title: Expression of the TrkA or TrkB receptor tyrosine kinase alters the double-strand break (DSB) repair capacity of SY5Y neuroblastoma cells.
abstract: In the childhood tumor neuroblastoma, high expression of the TrkA neurotrophin receptor is associated with a favorable prognosis and a lack of structural chromosomal changes, whereas TrkB is expressed in aggressive neuroblastomas demonstrating high genomic instability. The ability to repair DNA double-strand breaks (DSBs) is considered a central determinant of chromosomal stability with nonhomologous end joining (NHEJ) being the major pathway of DSB repair in vertebrates. Here, we used the SH-SY5Y human neuroblastoma cell line ectopically expressing either TrkA or TrkB as a model system to analyze the impact of Trk receptor expression on NHEJ-mediated DSB repair. In a cell-free NHEJ assay, SY5Y-TrkA cells displayed a significantly higher efficiency for NHEJ compared to SY5Y-TrkB cells. To detect possible underlying mechanisms, gene expression data (Affymetrix U95A microarray chips) obtained from the same SY5Y-TrkA/TrkB model system were reanalyzed focussing on genes involved in DNA repair. Expression of XRCC4, a central component of NHEJ, was significantly upregulated in SY5Y-TrkA compared to SY5Y-TrkB cells. Expression data were confirmed using real-time PCR and western blotting. Additionally, XRCC4 expression was enhanced in most primary neuroblastomas with high TrkA expression. The TrkA-induced increase in NHEJ activity could be reverted by XRCC4 knock-down, confirming the induction of XRCC4 by TrkA to be essential for the observed phenotype. Our data provide the first evidence for a functional relationship between tyrosine kinase receptor signaling and NHEJ-mediated DSB repair in cancer cells, potentially contributing to their genomic stability.
authors.affiliation: Division of Oncology, University Children's Hospital of Essen, Hufelandstrasse 55, Essen, Germany. johannes.schulte@uni-due.de
authors.forename: Johannes H
authors.initials: JH
authors.lastname: Schulte
authors.forename: Steffi
authors.initials: S
authors.lastname: Kuhfittig-Kulle
authors.forename: Ludger
authors.initials: L
authors.lastname: Klein-Hitpass
authors.forename: Alexander
authors.initials: A
authors.lastname: Schramm
authors.forename: Denis S F
authors.initials: DS
authors.lastname: Biard
authors.forename: Petra
authors.initials: P
authors.lastname: Pfeiffer
authors.forename: Angelika
authors.initials: A
authors.lastname: Eggert
mesh_terms: D045744:Cell Line, Tumor; D002474:Cell-Free System; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007700:Kinetics; D009447:Neuroblastoma / Q000201:enzymology* / Q000235:genetics / Q000473:pathology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020917:Receptor, trkA / Q000378:metabolism*; D020813:Receptor, trkB / Q000378:metabolism*; D011995:Recombination, Genetic; D015854:Up-Regulation
chemical_list: D004268:DNA-Binding Proteins; D012333:RNA, Messenger; C101467:XRCC4 protein, human; D020917:Receptor, trkA; D020813:Receptor, trkB