DNA Methylation-Mediated Silencing of Mir-204 Enhances the Occurrence of T-Cell Acute Lymphoblastic Leukemia By Upregulating MMP-2 and MMP-9 through the NF-Κb Signaling Pathway

Background: MicroRNAs (miR) are non-coding RNAs that play a role in regulation multiple functions in different cell types. Previous studies have shown that miR-204 is downregulated in T-ALL. We previously reported that matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9) gene polymorphisms may be associated with the risk of T-cell acute lymphoblastic leukemia (T-ALL). The present study aims to decipher the role of miR-204 and MMP-2/MMP-9 in T-ALL occurrence to guide the diagnosis and treatment of T-ALL in the clinics.

Methods: Expression of miR-204 was determined in the bone marrow and peripheral blood samples from 70 T-ALL patients and 70 healthy volunteers by real-time quantitative PCR (RT-qPCR). Bisulfite sequencing PCR (BSP) was used to detect the DNA methylation levels of the miR-204 promoter region in T-ALL patients and T-ALL cell lines.The effect of miR-204 on cell proliferation was evaluated with the cell counting kit-8 solution (CCK-8) assay and by Hoechst and PI double staining. The binding site of miR-204 on IRAK1 was predicted by the Primer Premier 5.0 and the defined binding sequences were used to construct luciferase-tag plasmids. The regulation of IRAK1 expression by miR-204 was evaluated by RT-qPCR and Western blot analysis. With the purpose to confirm the role of MMP-2 and MMP-9 in the occurrence of T-ALL, we investigated the effect of related proteins on T-ALL cells using Western blot. To determine that miR-204 affects the occurrence of T-ALL disease by regulating the NF-KB signaling pathway, RT-qPCR and Western Blot were used for verification.

Results: DNA methylation directly affects the miR-204 expression in the promoter region when T-ALL developed. Moreover, overexpression of miR-204 inhibited the proliferation and enhanced the apoptosis of T-ALL cells. Notably, overexpression of miR-204 inhibited IRAK1, which in turn inhibited the proliferation and enhanced the apoptosis of T-ALL cells. Furthermore, IRAK1 enhanced the expression of MMP-2 and MMP-9 through phosphorylation of of p65 NF-κB, and miR-204 modulated MMP-2 and MMP-9 expression through the IRAK1/NF-κB signaling pathway.

Conclusions: Our results demonstrate that in T-ALL cells, DNA methylation-mediated silencing of miR-204 regulates the expression of MMP-2 and MMP-9 through increased transcription of IRAK1, and activation of the NF-κB signaling pathway. These data provide a potential mechanism for the role of MMP-2 and MMP-9 in the occurrence of T-ALL. Further studies will be needed to demonstrate whether demethylation of miR-204 may be a promising treatment for T-ALL.