Colorectal carcinoma (CRC) is one of the most common cancers, and is associated with a poor clinical outcome. The key genes and potential prognostic markers in colorectal carcinoma remain to be identified and explored for clinical application. DNA expression/methylation profiles were downloaded from the Gene Expression Omnibus (GEO) database to identify differentially expressed/methylated genes (DEGs and DEMs). A total of 255 genes and 372 genes were identified as being up-regulated and down-regulated, respectively, in GSE113513, GSE81558, and GSE89076. There were a total of 3350 hypermethylated genes and 443 hypomethylated genes identified in GSE48684. Twenty genes were found to be hypermethylated as well as down-regulated, and a functional enrichment analysis revealed that these genes were mainly involved in cancer-related pathways. Among these 20 genes, GPM6A, HAND2 and C2orf40 were related to poor outcomes in cancer patients based on a survival analysis. Concurrent decreases of GPM6A, HAND2 and C2orf40 protein expression were observed in highly-differentiated colorectal carcinoma tissues, and higher expression levels were found in undifferentiated or minimally-differentiated colorectal carcinoma tissues. In conclusion, 20 genes were found to be downregulated and hypermethylated in CRC, among which GPM6A, HAND2 and C2orf40 were explored for their potential prognostic value.

结直肠癌（CRC）是最常见的癌症之一，并且与不良的临床结果相关。结直肠癌的关键基因和潜在的预后标志物仍有待鉴定和探索以用于临床应用。从基因表达综合 (GEO) 数据库下载 DNA 表达/甲基化谱，以识别差异表达/甲基化基因（DEG 和 DEM）。在 GSE113513、GSE81558 和 GSE89076 中，总共有 255 个基因被上调，372 个基因被下调。GSE48684中总共鉴定出3350个高甲基化基因和443个低甲基化基因。发现 20 个基因高甲基化和下调，功能富集分析显示这些基因主要参与癌症相关通路。根据生存分析，在这 20 个基因中，GPM6A、HAND2 和 C2orf40 与癌症患者的不良预后相关。高分化结直肠癌组织中GPM6A、HAND2和C2orf40蛋白表达量同时降低,未分化或微分化结直肠癌组织中表达量较高。总之，发现 20 个基因在 CRC 中下调和高甲基化，其中 GPM6A、HAND2 和 C2orf40 的潜在预后价值被探索。