Gastric Cancer Stem Cells: Mechanisms and Therapeutic Approaches

Nrf2: A critical participant in regulation of apoptosis, ferroptosis, and autophagy in gastric cancer

Nuclear factor erythroid 2-related factor-2 (Nrf2) is a specific transcription factor that maintains redox homeostasis by regulating the expression of anti-oxidative stress-related genes. Hyperactivation of Nrf2 is involved in tumor progression and is associated with chemoresistance in a large number of solid tumors. Programmatic cell death (PCD), such as apoptosis, ferroptosis, and autophagy, plays a crucial role in tumor development and chemotherapy sensitivity. Accumulating evidence suggests that some anti-tumor compounds and genes can induce massive production of reactive oxygen species (ROS) via inhibiting Nrf2 expression, which exacerbates oxidative stress and promotes Gastric cancer (GC) cell death, thereby enhancing the sensitivity of GC cells to chemotherapy-induced PCD. In this review, we summarize the role of antitumor drugs in interfering in three different types of PCD (apoptosis, ferroptosis, and autophagy) in GC cells by modulating Nrf2 expression, as well as the molecular mechanisms through which targeting Nrf2 brings about PCD and chemosensitivity. It is reasonable to believe that Nrf2 serves as a potential therapeutic target, and targeting Nrf2 by drug or gene regulation could provide a new strategy for the treatment of GC.

Rhaponticin suppresses the stemness phenotype of gastric cancer stem-like cells CD133+/CD166 + by inhibiting programmed death-ligand 1

BACKGROUND

Gastric cancer stem cells (GCSCs) are key contributors to tumorigenesis, recurrence and metastasis, complicating gastric cancer (GC) treatment. Rhaponticin (RA), a potential novel anticancer drug, has unexplored effects on GCSCs.

METHODS

GCSCs were isolated using CD133 and CD166 markers with magnetic bead separation method and then evaluated their response to the IC50 concentrations of RA (16.90 µg/mL for BGC-823 and 22.18 µg/mL for SGC-7901), and effects on cell proliferation, migration, invasion, and stemness were measured. We analyzed the GCSC-related microarray dataset GSE111556 and explored RA's role in restoring programmed cell death ligand 1 (PD-L1) function in CD133+/CD166 + cells post-PD-L1 knockdown. RA's impact on tumour growth and immune microenvironment was assessed in a xenograft mouse model.

RESULTS

The CD133+/CD166 + subpopulation exhibited stem-like characteristics, with the highest proportion in BGC-823 (38.85%) and SGC-7901 (43.81%) cells. These cells formed tumour spheres and had increased expression of stemness markers Sox2 and Oct-4 (compared to the parental cell line, P < 0.001). RA treatment showed no toxicity to normal GES-1 cells but reduced the viability of CD133+/CD166 + cells in a dose-dependent manner, with IC50 values of 16.90 µg/ml for BGC-823 and 22.18 µg/ml for SGC-7901. RA also decreased the proportion of CD133+/CD166 + cells and their stem-like properties (P < 0.001). Analysis of the GEO database identified PD-L1 as a key target gene of RA, with high expression in GC tissues. Knocking down PD-L1 in CD133+/CD166 + cells and introducing RA did not significantly change PD-L1 expression (P>0.05), suggesting RA's effect may be PD-L1 dependent. In a xenograft mouse model, the tumour size in the RA treatment group was approximately one-sixth that of the CD133+/CD166 + group (P < 0.001). Post-RA treatment, there was an elevation in the expression levels of CD4 and CD8, alongside a reduction in PD-L1 expression (P < 0.001).

CONCLUSIONS

RA suppresses GCSC stem - like phenotype by inhibiting PD - L1 and enhancing T cell tumour infiltration in the studied models. These findings suggest that RA may have potential for further exploration as a candidate for GC treatment, but extensive preclinical and clinical studies are required to determine its true therapeutic value.

Genomic biology and therapeutic strategies of liver metastasis from gastric cancer

The liver is a frequent site of metastasis in advanced gastric cancer (GC). Despite significant advancements in diagnostic and therapeutic techniques, the overall survival rate for patients afflicted with gastric cancer liver metastasis (GCLM) remains dismally low. Precision oncology has made significant progress in identifying therapeutic targets and enhancing our understanding of metastasis mechanisms through genome sequencing and molecular characterization. Therefore, it is crucial to have a comprehensive understanding of the various molecular processes involved in GCLM and the fundamental principles of systemic therapy to develop new treatment approaches. This paper aims to review recent findings on the diagnosis, potential biomarkers, and therapies targeting the multiple molecular processes of GCLM, with the goal of improving treatment strategies for patients with GCLM.

Inflammation-Associated Stem Cells in Gastrointestinal Cancers: Their Utility as Prognostic Biomarkers and Therapeutic Targets

Stem cells are critical for the development and homeostasis of the gastrointestinal (GI) tract. Inflammatory molecules are known to regulate the activity of stem cells. A comprehensive review specifically describing the role of inflammatory molecules in the regulation of stem cells within the GI tract and in GI cancers (GICs) is not available. This review focuses on understanding the role of inflammatory molecules and stem cells in maintaining homeostasis of the GI tract. We further discuss how inflammatory conditions contribute to the transformation of stem cells into tumor-initiating cells. We also describe the molecular mechanisms of inflammation and stem cell-driven progression and metastasis of GICs. Furthermore, we report on studies describing the prognostic value of cancer stem cells and the clinical trials evaluating their therapeutic utility. This review provides a detailed overview on the role of inflammatory molecules and stem cells in maintaining GI tract homeostasis and their implications for GI-related malignancies.

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.

Antiviral Shrimp lncRNA06 Possesses Anti-Tumor Activity by Inducing Apoptosis of Human Gastric Cancer Stem Cells in a Cross-Species Manner

Virus infection causes the metabolic disorder of host cells, whereas the metabolic disorder of cells is one of the major causes of tumorigenesis, suggesting that antiviral molecules might possess anti-tumor activities by regulating cell metabolism. As the key regulators of gene expression, long non-coding RNAs (lncRNAs) play vital roles in the regulation of cell metabolism. However, the influence of antiviral lncRNAs on tumorigenesis has not been explored. To address this issue, the antiviral and anti-tumor capacities of shrimp lncRNAs were characterized in this study. The results revealed that shrimp lncRNA06, having antiviral activity in shrimp, could suppress the tumorigenesis of human gastric cancer stem cells (GCSCs) via triggering apoptosis of GCSCs in a cross-species manner. Shrimp lncRNA06 could sponge human miR-17-5p to suppress the stemness of GCSCs via the miR-17-5p-p21 axis. At the same time, shrimp lncRNA06 could bind to ATP synthase subunit beta (ATP5F1B) to enhance the stability of the ATP5F1B protein in GCSCs, thus suppressing the tumorigenesis of GCSCs. The in vivo data demonstrated that shrimp lncRNA06 promoted apoptosis and inhibited the stemness of GCSCs through interactions with ATP5F1B and miR-17-5p, leading to the suppression of the tumorigenesis of GCSCs. Therefore, our findings highlighted that antiviral lncRNAs possessed anti-tumor capacities and that antiviral lncRNAs could be the anti-tumor reservoir for the treatment of human cancers.

Clinical significance of CD166 and HER-2 in different types of gastric cancer

INTRODUCTION

Cluster of differentiation 166 (CD166), a cancer stem cell (CSC) marker, and human epidermal growth factor receptor 2 (HER-2) are expressed in a diversity of malignancies and is associated with tumor progression. Although studies regarding the importance of CSC markers and HER-2 in gastric cancer (GC) have rapidly developed, their clinicopathological, prognosis, and diagnosis value still remain unsatisfying in GC. Therefore, the present study aims to investigate the clinical, prognostic, and diagnostic significance of CD166 and HER-2 in different histological types of GC.

MATERIALS AND METHODS

Bioinformatic analysis was applied to determine the clinical importance of CD166 and HER-2 expression based on their tissue localization in primary GC tumors and the normal adjacent samples. The expression patterns, clinical significance, prognosis, and diagnosis value of CD166 and HER-2 proteins in tissue microarrays (TMAs) of 206 GC samples, including Signet Ring Cell (SRC) and intestinal types and also 28 adjacent normal tissues were evaluated using immunohistochemistry (IHC).

RESULTS

The results indicated that the expression of CD166 (membranous and cytoplasmic) and HER-2 were significantly up-regulated in tumor cells compared to adjacent normal tissues (P = 0.010, P < 0.001, and P = 0.011, respectively). A statistically significant association was detected between a high level of membranous expression of CD166 and lymphovascular invasion (P = 0.006); We also observed a statistically significant association between high cytoplasmic expression of CD166 protein and more invasion of the subserosa (P = 0.040) in the SRC type. In contrast, there was no correlation between the expression of HER-2 and clinicopathologic characteristics. Both CD166 and HER-2 showed reasonable accuracy and high specificity as diagnostic markers.

CONCLUSION

Our results confirmed that increased membranous and cytoplasmic expression of CD166 showed clinical significance in the SRC type and is associated with the progression of the disease and more aggressive tumor behaviors. These findings can be used to assist in designating subgroups of patients that require different follow-up strategies, and also, they might be utilized as the prognostic or diagnostic biomarkers in these types of GC for prospective clinical application.

Systematic Analysis of Tumor Stem Cell-related Gene Characteristics to Predict the PD-L1 Immunotherapy and Prognosis of Gastric Cancer

AIMS

We aimed to develop a prognostic model with stemness-correlated genes to evaluate prognosis and immunotherapy responsiveness in gastric cancer (GC).

BACKGROUND

Tumor stemness is related to intratumoral heterogeneity, immunosuppression, and anti-tumor resistance. We developed a prognostic model with stemness-correlated genes to evaluate prognosis and immunotherapy responsiveness in GC.

OBJECTIVE

We aimed to develop a prognostic model with stemness-correlated genes to evaluate prognosis and immunotherapy responsiveness in GC.

METHODS

We downloaded single-cell RNA sequencing (scRNA-seq) data of GC patients from the Gene-Expression Omnibus (GEO) database and screened GC stemness- related genes using CytoTRACE. We characterized the association of tumor stemness with immune checkpoint blockade (ICB) and immunity. Thereafter, a 9-stemness signature-based prognostic model was developed using weighted gene co-expression network analysis (WGCNA), univariate Cox regression analysis, and the least absolute shrinkage and selection operator (LASSO) regression analysis. The model predictive value was evaluated with a nomogram.

RESULTS

Early GC patients had significantly higher levels of stemness. The stemness score showed a negative relationship to tumor immune dysfunction and exclusion (TIDE) score and immune infiltration, especially T cells and B cells. A stemness-based signature based on 9 genes (ERCC6L, IQCC, NKAPD1, BLMH, SLC25A15, MRPL4, VPS35, SUMO3, and CINP) was constructed with good performance in prognosis prediction, and its robustness was validated in GSE26942 cohort. Additionally, nomogram and risk score exhibited the most powerful ability for prognosis prediction. High-risk patients exhibited a tendency to develop immune escape and low response to PD-L1 immunotherapy.

CONCLUSION

We developed a stemness-based gene signature for prognosis prediction with accuracy and reliability. This signature also helps clinical decision-making of immunotherapy for GC patients.

Major Indole Alkaloids in Evodia Rutaecarpa: The Latest Insights and Review of Their Impact on Gastrointestinal Diseases

Evodia rutaecarpa, the near-ripe fruit of Euodia rutaecarpa (Juss.) Benth, Euodia rutaecarpa (Juss.) Benth. var. officinalis (Dode) Huang, or Euodia rutaecarpa (Juss.) Benth. var. bodinieri (Dode) Huang, is a famous herbal medicine with several biological activities and therapeutic values, which has been applied for abdominalgia, abdominal distension, vomiting, and diarrhea as a complementary and alternative therapy in clinic. Indole alkaloids, particularly evodiamine (EVO), rutaecarpine (RUT), and dedhydroevodiamine (DHE), are received rising attention as the major bioactivity compounds in Evodia rutaecarpa. Therefore, this review summarizes the physicochemical properties, pharmacological activities, pharmacokinetics, and therapeutic effects on gastrointestinal diseases of these three indole alkaloids with original literature collected by PubMed, Web of Science Core Collection, and CNKI up to June 2023. Despite sharing the same parent nucleus, EVO, RUT, and DHE have different structural and chemical properties, which result in different advantages of biological effects. In their wide range of pharmacological activities, the anti-migratory activity of RUT is less effective than that of EVO, and the neuroprotection of DHE is significant. Additionally, although DHE has a higher bioavailability, EVO and RUT display better permeabilities within blood-brain barrier. These three indole alkaloids can alleviate gastrointestinal inflammatory in particular, and EVO also has outstanding anti-cancer effect, although clinical trials are still required to further support their therapeutic potential.

Jian Yun Qing Hua Decoction inhibits malignant behaviors of gastric carcinoma cells via COL12A1 mediated ferroptosis signal pathway

BACKGROUND

Jian Yun Qing Hua Decoction (JYQHD), a traditional Chinese medicine decoction, which has been applied in the treatment of gastric cancer (GC). We attempt to confirm the anti-gastric cancer effect of JYQHD and explore the mechanism of JYQHD.

METHODS

Acute toxicity test was used to understand the toxicity of JYQHD. We studied the expression and prognostic outcome of COL12A1 within GC tissues through the network databases. Using several web-based databases, we analyzed the major components and targets of JYQHD, as well as known therapeutic targets in gastric cancer. The Venn diagram was utilized to obtain the overlapped genes. Lentiviral vector, shRNAs and plasmids, were used to transfect GC cells. Cell counting kit-8 (CCK8), sphere formation, malondialdehyde (MDA), glutathione (GSH), reactive oxygen species (ROS), Fe2+, transmission electron microscopy (TEM), quantitative Real-Time Polymerase Chain Reaction (qRT-PCR), Western-Blot (WB), and immunohistochemical (IHC) assays were employed to investigate the role and mechanism of COL12A1 and JYQHD in GC.

RESULTS

The results showed that JYQHD was non-toxic and safe. JYQHD inhibited growth and sphere formation ability through inducing the ferroptosis of GC cells, and suppressed the GC cells induced subcutaneous xenograft tumor growth. COL12A1 was highly expressed in gastric cancer tissues, indicating poor prognosis. COL12A1 specifically enhanced GC cell progression and stemness via suppressing ferroptosis. JYQHD down-regulated COL12A1 in order to suppress the stemness of GC cells via inducing ferroptosis.

CONCLUSION

COL12A1 inhibited ferroptosis and enhanced stemness in GC cells. JYQHD inhibited the development of GC cells by inhibiting cancer cell stemness via the ferroptosis pathway mediated by COL12A1.

Stem Cell Properties of Gastric Cancer Stem-Like Cells under Stress Conditions Are Regulated via the c-Fos/UCH-L3/β-Catenin Axis

Gastric cancer stem-like cells (GCSCs) possess stem cell properties, such as self-renewal and tumorigenicity, which are known to induce high chemoresistance and metastasis. These characteristics of GCSCs are further enhanced by autophagy, worsening the prognosis of patients. Currently, the mechanisms involved in the induction of stemness in GCSCs during autophagy remain unclear. In this study, we compared the cellular responses of GCSCs with those of gastric cancer intestinal cells (GCICs) whose stemness is not induced by autophagy. In response to glucose starvation, the levels of β-catenin and stemness-related genes were upregulated in GCSCs, while the levels of β-catenin declined in GCICs. The pattern of deubiquitinase ubiquitin C-terminal hydrolase-L3 (UCH-L3) expression in GCSCs and GCICs was similar to that of β-catenin expression depending on glucose deprivation. We also observed that inhibition of UCH-L3 activity reduced β-catenin protein levels. The interaction between UCH-L3 and β-catenin proteins was confirmed, and it reduced the ubiquitination of β-catenin. Our results suggest that UCH-L3 induces the stabilization of β-catenin, which is required to promote stemness during autophagy activation. Also, UCH-L3 expression was regulated by c-Fos, and the levels of c-Fos increased in response to autophagy activation. In summary, our findings suggest that the inhibition of UCH-L3 during nutrient deprivation could suppress stress resistance of GCSCs and increase the survival rates of gastric cancer patients.

Cancer stem cells: an insight into the development of metastatic tumors and therapy resistance

The term "cancer stem cells" (CSCs) refers to cancer cells that exhibit traits parallel to normal stem cells, namely the potential to give rise to every type of cell identified in a tumor microenvironment. It has been found that CSCs usually develops from other neoplastic cells or non-cancerous somatic cells by acquiring stemness and malignant characteristics through particular genetic modifications. A trivial number of CSCs, identified in solid and liquid cancer, can give rise to an entire tumor population with aggressive anticancer drug resistance, metastasis, and invasiveness. Besides, cancer stem cells manipulate their intrinsic and extrinsic features, regulate the metabolic pattern of the cell, adjust efflux-influx efficiency, modulate different signaling pathways, block apoptotic signals, and cause genetic and epigenetic alterations to retain their pluripotency and ability of self-renewal. Notably, to keep the cancer stem cells' ability to become malignant cells, mesenchymal stem cells, tumor-associated fibroblasts, immune cells, etc., interact with one another. Furthermore, CSCs are characterized by the expression of particular molecular markers that carry significant diagnostic and prognostic significance. Because of this, scientific research on CSCs is becoming increasingly imperative, intending to understand the traits and behavior of cancer stem cells and create more potent anticancer therapeutics to fight cancer at the CSC level. In this review, we aimed to elucidate the critical role of CSCs in the onset and spread of cancer and the characteristics of CSCs that promote severe resistance to targeted therapy.

The therapeutic potential value of Cancer-testis antigens in immunotherapy of gastric cancer

Gastric cancer (GC) is the fourth most common cause of mortality and the fifth for incidence, globally. Diagnosis, early prognosis, and therapy remains challenging for this condition, and new tumor-associated antigens are required for its detection and immunotherapy. Cancer-testis antigens (CTAs) are a subfamily of tumor-associated antigens (TAAs) that have been identified as potential biomarkers and targets for cancer immunotherapy. The CTAs-restricted expression pattern in tumor cells and their potential immunogenicity identify them as attractive target candidates in CTA-based diagnosis or prognosis or immunotherapy. To date, numerous studies have reported the dysregulation of CTAs in GC. Several clinical trials have been done to assess CTA-based immunotherapeutic potential in the treatment of GC patients. NY-ESO-1, MAGE, and KK-LC-1 have been used in GC clinical trials. We review recent studies that have investigated the potential of the CTAs in GC regarding the expression, function, aggressive phenotype, prognosis, and immunological responses as well as their possible clinical significance as immunotherapeutic targets with a focus on challenges and future interventions.

Modulation of Spheroid Forming Capacity and TRAIL Sensitivity by KLF4 and Nanog in Gastric Cancer Cells

The expression of pluripotency factors, and their associations with clinicopathological parameters and drug response have been described in various cancers, including gastric cancer. This study investigated the association of pluripotency factor expression with the clinicopathological characteristics of gastric cancer patients, as well as changes in the expression of these factors upon the stem cell-enriching spheroid culture of gastric cancer cells, regulation of sphere-forming capacity, and response to cisplatin and TRAIL treatments by Nanog and KLF4. Nanog expression was significantly associated with the emergence of a new tumor and a worse prognosis in gastric cancer patients. The expression of the pluripotency factors varied among six gastric cancer cells. KLF4 and Nanog were expressed high in SNU-601, whereas SOX2 was expressed high in SNU-484. The expression of KLF4 and SOX2 was increased upon the spheroid culture of SNU-601 (KLF4/Nanog-high) and SNU-638 (KLF4/Nanog-low). The spheroid culture of them enhanced TRAIL-induced viability reduction, which was accompanied by the upregulation of death receptors, DR4 and DR5. Knockdown and overexpression of Nanog in SNU-601 and SNU-638, respectively, did not affect spheroid-forming capacity, however, its expression was inversely correlated with DR4/DR5 expression and TRAIL sensitivity. In contrast, KLF4 overexpression in SNU-638 increased spheroid formation, susceptibility to cisplatin and TRAIL treatments, and DR4/DR5 expression, while the opposite was found in KLF4-silenced SNU-601. KLF4 is supposed to play a critical role in DR4/DR5 expression and responses to TRAIL and cisplatin, whereas Nanog is only implicated in the former events only. Direct regulation of death receptor expression and TRAIL response by KLF4 and Nanog have not been well documented previously, and the regulatory mechanism behind the process remains to be elucidated.

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.

The inhibitory effect and mechanism of Yi-qi-hua-yu-jie-du decoction on the drug resistance of gastric cancer stem cells based on ABC transporters

Background

The drug resistance of tumor stem cells is an obstacle in gastric cancer (GC) treatment and the high expression of ABC transporters is a classic reason for drug resistance. This study aimed to construct a reliable GC drug-resistant stem cell model and explore the inhibitory effect and mechanism of Yi-qi-hua-yu-jie-du medicated serum (YQHY) on the drug resistance of GC stem cells based on ABC transporters.

Methods

The tumor stemness biomarker CD44 was primary identification from WGCNA. The magnetic-activated cell sorting (MACS) method was used to separate CD44( +)BGC823/5-Fu (BGC823/5–Fu-CSCs) cells and the stemness characteristics were verified from multiple dimensions. Then, the drug resistance index and expression of ABC transporter genes MDR1 and MRP1 were detected in CD44(−)/CD44(+) cells. The inhibition and apoptosis rates of the cells administrated with YQHY or/and 5-Fu were calculated to confirm that YQHY can suppress the drug resistance of BGC823/5-Fu-CSCs. Afterwards, the effects of YQHY on the expression of MDR1 and MRP1 and the activation of the PI3K/Akt/Nrf2 pathway were observed. Finally, under the administration of IGF-1 (the activator of PI3K/Akt pathway) and Nrf2 siRNA, the mechanism of YQHY on reversing the drug resistance of BGC823/5–Fu-CSCs through inhibiting the expression of MDR1 and MRP1 via PI3K/Akt/Nrf2 was verified.

Results

CD44 was a reliable GC stemness biomarker and can be applied to construct the drug-resistant GC stem cell model CD44(+)BGC823/5-Fu. The growth rate, cell proliferation index, soft agar colony formation, expression of stemness specific genes and tumorigenesis ability of CD44(+)BGC823/5-Fu cells were significantly higher than those of CD44(−)BGC823/5-Fu cells. BGC823/5–Fu-CSCs exhibited strong drug resistance to 5-Fu and high expression of ABC transporter genes MDR1 and MRP1 compared to CD44(-) cells. YQHY increased the inhibition and apoptosis rates to efficiently inhibit the drug resistance of BGC823/5–Fu-CSCs. Meanwhile, it suppressed the expression of MDR1 and MRP1 and restrained the activation of PI3K/Akt/Nrf2 signaling pathway. Finally, it was found that IGF-1 partially restored the activation of PI3K/Akt/Nrf2 pathway, alleviated the inhibition of MDR1 and MRP1, blocked the proliferation-inhibitory and apoptosis-promotion effects. YQHY and si-Nrf2 synergistically suppressed the MDR1/MRP1 expression and the drug resistance of BGC823/5–Fu-CSCs.

Conclusions

CD44 was a reliable GC stemness biomarker, and the high expression of ABC transporter genes MDR1 and MRP1 was an important feature of drug-resistant stem cells. YQHY inhibited the MDR1 and MRP1 expression via PI3K/Akt/Nrf2 pathway, thus reversing the drug resistance of BGC823/5–Fu-CSCs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13020-022-00647-y.

Drug and apoptosis resistance in cancer stem cells: a puzzle with many pieces

Resistance to anticancer agents and apoptosis results in cancer relapse and is associated with cancer mortality. Substantial data have provided convincing evidence establishing that human cancers emerge from cancer stem cells (CSCs), which display self-renewal and are resistant to anticancer drugs, radiation, and apoptosis, and express enhanced epithelial to mesenchymal progression. CSCs represent a heterogeneous tumor cell population and lack specific cellular targets, which makes it a great challenge to target and eradicate them. Similarly, their close relationship with the tumor microenvironment creates greater complexity in developing novel treatment strategies targeting CSCs. Several mechanisms participate in the drug and apoptosis resistance phenotype in CSCs in various cancers. These include enhanced expression of ATP-binding cassette membrane transporters, activation of various cytoprotective and survival signaling pathways, dysregulation of stemness signaling pathways, aberrant DNA repair mechanisms, increased quiescence, autophagy, increased immune evasion, deficiency of mitochondrial-mediated apoptosis, upregulation of anti-apoptotic proteins including c-FLIP [cellular FLICE (FADD-like IL-1β-converting enzyme)-inhibitory protein], Bcl-2 family members, inhibitors of apoptosis proteins, and PI3K/AKT signaling. Studying such mechanisms not only provides mechanistic insights into these cells that are unresponsive to drugs, but may lead to the development of targeted and effective therapeutics to eradicate CSCs. Several studies have identified promising strategies to target CSCs. These emerging strategies may help target CSC-associated drug resistance and metastasis in clinical settings. This article will review the CSCs drug and apoptosis resistance mechanisms and how to target CSCs.

The Preparation of Gen-NH2-MCM-41@SA Nanoparticles and Their Anti-Rotavirus Effects

Genistein (Gen), a kind of natural isoflavone drug monomer with poor water solubility and low oral absorption, was incorporated into oral nanoparticles with a new mesoporous carrier material, NH₂-MCM-41, which was synthesized by copolycondensation. When the ratio of Gen to NH₂-MCM-41 was 1:0.5, the maximum adsorption capacity of Gen was 13.15%, the maximum drug loading was 12.65%, and the particle size of the whole core–shell structure was in the range of 370 nm–390 nm. The particles were characterized by a Malvern particle size scanning machine, XRD, Fourier transform infrared spectroscopy, scanning electron microscopy, and nitrogen adsorption and desorption. Finally, Gen-NH₂-MCM-41 was encapsulated by sodium alginate (SA), and the chimerism of this material, denoted as GEN-NH₂-MCM-41@SA, was investigated. In vitro release experiments showed that, after 5 h in artificial colon fluid (pH = 8.0), the cumulative release reached 99.56%. In addition, its anti-rotavirus (RV) effect showed that the maximum inhibition rate was 62.24% at a concentration of 30 μM in RV-infected Caco-2 cells, and it significantly reduced the diarrhea rate and diarrhea index in an RV-infected-neonatal mice model at a dose of 0.3 mg/g, which was better than the results of Gen. Ultimately, Gen-NH₂-MCM-41@SA was successfully prepared, which solves the problems of low solubility and poor absorption and provides an experimental basis for the application of Gen in the clinical treatment of RV infection.

Overcome Drug Resistance in Cholangiocarcinoma: New Insight Into Mechanisms and Refining the Preclinical Experiment Models

Cholangiocarcinoma (CCA) is an aggressive tumor characterized by a poor prognosis. Therapeutic options are limited in patients with advanced stage of CCA, as a result of the intrinsic or acquired resistance to currently available chemotherapeutic agents, and the lack of new drugs entering into clinical application. The challenge in translating basic research to the clinical setting, caused by preclinical models not being able to recapitulate the tumor characteristics of the patient, seems to be an important reason for the lack of effective and specific therapies for CCA. So, there seems to be two ways to improve patient outcomes. The first one is developing the combination therapies based on a better understanding of the mechanisms contributing to the resistance to currently available chemotherapeutic agents. The second one is developing novel preclinical experimental models that better recapitulate the genetic and histopathological features of the primary tumor, facilitating the screening of new drugs for CCA patients. In this review, we discussed the evidence implicating the mechanisms underlying treatment resistance to currently investigated drugs, and the development of preclinical experiment models for CCA.

An updated review of the contribution of noncoding RNAs to the progression of gastric cancer stem cells: Molecular mechanisms of viability, invasion, and chemoresistance of gastric cancer stem cells

Gastric cancer (GC) is a leading cause of death and cancer mortality in the world, with poor survival for cases with higher stages of GC. During the past decade, GC stem cells (GCSCs) - a group of cancer cells- have been the focus of numerous cancer researches. GCSCs have the capability of self-renewal and are identified to be participated in GC development, invasion, chemoresistance, and tumor relapse. Research projects have indicated the main activities of noncoding RNAs in cellular pathways. Micro (mi)RNAs and lncRNAs play important functions in the modulation of different cellular pathways in the post-transcriptional form, through their dysregulated expression in several cancers, including GC. In this paper, we highlight the impact of dysregulated expression of micro-and lncRNAs and their downstream transcripts on GCSCs. Data collection about the progression of GCSCs may be beneficial for the introduction of new insights to the GC treatment.

CHRNA5 Contributes to Hepatocellular Carcinoma Progression by Regulating YAP Activity

Hepatocellular carcinoma (HCC) is a major health concern worldwide. A better understanding of the mechanisms underlying the malignant phenotype is necessary for developing novel therapeutic strategies for HCC. Signaling pathways initiated by neurotransmitter receptors, such as α5-nicotinic acetylcholine receptor (CHRNA5), have been reported to be implicated in tumor progression. However, the functional mechanism of CHRNA5 in HCC remains unclear. In this study, we explored the role of CHRNA5 in HCC and found that CHRNA5 expression was increased in human HCC tissues and positively correlated with the T stage (p < 0.05) and AJCC phase (p < 0.05). The KM plotter database showed that the high expression level of CHRNA5 was strongly associated with worse survival in HCC patients. Both in vitro and in vivo assays showed that CHRNA5 regulates the proliferation ability of HCC by regulating YAP activity. In addition, CHRNA5 promotes the stemness of HCC by regulating stemness-associated genes, such as Nanog, Sox2 and OCT4. Cell migration and invasion assays demonstrated that CHRNA5 significantly enhanced the metastasis of HCC by regulating epithelial–mesenchymal transition (EMT)-associated genes. Furthermore, we found that CHRNA5 regulates the sensitivity of sorafenib in HCC. Our findings suggest that CHRNA5 plays a key role in the progression and drug resistance of HCC, and targeting CHRNA5 may be a strategy for the treatment of HCC.

Cancerous and non-neoplastic stem cells in the stomach similarly express CD44 and CD133

CD44 and CD133 have been considered as cancer stem cell (CSC) markers. Stem cell markers are rarely described in healthy stomach tissues. However, the clinicopathological and prognostic value of CD44 and CD133 in gastric cancer remains controversial. This study investigated the expression of CD44 and CD133 in gastric cancer and non-neoplastic gastric mucosa. We used samples of primary gastric adenocarcinomas (n = 69), metastatic lymph nodes (n = 30), intestinal metaplasia (n = 17), and histologically normal gastric tissues of surgical margins (n = 54). The expression of CD44 and CD133 were studied in samples by immunohistochemistry. Fisher's exact test and a logistic regression model were used in this study. CD44 expression was observed in 12% of samples with intestinal metaplasia, 20% with lymph node metastases, 22% with normal mucosa, to 30% of samples with primary tumors. Most of these positive tumors showed immunostaining in less than 4% of cancerous cells, mainly in the diffuse type. CD133 expression was observed in 7% (intestinal metaplasia) to 46% (normal mucosa). In the positive cases of cancer (24%), in most of them, less than 3% of cells were marked. CD44 and CD133 expression in the histologically normal gastric mucosa was restricted to the deeper regions of the gastric crypts at the level where stem cells and progenitor cells are usually found. CD44 and CD133 expression occurs in few gastric cancer cells, mainly in diffuse carcinomas, and are expressed in histologically normal gastric mucosae. None of the markers are specific for cancer and are also present in intestinal metaplasia and the normal mucosa.

RORβ suppresses the stemness of gastric cancer cells by downregulating the activity of the Wnt signaling pathway

Gastric cancer (GC) is the third leading cause of cancer-related mortality and the fifth most common type of cancer worldwide. GC stem cells (GCSCs) have been reported to be responsible for the malignant behavior of GC. However, the key molecular mechanism controlling GCSC function remains unclear. The present study aimed to investigate the function of retinoic acid-related orphan receptor β (RORβ) in GC. The expression levels of RORβ in GC cells and clinical GC tissues were analyzed using western blotting, reverse transcription-quantitative PCR (RT-qPCR) and immunohistochemistry. The association between RORβ expression levels and GCSC markers was analyzed using Gene Set Enrichment Analysis, and GeneChip was performed to identify differentially expressed genes between control and RORβ-overexpressing GC cells. CCK-8 and flow cytometric assays were used to evaluate the effect of RORβ on cell viability and apoptosis, respectively. The effect of RORβ on the self-renewal capacity of GCSCs was measured using a sphere formation assay, the expression levels of induced pluripotent stem (iPS) factors and epithelial-mesenchymal transition (EMT)-related factors were measured by RT-qPCR and western blotting, and the tumorigenic capacity was measured by an in vivo mouse model. Finally, the impact of RORβ on the Wnt signaling pathway was determined using western blotting and a TOP/FOP flash assay. The results revealed that the expression levels of RORβ were downregulated in GC tissues compared with para-carcinoma tissues, and were inversely associated with the expression levels of GCSC markers. The overexpression of RORβ upregulated the expression levels of the pro-apoptotic gene, Bcl-2 like protein 11, which subsequently inhibited the viability and promoted the apoptosis of GC cells. In addition, RORβ decreased the sphere forming ability, and downregulated the expression levels of iPS cell- and EMT-related factors. In vivo, RORβ suppressed the tumorigenic capacity and stemness of GC cells. Mechanistically, RORβ was revealed to decrease the activity of the Wnt/β-catenin signaling pathway in GCSCs. In conclusion, the findings of the present study identified RORβ as a novel suppressor of GCSCs and highlighted the prospect of RORβ as a novel candidate target for stem cell-based GC therapy.

MiR-17-5p and MKL-1 modulate stem cell characteristics of gastric cancer cells

Effectively targeting cancer stem cells to treat cancer has great therapeutic prospects. However, the effect of microRNA miR-17/MKL-1 on gastric cancer stem cells has not been studied yet. This study preliminarily explored the mechanism of miR-17/MKL-1 in gastric cancer stem cells. Many previous reports have indicated that microRNA and EMT regulated cancer stem cell characteristics, and miR-17 and MKL-1 were involved as a critical gene in migration and invasion in the EMT pathway. Through RT-PCR, Western Blot, flow cytometry, immunofluorescence, sphere formation xenograft tumor assays and drug resistance, the role of miR-17-5p and MKL-1 on promoting stem cell-like properties of gastric cancer were verified in vivo and vitro. Next, MKL-1 targets CD44, EpCAM, and miR -17-5p promoter verified by luciferase assay and ChIP. Besides, the TCGA database analysis found that both miR-17-5p and MKL-1 increased in gastric cancer, and the prognostic survival of the MKL-1 high expression group was reduced. It is found that MKL-1 promotes expression by targeting miR-17, CD44 and EpCAM promoters. Besides, the TCGA database analysis found that both miR-17-5p and MKL-1 increased in gastric cancer, and the prognostic survival of the MKL-1 high expression group was reduced. These findings reveal new regulatory signaling pathways for gastric cancer stem cells, thus it give new insights on potential early diagnosis and/or molecular therapy for gastric cancer.

Human Gastric Cancer Stem Cell (GCSC) Markers Are Prognostic Factors Correlated With Immune Infiltration of Gastric Cancer

The prognosis of patients with gastric cancer (GC) is still unsatisfying. Numerous markers of gastric cancer stem cells (GCSCs) have been identified and were thought to be related to cancer aggressiveness. However, the roles of GCSC markers in GC patients’ prognosis and immune infiltration remain unknown. Expression of GCSC markers was analyzed using Oncomine and Gene Expression Profiling Interactive Analysis (GEPIA). Their associations with clinicopathological parameters were analyzed using UALCAN and LinkedOmics. Alternations and protein expression of GCSC markers were analyzed by cBioPortal and the Human Protein Atlas databases, respectively. The prognostic significance of GCSC markers was evaluated using Kaplan-Meier plotter. Correlations between the expression of GCSC markers and immune infiltration along with biomarkers of tumor-infiltrating immune cells (TIICs) were assessed combined Tumor Immune Estimation Resource and GEPIA. GeneMANIA was used to discover the interactive genes of GCSC markers, and enrichment analysis was performed using Database for Annotation, Visualization, and Integrated Discovery server. We identified six GCSC markers significantly up-expressed in GC, compared with normal stomach tissues. Among them, the overexpression of ICAM1, THY1, and CXCR4 significantly indicated adverse, while EPCAM indicated beneficial clinicopathological features of GC patients. The up-regulation of CXCR4 showed unfavorable prognostic significance, whereas EPCAM and TFRC showed the opposite. The six GCSC markers were all correlated with the infiltration and activation of distinct TIICs. Especially, ICAM1, THY1, and CXCR4 showed strongly positive correlations with tumor-associated macrophages. Besides, chemokine, Toll-like receptor, NF-kappa B, and HIF-1 signaling pathways might be involved in the regulation of GCSC markers on cancer development. This study proposed that GCSC markers might be promising targets of GC treatment to weaken cancer stem-like properties and strengthen anticancer immunity.

E2F1 Maintains Gastric Cancer Stemness Properties by Regulating Stemness-Associated Genes

Purpose

To determine the regulatory role of E2F1 in maintaining gastric cancer stemness properties and the clinical significance of E2F1 in gastric cancer.

Materials and Methods

We conducted a tumor spheroid formation assay to enrich gastric cancer stem-like cells. The protein and mRNA expression levels of genes were measured using Western Blot and qRT-PCR. Lentivirus-mediated overexpression and downregulation of E2F1 were performed to evaluate the effect of E2F1 on the stemness properties of gastric cancer cells. The effect of E2F1 on gastric cancer cell sensitivity of 5-Fu was evaluated using cell viability assay and TdT-mediated dUTP Nick-End Labeling staining. We also analyzed the association between E2F1 expression and clinical characteristics in gastric cancer patients. The KM plotter database was used to analyze the relationship between E2F1 and overall survival in GC patients.

Results

We found that E2F1 expression was significantly higher in gastric cancer tissues than in the paired adjacent normal tissues (p < 0.05) and was positively correlated with tumor size (p < 0.05), T stage (p < 0.05), and differentiation degree (p < 0.05). KM plotter database demonstrated a close association between higher E2F1 expression level and worse overall survival of gastric cancer patients (p < 0.05). In vitro assay illustrated that E2F1 could regulate the expression of stemness-associated genes, such as BMI1, OCT4, Nanog, and CD44, and maintain the tumor spheroid formation ability of gastric cancer cells. E2F1 enhanced 5-Fu resistance in gastric cancer cells, and the E2F1 expression level was correlated with the prognosis of gastric cancer patients receiving 5-Fu therapy. The expression levels of stemness-associated genes were also significantly higher in gastric cancer tissues than the paired adjacent normal tissues (p < 0.05). A positive correlation was observed between E2F1 and BMI1 (r = 0.422, p < 0.05), CD44 (r = 0.634, p < 0.05), OCT4 (r = 0.456, p < 0.05), and Nanog (r = 0.337, p < 0.05) in gastric cancer tissues. The co-overexpression of E2F1 and stemness-associated genes was associated with worse overall survival.

Conclusion

E2F1 plays a significant role in gastric cancer progression by maintaining gastric cancer stemness properties through the regulation of stemness-associated genes. The close association between E2F1 and poor prognosis of patients suggests that E2F1 could serve as a prognostic biomarker and a therapeutic target in gastric cancer patients.

Drug resistance and Cancer stem cells

Therapy resistance is a major problem when treating cancer patients as cancer cells develop mechanisms that counteract the effect of therapeutic compounds, leading to fit and more aggressive clones that contribute to poor prognosis. Therapy resistance can be both intrinsic and/or acquired. These are multifactorial events, and some are related to factors including adaptations in cancer stem cells (CSCs), epithelial-mesenchymal transition (EMT), deregulation of key signaling pathways, drug efflux through ABC transporters, acquired mutations, evading apoptosis, and activation of DNA damage response among others. Among these factors, CSCs represent the major source of therapy resistance. CSCs are a subset of tumor cells that are capable of self-renewal and multilineage progenitor expansion that are known to be intrinsically resistant to anticancer treatments. Multiple clones of CSCs pre-exist, and some can adopt and expand easily to changes in the tumor microenvironment (TME) and/or in response to radio- and chemotherapy. A combination of both intrinsic and extrinsic factors contributes to CSC-mediated therapy resistance. In this review, we will focus on CSCs and therapy resistance as well as suggest strategies to eliminate CSCs and, therefore, overcome resistance. Video abstract.

An integrated analysis to predict micro-RNAs targeting both stemness and metastasis in human gastric cancer

BACKGROUND AND AIM

Cancer stem cells (CSCs), a subpopulation of tumor cells, assess the capacity of self-renewal, metastasis, and therapeutic resistance. Regulation of CSCs and their epithelial to mesenchymal transition (EMT) potential is one of the promising strategies to eliminate cancer or to inhibit metastasis. Micro-RNAs (miRNAs) as regulators of several cell properties, such as self-renewal, metastasis, and resistance to the drug, could be proper targets in cancer diagnosis and therapy. The aim of the present study is to select common miRNAs targeting both self-renewal and metastasis in gastric cancer.

METHODS

Stemness-related and EMT-related genes were selected by literature mining. The common miRNAs targeting genes were chosen using different databases and r programming language. The expression pattern of selected miRNAs and genes was evaluated in gastrospheres-as a gastric CSC model-and gastric tumor biopsies.

RESULTS

Based on the integrated analysis, six miRNAs common to both stemness and metastasis were identified. miR-200c-3p and miR-520c-3p overexpressed in MKN-45 gastrospheres and grade III tumors. In AGS spheres, however, miR-520c-3p and miR-200c-3p upregulation and miR-34a-5p downregulation were similar to grade II tumors. Interestingly, miR-200c-3p and miR-520c-3p indicated a positive correlation with OCT4 and NOTCH1 expression in grade III tumors and MKN-45 spheres. Protein-protein network revealed that the EMT acquisition can be induced by stemness activation through intermediated core-regulatory genes, including CTNNB1, CTNND1, MAML1, KAT2A, and MAML3.

CONCLUSION

The upregulation of mir-200c-3p and mir-520c-3p could effect on stemness and metastasis in gastric cancer as well as gastric CSCs. Therefore, they can be used as diagnosis and prognostic factors.

The Aberrant Expression of MicroRNA-125a-5p/IGF2BP3 Axis in Advanced Gastric Cancer and Its Clinical Relevance

RNA-binding proteins have been associated with cancer development. The overexpression of a well-known RNA-binding protein, insulin-like growth factor 2 messenger RNA-binding protein 3, has been identified as an indicator of poor prognosis in patients with various types of cancer. Although gastric cancer is a relatively frequent and potentially fatal malignancy, the mechanism by which insulin-like growth factor 2 messenger RNA-binding protein 3 regulates the development of this cancer remains unclear. This study aimed to investigate the role and regulatory mechanism of insulin-like growth factor 2 messenger RNA-binding protein 3 in gastric cancer. An analysis of IGF2BP3 expression patterns reported in 4 public gastric cancer-related microarray data sets from the Gene Expression Omnibus and The Cancer Genome Atlas-Stomach Adenocarcinoma revealed strong expression of this gene in gastric cancer tissues. Insulin-like growth factor 2 messenger RNA-binding protein 3 expression in gastric cancer was further confirmed via quantitative reverse transcription polymerase chain reaction and immunohistochemistry, respectively, in an in-house gastric cancer cohort (n = 30), and the association of insulin-like growth factor 2 messenger RNA-binding protein 3 expression with clinical parameters and prognosis was analyzed. Notably, stronger IGF2BP3 expression significantly correlated with poor prognosis, and significant changes in insulin-like growth factor 2 messenger RNA-binding protein 3 expression were only confirmed in patients with advanced-stage gastric cancer in an independent cohort. The effects of insulin-like growth factor 2 messenger RNA-binding protein 3 on cell proliferation were confirmed through in vitro experiments involving the HGC-27 gastric cancer cell line. MicroR-125a-5p, a candidate microRNA that target on insulin-like growth factor 2 messenger RNA-binding protein 3, decreased in advanced-stage gastric cancer. Upregulation of microR-125a-5p inhibited insulin-like growth factor 2 messenger RNA-binding protein 3, and dual-luciferase report assay indicated that microR-125a-5p inhibited the translation of IGF2BP3 by directly targeting the 3' untranslated region. These results indicate that the microR-125a-5p/insulin-like growth factor 2 messenger RNA-binding protein 3 axis contributes to the oncogenesis of advanced gastric cancer.

Prognostic Factors After Hepatectomy for Gastric Adenocarcinoma Liver Metastases: Desmoplastic Growth Pattern as the Key to Improved Overall Survival

Purpose

Hepatectomy (Hp) is an alternative approach for the treatment of gastric carcinoma liver metastases (GCLM). However, prognostic factors that may assist patient selection are still controversial. Several pathologic features, such as the growth pattern (GP), associated with prognosis in colorectal cancer liver metastases, were never investigated in GCLM. Our principal aim was to assess if the GP has prognostic impact on GCLM.

Patients and Methods

Review of the clinical and pathological characteristics of 19 consecutive patients submitted to surgical resection of GCLM with curative intent at our department. Major potential prognostic factors considered were patients’ gender, age, timing and extent of Hp, postoperative course, as well as histopathological characteristics of primary and secondary tumors.

Results

Major morbidity occurred in four patients, mortality in one. Median and 5-year overall survival were 17 months and 26.7%, respectively. Ten patients developed recurrent disease and two patients survived more than 10 years. Factors independently associated with overall survival were the absence of major morbidity, distal location of the primary tumor, and desmoplastic GP (p<0.05).

Conclusion

The selection of patients is crucial for the improvement of survival rates of GCLM. Consequently, we demonstrate for the first time that the desmoplastic GP of GCLM is associated with improved outcomes, prompting further research on tumor–host interactions.

Cancer Stem Cells-Origins and Biomarkers: Perspectives for Targeted Personalized Therapies

The use of biomarkers in diagnosis, therapy and prognosis has gained increasing interest over the last decades. In particular, the analysis of biomarkers in cancer patients within the pre- and post-therapeutic period is required to identify several types of cells, which carry a risk for a disease progression and subsequent post-therapeutic relapse. Cancer stem cells (CSCs) are a subpopulation of tumor cells that can drive tumor initiation and can cause relapses. At the time point of tumor initiation, CSCs originate from either differentiated cells or adult tissue resident stem cells. Due to their importance, several biomarkers that characterize CSCs have been identified and correlated to diagnosis, therapy and prognosis. However, CSCs have been shown to display a high plasticity, which changes their phenotypic and functional appearance. Such changes are induced by chemo- and radiotherapeutics as well as senescent tumor cells, which cause alterations in the tumor microenvironment. Induction of senescence causes tumor shrinkage by modulating an anti-tumorigenic environment in which tumor cells undergo growth arrest and immune cells are attracted. Besides these positive effects after therapy, senescence can also have negative effects displayed post-therapeutically. These unfavorable effects can directly promote cancer stemness by increasing CSC plasticity phenotypes, by activating stemness pathways in non-CSCs, as well as by promoting senescence escape and subsequent activation of stemness pathways. At the end, all these effects can lead to tumor relapse and metastasis. This review provides an overview of the most frequently used CSC markers and their implementation as biomarkers by focussing on deadliest solid (lung, stomach, liver, breast and colorectal cancers) and hematological (acute myeloid leukemia, chronic myeloid leukemia) cancers. Furthermore, it gives examples on how the CSC markers might be influenced by therapeutics, such as chemo- and radiotherapy, and the tumor microenvironment. It points out, that it is crucial to identify and monitor residual CSCs, senescent tumor cells, and the pro-tumorigenic senescence-associated secretory phenotype in a therapy follow-up using specific biomarkers. As a future perspective, a targeted immune-mediated strategy using chimeric antigen receptor based approaches for the removal of remaining chemotherapy-resistant cells as well as CSCs in a personalized therapeutic approach are discussed.

Current Trends in ATRA Delivery for Cancer Therapy

All-Trans Retinoic Acid (ATRA) is the most active metabolite of vitamin A. It is critically involved in the regulation of multiple processes, such as cell differentiation and apoptosis, by activating specific genomic pathways or by influencing key signaling proteins. Furthermore, mounting evidence highlights the anti-tumor activity of this compound. Notably, oral administration of ATRA is the first choice treatment in Acute Promyelocytic Leukemia (APL) in adults and NeuroBlastoma (NB) in children. Regrettably, the promising results obtained for these diseases have not been translated yet into the clinics for solid tumors. This is mainly due to ATRA-resistance developed by cancer cells and to ineffective delivery and targeting. This up-to-date review deals with recent studies on different ATRA-loaded Drug Delivery Systems (DDSs) development and application on several tumor models. Moreover, patents, pre-clinical, and clinical studies are also reviewed. To sum up, the main aim of this in-depth review is to provide a detailed overview of the several attempts which have been made in the recent years to ameliorate ATRA delivery and targeting in cancer.

The miR-567/RPL15/TGF-β/Smad axis inhibits the stem-like properties and chemo-resistance of gastric cancer cells

BACKGROUND

Gastric cancer (GC) is the second most significant contributor to cancer-related mortality in China. GC treatment is often hindered by metastasis and chemoresistance, which leads to poor prognosis. This study set out to investigate the role of miR-567 on the stem-like properties and chemo-resistance of GC cells, as well as its potential molecular mechanism.

METHODS

The expression of miR-567 in GES-1, AGS, SCG-7901, MGC-803, SUN-16, and MKN1 cell lines was detected by Real-time PCR. AGS cells were transfected with NC or miR-567 mimics and RPL15 3'UTR (wt) or RPL15 3'UTR (mut) using Lipofectamine 2000. CCK-8, 5-ethynyl-2'-deoxyuridine (EdU) assay were detected the effect of miR-567/RPL15/TGF-β/Smad on gastric cancer cell viability and proliferation, respectively. Western blot were used to analyze the effects of miR-567/RPL15/TGF-β/Smad on protein levels of SOX2, NANOG, ALDH1A1, TGF-β1, TGFβ-R1, SMAD1, P-SMAD1, SMAD2 and P-SMAD2.

RESULTS

The results showed that the expression of miR-567 was down-regulated in GC cell lines. TargetScan and luciferase report assay indicated that RPL15 was the target of miR-567. Functional analysis discovered that the overexpression of miR-567 inhibited the microsphere formation of AGS stem cells, while PRL15 overexpression promoted the formation of microspheres in AGS cells. Through Western blot analysis, miR-567 overexpression was further revealed to inhibit the expression of stem-like marker proteins (SOX2, NANOG, and ALDH1A1). Furthermore, PRL15 overexpression was found to significantly promote the growth of AGS/DDP cells, while miR-567 overexpression reversed the effect of PRL15 on cisplatin-resistant cell growth. The relationship between miR-567 and the TGF-β1/TGFβ-R1/Smad2/Smad3 pathway was also shown. The addition of TGF-β/Smad pathway inhibitor LY 3200882 significantly inhibited the expression of PRL-15, TGF-β1, TGF-R1, p-Smad1, and p-sSmad2, while reversing the effect of miR-567 inhibitor on stem-like properties and chemical resistance.

CONCLUSIONS

Finally, this study elucidated the effect of miR-567 on the stem-like properties and chemical resistance of GC cells via the RPL15 /TGF-beta/Smad axis.

KIF15 facilitates gastric cancer via enhancing proliferation, inhibiting apoptosis, and predict poor prognosis

Background

Kinesin superfamily proteins (KIFs) can transport membranous organelles and protein complexes in an ATP-dependent manner. Kinesin family member 15 (KIF15) is overexpressed in various cancers. However, the function of KIF15 in gastric cancer (GC) is still unclear.

Methods

GC patients’ data from The Cancer Genome Atlas (TCGA) were analyzed by bioinformatics methods. The expression of KIF15 was examined in GC and paracarcinoma tissues from 41 patients to verify the analysis results. The relationship between KIF15 expression and clinical characteristics were also observed by bioinformatics methods. Kaplan–Meier survival analysis of 122 GC patients in our hospital was performed to explore the relationship between KIF15 expression levels and GC patients’ prognosis. KIF15 was downregulated in GC cell lines AGS and SGC-7901 by transfecting a lentivirus-mediated shRNA plasmid targeting KIF15. In vitro, GC cell proliferation and apoptosis were detected by MTT assay, colony formation assay, and Annexin V-APC staining. In vivo, xenograft experiments were used to verify the in vitro results. Furthermore, Human Apoptosis Antibody Array kit was used to screen possible targets of KIF15 in GC cell lines.

Results

The bioinformatics results showed that KIF15 expression levels were higher in GC tissues than in normal tissues. IHC showed same results. High expression of KIF15 was statistical correlated with high age and early histologic stage. Kaplan–Meier curves indicated that high KIF15 expression predict poor prognosis in patients with GC. MTT assay and colony formation assay showed that KIF15 promote GC cell proliferation. Annexin V-APC staining found that KIF15 can inhibit GC cell apoptosis. Xenograft experiments reveal that downregulating KIF15 can inhibit GC tumor growth and promote GC apoptosis. Through detection of 43 anti-apoptotic proteins by the Human Apoptosis Antibody Array kit, it was confirmed that knocking down KIF15 can reduce seven anti-apoptotic proteins expression.

Conclusions

Taken together, our study revealed a critical role for KIF15 to inhibit GC cell apoptosis and promote GC cell proliferation. KIF15 may decrease anti-apoptotic proteins expression by regulating apoptosis pathways. High expression of KIF15 predicts a poor prognosis in patients with GC. KIF15 might be a novel prognostic biomarker and a therapeutic target for GC.

Tomentosin induces apoptotic pathway by blocking inflammatory mediators via modulation of cell proteins in AGS gastric cancer cell line

In this study, we investigated the in vitro effect of tomentosin on cell proliferation by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, reactive oxygen species by 2',7'-dichlorofluorescein diacetate staining assay, apoptosis (AO/EtBr, propidium iodide, and 4',6-diamidino-2-phenylindole staining, mitochondrial membrane potential), cell adherent, cell migration, inflammation, apoptosis, and oxidative stress from gastric cancer cells (GCCs) AGS. Upon their relative cell proliferative, inflammatory, and apoptotic molecular markers were analyzed by using the enzyme-linked immunosorbent assay and Western blot analysis method. Treatment with tomentosin (IC₅₀  = 20 µM) significantly inhibited cell proliferation and oxidative stress-induced anti-cell proliferative (proliferating cell nuclear antigen and cyclin-D1) also regulated expression, drastically diminished tumor necrosis factor-α, nuclear factor-κB, interleukin-6, and interleukin-1β expression levels, significantly upregulated Bcl-2 and Bax expression. Thus, this tomentosin can significantly reduce GCC proliferation via cytotoxicity which is stimulated apoptosis markers via morphology staining changes and inhibitory inflammatory markers. The tomentosin-induced oxidative stress may be involved to stimulate apoptotic mechanisms via mitochondria-mediated signaling by the inhibition of inflammation. Taken together, our findings suggest a possible future use of chemotherapeutic agents for pharmacological benefits and as an anti-cancer treatment option.

Retinoic Acids in the Treatment of Most Lethal Solid Cancers

Although the use of oral administration of pharmacological all-trans retinoic acid (ATRA) concentration in acute promyelocytic leukaemia (APL) patients was approved for over 20 years and used as standard therapy still to date, the same use in solid cancers is still controversial. In the present review the literature about the top five lethal solid cancers (lung, stomach, liver, breast, and colon cancer), as defined by The Global Cancer Observatory of World Health Organization, and retinoic acids (ATRA, 9-cis retinoic acid, and 13-cis retinoic acid, RA) was compared. The action of retinoic acids in inhibiting the cell proliferation was found in several cell pathways and compartments: from membrane and cytoplasmic signaling, to metabolic enzymes, to gene expression. However, in parallel in the most aggressive phenotypes several escape routes have evolved conferring retinoic acids-resistance. The comparison between different solid cancer types pointed out that for some cancer types several information are still lacking. Moreover, even though some pathways and escape routes are the same between the cancer types, sometimes they can differently respond to retinoic acid therapy, so that generalization cannot be made. Further studies on molecular pathways are needed to perform combinatorial trials that allow overcoming retinoic acids resistance.

Oct4 expression in gastric carcinoma: association with tumor proliferation, angiogenesis and survival

BACKGROUND

Octamer-binding transcription factor 4 (Oct4) is a transcription factor that has an important role in stem cell differentiation and self-renewal. Oct4 has also been implicated in tumorigenicity of different cancers. This study aimed to analyze Oct4 expression in gastric carcinoma (GC) and to evaluate the relation between Oct4 expression and clinicopathologic parameters, tumor proliferation, and angiogenesis in addition to patient survival.

RESULTS

Oct4 mRNA was detected by quantitative reverse transcription PCR (qRT-PCR) in 45 GC specimens and adjacent non-cancerous tissues. We found a significant difference in Oct4 mRNA relative expression levels in GC tissue compared with adjacent non-cancerous tissues (p < 0.001). Furthermore, immunohistochemistry (IHC) was performed to study the Oct4 expression in GC cases. High Oct4 immunostaining was detected in 62.2% of GC specimens. High Oct4 expression both by mRNA relative quantitation and IHC were significantly related to poorly differentiated tumors, nodal metastasis, and stage III tumors. Moreover, high Oct4 IHC expression was also associated with cases positive for Ki-67 and VEGF expressions (p < 0.001 and 0.021, respectively). Oct4 expression identified by both mRNA relative quantitation and IHC was significantly related (p < 0.001). As regards patient survival, high Oct4 expression was significantly related to poor overall survival (OS) and disease-free survival (DFS) (p = 0.029 and 0.031, respectively).

CONCLUSION

Oct4 plays a valuable role in the progression and prognosis of GC. High Oct4 expression is associated with high tumor grade, nodal metastasis, stage III tumors, and poor OS and DFS. High Oct4 is also significantly associated with Ki-67 and VGEF expression, thus enhancing tumor proliferation and angiogenesis.

A Feedback Loop Regulation Of LINC01433 And YAP Promotes Malignant Behavior In Gastric Cancer Cells

Background

Gastric cancer (GC) is one of the most common cancers and the second leading cause of cancer-related death worldwide. Long noncoding RNAs (lncRNAs) are associated with GC development and progression. However, the functional roles and underlying mechanism of LINC01433 on GC progression remain elusive.

Methods

Firstly, the expression of LINC01433 was examined in 76 pairs of primary GC and corresponding adjacent non-tumorous tissues. Next, overexpression and knockdown experiments were conducted in GC cells to explore the effect of LINC01433 on the malignant behaviors of GC cells. Then, the interaction between LINC01433 and YAP was detected by RNA immunoprecipitation (RIP) and RNA pull-down assays.

Results

We found that LINC01433 was significantly upregulated in GC tissues and cell lines and correlated with poor prognosis. Through gain- and loss-of-function experiments, we demonstrated that LINC01433 promoted proliferation, migration, invasion and chemotherapy resistance in GC cells. Further mechanistic investigation revealed that LINC01433 could stabilize oncoprotein YAP through enhancing the interaction between deubiquitinase USP9X and YAP. LINC01433 decreased the phosphorylation of YAP via suppressing YAP-LATS1 association. Intriguingly, YAP directly bound to LINC01433 promoter region and activated its transcription. Thus, LINC01433 and YAP formed a positive feedback loop.

Conclusion

Collectively, our study demonstrates that the positive feedback loop between LINC01433 and YAP promotes GC progression, and implies that the LINC01433-YAP feedback loop may be a promising therapeutic target for GC treatment.

MicroRNA-598 inhibits the growth and maintenance of gastric cancer stem-like cells by down-regulating RRS1

Emerging evidence has identified the critical role of microRNAs in gastric cancer (GC). Herein, this study intends to characterize the tumor suppressive role of microRNA-598 (miR-598) in GC stem-like cells, with the involvement of RRS1. The CD133+ GC stem-like cells were sorted by flow cytometry, after which immunofluorescence assay was used to determine the co-localization of CD133 and CD44v8-10. The miR-598 expression was examined in the CD133+ and CD133- cells. Subsequently, the CD133+ cells were subjected to miR-598 mimics, miR-598 inhibitors or RRS1 siRNA to validate the effect of miR-598 on GC stem-like cell proliferation, colony formation, apoptosis, migration and invasion capacities. Besides, the effect of miR-598 on the expression of key factors (OCT4, SOX2 and NANOG) associated with stem cell characteristics was measured. The obtained results indicated that the sphere forming capacity was higher in CD133+ cells. CD133+ MKN-45 cells expressed CD133 and CD44v8-10, and were expressed on the cell membrane. MiR-598 was poorly expressed in CD133+ cells. Notably, miR-598 negatively regulated RRS1. In response to miR-598 mimics and RRS1 siRNA, the MKN-45 cells displayed inhibited proliferation, colony formation, migration and invasion, accompanied by elevated apoptosis. Besides, the miR-598 inhibitors reversed the situation. This study highlights that miR-598 a tumor suppressor in GC stem-like cells by inhibiting RRS1, whereby miR-598 represses MKN-45 cell growth and invasion by attenuating self-renewal of GC stem-like cells.

Role of miRNA-Regulated Cancer Stem Cells in the Pathogenesis of Human Malignancies

Recent biomedical discoveries have revolutionized the concept and understanding of carcinogenesis, a complex and multistep phenomenon which involves accretion of genetic, epigenetic, biochemical, and histological changes, with special reference to MicroRNAs (miRNAs) and cancer stem cells (CSCs). miRNAs are small noncoding molecules known to regulate expression of more than 60% of the human genes, and their aberrant expression has been associated with the pathogenesis of human cancers and the regulation of stemness features of CSCs. CSCs are the small population of cells present in human malignancies well-known for cancer resistance, relapse, tumorigenesis, and poor clinical outcome which compels the development of novel and effective therapeutic protocols for better clinical outcome. Interestingly, the role of miRNAs in maintaining and regulating the functioning of CSCs through targeting various oncogenic signaling pathways, such as Notch, wingless (WNT)/β-Catenin, janus kinases/ signal transducer and activator of transcription (JAK/STAT), phosphatidylinositol 3-kinase/ protein kinase B (PI3/AKT), and nuclear factor kappa-light-chain-enhancer of activated B (NF-kB), is critical and poses a huge challenge to cancer treatment. Based on recent findings, here, we have documented the regulatory action or the underlying mechanisms of how miRNAs affect the signaling pathways attributed to stemness features of CSCs, such as self-renewal, differentiation, epithelial to mesenchymal transition (EMT), metastasis, resistance and recurrence etc., associated with the pathogenesis of various types of human malignancies including colorectal cancer, lung cancer, breast cancer, head and neck cancer, prostate cancer, liver cancer, etc. We also shed light on the fact that the targeted attenuation of deregulated functioning of miRNA related to stemness in human carcinogenesis could be a viable approach for cancer treatment.

An investigation on the cytotoxicity and caspase-mediated apoptotic effect of biologically synthesized gold nanoparticles using Cardiospermum halicacabum on AGS gastric carcinoma cells

Background

Gastric cancer is the fourth most common cancer and second leading cause of cancer death worldwide. Cardiospermum halicacabum is used to treat nerve disorders, stiffness, rheumatism, ear ache, snake bite, and so on.

Methods

In this study, the reaction parameters were optimized to control the size of the nanoparticle, which was confirmed by transmission electron microscopy. Various characterization techniques such as selected area diffraction pattern, UV-visible spectroscopy, energy-dispersive X-ray analysis, dynamic light scattering, Fourier-transform infrared spectroscopy, and atomic force microscopy were employed to analyze the synthesized AuNPs obtained from C. halicacabum (CH-AuNP) against gastric carcinoma cell line.

Results

The cytotoxic effect of CH-AuNP against AGS, SNU-5, and SNU-16 cell lines was detected by MTT assay. The induction of apoptosis by CH-AuNP in AGS was analyzed by double staining technique using TUNEL and DAPI staining assays. Further to confirm the molecular mechanism exhibited by CH-AuNP to induce apoptosis, the intracellular ROS level was assessed and immunoblotting was performed to assess the apoptotic signaling molecules that often deregulated in cancerous condition.

Conclusion

The results clearly prove that CH-AuNP increases ROS and induces apoptosis in AGS, suggesting that CH-AuNP may be an effective anticancer drug with no side effects to treat gastric cancer.

Novel Gastric Cancer Stem Cell-Related Marker LINGO2 Is Associated with Cancer Cell Phenotype and Patient Outcome

The expression of leucine-rich repeat and immunoglobulin-like domain-containing nogo receptor-interacting protein 2 (LINGO2) has been reported in Parkinson’s disease; however, its role in other diseases is unknown. Gastric cancer is the second leading cause of cancer death. Cancer stem cells (CSC) are a subpopulation of cancer cells that contribute to the initiation and invasion of cancer. We identified LINGO2 as a CSC-associated protein in gastric cancers both in vitro and in patient-derived tissues. We studied the effect of LINGO2 on cell motility, stemness, tumorigenicity, and angiogenic capacity using cells sorted based on LINGO2 expression and LINGO2-silenced cells. Tissue microarray analysis showed that LINGO2 expression was significantly elevated in advanced gastric cancers. The overall survival of patients expressing high LINGO2 was significantly shorter than that of patients with low LINGO2. Cells expressing high LINGO2 showed elevated cell motility, angiogenic capacity, and tumorigenicity, while LINGO2 silencing reversed these properties. Silencing LINGO2 reduced kinase B (AKT)/extracellular signal-regulated kinase (ERK)/ERK kinase (MEK) phosphorylation and decreased epithelial-mesenchymal transition (EMT)-associated markers—N-Cadherin and Vimentin and stemness-associated markers— POU class 5 homeobox 1 (OCT4) and Indian hedgehog (IHH), and markedly decreased the CD44⁺ population. These indicate the involvement of LINGO2 in gastric cancer initiation and progression by altering cell motility, stemness, and tumorigenicity, suggesting LINGO2 as a putative target for gastric cancer treatment.