Abstract
T cell acute lymphoblastic leukaemia (T-ALL) is a highly aggressive haematological cancer of the bone marrow. The abnormal expression of microRNAs (miRNAs) is reportedly involved in T-ALL development and progression. Thus, we aimed to decipher the involvement of miR-204 silencing mediated by DNA methylation in the occurrence of T cell acute lymphoblastic leukaemia (T-ALL). miR-204 expression was determined in bone marrow and peripheral blood samples from T-ALL patients by real-time quantitative PCR (RT-qPCR) with its effect on cell proliferation evaluated by functional assays. In addition, bisulphite sequencing PCR was employed to detect the DNA methylation level of the miR-204 promoter region, and the binding site between miR-204 and IRAK1 was detected by luciferase assay. We found that miR-204 was down-regulated in T cells of T-ALL patients, which was caused by the increased DNA methylation in the promoter region of miR-204. Moreover, overexpression of miR-204 inhibited T-ALL cell proliferation while enhancing their apoptosis through interleukin receptor-associated kinase 1 (IRAK1), which enhanced the expression of matrix metalloproteinase-2 (MMP-2) and MMP-9 through activation of p-p65. Thus, miR-204 modulated MMP-2 and MMP-9 through IRAK1/NF-κB signalling pathway, which was confirmed by in vivo assay. Taken together, DNA methylation-mediated miR-204 silencing increased the transcription of IRAK1, thus activating the NF-κB signalling pathway and up-regulating the downstream targets MMP-2/MMP-9.