Background: Cholangiocarcinoma (CCA) is reported as an aggressive cancer which leads to high mortality and no effective therapeutic target has yet been discovered. Surgical resection is the main method to treat patients with CCA. However, only one-third of CCA patients have the opportunity to accept the operation, leading to poor prognosis for CCA patients. Therefore, it is necessary to search for new therapeutic targets of CCA or core genes involved in the happening and growth of CCA.
Aim: In this study, we utilized bioinformatics technology and accessed to several medical databases trying to find the core genes of CCA for the purpose of intervening CCA through figuring out an effective curative target.
Methods: Firstly, three differentially expressed genes (DEGs) were discovered from GEPIA, and by further observing the distribution and gene expression, CHST4 was obtained as the core gene. Afterwards, correlated genes of CHST4 in CCA were identified using UALCAN to construct a gene expression profile. We obtained PPI network by Search Tool for the Retrieval of Interacting Networks Genes (STRING) and screened core genes using cytoscape software. Functional enrichment analyses were carried out and the expression of CHST in human tissues and tumors was observed. Finally, a CCA model was established for qPCR and staining validation.
Results: Three differentially expressed genes (DEGs), CHST4, MBOAT4 and RP11-525K10.3, were obtained. All were more over-expressed in CCA samples than the normal, among which the change multiple and the gene expression difference of CHST4 was the most obvious. Therefore, CHST4 was selected as the core gene. We can see in our established protein-protein interaction (PPI) network that CHST4 had the highest degree of connectivity, demonstrating its close association with CCA. We found that genes were mainly enriched in CCs in the PPI networks genes which shows functional enrichment analysis results, including golgi lumen, extracellular space and extracellular region. CHST4 was found very specifically expressed in the bile duct and was significantly different from that in normal tissues. The overexpression of CHST4 was further verified in the established animal model of TAA-induced CCA in rats. Quantitative PCR (qPCR) demonstrated that CHST4 was significantly overexpressed in tumor tissues, verifying the role of CHST4 as the core gene of CCA.
Conclusion: CHST4 was increasingly expressed in CCA and CHST4 is worth being studied much further in the intervention of CCA.