m6A modification-mediated lncRNA TP53TG1 inhibits gastric cancer progression by regulating CIP2A stability.

Long noncoding RNAs (lncRNAs) are associated with various types of cancer. However, the precise roles of many lncRNAs in tumor progression remain unclear. In this study, we found that the expression of the lncRNA TP53TG1 was downregulated in gastric cancer (GC) and it functioned as a tumor suppressor. In addition, low TP53TG1 expression was significantly associated with poor survival in patients with GC. TP53TG1 inhibited the proliferation, metastasis, and cell cycle progression of GC cells, while it promoted their apoptosis. m6A modification sites are highly abundant on TP53TG1, and demethylase ALKBH5 reduces TP53TG1 stability and downregulates its expression. TP53TG1 interacts with cancerous inhibitor of protein phosphatase 2A (CIP2A) and triggers its ubiquitination-mediated degradation, resulting in the inhibition of the PI3K/AKT pathway. These results suggest that TP53TG1 plays an important role in inhibiting the progression of GC and provides a crucial target for GC treatment.

Sense and non-sense of imaging in the era of organ preservation for rectal cancer.

This review summarizes the current applications and benefits of imaging modalities for organ preservation in the treatment of rectal cancer. The concept of organ preservation in the treatment of rectal cancer has revolutionized the way rectal cancer is managed. Initially, organ preservation was limited to patients with locally advanced rectal cancer who needed neoadjuvant therapy to reduce tumor size before surgery and achieved complete response. However, neoadjuvant therapy is now increasingly utilized for smaller and less aggressive tumors to achieve primary organ preservation. Additionally, more intensive neoadjuvant strategies are employed to improve complete response rates and increase the chances of successful organ preservation. The selection of patients for organ preservation is a critical component of treatment, and imaging techniques such as digital rectal exam, endoscopy, and MRI are commonly used for this purpose. In this review, we provide an overview of what imaging modalities should be chosen and how they can aid in the selection and follow-up of patients undergoing organ-preserving strategies.

Erratum: Overexpression of TC2N is associated with poor prognosis in gastric cancer: Erratum.

[This corrects the article DOI: 10.7150/jca.50653.].

PMN-MDSCs accumulation induced by CXCL1 promotes CD8+ T cells exhaustion in gastric cancer.

Myeloid-derived suppressor cells (MDSCs) accumulation in multiple tumor is associated with immune checkpoint inhibitors (ICIs) resistance. However, mechanisms of MDSCs in ICIs resistance of gastric cancer (GC) have not been thoroughly explored. In this study, we found that the PMN-MDSCs frequency rather than the M-MDSCs frequency was correlated with the survival of GC patients and CXCL1 induced PMN-MDSCs accumulation in GC. S100A8/A9 heterodimer, a hallmark of MDSCs, upregulated the CXCL1 expression in GC cells through the TLR4/p38 MAPK/NF-κB pathway. Notably, PMN-MDSCs exerted immunosuppressive effect through S100A8/A9. Mechanically, S100A8/A9 led to CD8+ T cells exhaustion including inhibiting CD8+ T cells glycolysis, proliferation and TNF-α and IFN-γ production, which was dependent on TLR4/AKT/mTOR pathway. In tumor-bearing mice, the CXCR2 antagonist SB225002 decreased PMN-MDSCs accumulation, increased CD8+ T cells infiltration in GC and further enhanced anti-tumor efficacy of anti-PD-1. Taken together, our study identified that CXCL1 induced PMN-MDSCs accumulation in GC, and unveiled how PMN-MDSCs promoted CD8+ T cells exhaustion, which may provide a potential therapeutic strategy for GC.

Overexpression of TC2N is associated with poor prognosis in gastric cancer.

Background: Tac2-N (TC2N) is a tandem C2 domain-containing protein, acting as a novel oncogene or suppressor in different kinds of cancers. However, the status of TC2N expression and its significance in gastric cancer (GC) is still unclear. The present study is aimed to elucidate the clinicopathological significance and prognostic value of TC2N level in GC. Methods: We used sequencing data from the Cancer Genome Atlas (TCGA) database to analyze TC2N expression in GC by UALCAN database and Gene Expression Profiling Interactive Analysis tools (GEPIA). TC2N expression level in 12 pairs of fresh GC tissues and adjacent nontumorous tissues was detected by quantitative real-time reverse-transcription polymerase chain reaction (RT-PCR) and Western blot (WB) assays. Immunohistochemical (IHC) staining was used to detect TC2N protein expression in Paraffin-embedded tissues in our center. In vitro proliferation, migration and invasion assays were used to evaluate the effect of TC2N on functional capability of gastric cancer cells. LinkedOmics was used to identify gene expressions associated with TC2N. Results: The mRNA and protein expression of TC2N in gastric cancer were both significantly higher than normal gastric mucosa. It was also elevated in gastric cancer cells compared with normal gastric epithelium cell. In vitro assays suggested that TC2N facilitated proliferation, migration and invasion of gastric cancer cells. Bioinformatic analysis showed a widespread impact of TC2N on the transcriptome and a strong interaction with tumor associated genes. We also found that TC2N was an independent prognostic factor for long-term survival in GC patients and its high expression was evidently associated with poor overall survival and recurrence-free survival. Conclusions: Our results show that high level of TC2N correlates with poor prognosis in patients with gastric cancer and promotes the development of gastric cancer. Thus, TC2N expression can serve as a prognostic biomarker for patients with gastric cancer.

Necroptosis-Related lncRNAs: Predicting Prognosis and the Distinction between the Cold and Hot Tumors in Gastric Cancer.

BACKGROUND: In the face of poor prognosis and immunotherapy failure of gastric cancer (GC), this project tried to find new potential biomarkers for predicting prognosis and precision medication to ameliorate the situation. METHODS: To form synthetic matrices, we retrieved stomach adenocarcinoma transcriptome data from Genotype-Tissue Expression Project (GTEx) and The Cancer Genome Atlas (TCGA). Necroptosis-related prognostic lncRNA was identified by coexpression analysis and univariate Cox regression. Then we performed the least absolute shrinkage and selection operator (LASSO) to construct the necroptosis-related lncRNA model. Next, the Kaplan-Meier analysis, time-dependent receiver operating characteristics (ROC), univariate Cox (uni-Cox) regression, multivariate Cox (multi-Cox) regression, nomogram, and calibration curves were made to verify and evaluate the model. Gene set enrichment analyses (GSEA), principal component analysis (PCA), immune analysis, and prediction of the half-maximal inhibitory concentration (IC50) in risk groups were also analyzed. For further discussing immunotherapy between the cold and hot tumors, we divided the entire set into two clusters based on necroptosis-related lncRNAs. RESULTS: We constructed a model with 16 necroptosis-related lncRNAs. In the model, we found the calibration plots showed a good concordance with the prognosis prediction. The area's 1-, 2-, and 3-year OS under the ROC curve (AUC) were 0.726, 0.763, and 0.770, respectively. Risk groups could be a guide of systemic treatment because of significantly different IC50 between risk groups. Above all, clusters could help distinguish between the cold and hot tumors effectively and contribute to precise mediation. Cluster 2 was identified as the hot tumor and more susceptible to immunotherapeutic drugs. CONCLUSION: The results of this project supported that necroptosis-related lncRNAs could predict prognosis and help make a distinction between the cold and hot tumors for improving individual therapy in GC.

p53-Induced LINC00893 Regulates RBFOX2 Stability to Suppress Gastric Cancer Progression.

Long noncoding RNAs (lncRNAs) have been reported to regulate diverse tumorigenic processes. However, little is known about long intergenic non-protein coding RNA 00893 (LINC00893) and its role in gastric cancer (GC). Herein we investigated its biological functions and molecular mechanism in GC. LINC00893 was decreased in GC tissues but significantly elevated in AGS cells after treatment with Nutlin-3. In GC patients, it was found that low expression of LINC00893 was correlated with tumor growth, metastasis and poor survival. Functionally, overexpression of LINC00893 suppressed the proliferation, migration and invasion of GC cells. Mechanistically, LINC00893 regulated the expression of epithelial-mesenchymal transition (EMT)-related proteins by binding to RNA binding fox-1 homolog 2 (RBFOX2) and promoting its ubiquitin-mediated degradation, thus suppressing the EMT and related functions of GC. In addition, the transcription factor p53 can regulate the expression of LINC00893 in an indirect way. Taken together, these results suggested that LINC00893 regulated by p53 repressed GC proliferation, migration and invasion by functioning as a binding site for RBFOX2 to regulate its stability and the expression of EMT-related proteins. LINC00893 acts as a tumor-inhibiting lncRNA that is induced by p53 in GC and regulates EMT by binding to RBFOX2, thus providing a novel experimental basis for the clinical treatment of GC.

Association of Preoperative Serum Carcinoembryonic Antigen and Gastric Cancer Recurrence: A Large Cohort Study.

Background and Aim: Measuring postoperative carcinoembryonic antigen (CEA) is recommended by guidelines to help detecting recurrence of gastric cancer patients. However, the prognostic significance of elevated preoperative CEA is unclear. This study aims to investigate whether patients with elevated preoperative CEA have a higher risk of recurrence than patients with normal preoperative CEA. Methods: We conducted a retrospective cohort study at a gastric cancer center in South China. Consecutive patients with stage I to III gastric adenocarcinoma who underwent curative resection at the center from January 2001 to February 2016 were identified. Patients were grouped into two cohorts: normal preoperative CEA (≤ 5 ng/ml), and elevated preoperative CEA (> 5 ng/ml). 3-year recurrence-free survival (RFS) and hazard function curves over time were estimated. Results: A total of 1,596 patients (1,063 {66.6%} male; median {Interquartile range, IQR} age, 59 {50-66} years) were identified. Patients with elevated preoperative CEA had 15.5% lower 3-year RFS (n=222 {70.4%}) than the cohorts with normal preoperative CEA (n=1,374 {85.9%}). The hazard function of recurrence for the two cohorts peaked at the similar time (around 10 months after surgery). Multivariate Cox analyses confirmed that elevated preoperative CEA was independently associated with shorter RFS (Hazard Ratio {HR}, 1.69; 95% confidence interval {CI}, 1.26-2.27; P = 0.001). Conclusions: Patients with elevated preoperative CEA are at increased risk for recurrence, especially within the first 24 months after surgery.

Inflammation-Associated Senescence Promotes Helicobacter pylori-Induced Atrophic Gastritis.

BACKGROUND & AIMS: The association between cellular senescence and Helicobacter pylori-induced atrophic gastritis is not clear. Here, we explore the role of cellular senescence in H pylori-induced atrophic gastritis and the underlying mechanism. METHODS: C57BL/6J mice were infected with H pylori for biological and mechanistic studies in vivo. Gastric precancerous lesions from patients and mouse models were collected and analyzed using senescence-associated beta-galactosidase, Sudan Black B, and immunohistochemical staining to analyze senescent cells, signaling pathways, and H pylori infection. Chromatin immunoprecipitation, luciferase reporter assays, and other techniques were used to explore the underlying mechanism in vitro. RESULTS: Gastric mucosa atrophy was highly associated with cellular senescence. H pylori promoted gastric epithelial cell senescence in vitro and in vivo in a manner that depended on C-X-C motif chemokine receptor 2 (CXCR2) signaling. Interestingly, H pylori infection not only up-regulated the expression of CXCR2 ligands, C-X-C motif chemokine ligands 1 and 8, but also transcriptionally up-regulated the expression of CXCR2 via the nuclear factor-κB subunit 1 directly. In addition, CXCR2 formed a positive feedback loop with p53 to continually enhance senescence. Pharmaceutical inhibition of CXCR2 in an H pylori-infected mouse model attenuated mucosal senescence and atrophy, and delayed further precancerous lesion progression. CONCLUSIONS: Our study showed a new mechanism of H pylori-induced atrophic gastritis through CXCR2-mediated cellular senescence. Inhibition of CXCR2 signaling is suggested as a potential preventive therapy for targeting H pylori-induced atrophic gastritis. GEO data set accession numbers: GSE47797 and GSE3556.