Epigenetic inactivation of miR-9 family microRNAs in chronic lymphocytic leukemia - implications on constitutive activation of NFκB pathway

Molecular Cancer

Research

Chi Shan Bonnie Kho¹  Chor Sang Chim²  Kwan Yeung Wong²  Lu Qian Wang²  Yok Lam Kwong²  Kit Fai Wong³  Manuela Ferracin⁴  George A Calin⁵ 

[1] Department of Medicine, Pamela Youde Nethersole Hospital, Hong Kong, China;Department of Medicine, Queen Mary Hospital, The University of Hong Kong, Hong Kong, China;Department of Pathology, Queen Elizabeth Hospital, Hong Kong, China;Laboratory for Technologies of Advanced Therapies (LTTA) and Department of Morphology, Surgery and Experimental Medicine, University of Ferrara, Ferrara, Italy;MD Anderson Cancer Center, University of Texas, Houston, TX, USA;

关键词: microRNA;    miR-9-3;    Tumor suppressor;    DNA methylation;    NFκB;    Chronic lymphocytic leukemia;   

DOI  :  10.1186/1476-4598-12-173

 received in 2013-08-02, accepted in 2013-12-20,  发布年份 2013

来源: Springer

【 摘 要 】

BackgroundThe miR-9 family microRNAs have been identified as a tumor suppressor miRNA in cancers. We postulated that miR-9-1, miR-9-2 and miR-9-3 might be inactivated by DNA hypermethylation in chronic lymphocytic leukemia (CLL).MethodsMethylation of miR-9-1, miR-9-2 and miR-9-3 was studied in eight normal controls including normal bone marrow, buffy coat, and CD19-sorted peripheral blood B-cells from healthy individuals, seven CLL cell lines, and seventy-eight diagnostic CLL samples by methylation-specific polymerase chain reaction.ResultsThe promoters of miR-9-3 and miR-9-1 were both unmethylated in normal controls, but methylated in five (71.4%) and one of seven CLL cell lines respectively. However, miR-9-2 promoter was methylated in normal controls including CD19 + ve B-cells, hence suggestive of a tissue-specific but not tumor-specific methylation, and thus not further studied. Different MSP statuses of miR-9-3, including complete methylation, partial methylation, and complete unmethylation, were verified by quantitative bisulfite methylation analysis. 5-Aza-2′-deoxycytidine treatment resulted in miR-9-3 promoter demethylation and re-expression of pri-miR-9-3 in I83-E95 and WAC3CD5+ cells, which were homozygously methylated for miR-9-3. Moreover, overexpression of miR-9 led to suppressed cell proliferation and enhanced apoptosis together with downregulation of NFκB1 in I83-E95 cells, supporting a tumor suppressor role of miR-9-3 in CLL. In primary CLL samples, miR-9-3 was detected in 17% and miR-9-1 methylation in none of the patients at diagnosis. Moreover, miR-9-3 methylation was associated with advanced Rai stage (≥ stage 2) (P = 0.04).ConclusionsOf the miR-9 family, miR-9-3 is a tumor suppressor miRNA relatively frequently methylated, and hence silenced in CLL; whereas miR-9-1 methylation is rare in CLL. The role of miR-9-3 methylation in the constitutive activation of NFκB signaling pathway in CLL warrants further study.

【 授权许可】

Unknown   
© Wang et al.; licensee BioMed Central Ltd. 2013. This article is published under license to BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.