Mechanisms Down-Regulating Sprouty1, a Growth Inhibitor in Prostate Cancer

Authors: Bernard Kwabi-Addo; BAYLOR COLL OF MEDICINE HOUSTON TX

Abstract:

The Sprouty gene family negatively regulates growth factor-induced receptor tyrosine kinase signaling. I have demonstrated that Sprouty1 and 4 are down-regulated in human prostate cancers. The purpose off the present study is to elucidate the molecular mechanism(s) regulating Sprouty expression in prostate cancer. I have 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 and 4 genes. Results show hypermethylation of the Sprouty4 in prostate cancer tissues; more than half of all prostate cancer DNAs were methylated in this region and methylation significantly correlated with decrease in Sprouty4 expression as determined by quantitative RT-PCR. Methylation analysis of Sprouty1 5' untranslated region is currently being investigated. To investigate The transcriptional regulation of Sprouty1 in prostate cancer, I have identified transcription start site(s) in 5'RACE reaction and characterized the Sprouty1 promoter region. Transient transfections using luciferase reporter gene constricts with progressive deletions of the human Sprouty1 5'-flanking region revealed that the core promoter activity is located within The proximal 0.3-Kb region. Comparative analysis of The 5'-flanking region of The human and mouse Sprouty1 shows a highly conserved binding site for Wt1, a transcription factor involved in renal development and tumorigenesis suggesting That Wt1 may be a key transcriptional regulator in Sprouty1 gene expression. Work is currently underway to identity the transcription factors binding to this core promoter region using a novel protein-DNA interaction based method. My studies suggest a potential tumor suppressor activity of Sprouty1 and 4 in prostate cancer. Complete elucidation of the molecular mechanisms controlling Sprouty expression may prove useful iii understanding the regulation of growth factor signaling in prostate cancer.

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APPROVED FOR PUBLIC RELEASE