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PLoS One. 2014 Oct 17;9(10):e110973. doi: 10.1371/journal.pone.0110973. eCollection 2014.

Global epigenetic regulation of microRNAs in multiple myeloma.

Author information

1
Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts, United States of America; Nanfang Hospital, Southern Medical University, Guangzhou, China.
2
Center for Cancer Computational Biology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts, United States of America.
3
Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts, United States of America; The First People's Hospital of Yunnan Province, Kunming University of Science and Technology, Kunming, China.
4
Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts, United States of America; Department of Hematology, Hopital Claude Huriez, Hospital of Lille (CHRU), Lille, France.
5
Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts, United States of America.
6
Nanfang Hospital, Southern Medical University, Guangzhou, China.

Abstract

Epigenetic changes frequently occur during tumorigenesis and DNA hypermethylation may account for the inactivation of tumor suppressor genes in cancer cells. Studies in Multiple Myeloma (MM) have shown variable DNA methylation patterns with focal hypermethylation changes in clinically aggressive subtypes. We studied global methylation patterns in patients with relapsed/refractory MM and found that the majority of methylation peaks were located in the intronic and intragenic regions in MM samples. Therefore, we investigated the effect of methylation on miRNA regulation in MM. To date, the mechanism by which global miRNA suppression occurs in MM has not been fully described. In this study, we report hypermethylation of miRNAs in MM and perform confirmation in MM cell lines using bisulfite sequencing and methylation-specific PCR (MSP) in the presence or absence of the DNA demethylating agent 5-aza-2'-deoxycytidine. We further characterized the hypermethylation-dependent inhibition of miR-152, -10b-5p and -34c-3p which was shown to exert a putative tumor suppressive role in MM. These findings were corroborated by the demonstration that the same miRNAs were down-regulated in MM patients compared to healthy individuals, alongside enrichment of miR-152-, -10b-5p, and miR-34c-3p-predicted targets, as shown at the mRNA level in primary MM cells. Demethylation or gain of function studies of these specific miRNAs led to induction of apoptosis and inhibition of proliferation as well as down-regulation of putative oncogene targets of these miRNAs such as DNMT1, E2F3, BTRC and MYCBP. These findings provide the rationale for epigenetic therapeutic approaches in subgroups of MM.

PMID:
25330074
PMCID:
PMC4201574
DOI:
10.1371/journal.pone.0110973
[Indexed for MEDLINE]
Free PMC Article

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