TPMT mRNA Expression: A Novel Prognostic Biomarker for Patients with Colon Cancer by Bioinformatics Analysis.

Background: To explore the clinicopathological significance and prognostic value of thiopurine methyltransferase (TPMT) in patients with colon cancer by bioinformatics analysis.

Materials And Methods: The clinicopathological information and TPMT expression data were downloaded from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO). Wilcoxon signed-rank test was used to evaluate the relationship between TPMT mRNA expression levels and clinicopathological characteristics in patients with colon cancer. Then, the prognostic value of TPMT mRNA expression for disease-free survival (DFS) and overall survival (OS) in patients with colon cancer was assessed by Kaplan-Meier and Cox regression analyses. Additionally, gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed to explore potential functions of TPMT in patients with colon cancer.

Results: TPMT mRNA was significantly downregulated in colon cancer compared with normal tissues (P < 0.05). Wilcoxon analysis revealed that lower TPMT mRNA expression was remarkably associated with lymph node metastasis (P = 0.008), distant metastasis (P = 0.012) and advanced pathological stage (P = 0.010). Besides, the high TPMT mRNA level was also correlated with a favorable DFS and OS in colon cancer patients (both P < 0.05). Moreover, GO enrichment analysis indicated that the co-expressed genes of TPMT function as extracellular matrix (ECM) structural constituent, insulin-like growth factor binding, cell adhesion molecule binding and growth factor binding. KEGG enrichment analysis suggested that the co-expressed genes of TPMT were particularly enriched in amino sugar and nucleotide sugar metabolism, ECM-receptor interaction and focal adhesion.

Conclusion: TPMT mRNA level might be a novel prognostic biomarker for patients with colon cancer.