Angiotensin II type 1 receptor expression in human breast tissues

Abstract

Summary We demonstrate the expression of angiotensin 11 type 1 (AT1) receptors in normal and diseased human breast tissues. Using monoclonal antibody 6313/G2, directed against a specific sequence in the extracellular domain of the AT1 receptor, immunocytochemical analysis revealed positive immunoreactivity in membrane and cytoplasm of specific cell types. Immunoblotting of solubilized proteins separated by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) from benign and malignant tumours identified a single immunoreactive species with a molecular mass of approximately 60 kDa, consistent with that of the mature glycosylated receptor. In studies of [1251]angiotensin 11 binding using breast membrane preparations, concentrations of specific angiotensin 11 binding sites were found to range from 1.8 to 100 fmol mg-' protein, with a Kd of approximately 60 nm. Most of the specifically bound [1251]angiotensin II was displaced by losartan, a specific angiotensin 11 type 1 receptor antagonist, while less was displaced by the AT2 receptor type antagonist, CGP42112A, thus confirming the prevalence of AT1 receptors in this tissue type. These data suggest that the renin-angiotensin system may be involved in normal and abnormal breast tissue function.Keywords: breast cancer; renin-angiotensin system; losartan; immunocytochemistry; monoclonal antibody G313/G2 Angiotensin II plays a central role in mammalian electrolyte homeostasis and blood pressure control (Peach, 1977;Vinson et al, 1992). Two main subtypes of angiotensin II receptors, designated types 1 and 2 (ATl and AT2), have been recognized, but the majority of the well-known actions of angiotensin II occur via the ATI subtype (Herblin et al, 1991;Ouali et al, 1992). Local tissue renin-angiotensin systems have been demonstrated in several tissues, and in some cases it has been suggested that local production of angiotensin II may be particularly concerned in trophic actions (Vinson et al, 1995a).The availability of our recently developed monoclonal antibody (6313/G2) to the ATI receptor subtype (Barker et al, 1993a) has facilitated the further study of its distribution (Vinson et al, 1995a). We describe here studies investigating the presence of the ATl receptor in normal and diseased breast. Sections were then immersed in endogenous peroxidase blocking solution (3 ml of 100 volume hydrogen peroxide and 97 ml of methanol; 15 min), washed in tap water (10 min) and distilled water (5 min). Sections were immersed in 10 mm citrate buffer, pH 6.0, covered loosely with 'Saranwrap' (Dow Chemical Co.) and boiled in a microwave oven for 10 min at 630 w (H2500 BioRad, Watford, Herts., UK). After standing for 10 min in hot buffer, sections were washed in tap water (5 min) and transferred to 0.05 M Tris-buffered saline, pH 7.6 (TBS). MATERIAL AND METHODSTissue sections were then incubated with normal rabbit serum (Dako, High Wycombe, Bucks., UK) diluted 1:5 in Tris-buffered saline (20 min) and incubated (60 min) with mouse primary antibody 6313/G2 (Barker et al, 1...

Angiotensin II type 1 receptor expression in ovarian cancer and its correlation with tumour angiogenesis and patient survival

“…It has been reported that AT 1 R is expressed in various human malignant tumour tissues, including breast cancer (Inwang et al, 1997), skin cancer (Takeda and Kondo, 2001), pancreatic cancer (Fujimoto et al, 2001), laryngeal carcinoma (Marsigliante et al, 1996) and prostate cancer (Uemura et al, 2003). Furthermore, we recently demonstrated that AT 1 R was expressed in gynaecological malignancies, including cervical cancer , endometrial cancer (Watanabe et al, 2003), choriocarcinoma , and ovarian cancer (Suganuma et al, 2005).…”

“…Recent studies have proposed the concept of a localized tissue RAS in various organs (Nielsen et al, 1995), and activation of the RAS has been demonstrated under neoplastic conditions (Inwang et al, 1997;Takeda and Kondo, 2001;Juillerat-Jeanneret et al, 2004). In the tumour-related RAS, angiotensin II is abundantly generated from angiotensin I by angiotensin-converting enzyme (ACE), and AT 1 R expression is generally upregulated.…”

The Angiotensin II/Angiotensin II Receptor System Correlates with Nodal Spread in Intestinal Type Gastric Cancer

“…Members of the angiotensin II/angiotensin II receptor system, such as ACE, are regularly found in tumors (7,14). AT1R was detected in carcinomas of the larynx, lung, liver, pancreas, kidney, breast, ovary, cervix, in malignant melanoma, and in sarcomas (15)(16)(17)(18)(19)(20)(21)(22)(23). Epidemiologic studies found a significant inverse correlation between cancer mortality and the treatment with and the duration of administration of ACE inhibitors (24).…”

Local angiotensin II-generation in human gastric cancer: Correlation with tumor progression through the activation of ERK1/2, NF-κB and survivin

“…However, a number of reports exist on the concept of a localized RAS (tissue RAS) in various tissues. Angiotensin II type 1 (AT1) receptor has been also detected in carcinomas of the larynx, lung, liver, pancreas, kidney, bladder, prostate gland, breast, ovary, cervix, in malignant melanoma, and in sarcomas (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14). Lever et al reported the first clinical evidence that a long-term angiotensin II blockade might have a protective effect against carcinogenesis (17).…”