Glucocorticoid Receptor Changes Its Cellular Location with Breast Cancer Development
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Histol Histopathol (2008) 23: 77-85 Histology and http://www.hh.um.es Histopathology Cellular and Molecular Biology Glucocorticoid receptor changes its cellular location with breast cancer development Isabel Conde1, Ricardo Paniagua1, Benito Fraile1, Javier Lucio2 and Maria I. Arenas1 1Department of Cell Biology and Genetics, and 2Department of Physiology. University of Alcalá, Alcalá de Henares, Madrid. Spain Summary. Glucocorticoids play a major role in Introduction attenuation of the inflammatory response and they are useful in the primary combination chemotherapy of The hormonal regulation of breast cancer cell breast cancer, since in vitro studies have demonstrated an growth and survival is multifaceted and very complex antiproliferative effect in human breast cancer cells. In (Nass and Davidson, 1999) due to the potential for contrast, it was recently shown that glucocorticoids interaction or cross talk between the different classes of protect against apoptotic signals evoked by cytokines, hormones, especially the ability of certain hormones to cAMP, tumour suppressors, and death genes in regulate the abundance of the receptors for other mammary gland epithelia. Their actions are mediated by hormones (Traynor, 1995). Activated steroid receptors intracellular receptor (GR) that functions as a hormone- affect many genes that are involved in cellular dependent transcription factor; however, no previous metabolism and often affect the transcription of other studies have been focused on GR expression in different steroid receptors (Dickson and Lippman, 1988). One of pathologies of the human breast, and the possible these receptors is the glucocorticoid receptor (GR) relationship with that of mineralocorticoid receptor which operates on the mechanisms of cellular (MR) and COX-2. Also, the role of these proteins on differentiation and induces apoptosis in certain cells (Lee tumoral breast epithelial cells remains unclear. et al., 1988; Hulkko and Zilliacus, 2002). Taking into Therefore, we examined GR, MR and COX-2 expression account these properties, glucocorticoids have been used by immunohistochemistry and Western blot techniques in clinical oncology for more than three decades and in 142 samples of human breast obtained by total or have a proven anti-tumour effect against lympho- partial mastectomy. We found that the percentage of proliferative tumours (Walsh and Avashia, 2002). positive patients presenting nuclear immunoreaction to Glucocorticoids play a major role in attenuation of the GR decreased with tumor development, while all inflammatory response and they are useful in the samples analyzed showed cytoplasmic immunoreactions primary combination chemotherapy of breast cancer to MR. All positive samples to COX-2 antibody showed (Rubens et al., 1988), since in vitro studies have cytoplasmic location, a higher immunoreaction being demonstrated an antiproliferative effect in human breast observed in benign breast diseases than in carcinomatous cancer cells (Osborne et al., 1979; Zhou et al., 1989; lesions. Thus, breast cancer progression is associated Hundertmark et al., 1997). In contrast, it was recently with the accumulation of GR in the cytoplasm of shown that glucocorticoids protect against apoptotic tumoral cells and the decrease of COX-2 expression. signals evoked by cytokines, cAMP, tumour suppressors, and death genes in mammary gland epithelia, Key words: GR, MR, COX-2, Breast cancer hepatocytes, ovarian follicular cells and fibroblasts (Amsterdam et al., 2002). One of the functions of glucocorticoids is to reduce the production of prostanoids by inhibiting the expression of COX-2 (Half et al., 2002). These proteins catalyze the conversion of arachidonic acid to prostaglandins, which have been detected at elevated levels in cultured human breast cancer cells as well as in Offprint requests to: Dr. M.I. Arenas, Department of Cell Biology and invasive human breast cancers (Rolland et al., 1980; Genetics, University of Alcalá, 28871 Alcalá de Henares, Madrid, Spain. Karmali et al., 1983; Schrey and Patel, 1995; Liu and e-mail: [email protected] Rose, 1996). However, there are multiple contradictory 78 GR expression in human breast data on elevated COX-2 (an inducible isoform of Each specimen was divided into two approximately cyclooxygenases) expression in breast neoplasia (Half et equal portions: one portion was processed for al., 2002; Ma et al., 2004). Thus, Half and co-workers immunohistochemistry (10% formalin fixed and paraffin (2002) encountered that the apparently normal breast embedded), and another portion was frozen in liquid epithelia adjacent to the tumour site expressed COX-2 in nitrogen and maintained at -80°C for Western blot 81% of analyzed cases; whereas Watanabe et al. (2003) analysis. reported a low level of COX-2 expression in 50% of normal epithelia surrounding ductal carcinoma in situ, Methods but in only 15% of normal epithelia surrounding invasive disease. Moreover, it is well established that Immunoblotting prostaglandin production is greater in human breast tumours than benign tumours or normal breast tissues For Western blot analysis, tissues were homogenized (Rolland et al., 1980; Boland et al., 2004). in the extraction buffer (10 mM Tris-HCl, pH 7.6, 10 Not only glucocorticoids but also mineralocorticoids mM KCl, 1 mM 1,4-Ditio-L-threitol, and 0.2 M and its cognate receptors are involved in this regulation ethylenediamine tetracetic acid, pH 8) in addition to a of COX-2 expression (Zhang et al., 1999). Both cocktail of protease inhibitors (1 mM phenyl- receptors mediate biological responses to adrenal methanesulfonyl fluoride, 10 µg/ml of leupeptine and 1 corticosteroids and synthetic ligands, and although many mg/ml of aprotinine) and phosphatase inhibitors (200 characteristics of GR are applicable to mineralocorticoid mg/ml of sodium fluoride and 50 mg/ml of sodium receptor (MR), there are significant differences between orthovanadate) in presence of 0.5 % Triton X-100 and both receptors regarding their physiological effects in the 0.1% of SDS. Homogenates were centrifuged for 10 min target tissues (Bhargava and Pearce, 2004). Although the at 10000 rpm at 4°C. Supernatants were mixed with an regulation of COX-2 by mineralocorticoids was equivalent volume of SDS buffer (10% SDS in Tris/HCl described in rat renal medulla (Zhang et al., 2002), this pH 8, containing 50% glycerol, 0.1 mM 2-beta- regulation has not yet been identified in human breast mercaptoethanol and 0.1% bromophenol blue). Then the cancer. mixture was denatured for 4 min at 96°C, and aliquots of Multiple controversial data have promoted the 50 µ g protein were subjected to SDS-PAGE (9% development of this study to evaluate, in different breast acrylamide gel for GR and 12% for MR and COX-2). lesions by immunohistochemistry and Western blot Following SDS-PAGE, proteins were transferred to analysis, the expression profile of glucocorticoid nitrocellulose membranes (0.2 mm) in the transfer buffer receptor together with that of mineralocorticoid receptor (25 mM Tris-HCl, 192 mM glycine, 0.1% SDS and 20% and COX-2, in order to improve our knowledge of the methanol) for 4h at 250 mA constant current. Briefly, the relationship of these proteins in the development and blots were blocked in 5% Blotto (Santa Cruz progression of breast cancer and their possible influence Biotechnology CA, USA) for 1 hour. After blocking, in endocrine therapies responsiveness. blots were incubated with primary antibodies: mouse monoclonal GR (1:200) (Novocastra Laboratories LTD, Materials and methods UK; Santa Cruz), mouse monoclonal MR (1:4000) (Affinity Bioreagents Golden, CO; Santa Cruz), and Material rabbit polyclonal COX-2 (1:1000) (Santa Cruz). All of them diluted in blocking solution 1:9 overnight at room Breast samples used in this study were collected temperature. After extensive washing with TBS/Tween from 142 patients (from 35 to 91 years of age) diagnosed 20, the membranes were incubated with biotinylated between 1998 and 2000 and they had a follow-up of 60 immunoglobulins diluted in blocking solution 1:9, rabbit months, by the Pathology Service of the Hospital anti-mouse for GR and MR, or swine anti-rabbit for Príncipe de Asturias of Alcalá de Henares. Primary COX-2 (Dako, Barcelona, Spain) at 1:2000 and after an glandular breast lesions were classified as follows: 24 extensive wash, the sheets were incubated with cases of benign proliferative diseases, including ductal streptavidin-peroxidase (Zymed Laboratories Inc. South and lobular hyperplasia, apocrine metaplasia, San Francisco, CA, US) at 1:10000 dilution in the same fibroadenoma, and fibrocystic changes; 38 carcinomas in blocking solution 1:9. Finally, the membranes were situ (CIS); 80 infiltrative carcinomas: 46 ductal (IDC) developed with an enhanced chemiluminescence (ECL) and 34 lobular (ILC). Removal of tissues and the study kit, following the procedure described by the of archives samples were carried out with the consent of manufacturer (Amersham, Buckinghamshire, UK). Blots patients and/or their relatives and permission of the were stripped and re-probed with an anti-human ß-actin Ethics Committee of the Hospital. The hormonal monoclonal antibody (Amersham) to control for equal receptor status of infiltrative carcinomatous lesions was sample loading. determined together with the pathological diagnosis by Príncipe de Asturias Hospital Pathology Service. None Immunohistochemistry of these patients received radiotherapy, hormonal therapy or chemotherapy before