Impact of Cancer Stem Cells on Therapy Resistance in Gastric Cancer

Glioblastoma therapy: State of the field and future prospects

Glioblastoma (GB) is a cancerous brain tumor that originates from glial cells and leads to thousands of deaths each year and a five-year survival of only 6.8 %. Treatments for GB include surgery, chemotherapy, radiation, and immunotherapy. GB is an incurable fatal disease, necessitating the development of innovative strategies to find a developing effective therapy. Genetic therapies may be crucial in treating GB by identifying the mutations and amplifications of multiple genes, which drive its proliferation and spread. Use of small interfering RNAs (siRNAs) provides a novel technology used to suppress the genes associated with disease, which forms a basis for targeted therapy in GB and its stem cell population, which are recognized for their ability to develop resistance to chemotherapy and tumorigenic capabilities. This review examines the use of siRNAs in GB, emphasizing their effectiveness in suppressing key oncogenes and signaling pathways associated with tumor development, invasion, stemness, and resistance to standard treatments. siRNA-based gene silencing is a promising approach for developing targeted therapeutics against GB and associated stem cell populations, potentially enhancing patient outcomes and survival rates in this devastating disease.

Single-cell sequencing analysis revealed that WDR72 was a novel cancer stem cells related gene in gastric cancer

Background

Cancer stem cells (CSCs) are pivotal in tumor resistance to chemotherapy and gastric cancer's rapid proliferation and metastasis. We aimed to explore the CSCs-related genes in gastric cancer epithelial cells.

Methods

The mRNA expression profile and single-cell sequencing data of gastric cancer were downloaded from the public database.

Results

We identified WDR72 as a CSCs-related gene in gastric cancer epithelial cells. WDR72 was highly expressed in gastric cancer tissues, and high expression of WDR72 was associated with inferior prognosis of patients. WDR72 expression had a significant negative correlation with the infiltration of CD8 + T cells and activated memory CD4 + T cells. PD-L1 expression was significantly reduced in gastric cancer patients with high WDR72 expression. WDR72 was correlated with IC50 of multiple small-molecule drugs.

Conclusion

We identified a novel CSCs-related gene in gastric cancer epithelial cells, WDR72, which was highly expressed in patients with high stemness scores.

Identification of a novel gene signature related to prognosis and metastasis in gastric cancer

BACKGROUND

Gastric Cancer (GC) presents poor outcome, which is consequence of the high incidence of recurrence and metastasis at early stages. GC patients presenting recurrent or metastatic disease display a median life expectancy of only 8 months. The mechanisms underlying GC progression remain poorly understood.

METHODS

We took advantage of public available GC datasets from TCGA using GEPIA, and identified the matched genes among the 100 genes most significantly associated with overall survival (OS) and disease free survival (DFS). Results were confirmed in ACRG cohort and in over 2000 GC cases obtained from several cohorts integrated using our own analysis pipeline. The Kaplan-Meier method and multivariate Cox regression analyses were used for prognostic significance and linear modelling and correlation analyses for association with clinic-pathological parameters and biological hallmarks. In vitro and in vivo functional studies were performed in GC cells with candidate genes and the related molecular pathways were studied by RNA sequencing.

RESULTS

High expression of ANKRD6, ITIH3, SORCS3, NPY1R and CCDC178 individually and as a signature was associated with poor prognosis and recurrent disease in GC. Moreover, the expression of ANKRD6 and ITIH3 was significantly higher in metastasis and their levels associated to Epithelial to Mesenchymal Transition (EMT) and stemness markers. In line with this, RNAseq analysis revealed genes involved in EMT differentially expressed in ANKRD6 silencing cells. Finally, ANKRD6 silencing in GC metastatic cells showed impairment in GC tumorigenic and metastatic traits in vitro and in vivo.

CONCLUSIONS

Our study identified a novel signature involved in GC malignancy and prognosis, and revealed a novel pro-metastatic role of ANKRD6 in GC.

Investigating the mechanism and the effect of aquaporin 5 (AQP5) on the self-renewal capacity of gastric cancer stem cells

Aquaporin 5 (AQP5) has been shown to have a pro-carcinogenic effect in numerous types of malignancies. This research intends to investigate the role and the molecular mechanism of AQP5 on enriched gastric cancer stem cells (GCSCs). Methods: Immunohistochemistry, western blot (WB), and RT-qPCR techniques were employed to identify the presence of AQP5 in gastric cancer (GC) and the neighboring paracancerous tissues. Additionally, a statistical analysis was conducted to determine the correlation between AQP5 expression and the pathological and histological parameters. Furthermore, the study aimed to assess the predictive value of AQP5 expression in long-term survival after GC surgery. GCSCs were enriched using the serum-free culture method. The expression of AQP5 in enriched GCSCs was explored using RT-qPCR and WB. Plate cloning, transwell, WB, RT-qPCR, and the sphere-forming assay were utilized to monitor the proliferation, migration, and self-renewal capability of GCSCs after AQP5 knockdown. WB and Immunofluorescence for Detecting the Effect of AQP5 on Autophagy. WB, RT-qPCR, and other experiments were used for in-depth investigation of the potential molecular regulatory mechanism of AQP5 in GC. Results: AQP5 was highly expressed in GC tissues and GC cells, and overexpression of AQP5 was associated with lymph node metastasis, increased tumor size, and low 5-year postoperative survival in GC patients; other studies have shown that the AQP5 was highly expressed in GCSCs. Knockdown of AQP5 suppressed tumorigenesis in vivo and inhibited the proliferative, migratory, and self-renewal capability of GCSCs. It was also found that AQP5 could activate the autophagy phenomenon of GCSCs, and mechanistically, we found that AQP5 could regulate TRPV4 to affect the self-renewal ability of GCSCs. Conclusion: AQP5 can be further explored for GC therapy, as it has shown a significant impact on the self-renewal capability of GCSCs, which prevents GC progression.

Machine learning for identifying tumor stemness genes and developing prognostic model in gastric cancer

Gastric cancer presents a formidable challenge, marked by its debilitating nature and often dire prognosis. Emerging evidence underscores the pivotal role of tumor stem cells in exacerbating treatment resistance and fueling disease recurrence in gastric cancer. Thus, the identification of genes contributing to tumor stemness assumes paramount importance. Employing a comprehensive approach encompassing ssGSEA, WGCNA, and various machine learning algorithms, this study endeavors to delineate tumor stemness key genes (TSKGs). Subsequently, these genes were harnessed to construct a prognostic model, termed the Tumor Stemness Risk Genes Prognostic Model (TSRGPM). Through PCA, Cox regression analysis and ROC curve analysis, the efficacy of Tumor Stemness Risk Scores (TSRS) in stratifying patient risk profiles was underscored, affirming its ability as an independent prognostic indicator. Notably, the TSRS exhibited a significant correlation with lymph node metastasis in gastric cancer. Furthermore, leveraging algorithms such as CIBERSORT to dissect immune infiltration patterns revealed a notable association between TSRS and monocytes and other cell. Subsequent scrutiny of tumor stemness risk genes (TSRGs) culminated in the identification of CDC25A for detailed investigation. Bioinformatics analyses unveil CDC25A's implication in driving the malignant phenotype of tumors, with a discernible impact on cell proliferation and DNA replication in gastric cancer. Noteworthy validation through in vitro experiments corroborated the bioinformatics findings, elucidating the pivotal role of CDC25A expression in modulating tumor stemness in gastric cancer. In summation, the established and validated TSRGPM holds promise in prognostication and delineation of potential therapeutic targets, thus heralding a pivotal stride towards personalized management of this malignancy.

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.

Targeting Hippo pathway: A novel strategy for Helicobacter pylori-induced gastric cancer treatment

The Hippo pathway plays an important role in cell proliferation, apoptosis, and differentiation; it is a crucial regulatory pathway in organ development and tumor growth. Infection with Helicobacter pylori (H. pylori) increases the risk of developing gastric cancer. In recent years, significant progress has been made in understanding the mechanisms by which H. pylori infection promotes the development and progression of gastric cancer via the Hippo pathway. Exploring the Hippo pathway molecules may yield new diagnostic and therapeutic targets for H. pylori-induced gastric cancer. The current article reviews the composition and regulatory mechanism of the Hippo pathway, as well as the research progress of the Hippo pathway in the occurrence and development of H. pylori-related gastric cancer, in order to provide a broader perspective for the study and prevention of gastric cancer.

BEX2 is poor prognostic factor and required for cancer stemness in gastric cancer

Gastric cancer is the fifth most common malignancy worldwide. However, targeted therapy for advanced gastric cancer is still limited. Here, we report BEX2 (Brain expressed X-linked 2) as a poor prognostic factor in two gastric cancer cohorts. BEX2 expression was increased in spheroid cells, and its knockdown decreased aldefluor activity and cisplatin resistance. BEX2 was found to upregulate CHRNB2 (Cholinergic Receptor Nicotinic Beta 2 Subunit) expression, a cancer stemness-related gene, in a transcriptional manner, and the knockdown of which also decreases aldefluor activity. Collectively, these data are suggestive of the role of BEX2 in the malignant process of gastric cancer, and as a promising therapeutic target.

Antitumoral Activity of Leptocarpha rivularis Flower Extracts against Gastric Cancer Cells

Leptocarpha rivularis is a native South American plant used ancestrally by Mapuche people to treat gastrointestinal ailments. L. rivularis flower extracts are rich in molecules with therapeutic potential, including the sesquiterpene lactone leptocarpin, which displays cytotoxic effects against various cancer types in vitro. However, the combination of active molecules in these extracts could offer a hitherto unexplored potential for targeting cancer. In this study, we investigated the effect of L. rivularis flower extracts on the proliferation, survival, and spread parameters of gastric cancer cells in vitro. Gastric cancer (AGS and MKN-45) and normal immortalized (GES-1) cell lines were treated with different concentrations of L. rivularis flower extracts (DCM, Hex, EtOAc, and EtOH) and we determined the changes in proliferation (MTS assay, cell cycle analysis), cell viability/cytotoxicity (trypan blue exclusion assay, DEVDase activity, mitochondrial membrane potential MMP, and clonogenic ability), senescence (β-galactosidase activity) and spread potential (invasion and migration assays using the Boyden chamber approach) in all these cells. The results showed that the DCM, EtOAc, and Hex extracts display a selective antitumoral effect in gastric cancer cells by affecting all the cancer parameters tested. These findings reveal an attractive antitumoral potential of L. rivularis flower extracts by targeting several acquired capabilities of cancer cells.

Cancer organoid applications to investigate chemotherapy resistance

In clinical practice, a large proportion of cancer patients receive chemotherapy, yet tumors persist or acquire resistance; removing this obstacle could help to lower the number of cancer-related fatalities. All areas of cancer research are increasingly using organoid technology, a culture technique that simulates the in vivo environment in vitro, especially in the quickly developing fields of anticancer drug resistance, drug-tolerant persisters, and drug screening. This review provides an overview of organoid technology, the use of organoids in the field of anticancer drug resistance research, their relevance to clinical information and clinical trials, and approaches to automation and high throughput.

Potential value of the homologous recombination deficiency signature we developed in the prognosis and drug sensitivity of gastric cancer

Background: Homologous recombination is an important DNA repair mechanism, which deficiency is a common feature of many cancers. Defining homologous recombination deficiency (HRD) status can provide information for treatment decisions of cancer patients. HRD score is a widely accepted method to evaluate HRD status. This study aimed to explored HRD in gastric cancer (GC) patients' clinical outcomes with genes related to HRD score and HRD components score [HRD-loss of heterozygosity (LOH), large-scale state transitions (LST), and telomeric allelic imbalance (NtAI)]. Methods: Based on LOH, NtAI scores, LST, and integrated HRD scores-related genes, a risk model for stratifying 346 TCGA GC cases were developed by Cox regression analysis and LASSO Cox regression. The risk scores of 33 cancers in TCGA were calculated to analyze the relationship between risk scores of each cancer and HRD scores and 3 HRD component scores. Relationship between the risk model and patient survival, BRCA1, BRCA2 mutation, response to Cisplatin and Talazoparib treatment was analyzed by generating Kaplan-Meier curve, mutations waterfall map and conducting Pearson correlation analysis. Results: An gene signature was constructed based on 11 HRD scores-related gene (BEX2, C1QL2, DKK1, DRC1, GLUD2, HCAR1, IGFBP1, NXPH1, PROC, SERPINA5, and SLCA1A2). Risk groups were stratified by risk score. Prognosis of the high-risk score group was worse than the low-risk ones. Risk score was associated with BRCA2 mutation, and patients grouped according to BRCA2 mutation status had distinguishable risk score, NtAI score, HRD-LOH, LST, and HRD scores. The low-score group showed higher sensitivity to Cisplatin and Talazoparib. The risk score of adrenocortical carcinoma (ACC), stomach adenocarcinoma (STAD), uterine corpus endometrial carcinoma (UCEC), kidney renal clear cell carcinoma (KIRC), sarcoma (SARC), prostate adenocarcinoma (PRAD), breast invasive carcinoma (BRCA) was significantly positively correlated with HRD score. Conclusion: We developed an 11 HRD scores-related genes risk model and revealed the potential association between HRD status and GC prognosis, gene mutations, patients' sensitivity to therapeutic drugs.

MAGE-A3 regulates tumor stemness in gastric cancer through the PI3K/AKT pathway

Gastric cancer remains a malignant disease of the digestive tract with high mortality and morbidity worldwide. However, due to its complex pathological mechanisms and lack of effective clinical therapies, the survival rate of patients after receiving treatment is not satisfactory. A increasing number of studies have focused on cancer stem cells and their regulatory properties. In this study, we first constructed a co-expression network based on the WGCNA algorithm to identify modules with different degrees of association with tumor stemness indices. After selecting the most positively correlated modules of the stemness index, we performed a consensus clustering analysis on gastric cancer samples and constructed the co-expression network again. We then selected the modules of interest and applied univariate COX regression analysis to the genes in this module for preliminary screening. The results of the screening were then used in LASSO regression analysis to construct a risk prognostic model and subsequently a sixteen-gene model was obtained. Finally, after verifying the accuracy of the module and screening for risk genes, we identified MAGE-A3 as the final study subject. We then performed in vivo and in vitro experiments to verify its effect on tumor stemness and tumour proliferation. Our data supports that MAGE-A3 is a tumor stemness regulator and a potent prognostic biomarker which can help the prediction and treatment of gastric cancer patients.

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.

All-trans retinoic acid-mediated miR-30a up-regulation suppresses autophagy and sensitizes gastric cancer cells to cisplatin

AIMS

The potential of all-trans retinoic acid (ATRA) in regulating some microRNAs (miRNAs) involved in multiple cancer-related pathways, including resistance to chemotherapeutics, may be a valuable idea for overcoming the CDDP resistance of GC cells.

MAIN METHODS

Treatment of gastric AGS and MKN-45 cells with CDDP enriched the CDDP surviving cells (CDDP-SCs). The abilities of chemoresistance to CDDP drug, migration, either apoptosis or cell cycle distribution, spheroid body formation and changes at miRNA and protein levels were evaluated in vitro by MTT assay, colony formation assay, flow cytometry, tumor spheres culture, qRT-PCR and western blot assay in CDDP-SCs and ATRA-treated CDDP-SCs cells, respectively.

KEY FINDINGS

CDDP-based chemotherapy significantly reduced microRNA-30a (miR-30a) levels in GC cells. We also observed elevated autophagy activity in cancer cells that possess stem cell-like properties with overexpressed specific stem cell markers. Our extended study suggested that the reduction of miR-30a by CDDP treatment, is the possible underlying mechanism of enhanced autophagic activity, as demonstrated by enhancing autophagy-related protein beclin 1 and LC3-II/LC-I ratio. The addition of ATRA in the culture medium of GC cells increased the expression of miR-30a, and disturbed characteristic CSC-like properties. Additional studies revealed that the increased expression of miR-30a declined the expression level of its target gene, beclin 1, and beclin 1-mediated autophagy. This leads to promoted CDDP-induced GC cell apoptosis and G2/M cell cycle arrest.

SIGNIFICANCE

Overall, miR-30a/autophagy signaling has a critical role in regulating the chemoresistance of GC cells that ATRA could modulate.

Isoliquiritigenin Inhibits Gastric Cancer Stemness, Modulates Tumor Microenvironment, and Suppresses Tumor Growth through Glucose-Regulated Protein 78 Downregulation

Chemotherapy is the treatment of choice for gastric cancer; however, the currently available therapeutic drugs for treatment have limited efficacy. Cancer stemness and the tumor microenvironment may play crucial roles in tumor growth and chemoresistance. Glucose-regulated protein 78 (GRP78) is an endoplasmic reticulum chaperone facilitating protein folding and cell homeostasis during stress and may participate in chemoresistance. Isoliquiritigenin (ISL) is a bioactive flavonoid found in licorice. In this study, we demonstrated the role of GRP78 in gastric cancer stemness and evaluated GRP78-mediated stemness inhibition, tumor microenvironment regulation, and chemosensitivity promotion by ISL. ISL not only suppressed GRP78-mediated gastric cancer stem cell–like characteristics, stemness-related protein expression, and cancer-associated fibroblast activation but also gastric tumor growth in xenograft animal studies. The findings indicated that ISL is a promising candidate for clinical use in combination chemotherapy.