The Prostate 62:400 ^ 410 (2005) MolecularTargets of Doxazosin in Human Prostatic Stromal Cells Hongjuan Zhao, Frank Lai, Larisa Nonn, James D. Brooks, and Donna M. Peehl* Department of Urology, Stanford University School of Medicine, Stanford,California BACKGROUND. We used cDNA microarray analysis to obtain insights into the mechanisms of action of doxazosin, an a 1 -adrenergic receptor antagonist used to treat benign prostatic hyperplasia (BPH). METHODS. Hierarchical clustering analysis and significance analysis of microarray (SAM) were performed to identify genes differentially expressed between untreated stromal cells cultured from normal tissue and BPH, and changes in gene expression induced by doxazosin. Transcript levels of selected genes were validated by real-time reverse-transcription polymerase chain reaction (RT-PCR). RESULTS. Hierarchical clustering analyses separated untreated normal and BPH cells. Sixty- seven genes whose expression varied at least twofold after doxazosin treatment in both normal and BPH cells were identified, as were 93 genes differentially regulated in normal versus BPH cells. Molecular targets consistent with tumor necrosis factor (TNF)-a-related activity were identified. CONCLUSIONS. Normal versus BPH stromal cells differ in global gene transcription. Doxazosin induced gene expression changes relevant to proliferation/apoptosis, immune defense, cell–cell signaling/signal transduction, and transcriptional regulation. Prostate 62: 400–410, 2005. # 2004 Wiley-Liss, Inc. KEY WORDS: adrenergic receptor; benign prostatic hyperplasia; transforming growth factor-b; tumor necrosis factor-a INTRODUCTION Benign prostatic hyperplasia (BPH) is a common disease of older men, causing urinary obstructive symptoms that require clinical intervention in more than 35% of men age 50 or older in the United States each year [1]. Antagonists of a 1 -adrenergic receptors including doxazosin, terazosin, tamsulosin, and aflu- zosin are used to alleviate the symptoms of BPH [2], since blockade of adrenergic receptors in prostatic smooth muscle relaxes muscle tone, relieving constric- tive pressure of the enlarged prostate on the urethra. Doxazosin, in particular, has drawn a great deal of interest from both clinicians and basic research scien- tists because it is a first-line antihypertensive agent in addition to its use in treating BPH [2]. Studies on the mechanisms of actions of doxazosin and terazosin have revealed unanticipated adrenergic receptor-independent activities that may be relevant to their long-term effects in patients with BPH [3]. Speci- fically, increased rates of apoptosis have been observed in both the epithelium and stroma of BPH tissues in men treated with doxazosin and terazosin. Induction of apoptosis by doxazosin or terazosin was also shown in cultured prostatic stromal cells and in prostate cancer cell lines. Doxazosin’s apoptotic activity is not specific to prostate cells but extends to skin fibroblasts and non- prostatic cancer cell lines as well. However, some cells, such as normal prostatic epithelial cells and bladder and colon cell lines, are resistant to doxazosin-induced apoptosis for unknown reasons. Apoptosis occurs in Grant sponsor: Pfizer, Inc. (International Cardura Competitive Award); Grant sponsor: United States Army MRMC Prostate Cancer Research Program (Postdoctoral Traineeship Award); Grant number: W81XWH-04-1-0080. *Correspondence to: Donna M. Peehl, PhD, Department of Urology, Stanford Medical Center, Stanford, CA 94305-5118. E-mail: dpeehl@stanford.edu Received 29 April 2004; Accepted 7 July 2004 DOI 10.1002/pros.20161 Published online 17 September 2004 in Wiley InterScience (www.interscience.wiley.com). ß 2004 Wiley-Liss, Inc.