Preliminary screening of chemotherapy-resistant genes in esophageal cancer and its clinical significance

Objective 　To initially screen the genes associated with chemotherapeutic resistance in esophageal cancer cells, verify the correlation of the genes to the poor prognosis of patients with esophageal cancer, and predict the possible regulatory mechanism of esophageal cancer resistance. Methods 　The drug sensitivity data of esophageal cancer cell lines were analyzed from GDSC database to screen the cell lines that were relatively sensitive or resistant to both cisplatin and docetaxel. In order to obtain differentially expressed genes, the transcriptome data of the two groups of cell lines were analyzed by the edgeR package according to the following screening criteria: the log2 (fold change) more than –1 or less than1 and P value <0.05. The enrichment cluster analysis of GO biological process was performed in the relatively highly expressed genes of drug-resistant group to identify possible signaling pathways related with drug resistance, and the target genes related to chemotherapeutic resistance were identified based on previous studies. The associations between the expression level of target gene and the clinical pathological features and prognosis of patients were verified in the tissue transcriptome data of esophageal cancer patients. Finally, the proteins interacting with the target gene encoded protein were predicted online using the STRING database, and its possible mechanism of action was analyzed. Results 　Five cell lines with resistance to both cisplatin and docetaxel and 5 sensitive cell lines were obtained. According to the transcriptome data of the two groups of cell lines, 1097 differentially expressed genes were finally obtained, including 532 highly expressed and 565 low expressed genes in the drug resistant group. The results of GO enrichment analysis for the highly expressed genes indicated that the receptor protein tyrosine kinase pathway was obviously enriched. The expression level of FGR involved in this pathway was significantly correlated with tumor T stage (P=0.021), clinical stage (P=0.007) and prognosis (P=0.0021) of patients with esophageal cancer. In addition, protein interaction analysis indicated that FGR interacted directly or indirectly with multiple proteins, mainly in the form of kinase. Conclusions 　The receptor protein tyrosine kinase pathway is the most significant signaling pathway associated with chemotherapeutic resistance in esophageal cancer cells. The expression level of FGR in this signaling pathway is significantly correlated with the pathological stage and prognosis of patients with esophageal cancer. FGR may regulate the drug resistance of esophageal cancer cells by phosphorylating downstream target proteins. DOI: 10.11855/j.issn.0577-7402.2019.03.06