Androgen Regulation of 5a-Reductase Isoenzymes in Prostate Cancer: Implications for Prostate Cancer Prevention Jin Li1¤, Zhiyong Ding 1 , Zhengxin Wang2, Jing-Fang Lu3, Sankar N. Maity3, Nora M. Navone3, Christopher J. Logothetis3, Gordon B. Mills1, Jeri Kim3* 1 Department of Systems Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas, United States of America, 2 Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas, United States of America, 3 Department of Genitourinary Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas, United States of America Abstract The enzyme 5a-reductase, which converts testosterone to dihydrotestosterone (DHT), performs key functions in the androgen receptor (AR) signaling pathway. The three isoenzymes of 5a-reductase identified to date are encoded by different genes: SRD5A1, SRD5A2, and SRD5A3. In this study, we investigated mechanisms underlying androgen regulation of 5a-reductase isoenzyme expression in human prostate cells. We found that androgen regulates the mRNA level of 5a- reductase isoenzymes in a cell type–specific manner, that such regulation occurs at the transcriptional level, and that AR is necessary for this regulation. In addition, our results suggest that AR is recruited to a negative androgen response element (nARE) on the promoter of SRD5A3 in vivo and directly binds to the nARE in vitro. The different expression levels of 5a- reductase isoenzymes may confer response or resistance to 5a-reductase inhibitors and thus may have importance in prostate cancer prevention. Citation: Li J, Ding Z, Wang Z, Lu J-F, Maity SN, et al. (2011) Androgen Regulation of 5a-Reductase Isoenzymes in Prostate Cancer: Implications for Prostate Cancer Prevention. PLoS ONE 6(12): e28840. doi:10.1371/journal.pone.0028840 Editor: Natasha Kyprianou, University of Kentucky College of Medicine, United States of America Received May 16, 2011; Accepted November 16, 2011; Published December 14, 2011 Copyright: 2011 Li et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: This research was funded by the Prostate Cancer Research Program at MD Anderson Cancer Center and supported in part by the National Institutes of Health through MD Anderson’s Cancer Center Support Grant, CA016672. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. * E-mail: jekim@mdanderson.org ¤ Current address: Center for Applied Genomics, Abramson Research Center, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America Introduction The multiyear, multistep process of prostate carcinogenesis and its long latency period make prostate cancer ideal for chemopre- vention [1]. The androgen receptor (AR) signaling pathway, which is essential for prostate development and normal function, is also central to prostate cancer’s pathogenesis and progression [2,3]. The key enzyme in AR signaling, 5a-reductase, converts testosterone to the more potent androgen dihydrotestosterone (DHT) [4]. Although testosterone can bind to and activate the AR, DHT binds to it with a dissociation rate three times slower than that of testosterone [5,6]. Three isoenzymes of 5a-reductase, which are encoded by different genes (SRD5A1, SRD5A2, and SRD5A3), have been identified. Immunohistochemical and polymerase chain reaction (PCR) analyses of human prostate tissues suggest that SRD5A1 and SRD5A2 levels change with prostate cancer development and progression [7,8,9]. In vitro studies have confirmed the 5a- reductase activity of the more-recently identified SRD5A3 [10], which was overexpressed in hormone-refractory prostate cancer tissues [10,11]. Knockdown of SRD5A3 expression also reduced the growth and viability of prostate cancer cells [10]. By using a monoclonal antibody, Godoy et al. further showed increased level of SRD5A3 protein in the prostate cancer compared to benign prostate tissues [12]. These findings suggested that SRD5A3 may contribute to prostate cancer progression. It has also been recently reported that SRD5A3 may play an important role in protein glycosylation [13]. Mutations of SRD5A3 result in congenital disorders [13,14] and Kahrizi syndrome [15]. Two 5a-reductase inhibitors have been tested clinically. Finasteride specifically inhibits SRD5A2 activity [16], and dutasteride inhibits that of both SRD5A1 and SRD5A2 [17]. The Prostate Cancer Prevention Trial (PCPT) yielded encourag- ing results: finasteride reduced the overall incidence of prostate cancer by 25%, although potential effects of high-grade tumors were concerning [18]. Similarly, the Reduction by Dutasteride of Prostate Cancer Events (REDUCE) trial showed that dutasteride reduced the incidence of prostate cancer by 23% among men at high risk and revealed no statistically significant increase of high- grade tumor in dutasteride-treated men [19,20]. Three factors may confer response or resistance to 5a-reductase inhibitors. First, response or resistance may result from the presence of different isoenzymes [21]. Second, differences in sensitivity may be conferred by SRD5A2 genotypic variants [22]; Makridakis et al. [23] showed in vitro that SRD5A2 variants have different affinities for finasteride. Third, different expression levels PLoS ONE | www.plosone.org 1 December 2011 | Volume 6 | Issue 12 | e28840