Evidence that Sp1 positively and Sp3 negatively regulate and androgen does not directly regulate functional tumor suppressor 15-lipoxygenase 2 (15-LOX2) gene expression in normal human prostate epithelial cells

• Published in: Oncogene Vol. 23; no. 41; pp. 6942 - 6953
• Main Authors: SHAOHUA TANG, BHATIA, Bobby, JIANJUN ZHOU, MALDONADO, Carlos J, CHANDRA, Dhyan, KIM, Eunjung, FISCHER, Susan M, BUTLER, Andrew P, FRIEDMAN, Scott L, TANG, Dean G
• Format: Journal Article
• Language: English
• Published: Basingstoke Nature Publishing 09.09.2004; Nature Publishing Group
• Subjects: Androgen receptors; Androgens; Androgens - physiology; Arachidonate 15-Lipoxygenase - genetics; Base Sequence; Biological and medical sciences; Boxes; Cell physiology; Cell transformation and carcinogenesis. Action of oncogenes and antioncogenes; DNA-Binding Proteins - physiology; Electrophoretic mobility; Epithelial cells; Epithelial Cells - enzymology; Fundamental and applied biological sciences. Psychology; Gene deletion; Gene expression; Gene Expression Regulation, Enzymologic; Gene regulation; Gynecology. Andrology. Obstetrics; Humans; Lipoxygenase; LOX2 gene; Male; Male genital diseases; Medical sciences; Molecular and cellular biology; Molecular Sequence Data; Nephrology. Urinary tract diseases; Promoter Regions, Genetic; Prostate; Prostate - enzymology; Prostate cancer; Sp1 protein; Sp1 Transcription Factor - physiology; Sp3 Transcription Factor; Transcription factors; Transcription Factors - physiology; Tumor suppressor genes; Tumors; Tumors of the urinary system; Urinary tract. Prostate gland; Human; Urinary system disease; Prostate disease; Androgen; Enzyme; Malignant tumor; Gene expression; Normal; Carcinogenesis; Regulation(control); 15-lipoxygenase 2; Sp1; gene regulation; Sp3; Epithelial cell; Oxidoreductases; Sex steroid hormone; Transcription factor; Lipoxygenase; Male genital diseases; Urogenital system; Prostate cancer; Tumor suppressor gene
• ISSN: 0950-9232; 1476-5594
• DOI: 10.1038/sj.onc.1207913

In this project, we studied the gene regulation of 15-lipoxygenase 2 (15-LOX2), the most abundant arachidonate-metabolizing LOX in adult human prostate and a negative cell-cycle regulator in normal human prostate (NHP) epithelial cells. Through detailed in silico promoter examination and promoter deletion and activity analysis, we found that several Sp1 sites (i.e., three GC boxes and one CACCC box) in the proximal promoter region play a critical role in regulating 15-LOX2 expression in NHP cells. Several pieces of evidence further suggest that the Sp1 and Sp3 proteins play a physiologically important role in positively and negatively regulating the 15-LOX2 gene expression, respectively. First, mutations in the GC boxes affected the 15-LOX2 promoter activity. Second, both Sp1 and Sp3 proteins were detected in the protein complexes that bound the GC boxes revealed by electrophoretic mobility shift assay. Third, importantly, inhibition of Sp1 activity or overexpression of Sp3 both inhibited the endogenous 15-LOX2 mRNA expression. Since 15-LOX2 is normally expressed in the prostate luminal epithelial cells, we subsequently explored whether androgen/androgen receptor may directly regulate its gene expression. The results indicate that androgen does not directly regulate 15-LOX2 gene expression. Together, these observations provide insight on how 15-LOX2 gene expression may be regulated in NHP cells.