Ets transcriptional regulation of gastrin-releasing peptide receptor in neuroblastomas.
BACKGROUND
We have demonstrated that gastrin-releasing peptide (GRP) binds specifically to its cell surface receptor, GRP-R, to act as an autocrine/paracrine growth factor for neuroblastomas (NBs); an increased expression of GRP-R was found in more advanced-stage NBs. Ets family proteins are nuclear targets for intracellular kinase pathways that can lead to cell proliferation; however, a potential role of Ets in the expression of GRP-R in NBs is unknown. Therefore, the purpose of our study was to determine whether Ets regulates transcriptional activity of GRP-R in NBs.


METHODS
We identified multiple DNA-binding sites for various nuclear transcription factors in the proximal (ie, 263 bp) GRP-R promoter. Luciferase assay was performed to measure GRP-R promoter activity that contained site-specific mutations of various binding elements. Electrophoretic mobility shift assay was performed to determine transcription factor-binding activity.


RESULTS
Mutation of a consensus Ets-binding site in the GRP-R promoter significantly decreased GRP-R promoter activity. Electrophoretic mobility shift assay demonstrated a decrease in Ets nuclear protein-binding activity. Furthermore, overexpression of Ets1 resulted in upregulation of GRP-R promoter activity.


CONCLUSIONS
Our results demonstrate that Ets is a transcription factor that significantly contributes to the GRP-R transcription in NBs. This finding may allow us to develop novel molecular tools to downregulate expression of GRP-R and hence inhibit mitogenic effects of GRP in NBs.
Department of Surgery and the Sealy Center for Cancer Cell Biology, the University of Texas Medical Branch, Galveston, TX 77555-0353, USA.
Jingbo
J
Qiao
Jeremy
J
Cree
Junghee
J
Kang
Sunghoon
S
Kim
B Mark
BM
Evers
Dai H
DH
Chung
D004247:DNA / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D009447:Neuroblastoma / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D050784:Proto-Oncogene Protein c-ets-1; D011518:Proto-Oncogene Proteins / Q000502:physiology*; D050783:Proto-Oncogene Proteins c-ets; D018004:Receptors, Bombesin / Q000235:genetics*; D014157:Transcription Factors / Q000502:physiology*; D014158:Transcription, Genetic
C494041:ETS1 protein, human; D050784:Proto-Oncogene Protein c-ets-1; D011518:Proto-Oncogene Proteins; D050783:Proto-Oncogene Proteins c-ets; D018004:Receptors, Bombesin; D014157:Transcription Factors; D004247:DNA