37 REVIEW Sirtuin 1 (SIRT1) and steroid hormone receptor activity in cancer R L Moore1, Y Dai1,2 and D V Faller1,2,3,4,5,6 1Cancer Center, Departments of 2Medicine, 3Biochemistry, 4Pediatrics, 5Microbiology and 6Pathology and Laboratory Medicine, Boston University School of Medicine, 72 East Concord Street, Room K-701, Boston, Massachusetts 02118-2307, USA (Correspondence should be addressed to D V Faller at Boston University School of Medicine; Email: [email protected]) Abstract Sirtuins, which are class III NAD-dependent histone signaling through a variety of molecular mechanisms, deacetylases that regulate a number of physiological processes, including acting as co-regulatory transcription factors, play important roles in the regulation of metabolism, aging, deacetylating histones in the promoters of genes with nuclear oncogenesis, and cancer progression. Recently, a role for receptor-binding sites, directly deacetylating steroid hormone the sirtuins in the regulation of steroid hormone receptor nuclear receptors, and regulating pathways that modify steroid signaling is emerging. In this mini-review, we will summarize hormone receptors through phosphorylation. Furthermore, current research into the regulation of estrogen, androgen, disruption of sirtuin activity may be an important step in the progesterone, mineralocorticoid, and glucocorticoid signaling development of steroid hormone-refractory cancers. by sirtuins in cancer. Sirtuins can regulate steroid hormone Journal of Endocrinology (2012) 213, 37–48 Introduction cancer, ovarian cancer, and lung cancer among others (Miller & Langdon 1997, Gronemeyer et al. 2004, Huang et al. 2010). Steroid hormone receptors, such as the estrogen (ER) and Understanding of the steroid hormone dependency of androgen receptors (AR), as well as the progesterone (PR), certain cancer cells and the mechanisms underlying their glucocorticoid (GR), and mineralocorticoid receptors (MR) subsequent evolution to a hormone-refractory state is an are part of a large nuclear receptor family of eukaryotic important and challenging goal of molecular oncology. transcription factors (Tsai & Omalley 1994, Mangelsdorf et al. Abnormal function of the AR has been linked to both the 1995, Aoyagi & Archer 2008). Steroid hormone receptors pathogenesis and the progression of human prostate cancer play essential roles in numerous biological processes, such as (Edwards & Bartlett 2005, Wang et al. 2005, Fu et al. 2006), homeostasis, metabolism, cell growth, and development (Tsai and the ER plays a similar role in pathogenesis and & Omalley 1994, Mangelsdorf et al. 1995, Chawla et al. 2001). progression of breast cancer. In the healthy mammary glands, Initiation of steroid hormone receptor activity normally ER-positive cells are largely quiescent. Estrogen stimulates requires the binding of a specific ligand, such as estrogen in these cells to produce growth factors that cause the growth the case of the ER. The steroid hormone receptors then of neighboring ER-negative cells through paracrine effects dimerize and in some cases undergo post-translational involving stromal–epithelial cell interaction. ER-positive modifications, translocate to the nucleus, and bind to their breast cancer cells are stimulated to proliferate in response cognate hormone-responsive elements in the promoter or to estrogen. Estrogen not only stimulates growth in these other regulatory regions of their target genes. The promoter- cells, but also suppresses apoptosis. One early step in the bound steroid hormone receptor then recruits transcriptional neoplastic transformation of the breast epithelium is the co-regulatory proteins and ultimately RNA polymerase II autocrine mechanism becoming predominant (Streuli & and other components of the transcriptional machinery, Haslam 1998, Fuqua et al. 2000, Aghmesheh et al. 2005, eliciting a transcriptional response (Tsai & Omalley 1994, Song & Santen 2006). Prostate cancer progression can evolve Kinyamu & Archer 2004, Perissi & Rosenfeld 2005). through a similar pattern, including autocrine production Regulation of steroid hormone receptor signaling is of androgens, and eventual activation of AR signaling in a complex. Disruption in the physiological functions of ligand-independent fashion (Prins & Putz 2008). these receptors can lead to several types of malignancies Post-translational modification of the steroid hor- such as breast cancer, leukemia and lymphoma, prostate mone receptors can play a role in the evolution of steroid Journal of Endocrinology (2012) 213, 37–48 DOI: 10.1530/JOE-11-0217 0022–0795/12/0213–037 q 2012 Society for Endocrinology Printed in Great Britain Online version via http://www.endocrinology-journals.org Downloaded from Bioscientifica.com at 09/25/2021 04:43:20AM via free access 38 R L MOORE and others . Sirtuins and steroid hormone receptor activity responsiveness and independence in these tumors, by Vaquero et al. 2006). Mice carrying inactivating mutations of regulating signaling in response to steroid hormones. These SIRT1, SIRT2, or SIRT3 develop cancers, predominantly modifications include phosphorylation, ubiquitination, gly- in the mammary glands and the liver, accompanied by cosylation, and acetylation. For example, PRMT1-mediated genomic instability and/or abnormal energy metabolism. acetylation of ERa is required for recruitment of the SIRT2-deficient mice initially develop normally, but develop co-effector molecules SRC, PI3K, and Fak (Le Romancer mammary tumors and hepatocellular carcinoma as they age et al. 2008). ERa can be acetylated by p300 on two lysine (Deng et al. 2011). The functions of SIRT3–5 are, as yet, residues located in the hinge region of the molecule in vitro. unknown. Substrates for these sirtuins include acetyl- Acetylation at these sites decreases the hormone sensitivity of coenzyme A synthetase 2, glutamate dehydrogenase, and the receptor (Wang et al. 2001, Margueron et al. 2004). A cytochrome c (Haigis & Guarente 2006, Haigis et al. 2006, mutation at one of these acetylation sites, lysine 303, has been Hallows et al. 2006, Schlicker et al. 2008, Schwer & Verdin linked to premalignant lesions of the breast (Fuqua et al. 2000, 2008, Hirschey et al. 2010). Of all the sirtuins, SIRT1 remains Wang et al. 2001). It has not yet been determined whether the most intensively studied, and its actions on steroid acetylation affects ERa stability, intracellular localization, or hormone signaling will be the focus of this review (Table 1). its ability to interact with co-activators or co-repressors (Margueron et al. 2004). SIRT1 Sirtuins SIRT1 is a nicotinamide adenosine dinucleotide (NAD/ NADH)-dependent histone deacetylase (HDAC) that func- The sirtuins comprise a family of enzymes with increasing tions by deacetylating histone (H1, H3, and H4) and relevance to the regulation of steroid hormone receptor nonhistone proteins. SIRT1 has been linked to control of activity. The sirtuins are encoded by a family of genes that has longevity, gene silencing, cell-cycle progression, apoptosis, remained highly conserved from archaebacteria to eukaryotes and energy homeostasis (Haigis & Guarente 2006, Yang et al. (Frye 1999, 2000). In yeast, there are four other sirtuins 2006, Dali-Youcef et al. 2007, Yamamoto et al. 2007, Greiss & in addition to Sir2p, whereas seven homologs have been Gartner 2009). SIRT1 also has functions relating to identified in mammals, SIRT1–7 (Frye 1999, 2000, Ford et al. inflammation and neurodegeneration (Yamamoto et al. 2005, Yamamoto et al. 2007). Sirtuin activities are not 2007). SIRT1 interacts with nuclear steroid hormone limited to histone deacetylation; SIRT members can also receptor co-activator proteins such as p300, PPARg and deacetylate nonhistone proteins and have diverse functions in PGC-a in the differentiation of muscle cells, adipogenesis, fat multiple cellular compartments. Sirtuin (SIRT) 1, 6, and 7 storage, and metabolism in the liver (Fulco et al. 2003, Picard localize to the nucleus, whereas SIRT3, SIRT4, and SIRT5 et al. 2004, Puigserver et al. 2005, Rodgers et al. 2005). are mitochondrial, and SIRT2 is primarily cytoplasmic Recently, our understanding of the physiological control of (Liu et al. 2005, Michishita et al. 2005, 2008). SIRT6 has SIRT1 activity in the cell and its consequences on steroid been found to deacetylate histone H3, thereby regulating hormone receptor activity is expanding. Endogenous SIRT1 transcription and maintaining genomic stability (Liu et al. activity in normal cells is regulated by the absolute levels of 2005, Michishita et al. 2005, 2008, Lombard et al. 2008, SIRT1 protein (which do not generally appear to change Kawahara et al. 2009). SIRT7 regulates RNA polymerase temporally among cells of the same type), and more I-mediated expression of ribosomal RNA genes. SIRT7 has importantly by the ability of SIRT1 to act as a cellular energy also been linked to angiogenesis (Ford et al. 2006, Potente sensor controlled by the intracellular NAD/NADH ratio. et al. 2007). SIRT2 is involved in cell-cycle regulation, can Whether changes in the energy state of the cell thereby have deacetylate histone H4, and also acts as a tumor suppressor in an effect on the function of steroid hormone receptors, certain gliomas (Dryden et al. 2003, Hiratsuka et al. 2003, however, has not yet been explored. Furthermore, in tumor Table 1 Summary of actions of SIRT1 on steroid hormone receptor activity Deacetylase Physiological function SIRT1 regulation activity dependent of SIRT1 Estrogen receptor SIRT1 inhibits ligand-independent