Abnormal expression of ABCD3 is an independent prognostic factor for colorectal cancer

ATP binding cassette subfamily D member 3 (ABCD3) is a member of the superfamily of ATP-binding cassette (ABC) transporters, which serve crucial roles in the process of tumor cell resistance to chemotherapy. The present study investigated the diagnostic and prognostic capabilities of ABCD3 in colorectal cancer (CRC) by bioinformatics analysis. Gene expression data and corresponding clinical information of patients with CRC were collected from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. The results demonstrated that ABCD3 mRNA level was decreased in CRC tissues compared with normal tissues following Wilcoxon test analysis. Furthermore, ABCD3 protein expression was significantly higher in normal colon tissues compared with colon adenocarcinoma tissues according to the Human Protein Atlas. In addition, the area under the Receiver Operating Characteristic curve based on comparison between the tumor and normal groups derived from TCGA and GEO databases demonstrated that the use of ABCD3 mRNA level may be used for the diagnosis of CRC. ABCD3 expression was significantly associated with clinical stage, T stage, and lymph node status following Kruskal-Wallis test or Wilcoxon rank sum test, logistic regression and chi(2) test. Furthermore, the results from Kaplan-Meier survival analysis indicated that low ABCD3 mRNA expression had a poorer prognosis value compared with ABCD3 high expression in patients with CRC. In addition, results from univariate Cox regression analysis indicated that ABCD3 mRNA expression was associated with overall survival (OS), and results from multivariate Cox analysis indicated that ABCD3 mRNA expression may be considered an independent prognostic factor from other clinical factors, such as clinical stage, sex and age. The results from Gene Set Enrichment Analysis demonstrated that the ABCD3 high-expression phenotype was differentially enriched in five biological processes, including apoptosis, cell cycle, renal cell carcinoma, thyroid cancer and colorectal cancer. The findings from this study demonstrated that ABCD3 mRNA expression may be considered as a potential diagnostic and prognostic biomarker in patients with CRC. ABCD3 expression levels may participate in the regulation of cell apoptosis and cell cycle. In addition, GSEA analysis identified Kyoto Encyclopaedia of Genes and Genomes pathways for renal cell carcinoma, thyroid cancer and CRC involving ABCD3.