Background: Methylation-mediated inactivation of tumor-suppressor genes is a critical event during the pathogenesis of many malignancies. Vincristine is a conventional anticancer drug used to treat various types of cancers. However, few studies describe the epigenetic-based effects of vincristine. In this study, changes in the methylation of runt-related transcription factor-3 (RUNX3) were investigated in CCD18Co normal colon cells and DLD-1 colorectal adenocarcinoma cells.
Materials and methods: CCD18Co and DLD-1 cells were treated with vincristine, and the methylation status was assessed using quantitative methylation-specific polymerase chain reaction (QMSP). Eleven normal colon tissues and 105 colorectal cancer tissues were investigated by methylation and mRNA expression of RUNX3 using QMSP and real-time reverse transcription polymerase chain reaction (real time-PCR).
Results: RUNX3 was demethylated after vincristine treatment in DLD-1 cells. The expression of RUNX3 mRNA was down-regulated in DLD-1 cells because of DNA hypermethylation, but was restored after vincristine treatment. In addition, hypermethylation of RUNX3 was detected in 70 out of 105 colorectal carcinomas (66.7%). RUNX3 hypermethylation was greater in colon cancer tissues than in rectal cancer tissues. The expression of RUNX3 mRNA was reduced in 68 out of 105 colorectal cancer tissues (64.8%).
Conclusion: These results demonstrate that vincristine demethylates RUNX3 in colorectal adenocarcinoma cells, and restores its expression.
Keywords: DNA methylation; RUNX3; colonic neoplasms; demethylation; methylation-specific polymerase chain reaction; vincristine.