Open AccessDNA methylation patterns in luminal breast cancers differ from non‐luminal subtypes and can identify relapse risk independent of other clinical variables
Author(s) -
Kamalakaran Sitharthan,
Varadan Vinay,
Giercksky Russnes Hege E.,
Levy Dan,
Kendall Jude,
Janevski Angel,
Riggs Michael,
Banerjee Nilanjana,
Synnestvedt Marit,
Schlichting Ellen,
Kåresen Rolf,
Shama Prasada K.,
Rotti Harish,
Rao Ramachandra,
Rao Laxmi,
Eric Tang Man-Hung,
Satyamoorthy K.,
Lucito Robert,
Wigler Michael,
Dimitrova Nevenka,
Naume Bjorn,
Borresen-Dale Anne-Lise,
Hicks James B.
Publication year - 2011
Publication title -
molecular oncology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.332
H-Index - 88
eISSN - 1878-0261
pISSN - 1574-7891
DOI - 10.1016/j.molonc.2010.11.002
Subject(s) - biology , dna methylation , methylation , cpg site , cancer research , gene , differentially methylated regions , genetics , gene expression
The diversity of breast cancers reflects variations in underlying biology and affects the clinical implications for patients. Gene expression studies have identified five major subtypes– Luminal A, Luminal B, basal‐like, ErbB2+ and Normal‐Like. We set out to determine the role of DNA methylation in subtypes by performing genome‐wide scans of CpG methylation in breast cancer samples with known expression‐based subtypes. Unsupervised hierarchical clustering using a set of most varying loci clustered the tumors into a Luminal A majority (82%) cluster, Basal‐like/ErbB2+ majority (86%) cluster and a non‐specific cluster with samples that were also inconclusive in their expression‐based subtype correlations. Contributing methylation loci were both gene associated loci (30%) and non‐gene associated (70%), suggesting subtype dependant genome‐wide alterations in the methylation landscape. The methylation patterns of significant differentially methylated genes in luminal A tumors are similar to those identified in CD24 + luminal epithelial cells and the patterns in basal‐like tumors similar to CD44 + breast progenitor cells. CpG islands in the HOXA cluster and other homeobox (IRX2, DLX2, NKX2‐2) genes were significantly more methylated in Luminal A tumors. A significant number of genes (2853, p < 0.05) exhibited expression–methylation correlation, implying possible functional effects of methylation on gene expression. Furthermore, analysis of these tumors by using follow‐up survival data identified differential methylation of islands proximal to genes involved in Cell Cycle and Proliferation (Ki‐67, UBE2C, KIF2C, HDAC4), angiogenesis (VEGF, BTG1, KLF5), cell fate commitment (SPRY1, OLIG2, LHX2 and LHX5) as having prognostic value independent of subtypes and other clinical factors.