Mechanisms Down-Regulating Sprouty1, a Growth Inhibitor in Prostate Cancer
Abstract
The Sprouty gene family negatively regulates growth factor-induced receptor tyrosine kinase signaling with a potential tumor suppressor function in cancer. I have demonstrated that Sprouty1 is down-regulated in human prostate cancer (PCa). The purpose of the present study is to characterize the molecular mechanisms regulating Sprouty1 expression in the human PCa. Results. I have carried out deletion analysis coupled with reporter gene assays to characterize Sprouty1 promoter activity. Electrophoretic mobility shift assays, chromatin immunoprecipitation and TranSignal protein-DNA array were used to demonstrate binding interaction of Transcription factors (TFs) with Sprouty1 promoter. I have also carried out DNA methylation analysis on 20 matched normal prostate tissues and tumor prostate tissues (at least 70% of tissue is carcinoma) in the 5 untranslated region of Sprouty1. The results of deletion analysis demonstrated a strong promoter activity in the proximal 0.3-kb region of Sprouty1 promoter. Several potential binding sites for transcription factors (TFs) such as: AP-1/2, CREB, EGR1, GATA1, and SP1 were found within this region. In addition, TranSignal protein-DNA array analysis showed differential activation of a number of transcription factors (TFs) in the normal and prostate cancer cell lines with the consensus binding sites of Sprouty1 promoter. Gene knockdown of one such TF family: GATA (2 and 4) induced Sprouty1 expression demonstrating transcriptional repression by this TF. I did not observe any significant methylation of the Sprouty1 promoter region in the normal or the tumor samples analyzed. CONCLUSION. My studies suggest that Sprouty1 is not regulated in human prostate cancer by epigenetic mechanisms. Transcriptional repression may therefore represent a key mechanism for down-regulation of Sprouty1 expression in prostate cancer.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 2006
- Accession Number
- ADA462867
Entities
People
- Bernard Kwabi-addo
Organizations
- Baylor College of Medicine