CTNNB1 is a protein-coding gene that encodes a protein that is a key downstream component of the canonical Wnt signaling pathway. The Wnt / β-catenin signaling pathway plays an important role in tumors by regulating events such as cell survival, proliferation and differentiation. CTNNB1 gene mutation can cause abnormal expression of β-catenin protein in the cell, resulting in abnormal activation of Wnt / β-catenin signaling pathway. Aberrant activation of the classical Wnt signaling pathway has been confirmed in various human malignancies including gastric cancer [13–16]. Mutations in APC and CTNNB1 were prevalent in gastric carcinoma [17], which is responsible for gastrointestinal tumorigenesis. In another study, CTNNB1 mutations also were detected in all gastrointestinal tumor samples[18]. Beta-catenin is a multifunctional product of the CTNNB1 gene [19], which mediates cell adhesion and signal transduction. Overexpression of β catenin encoded by CTNNB1 gene might play important role in tumorigenesis and tumor progression[20]. Therefore, blocking the Wnt signaling pathway may be a promising strategy for cancer treatment.
In this study, we intend to identify the clinical significance of CTNNB1 mutations in GC progression, prognosis, and drug selection, to providing new ideas for the diagnosis, treatment, and prognosis of gastric cancer. We found that about 8% of 380 patients carry CTNNB1 mutations, including inframe mutation, truncating and missense mutations. Clinical analysis shows that the overall survival and disease-free survival of gastric cancer patients with CTNNB1 mutation is significantly improved. Detection of CTNNB1 mutation can help clinicians to judge the prognosis of gastric cancer patients and effectively choose a better personalized treatment strategy. In addition, the data from GDSC showed preliminary evidence that Nutlin-3a displayed sensitivity for GC with CTNNB1 mutation, which provides more evidence for the application of specific anti-tumor drugs to such patients and provides a foundation for further research. The compound could be used as a targeted drug for GC patients with CTNNB1 mutation.
To further investigate the mechanism of CTNNB1 mutations in GC progression, prognosis and drug selection, as well as identifying key pathways, we analyzed the GC RNA-Seq data set downloaded from TCGA. GSEA analysis in this study showed that CTNNB1 mutations were significantly associated with cell cycle, RNA degradation, spliceosome, pyrimidine metabolism, and p53 signaling pathway. P53 is an important tumor suppressor gene, which combines and activates the promoter of downstream target genes, promotes gene transcription, and participates in important processes such as tumor proliferation, apoptosis, and DNA damage [21, 22]. There are various ways to regulate p53, thereby regulating tumor cell senescence, which has potential clinical application prospects [23].
A total of 727 DEGs were identified in the RNA-Seq dataset from 22 CTNNB1 mutant patients and 353 CTNNB1 wild-type gastric cancer patients. Functional analysis of DEGs showed that differentially expressed genes in CTNNB1 mutant gastric cancer patients were mainly involved in the antimicrobial humoral response, humoral immune response. In addition, in KEGG pathway analysis, DEGs were significantly enriched in pancreas secretion, protein digestion and absorption, PPAR signaling pathway, bile secretion, and cAMP signaling pathway. The above indicates that CTNNB1 mutation may be involved in the occurrence and development of gastric cancer. The occurrence of gastric cancer is not mediated by a single factor, but a multi-step process involving many complex cell signaling pathways.
In the PPI network analysis, we identified the top 30 genes with the highest degree of interaction, among which ALB had the highest degree of nodes with 32. This gene encodes the most abundant protein in human blood. Gene Ontology (GO) annotations related to this gene include enzyme binding and chaperone binding. An important paralog of this gene is AFP. The KEGG and GO enrichment analysis of the three most important modules in the PPI network showed that modules 1–3 were mainly related to G protein-coupled receptor binding, second-messenger-mediated signaling, neuropeptide signaling pathway, G protein-coupled receptor signaling pathway, coupled to cyclic nucleotide second messenger, endoplasmic reticulum lumen,post-translational protein modification, epidermal cell differentiation. It indicates that gastric cancer cells with CTNNB1 mutation are more active in cell differentiation and cell signal transmission.
Our study is only a preliminary exploration of whether CTNNB1 mutations in GC affect disease progression, prognosis, and drug selection. The mechanism of CTNNB1 mutation in GC needs further verification. At present, it is still an important research direction to find new mutant genes related to GC in the research of GC, and to further explore the role of related cell signaling pathways in the occurrence and progression of GC. It is believed that in the near future, with the advancement of molecular biology technology and the development of the etiology and mechanism of GC, we will be able to develop new therapeutic methods for GC through molecular targets in gastric cancer-related cell signaling pathways.
In conclusion, with this study, we identified the main pathways and genes associated with the CTNNB1 mutation in GC, implicated these factors as possible targets for future therapeutic strategies in patients with GC.