SIRT1 mediated gastric cancer progression under glucose deprivation through the FoxO1-Rab7-autophagy axis

CCKBR+ cancer cells contribute to the intratumor heterogeneity of gastric cancer and confer sensitivity to FOXO inhibition

The existence of heterogeneity has plunged cancer treatment into a challenging dilemma. We profiled malignant epithelial cells from 5 gastric adenocarcinoma patients through single-cell sequencing (scRNA-seq) analysis, demonstrating the heterogeneity of gastric adenocarcinoma (GA), and identified the CCKBR+ stem cell-like cancer cells associated poorly differentiated and worse prognosis. We further conducted targeted analysis using single-cell transcriptome libraries, including 40 samples, to confirm these screening results. In addition, we revealed that FOXOs are involved in the progression and development of CCKBR+ gastric adenocarcinoma. Inhibited the expression of FOXOs and disrupting cancer cell stemness reduce the CCKBR+ GA organoid formation and impede tumor progression. Mechanically, CUT&Tag sequencing and Lectin pulldown revealed that FOXOs can activate ST3GAL3/4/5 as well as ST6GALNAC6, promoting elevated sialyation levels in CCKBR+ tumor cells. This FOXO-sialyltransferase axis contributes to the maintenance of homeostasis and the growth of CCKBR+ tumor cells. This insight provides novel perspectives for developing targeted therapeutic strategies aimed at the treating CCKBR associated gastric cancer.

Association of tumour mutation burden with prognosis and its clinical significance in stage III gastric cancer

Introduction

To explore the correlation between the tumour mutation burden (TMB) and prognosis and its clinical significance among patients with stage III gastric cancer (GC).

Methods

Patients with stage III GC were divided into a high TMB and low TMB group in both a study cohort of 38 patients and the Cancer Genome Atlas (TCGA) cohort of 173 patients. In the study cohort, next-generation sequencing was used to detect mutated GC genes and obtain TMB data. In the TCGA cohort, gene set enrichment analysis was performed, and the relationship between TMB, prognosis and clinicopathologic factors was analysed. Western blot and quantitative real-time polymerase chain reaction were used to detect the expression levels of both proteins and genes. Cell viability was measured using methyl thiazolyl tetrazolium and transwell cell assays.

Results

Patients in the high TMB group had better overall survival (OS) rates than patients in the low TMB group for both cohorts and TMB was associated with age, mutation signature 1 and mutation signature 17. The Cox regression analysis revealed that age, not TMB, was an independent prognosis factor. Furthermore, genes with high-frequency mutations were significantly enriched in the RTK-RAS and Notch signalling pathways. The activation of these pathways was lower in the high TMB compared with the low TMB group, and the proliferation and migration abilities of GC cells showed a similar pattern in both TMB groups.

Conclusion

Patients in the high TMB group had better OS rates than patients in the low TMB group. Genes with high-frequency mutations were significantly enriched in the RTK-RAS and Notch pathways. Hence, TMB could serve as a prognosis biomarker with potential clinical significance.

Sirt6-Mediated Cell Death Associated with Sirt1 Suppression in Gastric Cancer

BACKGROUND

Gastric cancer, one of the leading causes of cancer-related death, is strongly associated with H. pylori infection, although other risk factors have been identified. The sirtuin (Sirt) family is involved in the tumorigenesis of gastric cancer, and sirtuins can have pro- or anti-tumorigenic effects.

METHODS

After determining the overall survival rate of gastric cancer patients with or without Sirt6 expression, the effect of Sirt6 upregulation was also tested using a xenograft mouse model. The regulation of Sirt6 and Sirt1, leading to the induction of mouse double minute 2 homolog (MDM2) and reactive oxygen species (ROS), was mainly analyzed using Western blotting and immunofluorescence staining, and gastric cancer cell (SNU-638) death associated with these proteins was measured using flow cytometric analysis.

RESULTS

Sirt6 overexpression led to Sirt1 suppression in gastric cancer cells, resulting in a higher level of gastric cancer cell death in vitro and a reduced tumor volume. ROS and MDM2 expression levels were upregulated by Sirt6 overexpression and/or Sirt1 suppression according to Western blot analysis. The upregulated ROS ultimately led to gastric cancer cell death as determined via Western blot and flow cytometric analysis.

CONCLUSION

We found that the upregulation of Sirt6 suppressed Sirt1, and Sirt6- and Sirt1-induced gastric cancer cell death was mediated by ROS production. These findings highlight the potential of Sirt6 and Sirt1 as therapeutic targets for treating gastric cancer.

The crosstalk among the physical tumor microenvironment and the effects of glucose deprivation on tumors in the past decade

The occurrence and progression of tumors are inseparable from glucose metabolism. With the development of tumors, the volume increases gradually and the nutritional supply of tumors cannot be fully guaranteed. The tumor microenvironment changes and glucose deficiency becomes the common stress environment of tumors. Here, we discuss the mutual influences between glucose deprivation and other features of the tumor microenvironment, such as hypoxia, immune escape, low pH, and oxidative stress. In the face of a series of stress responses brought by glucose deficiency, different types of tumors have different coping mechanisms. We summarize the tumor studies on glucose deficiency in the last decade and review the genes and pathways that determine the fate of tumors under harsh conditions. It turns out that most of these genes help tumor cells survive in glucose-deprivation conditions. The development of related inhibitors may bring new opportunities for the treatment of tumors.