title: Abundant hypermethylation of SOCS-1 in clinically silent pituitary adenomas.
abstract: Janus kinase (JAK)/signal transducers and activators of transcription (STAT) cascade are required for cytokines, growth factors, G-proteins and hormones (growth hormone and prolactin). Gatekeepers in this pathway are the suppressor of cytokine signalling (SOCS) family of proteins. Their expression level is epigenetically regulated by DNA methylation. We have investigated the CpG island methylation status of SOCS-1 in a cohort of pituitary adenomas (PA; n=57), craniopharyngiomas (CP; n=30) and normal pituitary tissue (NP; n=11) using methylation sensitive single-strand conformation polymorphism analysis (MS-SSCP) and direct sequencing. SOCS-1 hypermethylation was identified in 51% (29/57) of surgical specimens obtained from PA patients. 83% of these tumours were clinically silent. In contrast, no methylation of SOCS-1 was observed in CPs or NPs. Quantitative real-time PCR and western blot analysis confirmed reduced SOCS-1 expression in the majority of pituitary adenomas. The data is compatible with epigenetic silencing of the SOCS-1 gene and constitutive activation of the JAK-STAT pathway in PA. This appears to contribute particularly to those tumours characterized by a hormone-inactive status.
authors.affiliation: Department of Neuropathology, Friedrich-Alexander University of Erlangen-Nuremberg, Krankenhausstrasse 8-10, 91054, Erlangen, Germany. rolf.buslei@neuropatho.imed.uni-erlangen.de
authors.forename: Rolf
authors.initials: R
authors.lastname: Buslei
authors.forename: Jürgen
authors.initials: J
authors.lastname: Kreutzer
authors.forename: Bernd
authors.initials: B
authors.lastname: Hofmann
authors.forename: Verena
authors.initials: V
authors.lastname: Schmidt
authors.forename: Florian
authors.initials: F
authors.lastname: Siebzehnrübl
authors.forename: Eric
authors.initials: E
authors.lastname: Hahnen
authors.forename: Ilker Y
authors.initials: IY
authors.lastname: Eyupoglu
authors.forename: Rudolf
authors.initials: R
authors.lastname: Fahlbusch
authors.forename: Ingmar
authors.initials: I
authors.lastname: Blümcke
mesh_terms: D000236:Adenoma / Q000235:genetics / Q000378:metabolism*; D000293:Adolescent; D000328:Adult; D000368:Aged; D003397:Craniopharyngioma / Q000235:genetics / Q000378:metabolism; D019175:DNA Methylation; D004273:DNA, Neoplasm / Q000378:metabolism; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D006801:Humans; D053612:Janus Kinases / Q000502:physiology; D008297:Male; D008875:Middle Aged; D010911:Pituitary Neoplasms / Q000235:genetics / Q000378:metabolism*; D050791:STAT Transcription Factors / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology; D000071222:Suppressor of Cytokine Signaling 1 Protein; D050826:Suppressor of Cytokine Signaling Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D004273:DNA, Neoplasm; C108944:SOCS1 protein, human; D050791:STAT Transcription Factors; D000071222:Suppressor of Cytokine Signaling 1 Protein; D050826:Suppressor of Cytokine Signaling Proteins; D053612:Janus Kinases