N-MYC regulates focal adhesion kinase expression in human neuroblastoma

J Biol Chem. 2007 Apr 27;282(17):12503-16. doi: 10.1074/jbc.M701450200. Epub 2007 Feb 27.

Abstract

N-MYC is a transcription factor that plays an important role in cellular survival in neuroblastoma, and amplification of the N-MYC oncogene is the primary adverse prognostic indicator for neuroblastoma. Focal adhesion kinase (FAK) is a survival factor that has been shown to be overexpressed in many types of human cancers. In this study, we investigated the role of N-MYC regulation of FAK expression in neuroblastoma. We first found a correlation between N-MYC and FAK expression in neuroblastoma. Real time quantitative PCR demonstrated an increase in FAK mRNA abundance in the N-MYC-amplified IMR-32 compared with the nonamplified SK-N-AS neuroblastoma cell lines. FAK protein expression also correlated positively with N-MYC expression in the N-MYC-amplified IMR-32 versus nonamplified SK-N-AS neuroblastoma cell lines. The same results were seen with the isogenic N-MYC(+) (Tet(-)) and N-MYC(-) (Tet(+)) neuroblastoma cell lines. Promoter-reporter assays showed that activity of the FAK promoter was increased in the N-MYC-amplified IMR-32 cell line, in the N-MYC-transfected SK-N-AS nonamplified cell line, and in the isogenic N-MYC(+) (Tet(-)) neuroblastoma cell lines compared with the nonamplified and N-MYC-nonexpressing cell lines. We also identified two N-MYC binding sites in the FAK promoter sequence and showed binding of N-MYC transcription factor to the FAK promoter through electrophoretic mobility shift, chromatin immunoprecipitation, and dual luciferase assays. Finally down-regulation of FAK expression in N-MYC-inducible neuroblastoma cell lines with FAK small interfering RNA or a dominant-negative FAK inhibitor (AdFAK-CD) significantly decreased viability and increased apoptosis in the N-MYC(+) (Tet(-)) cells compared with the isogenic N-MYC(-) (Tet(+)) cells, demonstrating the biological significance of FAK overexpression in the N-MYC-expressing cell lines. This is the first report linking N-MYC and FAK in neuroblastoma, and it clearly demonstrates that N-MYC induces FAK expression. The results indicate that N-MYC regulation of FAK expression can control cellular functions in isogenic N-MYC(-/+) (Tet(+/-)) neuroblastoma cell lines.

Publication types

  • Comparative Study

MeSH terms

  • Cell Line, Tumor
  • Focal Adhesion Kinase 1 / antagonists & inhibitors
  • Focal Adhesion Kinase 1 / biosynthesis*
  • Focal Adhesion Kinase 1 / genetics
  • Gene Amplification*
  • Gene Expression Regulation, Enzymologic* / drug effects
  • Gene Expression Regulation, Neoplastic* / drug effects
  • Humans
  • Neuroblastoma / enzymology*
  • Neuroblastoma / genetics
  • Protein Kinase Inhibitors / pharmacology
  • Proto-Oncogene Proteins c-myc / metabolism*
  • RNA, Small Interfering / pharmacology
  • Response Elements

Substances

  • Protein Kinase Inhibitors
  • Proto-Oncogene Proteins c-myc
  • RNA, Small Interfering
  • Focal Adhesion Kinase 1
  • PTK2 protein, human