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Differential DNA methylation analysis of breast cancer reveals the impact of immune signaling in radiation therapy
Author(s) -
Halvorsen Ann Rita,
Helland Åslaug,
Fleischer Thomas,
Haug Karen Marie,
Grenaker Alnæs Grethe Irene,
Nebdal Daniel,
Syljuåsen Randi G.,
Touleimat Nizar,
Busato Florence,
Tost Jörg,
Sætersdal Anna B.,
BørresenDale AnneLise,
Kristensen Vessela,
Edvardsen Hege
Publication year - 2014
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.28862
Subject(s) - dna methylation , epigenetics , methylation , breast cancer , cancer research , biology , radiation therapy , immune system , cancer , oncology , bioinformatics , gene , microbiology and biotechnology , medicine , immunology , genetics , gene expression
Radiotherapy (RT) is a central treatment modality for breast cancer patients. The purpose of our study was to investigate the DNA methylation changes in tumors following RT, and to identify epigenetic markers predicting treatment outcome. Paired biopsies from patients with inoperable breast cancer were collected both before irradiation ( n = 20) and after receiving 10–24 Gray (Gy) ( n = 19). DNA methylation analysis was performed by using Illumina Infinium 27K arrays. Fourteen genes were selected for technical validation by pyrosequencing. Eighty‐two differentially methylated genes were identified in irradiated ( n = 11) versus nonirradiated ( n = 19) samples (false discovery rate, FDR = 1.1%). Methylation levels in pathways belonging to the immune system were most altered after RT. Based on methylation levels before irradiation, a panel of five genes ( H2AFY, CTSA, LTC4S, IL5RA and RB1 ) were significantly associated with clinical response ( p = 0.041). Furthermore, the degree of methylation changes for 2,516 probes correlated with the given radiation dose. Within the 2,516 probes, an enrichment for pathways involved in cellular immune response, proliferation and apoptosis was identified (FDR < 5%). Here, we observed clear differences in methylation levels induced by radiation, some associated with response to treatment. Our study adds knowledge on the molecular mechanisms behind radiation response.