Epigenetic silencing of miR-342-3p in B cell lymphoma and its impact on autophagy

Clinical Epigenetics

Chor Sang Chim¹  Min Yue Zhang²  Dong Yan Jin³  Kit San Yuen³  George A. Calin⁴ 

[1] Department of Medicine, Queen Mary Hospital, The University of Hong Kong, Pokfulam Road, Pokfulam, Hong Kong;Division of Hematology, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China;Department of Medicine, Queen Mary Hospital, The University of Hong Kong, Pokfulam Road, Pokfulam, Hong Kong;School of Biomedical Sciences, The University of Hong Kong, Pokfulam Road, Pokfulam, Hong Kong;Translational Molecular Pathology Department, The University of Texas MD Anderson Cancer Center, Houston, TX, USA;

关键词: Autophagy;    B cell lymphoma;    DNA methylation;    miR-342-3p;    Tumor suppressor miRNA;   

DOI  :  10.1186/s13148-020-00926-1

来源: Springer

【 摘 要 】

BackgroundmiR-342-3p, localized to 14q32, is a tumor suppressor miRNA implicated in carcinogenesis. Given the presence of a promotor-associated CpG island for its host gene, EVL, we hypothesized that intronic miR-342-3p is a tumor suppressor co-regulated with host gene by promoter DNA methylation in B cell lymphoma.ResultsBy bisulfite pyrosequencing-verified methylation-specific PCR (MSP), EVL/MIR342 methylation was detected in five (50%) lymphoma cell lines but not normal peripheral blood and tonsils. EVL/MIR342 methylation correlated with repression of both miR-342-3p and EVL in cell lines. In completely methylated SU-DHL-16 cells, 5-AzadC treatment resulted in promoter demethylation and re-expression of miR-342-3p and EVL. In 132 primary lymphoma samples, EVL/MIR342 was preferentially methylated in B cell lymphomas (N = 68; 68.7%) than T cell lymphoma (N = 8; 24.2%) by MSP (P < 0.0001). Moreover, EVL/MIR342 methylation was associated with lower miR-342-3p expression in 79 primary NHL (P = 0.0443). In SU-DHL-16 cells, the tumor suppressor function of miR-342-3p was demonstrated by the inhibition of cellular proliferation and increase of cell death upon over-expression of miR-342-3p. Mechanistically, overexpression of miR-342-3p resulted in a decrease of LC3-II, a biomarker of autophagy, which was pro-survival for SU-DHL-16. Pre-treatment with 3-methyladenine, an autophagy inhibitor, abrogated tumor suppression associated with miR-342-3p overexpression. By luciferase assay, MAP1LC3B, a precursor of LC3-II, was confirmed as a direct target of miR-342-3p. Finally, in SU-DHL-16 cells, overexpression of miR-342-3p downregulated the known target DNMT1, with promoter demethylation and re-expression of tumor suppressor E-cadherin.ConclusionsIntronic miR-342-3p is co-regulated with its host gene EVL by tumor-specific promoter DNA methylation in B cell lymphoma. The tumor suppressor function of miR-342-3p was mediated via inhibition of pro-survival autophagy by targeting MAP1LC3B and downregulation of DNMT1 with demethylation and re-expression of tumor suppressor genes.

【 授权许可】

CC BY