Epigenetic inactivation of the MIR129-2 in hematological malignancies

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MIR129-2 has been shown to be a tumor suppressor microRNA hypermethylated in epithelial cancers. Patients and methods Epigenetic inactivation of MIR129-2 was studied by methylation-specific PCR (MSP) in 13 cell lines (eight myeloma and five lymphoma), 15 normal controls and 344 primary samples including acute myeloid leukemia (AML), acute lymphoblastic leukemia (ALL), chronic myeloid leukemia (CML), chronic lymphocytic leukemia (CLL), non-Hodgkin’s lymphoma (NHL), multiple myeloma (MM) at diagnosis, MM at relapse/progression, and monoclonal gammopathy of undetermined significance (MGUS). Expression of MIR129 and its target, SOX4 , in cell lines was measured before and after hypomethylating treatment and MIR129 overexpression. MIR129 expression was correlated with MIR129-2 methylation status in primary lymphoma samples. Tumor suppressor function of MIR129 was demonstrated by MTT and trypan blue exclusion assay after MIR129 overexpression. Results The sensitivity of the methylated-MSP was one in 10 3 . Different MSP statuses, including complete methylation, partial methylation, and complete unmethylation, were verified by quantitative bisulfite pyrosequencing. All five lymphoma and seven of eight myeloma cell lines showed complete and partial MIR129-2 methylation. In primary samples, MIR129-2 methylation was absent in AML and CML, but detected in 5% ALL, 45.9% CLL, 49.5% MM at diagnosis, and 59.1% NHL. In CLL, MIR129-2 methylation adversely impacted on survival (p=0.004). In MM, MIR129-2 methylation increased from 27.5% MGUS to 49.5% MM at diagnosis and 41.5% at relapse/progression (p=0.023). In NHL, MIR129-2 methylation was associated with MIR124-1 and MIR203 methylation (p<0.001), and lower MIR129 expression (p=0.009). Hypomethylation treatment of JEKO-1, homozygously methylated for MIR129-2 , led to MIR129-2 demethylation and MIR129 re-expression, with downregulation of SOX4 mRNA. Moreover, MIR129 overexpression in both mantle cell lines, JEKO-1 and GRANTA-519, inhibited cellular proliferation and enhanced cell death, with concomitant SOX4 mRNA downregulation. Conclusions MIR129-2 is a tumor suppressive microRNA frequently methylated in lymphoid but not myeloid malignancies, leading to reversible MIR129-2 silencing. In CLL, MIR129-2 methylation was associated with an inferior survival. In MM, MIR129-2 methylation might be acquired during progression from MGUS to symptomatic MM. In NHL, MIR129-2 methylation might collaborate with MIR124-1 and MIR203 methylation in lymphomagenesis.

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Publié le 01 janvier 2013
Nombre de lectures 40
Langue English
Poids de l'ouvrage 2 Mo
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Wonget al. Journal of Hematology & Oncology2013,6:16 http://www.jhoonline.org/content/6/1/16
R E S E A R C H
JOURNAL OF HEMATOLOGY & ONCOLOGY
Open Access
Epigenetic inactivation of theMIR1292in hematological malignancies 1131 2 KwanYeung Wong , Rita LokHay Yim , YokLam Kwong , ChungYing Leung , PakKwan Hui , 4 1 5 1* Florence Cheung , Raymond Liang , DongYan Jin and ChorSang Chim
Abstract Background:MIR1292has been shown to be a tumor suppressor microRNA hypermethylated in epithelial cancers. Patients and methods:Epigenetic inactivation ofMIR1292was studied by methylationspecific PCR (MSP) in 13 cell lines (eight myeloma and five lymphoma), 15 normal controls and 344 primary samples including acute myeloid leukemia (AML), acute lymphoblastic leukemia (ALL), chronic myeloid leukemia (CML), chronic lymphocytic leukemia (CLL), nonHodgkins lymphoma (NHL), multiple myeloma (MM) at diagnosis, MM at relapse/progression, and monoclonal gammopathy of undetermined significance (MGUS). Expression ofMIR129and its target,SOX4, in cell lines was measured before and after hypomethylating treatment andMIR129overexpression.MIR129expression was correlated withMIR1292methylation status in primary lymphoma samples. Tumor suppressor function of MIR129was demonstrated by MTT and trypan blue exclusion assay afterMIR129overexpression. 3 Results:The sensitivity of the methylatedMSP was one in 10 . Different MSP statuses, including complete methylation, partial methylation, and complete unmethylation, were verified by quantitative bisulfite pyrosequencing. All five lymphoma and seven of eight myeloma cell lines showed complete and partialMIR1292 methylation. In primary samples,MIR1292methylation was absent in AML and CML, but detected in 5% ALL, 45.9% CLL, 49.5% MM at diagnosis, and 59.1% NHL. In CLL,MIR1292methylation adversely impacted on survival (p=0.004). In MM,MIR1292methylation increased from 27.5% MGUS to 49.5% MM at diagnosis and 41.5% at relapse/ progression (p=0.023). In NHL,MIR1292methylation was associated withMIR1241andMIR203methylation (p<0.001), and lowerMIR129expression (p=0.009). Hypomethylation treatment of JEKO1, homozygously methylated forMIR1292, led toMIR1292demethylation andMIR129reexpression, with downregulation ofSOX4mRNA. Moreover,MIR129overexpression in both mantle cell lines, JEKO1 and GRANTA519, inhibited cellular proliferation and enhanced cell death, with concomitantSOX4mRNA downregulation. Conclusions:MIR1292is a tumor suppressive microRNA frequently methylated in lymphoid but not myeloid malignancies, leading to reversibleMIR1292silencing. In CLL,MIR1292methylation was associated with an inferior survival. In MM,MIR1292methylation might be acquired during progression from MGUS to symptomatic MM. In NHL,MIR1292methylation might collaborate withMIR1241andMIR203methylation in lymphomagenesis. Keywords:microRNA, Tumor suppressor, Hypermethylation,MIR129, Hematological cancers
* Correspondence: jcschim@hku.hk Equal contributors 1 Department of Medicine, Queen Mary Hospital, The University of Hong Kong, Hong Kong, Hong Kong Full list of author information is available at the end of the article
© 2013 Wong et al.; licensee 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.