title: Oncogenic tyrosine kinase NPM-ALK induces expression of the growth-promoting receptor ICOS.
abstract: Here we report that T-cell lymphoma cells carrying the NPM-ALK fusion protein (ALK(+) TCL) frequently express the cell-stimulatory receptor ICOS. ICOS expression in ALK(+) TCL is moderate and strictly dependent on the expression and enzymatic activity of NPM-ALK. NPM-ALK induces ICOS expression via STAT3, which triggers the transcriptional activity of the ICOS gene promoter. In addition, STAT3 suppresses the expression of miR-219 that, in turn, selectively inhibits ICOS expression. ALK(+) TCL cell lines display extensive DNA methylation of the CpG island located within intron 1, the putative enhancer region, of the ICOS gene, whereas cutaneous T-cell lymphoma cell lines, which strongly express ICOS, show no methylation of the island. Treatment of the ALK(+) TCL cell lines with DNA methyltransferase inhibitor reversed the CpG island methylation and augmented the expression of ICOS mRNA and protein. Stimulation of the ICOS receptor with anti-ICOS antibody or ICOS ligand-expressing B cells markedly enhanced proliferation of the ALK(+) TCL cells. These results demonstrate that NPM-ALK, acting through STAT3 as the gene transcriptional activator, induces the expression of ICOS, a cell growth promoting receptor. These data also show that the DNA methylation status of the intronic CpG island affects transcriptional activity of the ICOS gene and, consequently, modulates the concentration of the expressed ICOS protein.
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, USA. qian2@mail.med.upenn.edu
authors.forename: Qian
authors.initials: Q
authors.lastname: Zhang
authors.forename: Hongyi
authors.initials: H
authors.lastname: Wang
authors.forename: Kanchan
authors.initials: K
authors.lastname: Kantekure
authors.forename: Jennifer C
authors.initials: JC
authors.lastname: Paterson
authors.forename: Xiaobin
authors.initials: X
authors.lastname: Liu
authors.forename: Andras
authors.initials: A
authors.lastname: Schaffer
authors.forename: Chrystal
authors.initials: C
authors.lastname: Paulos
authors.forename: Michael C
authors.initials: MC
authors.lastname: Milone
authors.forename: Niels
authors.initials: N
authors.lastname: Odum
authors.forename: Suzanne
authors.initials: S
authors.lastname: Turner
authors.forename: Teresa
authors.initials: T
authors.lastname: Marafioti
authors.forename: Mariusz A
authors.initials: MA
authors.lastname: Wasik
mesh_terms: D000328:Adult; D001483:Base Sequence; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D018899:CpG Islands / Q000235:genetics; D019175:DNA Methylation / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D060889:Inducible T-Cell Co-Stimulator Protein / Q000235:genetics* / Q000378:metabolism; D019169:Jurkat Cells; D008954:Models, Biological; D009857:Oncogenes / Q000502:physiology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
chemical_list: C556692:ICOS protein, human; D060889:Inducible T-Cell Co-Stimulator Protein; D047428:Protein Kinase Inhibitors; C107023:p80(NPM-ALK) protein; D011505:Protein-Tyrosine Kinases