Targeting DNMT1 restores PTEN expression in colorectal cancer cells.

Epigenetic silencing of tumor suppressor genes (TSGs) is a key driver of colorectal cancer (CRC) progression, with phosphatase and tensin homolog deleted on chromosome 10 (PTEN) frequently inactivated through promoter hypermethylation. This study explored the association between DNA methyltransferase 1 (DNMT1) suppression, PTEN reactivation, and miR-29a-3p modulation following 5-aza-2'-deoxycytidine (5-aza-dC) treatment in CRC cell models. Bioinformatic analyses revealed DNMT1 overexpression, increased PTEN promoter methylation, and a potential regulatory network associated with miR-29a-3p. In vitro, HCT116 and SW620 cells treated with 5-aza-dC exhibited dose-dependent reductions in cell viability, with IC50 values of 12.38 ± 0.98 μM and 10.04 ± 0.98 μM, respectively. Treatment with 5-aza-dC induced significant PTEN re-expression and DNMT1 downregulation at both the mRNA and protein levels. Methylation-specific PCR (MSP-PCR) suggested reduced PTEN promoter methylation following treatment. Additionally, miR-29a-3p expression was significantly upregulated. These findings suggest that 5-aza-dC restores PTEN expression in association with DNMT1 suppression and PTEN promoter demethylation, while miR-29a-3p upregulation may reflect an associated epigenetic response requiring further mechanistic validation.