, migration, and invasion compared with negative control cells. Both the number and size of spheres produced by the CRC cells were significantly reduced by ALDOC knockdown. Additionally, inhibition of ALDOC reduced lactate production. Immunohistochemistry was used to analyze ALDOC protein expression in tissues from 135 CRC patients and revealed that 66 (49%) cases were positive for ALDOC. The ALDOC-positive cases were associated with higher T and M grades and, as determined by Kaplan-Meier analysis, a poorer prognosis. Univariate and multivariate analyses indicated that ALDOC expression was an independent prognostic factor for CRC patients. Furthermore, ALDOC expression was associated with CD44 expression. These results suggest that ALDOC contributes to CRC progression and plays an important role in CSCs derived from CRC.

TRIM21 improves apatinib treatment in gastric cancer through suppressing EZH1 stability

Gastric cancer (GC) is a common tumor with high metastatic rate worldwide. Promoting chemosensitivity is effective for improving therapeutic outcome and survival rate for GC patients. Tripartite motif-containing 21 (TRIM21), a member of TRIM-containing proteins, plays crucial roles in regulating numerous cellular events involved in tumor progression. However, it's regulatory effects on GC growth and drug sensitivity are still unclear. In the present study, we identified that TRIM21 expression was remarkably decreased in human GC tissues compared with the adjacent normal ones, and its down-regulation was closely linked to higher recurrence and lower overall survival rate among GC patients. We then found that apatinib (APA)-reduced GC cell proliferation was significantly abolished by TRIM21 knockdown; however, promoting TRIM21 expression further improved the sensitivity of GC cells to APA treatment, as proved by the remarkably decreased cell viability and colony formation. Furthermore, TRIM21 over-expression dramatically enhanced apoptosis, while its knockdown markedly diminished apoptotic cell death in APA-incubated GC cells. Moreover, stem cell properties of GC cells were also restrained by TRIM21. Our in vivo experiments showed that APA-repressed tumor growth was considerably abolished by TRIM21 knockdown, whereas being further elevated by TRIM21 over-expression. In addition, we showed that TRIM21 markedly decreased enhancer of zeste homolog 1 (EZH1) protein expression levels in GC cells, and importantly, a direct interaction between TRIM21 and EZH1 was verified. Of note, our in vitro studies revealed that EZH1 over-expression remarkably abolished the function of TRIM21 to restrain cell viability and induce apoptosis in APA-incubated GC cells, indicating that EZH1 suppression was necessary for TRIM21 to inhibit GC progression. Together, our findings demonstrated that TRIM21 may be a novel therapeutic target for GC treatment through reducing EZH1 to improve chemosensitivity.

MiR-144-3p inhibits gastric cancer progression and stemness via directly targeting GLI2 involved in hedgehog pathway

Background

Gastric cancer (GC) is the fifth most commonly diagnosed cancer worldwide. Due to the dismal prognosis, identifying novel therapeutic targets in GC is urgently needed. Evidences have shown that miRNAs played critical roles in the regulation of tumor initiation and progression. GLI family zinc finger 2 (GLI2) has been reported to be up-regulated and facilitate cancer progression in multiple malignancies. In this study, we focused on identifying GLI2-targeted miRNAs and clarifying the underlying mechanism in GC.

Methods

Paired fresh gastric cancer tissues were collected from gastrectomy patients. GLI2 and miRNAs expression were detected in gastric cancer tissues and cell lines. Bioinformatics analysis was used to predict GLI2-targeted miRNAs and dual-luciferase reporter assay was applied for target verification. CCK-8, clone formation, transwell and flow cytometry were carried out to determine the proliferation, migration, invasion and cell cycle of gastric cancer cells. Tumorsphere formation assay and flow cytometry were performed to detail the stemness of gastric cancer stem cells (GCSCs). Xenograft models in nude mice were established to investigate the role of the miR-144-3p in vivo.

Results

GLI2 was frequently upregulated in GC and indicated a poor survival. Meanwhile, miR-144-3p was downregulated and negatively correlated with GLI2 in GC. GLI2 was a direct target gene of miR-144-3p. MiR-144-3p overexpression inhibited proliferation, migration and invasion of gastric cancer cells. Enhanced miR-144-3p expression inhibited tumorsphere formation and CD44 expression of GCSCs. Restoration of GLI2 expression partly reversed the suppressive effect of miR-144-3p. Xenograft assay showed that miR-144-3p could inhibit the tumorigenesis of GC in vivo.

Conclusions

MiR-144-3p was downregulated and served as an essential tumor suppressor in GC. Mechanistically, miR-144-3p inhibited gastric cancer progression and stemness by, at least in part, regulating GLI2 expression.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-021-03093-w.

hnRNPA2B1 regulates the alternative splicing of BIRC5 to promote gastric cancer progression

Background

Systematic profiling studies have implicated regulators of pre-mRNA splicing as important disease determinants in gastric cancer (GC), but the underlying mechanisms have remained elusive. Here we focused on hnRNPA2B1 splicing factor-dependent mechanisms governing GC development.

Methods

The expression of hnRNPA2B1 was analyzed among the Cancer Genome Atlas (TCGA) datasets of GC and validated at mRNA level. The function of hnRNPA2B1 in GC cells was analyzed and its downstream gene was identified using RNA immunoprecipitation. Further, effect of hnRNPA2B1 on BIRC5 alternative splicing was investigated.

Results

We show that overexpression of hnRNPA2B1 in GC is correlated with poor survival, and hnRNPA2B1 is required for maintaining GC malignant phenotype by promoting cell proliferation, inhibiting cell apoptosis and increasing cell metastasis. Mechanistically, hnRNPA2B1 co-expressed with several core spliceosome components and controls alternative splicing of anti-apoptotic factor BIRC5. BIRC5 isoform 202 (BIRC5-202) played the oncogenic function in GC cells, and overexpression of the BIRC5-202 transcript partly rescued the decrease in cisplatin resistance induced by downregulation of hnRNPA2B1.

Conclusions

We demonstrate that hnRNPA2B1 regulates BIRC5 splicing and might act as a therapeutic target of chemo-resistant GC cells.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-01968-y.

Stem Cells: A Historical Review about Biological, Religious, and Ethical Issues

Stem cells can be used to replace damaged cells or regenerate organs and have broadened our knowledge of the development and progression of certain diseases. Despite significant advances in understanding stem cell biology, several problems limit their use. These problems are related not only to the growth of tumors in animal models and their rejection in transplant cases but also to ethical and social issues about the use of embryonic cells. The ethical-scientific debate on this type of cells has taken on great interest both for their application in regenerative medicine and for the potential possibilities in the field of cell and gene therapy. Different points of view often have the expression of a perception that depends on scientific goals or opportunities or on religious traditions and beliefs. Therefore, as the questions and doubts about when life begins, so do the answers for the use of these cells as therapy or otherwise. So, in addition to the origin of stem cells, there are currently some social bioethical (such as political and legislative issues) and religious dilemmas. The purpose of the study is aimed at being a narrative on the history of stem cells and the evolution of their use to date, as well as to clarify the bioethical position of the various religions today in comparison with the social ones regarding the research and use of embryonic and adult ones. Hence, their biological hypostasis regarding the concepts of “conception” and “fertilization” and their development and therapeutic use compared to those of the main theological doctrines.

Insight Into Chromatin-Enriched RNA: A Key Chromatin Regulator in Tumors

Chromatin-enriched RNAs (cheRNAs) constitute a special class of long noncoding RNAs (lncRNAs) that are enriched around chromatin and function to activate neighboring or distal gene transcription. Recent studies have shown that cheRNAs affect chromatin structure and gene expression by recruiting chromatin modifiers or acting as bridges between distal enhancers and promoters. The abnormal transcription of cheRNAs plays an important role in the occurrence of many diseases, particularly tumors. The critical effect of cancer stem cells (CSCs) on the formation and development of tumors is well known, but the function of cheRNAs in tumorigenesis, especially in CSC proliferation and stemness maintenance, is not yet fully understood. This review focuses on the mechanisms of cheRNAs in epigenetic regulation and chromatin conformation and discusses the way cheRNAs function in CSCs to deepen the understanding of tumorigenesis and provide novel insight to advance tumor-targeting therapy.

KIFC1 regulates ZWINT to promote tumor progression and spheroid formation in colorectal cancer

Colorectal cancer (CRC) is the second leading cause of cancer-related mortality worldwide. Kinesin Family Member C1 (KIFC1) has been proposed as a promising therapeutic target due to its pivotal role in centrosome clustering to mediate cancer cell progression. This study aimed to analyze the expression and biological function of KIFC1 in CRC. Immunohistochemically, 67 (52%) of 129 CRC cases were positive for KIFC1 and statistically associated with poorer overall survival. KIFC1 small interfering RNA (siRNA)-transfected cells demonstrated lower cell proliferation as compared to the negative control cells. A specific KIFC1 inhibitor, kolavenic acid analog (KAA) drastically inhibited CRC cell proliferation. Microarray analysis revealed that KAA-treated CRC cells presented reduced ZW10 interacting kinetochore protein (ZWINT) expression as compared to control cells. Immunohistochemical analysis demonstrated that 61 (47%) of 129 CRC cases were positive for ZWINT and ZWINT expression was significantly correlated with KIFC1 expression. ZWINT-positive cases exhibited significantly worse overall survival. KIFC1 siRNA-transfected cells showed reduced ZWINT expression while ZWINT siRNA-transfected cells decreased cell proliferation. Both KIFC1 and ZWINT knockdown cells attenuated spheroid formation ability. This study provides new insights into KIFC1 regulating ZWINT in CRC progression and its potential as a therapeutic target.

Clinical crosstalk between microRNAs and gastric cancer (Review)

Globally, there were over 1 million new gastric cancer (GC) patients in 2018 and GC has become the sixth most common cancer worldwide. GC caused 783,000 deaths worldwide in 2018, making it the third most deadly cancer type. miRNAs are short (~22 nucleotides in length) non‑coding RNA molecules, which can regulate gene expression passively at a post‑transcriptional level. There are more and more in‑depth studies on miRNAs. There are numerous conclusive evidences that there is an inseparable link between miRNAs and GC. miRNAs can affect the entire process of GC, including the oncogenesis, development, diagnosis, treatment and prognosis of GC. Although many miRNAs have been linked to GC, few can be applied to clinical practice. This review takes the clinical changes of GC as a clue and summarizes the miRNAs related to GC that have confirmed the mechanism of action in the past three years. Through in‑depth study and understanding of the mechanism of those miRNAs, we predict their possible clinical uses, and suggest some new insights to overcome GC.

The Expression Analysis of Intestinal Cancer Stem Cell Marker Lgr5 in Colorectal Cancer Patients and the Correlation with Histopathological Markers

INTRODUCTION

Cancer stem cells (CSCs) have frequently been utilized in the cell characterization and identified responsible for tumor development, metastasis, recurrence, and chemoresistance. CSC surface markers function in cancer cell signaling and are indicated as potential biomarkers for cancer diagnosis and prognosis. As well, dysregulation of cancer-related signaling pathways could promote CSC development and progression. Our aim was to evaluate the expression of colorectal CSC markers and their correlation with cancer proliferation and angiogenesis.

METHODS

In this case-control study, total RNA was extracted from a total of 74 colorectal tumors and 74 adjacent normal tissue biopsies. Then, using a quantitative real-time PCR, the relative expression levels of Lgr5 and Lrig1 were measured in all malignant and healthy samples. Also, immunohistochemical (IHC) staining of tumor tissues was performed for Ki-67 (proliferation) and CD34 (angiogenesis) markers, and the immunoexpression staining scores were obtained. The diagnostic value of the genes was evaluated using receiver operating characteristic (ROC) curve. Possible correlation between CSC markers and immunohistochemical markers in CRC was analyzed by Pearson's correlation test and linear regression.

RESULTS

The expression level of Lgr5 in tumor samples showed a significant increase compared with normal samples (p < 0.001) with a fold change of 2.54 (± 0.182). However, there was no significant difference in the relative expression of Lrig1 gene in tissue samples of healthy subjects and patients. The analysis of the ROC showed an AUC of 0.92 for Lgr5 and sensitivity 80% and specificity 96%. Further analysis revealed a significant correlation between mRNA levels of Lgr5 and immunoexpression of Ki-67 (r² = 0.680, p < 0.001).

CONCLUSION

The high expression levels of Lgr5 found in tumor tissues were correlated with histological parameters, indicating a significant role in CRC development and diagnosis.

Molecular Therapeutics of Pancreatic Ductal Adenocarcinoma: Targeted Pathways and the Role of Cancer Stem Cells

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers in humans due to late detection and highly metastatic characteristics. PDAC cells vary in their tumorigenic capabilities with the presence of a subset of PDAC cells known as pancreatic cancer stem cells (CSCs), which are more resistant to currently used therapeutics. Here, we describe the role of CSCs and tumour stroma in developing therapeutic strategies for PDAC and suggest that developmental plasticity could be considered a hallmark of cancers. We provide an overview of the molecular targets in PDAC treatments, including targeted therapies of cellular processes such as proliferation, evasion of growth suppressors, activating metastasis, and metabolic effects. Since PDAC is an inflammation-driven cancer, we also revisit therapeutic strategies targeting inflammation and immunotherapy. Lastly, we suggest that targeting epigenetic mechanisms opens therapeutic routes for heterogeneous cancer cell populations, including CSCs.

Identification of key genes controlling cancer stem cell characteristics in gastric cancer

BACKGROUND

Self-renewal of gastric cancer stem cells (GCSCs) is considered to be the underlying cause of the metastasis, drug resistance, and recurrence of gastric cancer (GC).

AIM

To characterize the expression of stem cell-related genes in GC.

METHODS

RNA sequencing results and clinical data for gastric adenoma and adenocarcinoma samples were obtained from The Cancer Genome Atlas database, and the results of the GC mRNA expression-based stemness index (mRNAsi) were analyzed. Weighted gene coexpression network analysis was then used to find modules of interest and their key genes. Survival analysis of key genes was performed using the online tool Kaplan-Meier Plotter, and the online database Oncomine was used to assess the expression of key genes in GC.

RESULTS

mRNAsi was significantly upregulated in GC tissues compared to normal gastric tissues (P < 0.0001). A total of 16 modules were obtained from the gene coexpression network; the brown module was most positively correlated with mRNAsi. Sixteen key genes (BUB1, BUB1B, NCAPH, KIF14, RACGAP1, RAD54L, TPX2, KIF15, KIF18B, CENPF, TTK, KIF4A, SGOL2, PLK4, XRCC2, and C1orf112) were identified in the brown module. The functional and pathway enrichment analyses showed that the key genes were significantly enriched in the spindle cellular component, the sister chromatid segregation biological process, the motor activity molecular function, and the cell cycle and homologous recombination pathways. Survival analysis and Oncomine analysis revealed that the prognosis of patients with GC and the expression of three genes (RAD54L, TPX2, and XRCC2) were consistently related.

CONCLUSION

Sixteen key genes are primarily associated with stem cell self-renewal and cell proliferation characteristics. RAD54L, TPX2, and XRCC2 are the most likely therapeutic targets for inhibiting the stemness characteristics of GC cells.

Enolase 1 regulates stem cell-like properties in gastric cancer cells by stimulating glycolysis

Recent studies have demonstrated that gastric cancer stem cells (CSCs) are a rare sub-group of gastric cancer (GC) cells and have an important role in promoting the tumor growth and progression of GC. In the present study, we demonstrated that the glycolytic enzyme Enolase 1 (ENO1) was involved in the regulation of the stem cell-like characteristics of GC cells, as compared to the parental cell lines PAMC-82 and SNU16, the expression of ENO1 in spheroids markedly increased. We then observed that ENO1 could enhance stem cell-like characteristics, including self-renewal capacity, cell invasion and migration, chemoresistance, and even the tumorigenicity of GC cells. ENO1 is known as an enzyme that is involved in glycolysis, but our results showed that ENO1 could markedly promote the glycolytic activity of cells. Furthermore, inhibiting glycolysis activity using 2-deoxy-D-glucose treatment significantly reduced the stemness of GC cells. Therefore, ENO1 could improve the stemness of CSCs by enhancing the cells' glycolysis. Subsequently, to further confirm our results, we found that the inhibition of ENO1 using AP-III-a4 (ENOblock) could reduce the stemness of GC cells to a similar extent as the knockdown of ENO1 by shRNA. Finally, increased expression of ENO1 was related to poor prognosis in GC patients. Taken together, our results demonstrated that ENO1 is a significant biomarker associated with the stemness of GC cells.

S100P is a molecular determinant of E-cadherin function in gastric cancer

Background

E-cadherin has been awarded a key role in the aetiology of both sporadic and hereditary forms of gastric cancer. In this study, we aimed to identify molecular interactors that influence the expression and function of E-cadherin associated to cancer.

Methods

A data mining approach was used to predict stomach-specific candidate genes, uncovering S100P as a key candidate. The role of S100P was evaluated through in vitro functional assays and its expression was studied in a gastric cancer tissue microarray (TMA).

Results

S100P was found to contribute to a cancer pathway dependent on the context of E-cadherin function. In particular, we demonstrated that S100P acts as an E-cadherin positive regulator in a wild-type E-cadherin context, and its inhibition results in decreased E-cadherin expression and function. In contrast, S100P is likely to be a pro-survival factor in gastric cancer cells with loss of functional E-cadherin, contributing to an oncogenic molecular program. Moreover, expression analysis in a gastric cancer TMA revealed that S100P expression impacts negatively among patients bearing Ecad⁻ tumours, despite not being significantly associated with overall survival on its own.

Conclusions

We propose that S100P has a dual role in gastric cancer, acting as an oncogenic factor in the context of E-cadherin loss and as a tumour suppressor in a functional E-cadherin setting. The discovery of antagonist effects of S100P in different E-cadherin contexts will aid in the stratification of gastric cancer patients who may benefit from S100P-targeted therapies.

Graphical abstract

DNA-methylation-mediated silencing of miR-7-5p promotes gastric cancer stem cell invasion via increasing Smo and Hes1

Cancer stem cells are undifferentiated cancer cells that have self-renewal ability, a high tumorigenic activity, and a multilineage differentiation potential. MicroRNAs play a critical role in regulating gene expression during carcinogenesis. Here, we investigated the role of miR-7 and the mechanism by which it is dysregulated in gastric cancer stem cells (GCSCs). The stem cell marker, CD44, was used to sort GCSCs by fluorescence-activated cell sorting. We found that CD44 (+) cells have higher invasiveness and form more number of sphere colonies than CD44 (-) cells. Quantitative real-time polymerase chain reaction (PCR) revealed that the miR-7-5p expression was remarkably downregulated in GCSCs but was significantly increased in the methionine-deprived medium. The downregulation of miR-7-5p results from the increased DNA methylation in the promoter region using the methylation-specific PCR. Overexpression of miR-7-5p reduced the formation of colony and decreased the invasion of GCSCs through targeting Smo and Hes1 and subsequent repressing Notch and Hedgehog signaling pathways in vitro. Notably, upregulating miR-7-5p inhibited the growth of tumor in the xenograft model. Hence, these data demonstrated that miR-7-5p represses GCSC invasion through inhibition of Smo and Hes1, which provides a potential therapeutic target of gastric cancer treatment.

Chemoprevention of gastric cancer by Helicobacter pylori eradication and its underlying mechanism

The cascade of gastric cancer, a leading cause of cancer incidence and mortality, is multifactorial. Helicobacter pylori (HP) infection plays a major role in gastric cancer (GC), and there has been an accumulation of data regarding the chemopreventive effect of HP eradication. However, it remains unclear how HP infection causes GC and how HP eradication prevents GC. To clarify this issue, the following approaches were performed in this review article. First, how HP-induced atrophic gastritis (AG) and intestinal metaplasia (IM) provoke the development of GC is shown, followed by how long HP eradication takes to induce a reversible change in AG and IM. Second, epigenetic studies of PTPN6, MOS, DCC, CRK, and VAV1 were performed in noncancerous gastric specimens in terms of HP status. Among these genes, MOS was found to be a possible surrogate marker for GC development. HP eradication decreased aberrant DNA methylation in a gene-specific manner, and MOS played a role in metachronous gastric neoplasms. Third, transforming growth factor-β1 (TGF-β1) and TGF-β1-induced epithelial-mesenchymal transition (EMT) markers were investigated in gastric mucosa. HP infection triggered the TGF-β1-induced EMT pathway and caused the emergence of GC stem cells, such as CD44v8-10. When HP was eradicated, these two pathways were inhibited. Finally, a 2222 cohort study showed that HP eradication significantly decreased the risk of noncardiac GC. Taken together, HP eradication is effective as a primary GC prevention method, and its underlying mechanism includes reversibility of AG and IM, methylation, EMT, and stem cells.

Expression of cancer stem cell markers is prognostic in metastatic gastroesophageal adenocarcinoma

Gastroesophageal adenocarcinoma is a common and highly lethal malignancy. Cancer stem cells (CSCs) have a key role in the development and progression of metastatic disease. While expression of CSC markers CD44, CD133 and aldehyde dehydrogenase 1 (ALDH1) in locoregional gastroesophageal cancer is known to be associated with poorer clinical outcomes, the significance of CSC marker expression in distal metastatic disease is unknown. We investigated the clinicopathological and prognostic associations of the CSC markers, CD44, CD133, and ALDH1, on metastatic deposits from gastroesophageal adenocarcinomas, and evaluated the association of CSC expression with urokinase-type plasminogen activator receptor (uPAR) expression. Of the 36 patients included in the study, 16 (44%) were positive for CD44, 13 (36%) were positive for CD133, and 26 (72%) were positive for ALDH1. CD44 expression was significantly associated with poorer overall survival (OS) in univariate [hazard ratio (HR) 2.9, 95% confidence interval (CI) 1.3-6.9, p=0.008] and multivariate analyses (HR 2.5, 95%CI 1.1-6.2, p=0.04). ALDH1 expression was significantly associated with poorer OS in univariate (HR 2.4, 95% CI 1.01-5.7, p=0.04) analysis but was not significant in multivariate analysis. Both CD44 and ALDH1 expression were significantly associated with uPAR expression. We found no association between CD133 expression and OS. CD44 expression on metastatic disease from gastroesophageal adenocarcinomas is an independent prognostic marker associated with poorer OS. These results expand current evidence to support the role of CSCs as biomarkers in metastatic gastroesophageal cancer.

Molecular carcinogenesis of gastric cancer: Lauren classification, mucin phenotype expression, and cancer stem cells

Gastric cancer (GC), one of the most common human cancers, is a heterogeneous disease with different phenotypes, prognoses, and responses to treatment. Understanding the pathogenesis of GC at the molecular level is important for prognosis prediction and determining treatments. Microsatellite instability (MSI), silencing of MLH1, MGMT, and CDKN2A genes by DNA hypermethylation, KRAS mutation, APC mutation, and ERBB2 amplification are frequently found in intestinal type GC. Inactivation of CDH1 and RARB by DNA hypermethylation, and amplification of FGFR and MET, are frequently detected in diffuse type GC. In addition, BST2 and PCDHB9 genes are overexpressed in intestinal type GC. Both genes are associated with GC progression. GC can be divided into gastric/intestinal mucin phenotypes according to mucin expression. MSI, alterations of TP73, CDH1 mutation, and DNA methylation of MLH are detected frequently in the gastric mucin phenotype. TP53 mutation, deletion of APC, and DNA methylation of MGMT are detected frequently in the intestinal mucin phenotype. FKTN is overexpressed in the intestinal mucin phenotype, and IQGAP3 is overexpressed in the gastric mucin phenotype. These genes are involved in GC progression. To characterize cancer stem cells, a useful method is spheroid colony formation. KIFC1 and KIF11 genes show more than twofold higher expression in spheroid-forming cells than that in parental cells. Both KIF genes are overexpressed in GC, and knockdown of these genes inhibits spheroid formation. Alterations of these molecules may be useful to understand gastric carcinogenesis. Specific inhibitors of these molecules may also be promising anticancer drugs.

Gastric Cancer Stem Cells Effect on Th17/Treg Balance; A Bench to Beside Perspective

Gastric cancer stem cells (GCSCs), a small population among tumor cells, are responsible for tumor initiation, development, metastasis, and recurrence. They play a crucial role in immune evasion, immunomodulation, and impairment of effector immunity and believed to be emerged to change the balance of the immune system, importantly CD4+ T cells in the chronic inflamed tumor site. However, different subtypes of innate and adaptive immune cells are involved in the formation of the immune system in the tumor microenvironment, we would look at T cells in this study. Tumor microenvironment induces differentiation of CD4+ T cells into different subsets of T cells, mainly suppressive regulatory T cells (Treg), and T helper 17 (Th17) cells, although their exact role in tumor immunity is still under debate depending on tumor types and stages. Counterbalance between Th17 and Treg cells in the gastrointestinal system result in the homeostasis and normal function of the immune system, particularly mucosal immunity. Recent data demonstrated a high infiltration of Th17 and Treg cells into the gastric tumor site and proved that tumor microenvironment might disturb the balance between Th17 and Treg. It is possible to assume an association between activation of CSCs which contribute to metastasis in late stages, and the imbalanced Th17/Treg cells observed in advanced gastric cancer patients. This review intends to clarify the importance of gastric tumor microenvironment specifically CSCs in relation to Th17/Tregs balance firstly and to highlight the relevance of imbalanced Th17/Treg subsets in determining the stages and behavior of the tumor secondly. Finally, the present study suggests a clinical approach looking at the plasticity of T cells with a focus on Th17 as a promising dedicated arm in cancer immunotherapy.

Hyaluronan-mediated motility receptor confers resistance to chemotherapy via TGFβ/Smad2-induced epithelial-mesenchymal transition in gastric cancer

Chemotherapy is one of the vital treatments for gastric cancer (GC) patients, especially those suffering advanced stages. Chemoresistance results in tumor relapse, leading to poor prognosis in GC patients; thus, identifying key regulators in this process might provide novel clues for GC therapy. Herein, we identify hyaluronan-mediated motility receptor (HMMR) as a key regulator of chemoresistance in GC. HMMR was found to be substantially up-regulated in 5-fluorouracil (5-Fu)-resistant GC biopsies and cell lines. High expression of HMMR significantly correlates with tumor relapse and predicts poorer prognosis in GC patients. Moreover, we observed that HMMR induced epithelial-mesenchymal transition and increased the cancer stem cell properties of GC, thus rendering resistance to chemotherapy. Importantly, silencing of HMMR effectively increased the susceptibility to 5-Fu therapy both in vitro and in vivo. Furthermore, we demonstrated that HMMR activates the TGF-β/Smad2 signaling pathway, which was required for the HMMR-mediated oncogenic effects and exhibited significant clinical relevance with HMMR expression. These findings reveal a critical role for HMMR in the chemoresistance of GC and suggest that HMMR might be a potential prognostic marker or therapeutic target against the disease.-Zhang, H., Ren, L., Ding, Y., Li, F., Chen, X., Ouyang, Y., Zhang, Y., Zhang, D. Hyaluronan-mediated motility receptor confers resistance to chemotherapy via TGFβ/Smad2-induced epithelial-mesenchymal transition in gastric cancer.

Obesity and the Risk of Gastrointestinal Cancers

Obesity is a risk factor for all major gastrointestinal cancers. With the rapid increase in the prevalence of obesity worldwide, this link could lead to an elevated burden of cancers of the digestive system. Currently, three main mechanisms explaining the link between excess adiposity and gastrointestinal cancer risk are being considered, including altered insulin signaling, obesity-associated chronic low-grade inflammation, and altered sex hormone metabolism, although new potential mechanisms emerge. This review is aimed to present our current knowledge on biological mechanisms involved in adiposity-related gastrointestinal carcinogenesis supported by results collected in epidemiological studies.

DEAD-box helicase 27 plays a tumor-promoter role by regulating the stem cell-like activity of human colorectal cancer cells

Background

Cancer stem cells (CSCs) are responsible for all important characteristics of tumors. DEAD-box helicase 27 (DDX27) is a member of the DEAD-box RNA helicase family, and there have been only a few studies on DDX27 function in cancer cells. This study is aimed at exploring whether DDX27 has any relation to tumorigenesis of colorectal cancer (CRC) and elucidating the potential mechanism.

Methods

Data from Catalog Of Somatic Mutations In Cancer, Gene Expression Omnibus, and The Cancer Genome Atlas databases reveal that DDX27 is overexpressed in CRC tissues. qRT-PCR and Western blots were used to evaluate the expression level of DDX27 in 40 paired clinical CRC samples. DDX27 was knockdown in HT29 and HCT116 cell line with shRNA. Then CCK-8, colony formation assay and flow cytometry assay were performed to examine proliferative ability, cell cycle and sensitivity to 5-fluorouracil. Sphere-formation assay and in vivo subcutaneous tumor-formation assay were used to assess self-renewal in vitro and vivo as well as the tumor-initiating potential.

Results

DDX27 is upregulated in CRC tissues and downregulation of DDX27 inhibits proliferation of colorectal cancer cell and promotes sensitivity to 5-fluorouracil. Downregulation of DDX27 can downregulate the gene expression of known CSC markers in CRC cells, inhibit sphere-formation ability, and promote colonosphere differentiation. Downregulation of DDX27 in CSCs can decrease the tumor-initiating ability of CRC cells in vivo.

Conclusion

DDX27 may play a tumorpromoter role of CRC by regulating the stem cell-like activity of CRC cells.

Targeted eradication of gastric cancer stem cells by CD44 targeting USP22 small interfering RNA-loaded nanoliposomes

AIM

USP22, a member of ubiquitin-specific proteases (USPs), is a well-defined protein that promotes poor prognosis, invasion and metastasis, and also participates in the maintenance of cancer stem cells. USP22 siRNA-loaded nanoliposomes conjugated with CD44 antibodies (USP22-NLs-CD44) were constructed to enhance the therapeutic effect of USP22 siRNA against gastric cancer stem cells.

MATERIALS & METHODS

The targeting and therapeutic efficacies of USP22-NLs-CD44 against gastric cancer stem cells were evaluated.

RESULTS & CONCLUSION

USP22-NLs-CD44 was demonstrated to be able to effectively deliver USP22 siRNA to CD44⁺ gastric cancer stem cells, achieving superior therapeutic effects against CD44⁺ gastric cancer stem cells than nontargeted nanoliposomes. USP22-NLs-CD44 may provide a novel approach to eradicate gastric cancer stem cells in the near future.

Energy balance and gastrointestinal cancer: risk, interventions, outcomes and mechanisms

Obesity increases the risk of multiple gastrointestinal cancers and worsens disease outcomes. Conversely, strong inverse associations have emerged between physical activity and colon cancer and possibly other gastrointestinal malignancies. The effect of weight loss interventions - such as modifications of diet and/or physical activity or bariatric surgery - remains unclear in patients who are obese and have gastrointestinal cancer, although large clinical trials are underway. Human intervention studies have already shed light on potential mechanisms underlying the energy balance-cancer relationship, with preclinical models supporting emerging pathway effects. Central to interventions that reduce obesity or increase physical activity are pluripotent cancer-preventive effects (including reduced systemic and adipose tissue inflammation and angiogenesis, altered adipokine levels and improved insulin resistance) that directly interface with the hallmarks of cancer. Other mechanisms, such as DNA repair, oxidative stress and telomere length, immune function, effects on cancer stem cells and the microbiome, could also contribute to energy balance effects on gastrointestinal cancers. Although some mechanisms are well understood (for instance, systemic effects on inflammation and insulin signalling), other areas remain unclear. The current state of knowledge supports the need to better integrate mechanistic approaches with preclinical and human studies to develop effective, personalized diet and exercise interventions to reduce the burden of obesity on gastrointestinal cancer.

NANOGP8 expression regulates gastric cancer cell progression by transactivating DBC1 in gastric cancer MKN-45 cells

NANOGP8 is one of the NANOG pseudogenes and is expressed together with NANOG in multiple tumor tissues and cell lines. The biological functions of NANOGP8 in progression of gastric cancer are unclear. In the present study, the role of NANOGP8 was investigated in gastric cancer cells. The gathered data demonstrated that NANOG expression in both mRNA and protein was elevated in gastric cancer cell lines relative to a normal gastric epithelial cell line. Downregulation of NANOGP8 inhibited cell proliferation and increased apoptosis in human gastric carcinoma cell lines. Furthermore, silencing of NANOGP8 suppressed tumor growth in vivo. Interestingly, it was identified that deleted in breast cancer 1 (DBC1) expression was also markedly downregulated following NANOGP8 knockdown. DNA microarray and dual-luciferase assays further indicated that NANOGP8 may bind to the DBC1 promoter region and regulate DBC1 expression. Therefore, the gathered data provided evidence that NANOGP8 contributes to progression of gastric cancer via DBC1 and may have potential translational significance.

SATB1 siRNA-encapsulated immunoliposomes conjugated with CD44 antibodies target and eliminate gastric cancer-initiating cells

Purpose

Gastric cancer, the cancer initiated from the stomach, is ranked as the third most frequent reason of cancer death worldwide. Gastric cancer-initiating cells (CICs) are one of the crucial causes for the metastasis and recurrence of gastric cancer, and CD44 is considered to be one marker for gastric CICs. Special AT-rich sequence binding protein 1 (SATB1) is a protein that promotes cancer progression, metastasis, and invasion and also participates in the maintenance of CICs. In this study, we investigated the therapeutic effect of SATB1 siRNA against gastric CICs and we constructed SATB1 siRNA-encapsulated immunoliposomes conjugated with CD44 antibodies (CD44-SATB1-ILs) to enhance the therapeutic effect of SATB1 siRNA against gastric CICs.

Methods

We investigated the therapeutic effect of the SATB1 suppression by SATB1 siRNA on CD44⁺ gastric CICs. CD44-SATB1-ILs were developed by the lyophilization/hydration approach. The targeting and cytotoxic effect of CD44-SATB1-ILs toward gastric CICs were evaluated in vitro.

Results

In this study, for the first time, we confirmed that SATB1 suppression by SATB1 siRNA preferentially eliminated CD44⁺ gastric CICs. The results showed that CD44-SATB1-ILs could efficiently and specifically promote the SATB1 siRNA delivery to CD44⁺ gastric CICs, achieving superior therapeutic effects against CD44⁺ gastric CICs than non-targeted liposomes.

Conclusion

As far as we know, our report is the first research that indicated the promotion of siRNA delivery via nanoparticles to gastric CICs and achievement of superior therapeutic effect against gastric CICs by utilization of CD44 antibody. Therefore, CD44-SATB1-ILs represent an up-and-coming approach for eliminating gastric CICs and also a promising treatment for therapy of gastric cancer.

Clinicopathological significance of claspin overexpression and its association with spheroid formation in gastric cancer

Gastric cancer (GC) is one of the leading causes of cancer-related death worldwide. Spheroid colony formation is a useful method to identify cancer stem cells (CSCs). The aim of this study was to identify a novel prognostic marker or therapeutic target for GC using a method to identify CSCs. We analyzed the microarray data in spheroid body-forming and parental cells and focused on the CLSPN gene because it is overexpressed in the spheroid body-forming cells in both the GC cell lines MKN-45 and MKN-74. Quantitative reverse-transcription polymerase chain reaction analysis revealed that CLSPN messenger RNA expression was up-regulated in GC cell lines MKN-45, MKN-74, and TMK-1. Immunohistochemistry of claspin showed that 94 (47%) of 203 GC cases were positive. Claspin-positive GC cases were associated with higher T and N grades, tumor stage, lymphatic invasion, and poor prognosis. In addition, claspin expression was coexpressed with CD44, human epidermal growth factor receptor type 2, and p53. CLSPN small interfering RNA treatment decreased GC cell proliferation and invasion. These results indicate that the expression of claspin might be a key regulator in the progression of GC and might play an important role in CSCs of GC.