Molecular Features Distinguish Gastric Cancer Subtypes

Potential therapeutic targets of gastric cancer explored under endogenous network modeling of clinical data

Improvement in the survival rate of gastric cancer, a prevalent global malignancy and the leading cause of cancer-related mortality calls for more avenues in molecular therapy. This work aims to comprehend drug resistance and explore multiple-drug combinations for enhanced therapeutic treatment. An endogenous network modeling clinic data with core gastric cancer molecules, functional modules, and pathways is constructed, which is then transformed into dynamics equations for in-silicon studies. Principal component analysis, hierarchical clustering, and K-means clustering are utilized to map the attractor domains of the stochastic model to the normal and pathological phenotypes identified from the clinical data. The analyses demonstrate gastric cancer as a cluster of stable states emerging within the stochastic dynamics and elucidate the cause of resistance to anti-VEGF monotherapy in cancer treatment as the limitation of the single pathway in preventing cancer progression. The feasibility of multiple objectives of therapy targeting specified molecules and/or pathways is explored. This study verifies the rationality of the platform of endogenous network modeling, which contributes to the development of cross-functional multi-target combinations in clinical trials.

LncRNAs and PTEN/PI3K signaling: A symphony of regulation in cancer biology

The Emergence of Long Non-coding RNAs (lncRNAs) as Key Regulators in Diverse Biological Processes: A Paradigm Shift in Understanding Gene Expression and its Impact on Cancer. The PTEN/PI3K pathway, a pivotal signaling cascade involved in cancer progression, orchestrates critical cellular functions such as survival, proliferation, and growth. In light of these advances, our investigation delves into the intricate and multifaceted interplay between lncRNAs and the PTEN/PI3K signaling pathway, unearthing previously undisclosed mechanisms that underpin cancer growth and advancement. These elusive lncRNAs exert their influence through direct targeting of the PTEN/PI3K pathway or by skillfully regulating the expression and activity of specific lncRNAs. This comprehensive review underscores the paramount significance of the interaction between lncRNAs and the PTEN/PI3K signaling pathway in cancer biology, unveiling an auspicious avenue for novel diagnostic tools and targeted therapeutic interventions. In this review, we navigate through the functional roles of specific lncRNAs in modulating PTEN/PI3K expression and activity. Additionally, we scrutinize their consequential effects on downstream components of the PTEN/PI3K pathway, unraveling the intricacies of their mutual regulation. By advancing our understanding of this complex regulatory network, this study holds the potential to revolutionize the landscape of cancer research, paving the way for tailored and efficacious treatments to combat this devastating disease.

CircRHOT1 restricts gastric cancer cell ferroptosis by epigenetically regulating GPX4

Background

Gastric cancer (GC) is a malignant form of cancer that severely threatens human health. Despite developments on treatment, the prognosis of patients with advanced GC remains poor. Hence, the identification of detailed molecular mechanisms and potential therapeutic targets is of great importance for GC study. In recent years, circular RNAs have been widely reported to be important regulators in cancer initiation and progression. This study sought to evaluate the function of circRHOT1 in GC development.

Methods

Clinical specimens were collected from patients with GC to detect the level of circRHOT1. The expression of circRHOT1 in several GC cell lines was detected by quantitative real-time polymerase chain reaction. Cell Counting Kit 8 (CCK-8), colony formation, and xenograft tumor growth experiments were performed to check cell proliferation. Cell ferroptosis was determined by the levels of intracellular iron, Fe2+ (Divalent iron ion), lipid reactive oxygen species, malondialdehyde, and glutathione. The protein levels of SLC7A11 and glutathione peroxidase-4 (GPX4) were detected by western blot assays. The epigenetic regulation of the GPX4 gene was analyzed by chromatin immunoprecipitation assays.

Results

CircRHOT1 was more highly expressed in the GC tumors than the adjacent non-tumor tissues. The knockdown of circRHOT1 significantly suppressed cell growth (P<0.05) and stimulated the ferroptosis of the GC cells (P<0.05). CircRHOT1 recruited KAT5 (Acetyltransferase Tip60) to promote the acetylation of lysine 27 on histone H3 protein subunit (H3k27Ac) of the GPX4 gene and stimulated gene transcription. The overexpression of KAT5 and GPX4 notably reversed the anti-proliferation effect of circRHOT1 depletion (P<0.05).

Conclusions

CircRHOT1 promoted GC progression and suppressed ferroptosis by recruiting KAT5 to initiate GPX4 transcription. Our findings showed that cirRHOT1 is a promising target for GC treatment.

Efficacy of PD-1 Inhibitors in First-Line Treatment for Advanced Gastroesophageal Junction and Gastric Cancer by Subgroups: A Systematic Review and Meta-Analysis

BACKGROUND

PD-1 inhibitors have been approved for the first-line treatment of patients with advanced gastric cancer, gastroesophageal junction cancer, or esophageal adenocarcinoma. However, the results of several clinical trials are not entirely consistent, and the dominant population of first-line immunotherapy for advanced gastric/gastroesophageal junction cancer still needs to be precisely determined.

OBJECTIVE

This objective of this study is to evaluate the efficacy of anti-PD-1/PD-L1 therapy in advanced gastric/gastroesophageal junction adenocarcinoma patients through a systematic review and meta-analysis of relevant clinical trials.

METHOD

The PubMed, Embase, and Cochrane Library electronic databases were searched up to August 1, 2022, for clinical trials of anti-PD-1/PD-L1 immunotherapy for the first-line treatment of advanced gastroesophageal cancer. Hazard ratios and 95% confidence intervals for overall survival, progression-free survival, and objective response rates were extracted and pooled for meta-analysis. Prespecified subgroups included the following: agent type, PD-L1 expression, and high microsatellite instability.

RESULTS

This study analyzed 5 RCTs involving 3,355 patients. Compared with the chemotherapy group, the combined immunotherapy group had a significantly higher objective response rate (OR = 0.63, 95% CI: 0.55-0.72, p < 0.00001) and prolonged overall survival (HR = 0.82, 95% CI: 0.76-0.88, p < 0.00001) and progression-free survival (HR = 0.75, 95% CI: 0.69-0.82, p < 0.00001). The combination of immunotherapy and chemotherapy prolonged OS in both MSI-H (HR = 0.38, p = 0.002) and MSS (HR = 0.78, p < 0.00001) populations, but there was a significant difference between groups (p = 0.02). However, in improving ORR, the benefit of ICI combined with chemotherapy in the MSS group and MSI-H group was not significantly different between groups (p = 0.52). Combination therapy with ICIs was more effective than chemotherapy alone in prolonging OS in the subgroup with a high CPS, regardless of the CPS cutoff for PD-L1. However, when the cutoff of CPS was 1, the difference between subgroups did not reach statistical significance (p = 0.12), while the benefit ratio of the MSI-H group was higher when the cutoff was 10 (p = 0.004) than when the cutoff value was 5 (p = 0.002).

CONCLUSIONS

For first-line treatment of advanced gastroesophageal cancer, an ICI combination strategy is more effective than chemotherapy. The subgroup of patients with a CPS ≥10 has a more significant benefit, and CPS ≥10 has the potential to be used as an accurate marker of the dominant population of immuno-combined therapy.

Development of a novel copper metabolism-related risk model to predict prognosis and tumor microenvironment of patients with stomach adenocarcinoma

Background: Stomach adenocarcinoma (STAD) is the fourth highest cause of cancer mortality worldwide. Alterations in copper metabolism are closely linked to cancer genesis and progression. We aim to identify the prognostic value of copper metabolism-related genes (CMRGs) in STAD and the characteristic of the tumor immune microenvironment (TIME) of the CMRG risk model. Methods: CMRGs were investigated in the STAD cohort from The Cancer Genome Atlas (TCGA) database. Then, the hub CMRGs were screened out with LASSO Cox regression, followed by the establishment of a risk model and validated by GSE84437 from the Expression Omnibus (GEO) database. The hub CMRGs were then utilized to create a nomogram. TMB (tumor mutation burden) and immune cell infiltration were investigated. To validate CMRGs in immunotherapy response prediction, immunophenoscore (IPS) and IMvigor210 cohort were employed. Finally, data from single-cell RNA sequencing (scRNA-seq) was utilized to depict the properties of the hub CMRGs. Results: There were 75 differentially expressed CMRGs identified, 6 of which were linked with OS. 5 hub CMRGs were selected by LASSO regression, followed by construction of the CMRG risk model. High-risk patients had a shorter life expectancy than those low-risk. The risk score independently predicted STAD survival through univariate and multivariate Cox regression analyses, with ROC calculation generating the highest results. This risk model was linked to immunocyte infiltration and showed a good prediction performance for STAD patients' survival. Furthermore, the high-risk group had lower TMB and somatic mutation counters and higher TIDE scores, but the low-risk group had greater IPS-PD-1 and IPS-CTLA4 immunotherapy prediction, indicating a higher immune checkpoint inhibitors (ICIs) response, which was corroborated by the IMvigor210 cohort. Furthermore, those with low and high risk showed differential susceptibility to anticancer drugs. Based on CMRGs, two subclusters were identified. Cluster 2 patients had superior clinical results. Finally, the copper metabolism-related TIME of STAD was concentrated in endothelium, fibroblasts, and macrophages. Conclusion: CMRG is a promising biomarker of prognosis for patients with STAD and can be used as a guide for immunotherapy.

Comprehensive Profiling of Early Neoplastic Gastric Microenvironment Modifications and Biodynamics in Impaired BMP-Signaling FoxL1+-Telocytes

FoxL1⁺telocytes (TC^FoxL1+) are novel gastrointestinal subepithelial cells that form a communication axis between the mesenchyme and epithelium. TC^FoxL1+ are strategically positioned to be key contributors to the microenvironment through production and secretion of growth factors and extracellular matrix (ECM) proteins. In recent years, the alteration of the bone morphogenetic protein (BMP) signaling in TC^FoxL1+ was demonstrated to trigger a toxic microenvironment with ECM remodeling that leads to the development of pre-neoplastic gastric lesions. However, a comprehensive analysis of variations in the ECM composition and its associated proteins in gastric neoplasia linked to TC^FoxL1+ dysregulation has never been performed. This study provides a better understanding of how TC^FoxL1+ defective BMP signaling participates in the gastric pre-neoplastic microenvironment. Using a proteomic approach, we determined the changes in the complete matrisome of BmpR1a^△FoxL1+ and control mice, both in total antrum as well as in isolated mesenchyme-enriched antrum fractions. Comparative proteomic analysis revealed that the deconstruction of the gastric antrum led to a more comprehensive analysis of the ECM fraction of gastric tissues microenvironment. These results show that TC^FoxL1+ are key members of the mesenchymal cell population and actively participate in the establishment of the matrisomic fraction of the microenvironment, thus influencing epithelial cell behavior.

Expression of hepatocyte nuclear factor 4 alpha, wingless-related integration site, and β-catenin in clinical gastric cancer

BACKGROUND

Gastric cancer (GC) is the second most common cause of cancer-related deaths worldwide. Hepatocyte nuclear factor 4 alpha (HNF4α) that belongs to the nuclear hormone receptor superfamily, is overexpressed in GC tissues, and might be involved in the development of GC by regulating its downstream wingless-related integration site (WNT)/β-catenin signaling.

AIM

To clarify the expression of HNF4α/WNT5a/β-catenin signaling proteins in clinical GC tissues.

METHODS

We immunohistochemically stained pathological blocks of GC and matched para-cancerous tissues. The intensity of HNF4α, WNT5a and β-catenin staining in the tumor cells was determined according to cell rates and staining intensity. The correlations between GC and HNF4α, WNT5a, and β-catenin expression using chi-square and paired chi-square tests. Relationships between double-positive HNF4α and WNT5a expression and types of gastric tumor tissues were assessed using regression analysis. Correlations between HNF4α and WNT5a expression at the RNA level in GC tissues found in the TCGA database were analyzed using Pearson correlation coefficients.

RESULTS

We found more abundant HNF4α and WNT5a proteins in GC, especially in mucinous adenocarcinoma and mixed GC than in adjacent tissues (P < 0.001). Low and high levels of cytoplasmic β-catenin respectively expressed in GC and adjacent tissues (P < 0.001) were not significantly associated with pathological parameters.

CONCLUSION

The expressions of HNF4α and WNT5a could serve as early diagnostic biomarkers for GC.

Evaluation of the 18F-FDG-PET/CT uptake association with pathological and immunohistochemistry features in esophagogastric adenocarcinoma

BACKGROUND

The present study aimed to analyze the association between 18F-fluorodeoxyglucose (FDG) uptake and histologic panel in esophagogastric adenocarcinoma.

METHODS

We retrospectively enrolled 26 patients with histologically confirmed esophageal, gastroesophageal junction and gastric adenocarcinoma that have been submitted to pretreatment FDG-PET/CT. We collected the cancer tissue sample of each patient and performed immunohistochemical analyses of the glucose transport protein 1 (GLUT-1), Ki-67, cysteine aspartate-specific proteinases (Caspase)-3 and hexokinase-1, and evaluated the association of these parameters with FDG uptake. The FDG uptake was measured by tumor standardized uptake value (SUV), metabolic tumor volume (MTV), and Total Lesion Glycolysis (TLG). Besides, we analyzed the association of FDG uptake and tumor location, Lauren's histologic subtype, grade of cellular differentiation and intratumoral inflammatory infiltrate.

RESULTS

We found a positive association between GLUT-1 with SUV and TLG, Caspase-3 and SUV and inflammation grade with SUV.

CONCLUSION

Tumor inflammation infiltrate, GLUT-1 and Caspase-3 correlated with 18F-FDG uptake in PET/CT in esophagogastric adenocarcinoma. These findings may help understand the pathologic PET/CT significance in cancer. Understanding the meaning of the 18F-FDG uptake in the field of tumor histologic and immunohistochemistry features is essential to allow the evolution of PET/CT application in esophageal and gastric carcinomas.

LC3B, mTOR, AMPK Are Molecular Targets for Neoadjuvant Chemotherapy in Gastric Cancers

Autophagy plays a dual role in oncogenesis processes. On one hand, autophagy enhances the cell resistance to oncogenic factors, and on the other hand, it participates in the tumor progression. The aim of the study was to find the associations between the effectiveness of the FLOT regimen in resectable gastric cancers (GCs) with the key autophagy-related proteins. Materials and Methods: The study included 34 patients with morphologically verified gastric cancer. All patients had FLOT neoadjunvant chemotherapy (NACT) (fluorouracil, leucovorin, oxaliplatin, and docetaxel) followed by gastrectomy. The studied tissue material was the non-transformed and tumor tissues obtained during diagnostic video gastroscopy in patients before the start of the combined treatment and after surgical treatment, frozen after collection. The LC3B, mTOR, and AMPK expression was determined by real-time PCR. The content of the LC3B protein was determined by Western blotting analysis. Results: The mRNA level and the content of the LC3B protein were associated with the tumor stage and the presence of signet ring cells. The AMPK mRNA level was increased in patients with the T4N0-2M0 stage by 37.7 and 7.33 times, which was consequently compared with patients with the T2N0M0 and T3N0-1M0 stages. The opposite changes in the mTOR and AMPK in the GCs before anti-cancer therapy were noted. The tumor size and regional lymph node affections were associated with a decrease in the mTOR mRNA level. A decrease in the mTOR expression was accompanied by an increase in the AMPK expression in the GCs. The mTOR expression was reduced in patients with a cancer spreading; in contrast, AMPK grew with the tumor size. There was an increase in the LC3B expression, which can probably determine the response to therapy. An increase in LC3B mRNA before the start of treatment and the protein content in cancers after NACT with a decrease in therapy effectiveness was recorded. There was an increase in the protein level in patients with partial regression and stabilization by 3.65 and 5.78 times, respectively, when compared with patients with complete tumor regression was noted. Conclusions: The anticancer effectiveness in GCS is down to the LC3B, mTOR, and AMPK expression. These were found to be entire molecular targets affecting the cancer progression and metastasis as well as the NACT effectiveness.

SNHG3 Affects Gastric Cancer Development by Regulating SEPT9 Methylation

Background

Gastric cancer (GC) is a common malignancy that can be formed by methylation-induced deactivation of tumor silencer genes, which is one of the key mechanisms of tumorigenesis. SEPT9 methylation, a symptomatic marker for tumors, can downregulate gene expression. Long noncoding RNA small nucleolar host gene 3 (lncRNA SNHG3) is a new type of lncRNA related to cancer. Our study investigated the mechanism of SNHG3 regulation of SEPT9 methylation and its effects on the growth, metastasis, and spread of gastric cancer cells.

Methods

Quantitative real-time PCR (qRT–PCR) was used to detect SNHG3 and miR-448 in gastric cancer, and a dual-luciferase experiment verified the effects of SNHG3, miR-448, and DNMT1. After abnormally expressing SNHG3, miR-448, and DNMT1 alone or together, methylation-specific PCR was performed to determine the methylation of SEPT9, Western blotting was performed to detect the expression of DNA methyltransferase 1 (DNMT1) and SEPT9, and Transwell, scratch, and CCK-8 assays were performed to reveal the invasion, migration, and cell growth of gastric cancer cells.

Results

We found that SNHG3 was upregulated in gastric cancer and that SNHG3 knockdown or miR-448 overexpression inhibited SEP9 methylation and therefore increased its expression, thereby inhibiting the growth, metastasis, and spread of gastric cancer cells.

Conclusion

Our study indicates that SNHG3 regulates SEPT9 methylation by targeting miR-448/DNMT1 and subsequently affecting the occurrence and development of gastric cancer.

Single-Cell Sequencing Analysis Based on Public Databases for Constructing a Metastasis-Related Prognostic Model for Gastric Cancer

Background

Although incidences of gastric cancer have decreased in recent years, the disease remains a significant danger to human health. Lack of early symptoms often leads to delayed diagnosis of gastric cancer, so that many patients miss the opportunity for surgery. Treatment for advanced gastric cancer is often limited. Immunotherapy, targeted therapy, and the mRNA vaccine have all emerged as potentially viable treatments for advanced gastric cancer. However, our understanding of the immune microenvironment of gastric cancer is far from sufficient; now is the time to explore this microenvironment.

Methods

In our study, using TCGA dataset and the GEO dataset GSE62254, we performed in-depth transcriptome and single-cell sequencing analyses based on public databases. We analyzed differential gene expressions of immune cells in metastatic and nonmetastatic gastric cancer and constructed a prognostic model of gastric cancer patients based on these differential gene expressions. We also screened candidate vaccine genes for gastric cancer.

Results

This prognostic model can accurately predict the prognosis of gastric cancer patients by dividing them into high-risk and low-risk groups. In addition to this, we identified a candidate vaccine gene for gastric cancer: PTPN6.

Conclusions

Our study could provide new ideas for the treatment of gastric cancer.

LncRNA GACAT3: A Promising Biomarker and Therapeutic Target in Human Cancers

Long non-coding RNAs (lncRNAs) are a class of functional RNA molecules that do not encode proteins and are composed of more than 200 nucleotides. LncRNAs play important roles in epigenetic and gene expression regulation. The oncogenic lncRNA GACAT3 was recently discovered to be dysregulated in many tumors. Aberrant expression of GACAT3 contributes to clinical characteristics and regulates multiple oncogenic processes. The association of GACAT3 with a variety of tumors makes it a promising biomarker for diagnosis, prognosis, and targeted therapy. In this review, we integrate the current understanding of the pathological features, biological functions, and molecular mechanisms of GACAT3 in cancer. Additionally, we provide insight into the utility of GACAT3 as an effective diagnostic and prognostic marker for specific tumors, which offers novel opportunities for targeted therapeutic intervention.

Transcriptional and Epigenetic Bioinformatic Analysis of Claudin-9 Regulation in Gastric Cancer

Gastric cancer is a heterogeneous disease that represents 5% to 10% of all new cancer cases worldwide. Advances in histological diagnosis and the discovery of new genes have admitted new genomic classifications. Nevertheless, the bioinformatic analysis of gastric cancer databases has favored the detection of specific differentially expressed genes with biological significance. Claudins, a family of proteins involved in tight junction physiology, have emerged as the key regulators of cellular processes, such as growth, proliferation, and migration, associated with cancer progression. The expression of Claudin-9 in the gastric cancer tissue has been linked to poor prognosis, however, its transcriptional and epigenetic regulations demand a more comprehensive analysis. Using the neural network promoter prediction, TransFact, Uniprot-KB, Expasy-SOPMA, protein data bank, proteomics DB, Interpro, BioGRID, String, and the FASTA protein sequence databases and software, we found the following: (1) the promoter sequence has an unconventional structure, including different transcriptional regulation elements distributed throughout it, (2) GATA 4, GATA 6, and KLF5 are the key regulators of Claudin-9 expression, (3) Oct1, NF-κB, AP-1, c-Ets-1, and HNF-3β have the higher binding affinity to the CLDN9 promoter, (4) Claudin-9 interacts with cell differentiation and development proteins, (5) CLDN9 is highly methylated, and (6) Claudin-9 expression is associated with poor survival. In conclusion, Claudin-9 is a protein that should be considered a diagnostic marker as its gene promoter region binds to the transcription factors associated with the deregulation of cell control, enhanced cell proliferation, and metastasis.

Transcription factor KLF15 inhibits the proliferation and migration of gastric cancer cells via regulating the TFAP2A-AS1/NISCH axis

BACKGROUND

Recently, overwhelming evidence supports that long noncoding RNAs (lncRNAs) play crucial roles in the occurrence and progression of tumors. However, the role and mechanism of lncRNA TFAP2A-AS1 in human gastric cancer (GC) remains unclear. Thus, the biological role and regulatory mechanisms of TFAP2A-AS1 in GC were explored.

METHODS

Quantitative real-time PCR (qPCR) was applied to detect gene expression. Western blot was used to measure protein expression. Cell proliferation and migration were determined by functional assays. Fluorescence in situ hybridization (FISH) assays were performed to determine the subcellular distribution of TFAP2A-AS1 in GC. Mechanism investigations were conducted to explore the downstream genes of TFAP2A-AS1 and the upstream transcription factor of TFAP2A-AS1 in GC cells.

RESULTS

TFAP2A-AS1 inhibits the proliferation and migration of GC cells. In the downstream regulation mechanism, miR-3657 was verified as the downstream gene of TFAP2A-AS1 and NISCH as the target of miR-3657. NISCH also suppresses cell proliferation and migration in GC. In the upstream regulation mechanism, transcription factor KLF15 positively mediates TFAP2A-AS1 to suppress GC cell proliferation and migration.

CONCLUSION

KLF15-mediated TFAP2A-AS1 hampers cell proliferation and migration in GC via miR-3657/NISCH axis.

The Therapeutic Value and Molecular Mechanisms of lncRNA FENDRR in Human Cancer

BACKGROUND

Long noncoding RNA (lncRNA) fetal-lethal non-coding developmental regulatory RNA (FENDRR), a newly known lncRNA, has been reported to be abnormally expressed in diverse tumors. This review is focused on clarifying the mechanism of FENDRR to regulate the biological process of tumors, affirming its value as a target for tumor therapy.

METHODS

The pathophysiological mechanism of FENDRR acting on tumors has been analyzed and summarized by reviewing PubMed.

RESULTS

The expression of lncRNA FENDRR is abnormally altered in clinical cancers, promoting the malignant transformation of a variety of tumors, including colon cancer, cervical cancer, hepatocellular carcinoma, prostate cancer, Malignant melanoma, lung cancer, osteosarcoma, breast cancer, etc. Cellular processions, including proliferation, invasion, apoptosis and migration affected by FENDRR, have been revealed.

CONCLUSION

Specific evidences for the involvement of LncRNA FENDRR in cancer regulatory processes suggest that FENDRR has the potential to be a biomarker or clinical therapeutic target for malignant tumors.

CircRNA_0043691 sponges miR-873-3p to promote metastasis of gastric cancer

Circular RNAs (circRNAs) are a class of novel RNAs, and aberrant expression of circRNAs has been implicated in human diseases, including gastric cancer (GC). This study aimed to identify the mechanism of circRNA_0043691 in regulating the progression of GC. GSE141977 was downloaded from Gene Expression Omibus ( http://www.ncbi.nlm.nih.gov/geo/ ). Differentially expressed circRNAs were obtained by R software. The expression levels of circRNA_0043691 in GC tissue and normal tissue were identified by quantitative real-time polymerase chain reaction (qRT-PCR). Knockdown of circRNA_0043691 was then constructed and verified by qRT-PCR. Cell viability, migration, and invasion capacity were determined by Cell Counting Kit-8 assay, Transwell migration, and invasion, respectively. Next, knockdown of miR-873-3p was constructed and co-cultured with circRNA_0043691 knockdown to identify whether knockdown of miR-873-3p could attenuate the circRNA_0043691 knockdown on GC cells proliferation, migration, and invasion. The relationship between miR-873-3p and circRNA_0043691 or GART was predicted by bioinformatics tools and verified by dual-luciferase reporter. A total of 211 circRNAs were significantly differentially expressed, including 143 remarkably downregulated circRNAs and 68 significantly upregulated circRNAs. CircRNA_0043691 was upregulated in GC tissue. Knockdown of circRNA_0043691 decreased cell viability, migration, and invasion in GC cells. CircRNA_0043691 has potential putative binding sites with miR-873-3p. Moreover, CircRNA_0043691 positively regulated GART expression by sponging miR-873-3p. Furthermore, knockdown of miR-591 could partially attenuate the si-circRNA_0043691 on the GART expression. GART was upregulated in GC tissue and knockdown of GART could inhibit GC cells proliferation and invasion. Knockdown of circRNA_0043691 delayed the progression of GC via modulating the miR-873-3p-GART axis.

CDC37L1 acts as a suppressor of migration and proliferation in gastric cancer by down-regulating CDK6

The co-chaperone protein CDC37 (Cell division cycle 37) is well known to regulate multiple protein kinases and involved in tumor progression. However to date, little is known about its analogue CDC37L1 (Cell division cycle 37 like 1) in tumorigenesis. This study aimed to explore the expression and function of CDC37L1 in gastric cancer (GC). The immunohistochemical staining in a tissue microarray showed a weak expression of CDC37L1 in high grade GC tissues compared with low grade tissues. Consistently, data from online database analysis demonstrated that CDC37L1 level was decreased in stage 4 patients and low expression of CDC37L1 indicated a poor prognosis. Functional studies revealed that CDC37L1 could inhibit GC cell proliferation and migration in CCK8, EdU incorporation, colony formation and transwell assays. In the meantime, CDC37L1 also inhibited the tumorigenicity of GC cells in nude mice. Mechanistically, we found that CDC37L1 had an impact on CDK6 protein expression by western blotting. Palbociclib, a specific CDK4/6 inhibitor, was discovered to block the rapid growth phenotype of GC cells induced by CDC37L1 silencing. Taken together, these findings unveiled a tumor-suppressive role of CDC37L1 in GC, and CDK6 may act as a downstream effector in this process.

Identification of long noncoding RNA TC0101441 as a novel biomarker for diagnosis and prognosis of gastric cancer

The present work aimed to explore the prognostic values of lncRNA TC0101441 (TC0101441) in patients with gastric cancer (GC). The expression of TC0101441 in a total of 159 GC specimens and matched normal specimens was detected by quantitative RT-PCR. ROC assays were conducted to determine the diagnostic value of TC0101441 expression in GC patients. The association of TC0101441 expression with clinical characteristics of 159 patients was analyzed using chi-square test. Kaplan-Meier methods were employed to determine the prognostic value of TC0101441 expression in the survival rate of GC patients. Multivariate Cox regression assays were used to identify whether TC0101441 could be a prognostic biomarker for GC patients. We found that TC0101441 expression was significantly increased in GC specimens compared to that in the normal specimens (P < 0.01). High TC0101441 expression was correlated with lymphatic metastasis (P = 0.027) and TNM stage (P = 0.015). TC0101441 could distinguish GC specimens from adjacent normal gastric specimens with an area under the receiver operating characteristic curve (AUC) of 0.8082. Survival data revealed that patients with high TC0101441 expression had worse overall survival (P = 0.0009) and disease-free survival (P < 0.0001) rates than those with low TC0101441 expression. Multivariate assays showed that TC0101441 expression was an independent biomarker for GC patients. The present study suggested that TC0101441 expression was increased in GC and may be aprognostic and diagnostic biomarker for GC.

LINC01089 is a tumor-suppressive lncRNA in gastric cancer and it regulates miR-27a-3p/TET1 axis

Background

Gastric cancer (GC) is one of the most common malignancies around the world. Recently, the role of long non-coding RNA (lncRNA) in cancer biology has become a hot research topic. This work aimed to explore the biological function and underlying mechanism of LINC01089 in GC.

Methods

Quantitative real-time polymerase chain reaction (qRT-PCR) was employed to investigate the expression of LINC01089 in GC tissues and cells. The relationship between the expression level of LINC01089 and the clinicopathological parameters of GC was assessed. Cell models of LINC01089 overexpression, LINC01089 knockdown, miR-27a-3p overexpression, and miR-27a-3p inhibition were established by transfection. CCK-8 assay, BrdU assay, and Transwell assay were utilized to investigate the malignant biological behaviors of GC cell lines after transfection. Dual luciferase activity reporter assay, Pearson’s correlation analysis, and Western blot were utilized to the regulatory relationships among LINC01089, miR-27a-3p and tet methylcytosine dioxygenase 1 (TET1).

Result

LINC01089 down-regulation was observed in GC tissues and cell lines. Low expression level of LINC01089 in GC tissues was markedly linked to larger tumor size, higher T stage, as well as lymphatic metastasis of the patients. Functional experiments implied that LINC01089 overexpression impeded the proliferation, migration, as well as invasion of GC cells, whereas LINC01089 knockdown promoted the above malignant phenotypes. Additionally, up-regulation of miR-27a-3p was also observed in GC tissues. Functional experiments also showed that, miR-27a-3p overexpression boosted the malignant biological behaviors of GC cells; on the contrast, these phenotypes were impeded by miR-27a-3p inhibition. Moreover, LINC01089 interacted with and repressed miR-27a-3p, and miR-27a-3p antagonized the impact of LINC01089 on GC cells. Additionally, TET1 was verified as a target gene of miR-27a-3p, and could be positively regulated by LINC01089.

Conclusion

LINC01089 impedes the proliferation, migration, and invasion of GC cells by adsorbing miR-27a-3p and up-regulating the expression of TET1.

Immunological Aspects of the Tumor Microenvironment and Epithelial-Mesenchymal Transition in Gastric Carcinogenesis

Infection with Helicobacter pylori, a Gram-negative, microaerophilic pathogen often results in gastric cancer in a subset of affected individuals. This explains why H. pylori is the only bacterium classified as a class I carcinogen by the World Health Organization. Several studies have pinpointed mechanisms by which H. pylori alters signaling pathways in the host cell to cause diseases. In this article, the authors have reviewed 234 studies conducted over a span of 18 years (2002-2020). The studies investigated the various mechanisms associated with gastric cancer induction. For the past 1.5 years, researchers have discovered new mechanisms contributing to gastric cancer linked to H. pylori etiology. Alongside alteration of the host signaling pathways using oncogenic CagA pathways, H. pylori induce DNA damage in the host and alter the methylation of DNA as a means of perturbing downstream signaling. Also, with H. pylori, several pathways in the host cell are activated, resulting in epithelial-to-mesenchymal transition (EMT), together with the induction of cell proliferation and survival. Studies have shown that H. pylori enhances gastric carcinogenesis via a multifactorial approach. What is intriguing is that most of the targeted mechanisms and pathways appear common with various forms of cancer.