Inducible short-term and stable long-term cell culture systems reveal that the PAX3-FKHR fusion oncoprotein regulates CXCR4, PAX3, and PAX7 expression

Lab Invest. 2004 Aug;84(8):1060-70. doi: 10.1038/labinvest.3700125.

Abstract

In the pediatric cancer alveolar rhabdomyosarcoma (ARMS), the 2;13 chromosomal translocation juxtaposes the PAX3 and FKHR genes to generate a chimeric transcription factor. To explore molecular pathways altered by this oncoprotein, we generated an inducible form by fusing PAX3-FKHR to a modified estrogen receptor ligand-binding domain and expressed this construct in the RD embryonal rhabdomyosarcoma cell line. This inducible system permits short-term evaluation of downstream expression targets of PAX3-FKHR and complements a panel of stable long-term RD subclones constitutively expressing PAX3-FKHR. Using these two sets of resources, we investigated several candidate PAX3-FKHR target genes. First, we demonstrated in both short-term and long-term systems that PAX3-FKHR upregulates expression of the gene encoding the chemokine receptor CXCR4. In addition, we found that expression of wild-type PAX3 is upregulated, whereas expression of wild-type PAX7 is downregulated by PAX3-FKHR. In the presence of cycloheximide, CXCR4 and PAX3 are still inducible, supporting the hypothesis that these genes are direct transcriptional targets of PAX3-FKHR. Finally, studies of ARMS tumors revealed CXCR4, PAX3, and PAX7 expression levels consistent with our cell culture results. These findings of genes regulated by PAX3-FKHR will direct future biological and clinical investigation to important pathways contributing to ARMS tumorigenesis and progression.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Base Sequence
  • Binding Sites / genetics
  • Cell Division
  • Cell Line, Tumor
  • DNA Primers / genetics
  • DNA, Neoplasm / genetics
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism*
  • Forkhead Box Protein O1
  • Forkhead Transcription Factors
  • Gene Expression Regulation, Neoplastic
  • Homeodomain Proteins / genetics
  • Homeodomain Proteins / metabolism*
  • Humans
  • Oncogene Proteins, Fusion / genetics
  • Oncogene Proteins, Fusion / metabolism*
  • PAX3 Transcription Factor
  • PAX7 Transcription Factor
  • Paired Box Transcription Factors
  • Receptors, CXCR4 / genetics
  • Receptors, CXCR4 / metabolism*
  • Receptors, Estrogen / genetics
  • Receptors, Estrogen / metabolism
  • Rhabdomyosarcoma, Embryonal / genetics
  • Rhabdomyosarcoma, Embryonal / metabolism
  • Rhabdomyosarcoma, Embryonal / pathology
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*

Substances

  • DNA Primers
  • DNA, Neoplasm
  • DNA-Binding Proteins
  • FOXO1 protein, human
  • Forkhead Box Protein O1
  • Forkhead Transcription Factors
  • Homeodomain Proteins
  • Oncogene Proteins, Fusion
  • PAX3 Transcription Factor
  • PAX3 protein, human
  • PAX7 Transcription Factor
  • PAX7 protein, human
  • Paired Box Transcription Factors
  • Receptors, CXCR4
  • Receptors, Estrogen
  • Transcription Factors
  • Pax3 protein, mouse