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Epigenetic Modification of MicroRNA-219-1 and Its Association with Glioblastoma Multiforme

Asghar Ghasemi1,a, Asghar Mohammadi2,b, and Soudabeh Fallah2,c*

1Department of Clinical Biochemistry, School of Medicine, Tehran University of Medical Sciences (TUMS), 1417613151 Tehran, Iran

2Department of Clinical Biochemistry, School of Medicine, Iran University of Medical Sciences (IUMS), 1449614535 Tehran, Iran

* To whom correspondence should be addressed.

Received August 5, 2020; Revised December 8, 2020; Accepted December 29, 2020
MicroRNA-219-1 (miR-219-1) acts as a tumor suppressor in a variety of cancers but, the regulatory epigenetic mechanism involved in its gene expression level has not been studied. Using real-time polymerase chain reaction (real-time PCR) and bisulfite genomic sequencing technology, promoter methylation level of miR-219-1 and gene expression levels of miR-219-5p and miR-219-1-3p were determined respectively, in glioblastoma multiforme (GBM) (n = 31), their adjacent normal tissues (n = 31), and GBM U87 cell line. Following treatment of GBM U87 cells with 5-aza-2′-deoxycitidine (5-aza-dC), miR-219-1 promoter methylation, their target mRNA, and protein levels were determined by genomic bisulfite modification, real-time-PCR, and ELISA techniques, respectively. Our results showed that gene expression levels of miR-219-5p and miR-219-1-3p were significantly lower in GBM patients relative to their adjacent normal tissues (p < 0.01). MiR-219-1 promoter had a high level of methylation in GBM tissues (p < 0.01) and a negative correlation was observed between the miRNAs gene expression and methylation levels in GBM tissues (p < 0.01). Treatment of GBM U87 cells by 5-aza-dC decreased the level of miR-219-1 methylation, amount of target mRNA, and levels of cyclin A2 and mucin 4 (MUC4) proteins, and increased the expression levels of miR-219-5p and miR-219-1-3p (p < 0.01). Using external miR-219-5p and miR-219-1-3p, the expression of cyclin A2 and MUC4 were suppressed and proliferative activity of the U87MG cell line was reduced (p < 0.01). These findings suggested that DNA methylation has a crucial role in the regulation of miR-219-1 gene expression and that hypermethylated miR-219-1 may be involved in GBM pathogenesis.
KEY WORDS: miR-219-1, epigenetic, GBM

DOI: 10.1134/S0006297921040040