Elevated Methylation Contributes to Suppressed Expression of Special AT-Rich Sequence-Binding Protein 2 in Colorectal Cancer: A Gene-Disease Association Study.

BACKGROUND AND AIMS: Special AT-rich sequence-binding protein 2 (SATB2) is a commonly used clinical marker for colorectal cancer (CRC) diagnosis. It has been reported that SATB2 expression is significantly downregulated in CRC tissues; however, the underlying mechanism remains unclear. Methylation represents one of the key epigenetic modifications involved in regulating gene expression. The objective of this study was to investigate the relationship between the methylation status of SATB2 and its expression levels in CRC tissues. METHODS: We first investigated the methylation status and expression level of SATB2 via the use of transcriptional and methylation data from CRC patients in The Cancer Genome Atlas via bioinformatics analysis. Next, we explored the methylation status of the SATB2 promoter and SATB2 expression patterns in the collected CRC tumor and adjacent normal tissues, as well as different cell lines, via methylation-specific PCR and quantitative PCR. Next, the normal colorectal FHC cell line and CRC cell lines were treated with azacytidine (AZA) to investigate whether the mRNA expression of SATB2 could be restored by demethylating agents. Finally, associations between clinicopathological characteristics and SATB2 methylation status were analyzed. RESULTS: The results of both bioinformatics and experimental analyses demonstrated that SATB2 expression was downregulated in CRC tumor tissues and that SATB2 hypermethylation was detected in various regions, including the promoter. The downregulated expression of SATB2 in CRC tumor tissues was significantly correlated with SATB2 hypermethylation, and the mRNA expression level of SATB2 significantly increased following AZA treatment in certain CRC cell lines. Additionally, the methylation state of SATB2 was correlated with tumor differentiation and metastasis. CONCLUSION: In summary, increased methylation levels contribute to decreased SATB2 expression in CRC, indicating the clinical relevance of SATB2 methylation as a potential therapeutic target for CRC.