Histone acetylation and DNA demethylation of T cells result in an anaplastic large cell lymphoma-like phenotype.
A characteristic feature of anaplastic large cell lymphoma is the significant repression of the T-cell expression program despite its T-cell origin. The reasons for this down-regulation of T-cell phenotype are still unknown. To elucidate whether epigenetic mechanisms are responsible for the loss of the T-cell phenotype, we treated anaplastic large cell lymphoma and T-cell lymphoma/leukemia cell lines (n=4, each) with epigenetic modifiers to evoke DNA demethylation and histone acetylation. Global gene expression data from treated and untreated cell lines were generated and selected, and differentially expressed genes were evaluated by real-time reverse transcriptase polymerase chain reaction and western blot analysis. Additionally, histone H3 lysine 27 trimethylation was analyzed by chromatin immunoprecipitation. Combined DNA demethylation and histone acetylation of anaplastic large cell lymphoma cells was not able to reconstitute their T-cell phenotype. Instead, the same treatment induced in T cells: (i) an up-regulation of anaplastic large cell lymphoma-characteristic genes (e.g. ID2, LGALS1, c-JUN), and (ii) an almost complete extinction of their T-cell phenotype including CD3, LCK and ZAP70. In addition, suppressive trimethylation of histone H3 lysine 27 of important T-cell transcription factor genes (GATA3, LEF1, TCF1) was present in anaplastic large cell lymphoma cells, which is in line with their absence in primary tumor specimens as demonstrated by immunohistochemistry. Our data suggest that epigenetically activated suppressors (e.g. ID2) contribute to the down-regulation of the T-cell expression program in anaplastic large cell lymphoma, which is maintained by trimethylation of histone H3 lysine 27.
Institute of Pathology, Charité-Universitätsmedizin Berlin, Campus Benjamin Franklin, Berlin, Germany.
Maria
M
Joosten
Volkhard
V
Seitz
Karin
K
Zimmermann
Anke
A
Sommerfeld
Erika
E
Berg
Dido
D
Lenze
Ulf
U
Leser
Harald
H
Stein
Michael
M
Hummel
D001374:Azacitidine / Q000031:analogs & derivatives / Q000494:pharmacology; D001402:B-Lymphocytes / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D016000:Cluster Analysis; D019175:DNA Methylation; D000077209:Decitabine; D044127:Epigenesis, Genetic / Q000187:drug effects; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D020868:Gene Silencing; D006657:Histones / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D051797:Inhibitor of Differentiation Protein 2 / Q000235:genetics / Q000378:metabolism; D017728:Lymphoma, Large-Cell, Anaplastic / Q000175:diagnosis / Q000235:genetics* / Q000378:metabolism*; D010641:Phenotype; D011401:Promoter Regions, Genetic; D013601:T-Lymphocytes / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
D006657:Histones; D006877:Hydroxamic Acids; D051797:Inhibitor of Differentiation Protein 2; D014157:Transcription Factors; C012589:trichostatin A; D000077209:Decitabine; D001374:Azacitidine