Decreased expression levels of DAL-1 and TOB1 are associated with clinicopathological features and poor prognosis in gastric cancer

A pan-cancer analysis of anti-proliferative protein family genes for therapeutic targets in cancer

The recently discovered APRO (anti-proliferative protein) family encodes a group of trans-membrane glycoproteins and includes 6 members: TOB1, TOB2, BTG1, BTG2, BTG3 and BTG4. The APRO family is reportedly associated with the initiation and progression of cancers. This study aims to undertake a comprehensive investigation of the APRO family of proteins as a prognostic biomarker in various human tumors. We performed a pan-cancer analysis of the APRO family based on The Cancer Genome Atlas (TCGA). With the bioinformatics methods, we explored the prognostic value of the APRO family and the correlation between APRO family expression and tumor mutation burden (TMB), microsatellite instability (MSI), drug sensitivity, and immunotherapy in numerous cancers. Our results show that the APRO family was primarily down-regulated in cancer samples. The expression of APRO family members was linked with patient prognosis. In addition, APRO family genes showed significant association with immune infiltrate subtypes, tumor microenvironment, and tumor cell stemness. Finally, our study also demonstrated the relationship between APRO family genes and drug sensitivity. This study provides comprehensive information to understand the APRO family's role as an oncogene and predictor of survival in some tumor types.

A budding concept with certain microbiota, anti-proliferative family proteins, and engram theory for the innovative treatment of colon cancer

Inflammatory bowel disease (IBD) is a multifactorial chronic disease. Patients with IBD have an increased risk of developing colorectal cancer which has become a major health concern. IBD might exert a role of engrams for making the condition of specific inflammation in the gut. Dysregulation of immune cells induced by the command of engrams might be crucial in the pathogenesis of damages in gut epithelium. The anti-proliferative (APRO) family of anti-proliferative proteins characterized by immediate early responsive gene-products that might be involved in the machinery of the carcinogenesis in IBD. Herein, it is suggested that some probiotics with specific bacteria could prevent the development and/or progression of the IBD related tumors. In addition, consideration regarding the application of studying APRO family proteins for the comprehension of IBD related tumors has been presented. It is hypothesized that overexpression of Tob1, a member of APRO family proteins, in the epithelium of IBD could suppress the function of adjacent cytotoxic immune cells possibly via the paracrine signaling.

Methylation Mediated Downregulation of TOB1-AS1 and TOB1 Correlates with Malignant Progression and Poor Prognosis of Esophageal Squamous Cell Carcinoma

BACKGROUND

TOB1, a member of the transducer of erbB-2 /B-cell translocation gene family, was detected to be down-regulated in ESCC by RNA sequencing. TOB1-AS1, a head-to-head antisense lncRNA with TOB1, was down-regulated in several cancers. However, the roles of them in esophageal squamous cell carcinoma (ESCC) remained unclarified.

AIMS

To investigate the roles and functions of TOB1-AS1 and TOB1 in ESCC tumorigenesis.

MATERIALS AND METHODS

The expression levels, methylation status, biological function and mechanisms of TOB1-AS1 and TOB1 in ESCC were, respectively, detected.

RESULTS

Frequent down-regulation of TOB1-AS1 and TOB1 was verified in esophageal cancer cells and ESCC tissues, and there was a positive correlation between them in ESCC tissues. The CpG sites hypermethylation within proximal promoter of TOB1-AS1 and TOB1 could lead to transcriptional inhibition of both genes. Furthermore, expression and proximal promoter methylation status of TOB1-AS1 or TOB1 may be associated with ESCC patients' prognosis. TOB1-AS1 and TOB1 may function as tumor suppressors by inhibiting growth, migration, and invasion of esophageal cancer cells. Up-regulation of TOB1-AS1 increased expression level of TOB1, and TOB1-AS1 could work as a ceRNA to modulate ATF3 expression via competitively binding with miR-103a-2-5p. Meanwhile, ATF3, as a transcription factor, could regulate transcription of TOB1; down-regulation of TOB1-AS1 in ESCC led to decreased expression of ATF3 through ceRNA mechanism, and further influenced the transcription of TOB1.

CONCLUSION

TOB1-AS1 and TOB1 may act as tumor suppressors and may serve as potential targets for antitumor therapy in ESCC.

The Overexpression of TOB1 Induces Autophagy in Gastric Cancer Cells by Secreting Exosomes

We previously confirmed that transducer of ERBB2, 1 (TOB1) gene, can induce autophagy in gastric cancer cells. Studies have shown the biogenesis of exosomes overlaps with different autophagy processes, which helps to maintain the self-renewal and homeostasis of body cells. This study is aimed at verifying whether overexpressing TOB1 induces autophagy by secreting exosomes in gastric cancer cells and its underlying mechanisms. Differential ultracentrifugation was used to extracted the exosomes from the culture medium of gastric cancer cell line AGS-TOB1 ectopically overexpressing TOB1 (exo-AGS-TOB1, experimental group) and AGS-empty-vector cell line with low expression of endogenous TOB1 (exo-AGS-Vector, control group). Exosomal markers CD9 and TSG101 were determined in both the cell supernatants of exo-AGS-TOB1 and exo-AGS-Vector by Western blot. Under the transmission electron microscope (TEM), the exosomes were round and saucer-like vesicles with double-layer membrane structure, and the vesicles showed different translucency due to different contents. The peak size of exosomes detected by nanoparticle tracking analysis (NTA) was about 100 nm. When the exosomes of exo-AGS-TOB1 and exo-AGS-Vector were cocultured with TOB1 knockdown gastric cancer cell line HGC-27-TOB1-6E12 for 48 hours, the conversion of autophagy-related protein LC3-I to LC3-II in HGC-27-TOB1-6E12 gastric cancer cells cocultured with exo-AGS-TOB1 was significantly higher than that in the control group, and the ratio of LC3-II/LC3-I was statistically different (P < 0.05). More autophagosomes in HGC-27-TOB1-6E12 cells cocultured with exo-AGS-TOB1 for 48 hours were observed under TEM, while fewer autophagosomes were found in the control group. Lastly, miRNAs were differentially expressed by cell supernatant-exosomal whole transcriptome sequencing. Thus, our results provide new insights into TOB1-induced autophagy in gastric cancer.

Involvement of TOB1 on autophagy in gastric cancer AGS cells via decreasing the activation of AKT/mTOR signaling pathway

BACKGROUND

We previously identified the tumor suppressor gene TOB1 as related to gastric cancer. The purpose of this study was to explore whether TOB1 induces autophagy through the AKT/mTOR signaling pathway in gastric cancer.

METHODS

Western blotting was used to detect the protein levels of TOB1, LC3, AKT, mTOR, phosphorylated (p) AKT, and p-mTOR. A double fluorescent GFP-RFP-LC3 fusion protein was used to trace autophagy by laser confocal microscopy. Autophagosomes were observed by transmission electron microscopy.

RESULTS

The conversion of LC3-I to LC3-II and the LC3-II/LC3-I ratio were significantly increased in AGS cells overexpressing TOB1 compared with control cells. Fluorescence imaging showed LC3 puncta at 48 h, and these puncta increased significantly at 72 h after TOB1 transfection compared with control tumor cells. The presence of autophagosomes in AGS cells was observed at 72 h after TOB1 transfection by transmission electron microscopy, and no autophagosomes were found in the control cells. Moreover, the levels of p-AKT and p -mTOR were lower in AGS cells than in control cancer cells.

CONCLUSION

Our results provide novel insight that TOB1 might suppress gastric cancer by inducing autophagy, possibly through decreasing phosphorylation and the subsequent activation of the AKT/mTOR signaling pathway.

The rs9953490 polymorphism of DAL-1 gene is associated with gastric cancer risk in the Han population in Northeast China

Background

DAL-1 gene was reported to inhibit proliferation, migration, invasion, and epithelial to mesenchymal transition (EMT) of gastric cancer (GC) cells in our previous study. The association between the genomic variants in DAL-1 gene with risk of GC is still unclear.

Methods

In this study, 505 GC cases and 544 healthy controls (HCs) were collected to evaluate the association between six single nucleotide polymorphisms (SNPs) (rs7240736, rs73937194, rs3817466, rs8082898, rs73381527, rs9953490) of DAL-1 gene and GC risk in the Han population in Northeast China.

Results

The TA + AA genotypes of rs9953490 were significantly associated with an increased risk in N3 compared with N0 subgroup (adjusted OR = 4.56, 95% CI = 1.49–13.98, P = 0.008), and also showed evident association with an increased risk in TNM stage III compared with stage I-II (adjusted OR = 2.33, 95% CI = 1.16–4.67, P = 0.017).

Conclusion

The rs9953490 of DAL-1 gene may play an important role in the occurrence and development of GC in the Han population in Northeast China.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12876-021-01929-9.