MicroRNA expression is deregulated by aberrant methylation in B-cell acute lymphoblastic leukemia mouse model

The expression of microRNAs (miRNAs) in the serum of B-cell acute lymphoblastic leukemia (B-ALL) patients is abnormal. Nevertheless, the underlying mechanism remains unclear. Recent studies indicate that the methylation state of circulating cell-free DNA (cfDNA) is different between cancer patients and healthy individuals. Therefore, we speculate that abnormal expression of miRNA may be associated with cfDNA methylation.

A green fluorescent protein (GFP) labeled B-ALL transplantation animal model was established to explore the relationship between the miRNA expression and cfDNA methylation of the related gene. Quantitative real-time PCR (qRT-PCR) was used to detect the expression levels of miRNAs. Further, cfDNA methylation levels of the related genes were evaluated through bisulfite sequencing polymerase chain reaction (BSP).

The expression levels of miR-196b, miR-203, miR-34a-5p, miR-335-3p, miR-34b-5p, miR-615, miR-375-3p and miR-193b-5p in the serum of the model mice were significantly lower than those of the control group (P < 0.05). The methylation level of miR-196b promoter in cfDNA of the model group was significantly lower than that of the control group (P < 0.05), whereas no significant difference was noted in miR-203 promoter. The methylation levels of miR-196b and miR-203 coding region in cfDNA of the model group were significantly higher than those of the control group (P < 0.05).

These results showed that CpG island hypermethylation in the miRNA coding region of cfDNA is related to the low expression of miR-196b and miR-203.