Non-nuclear estrogen receptor α signaling promotes cardiovascular protection but not uterine or breast cancer growth in mice
Ken L. Chambliss, … , Benita S. Katzenellenbogen, Philip W. Shaul
Ken L. Chambliss, … , Benita S. Katzenellenbogen, Philip W. Shaul
Published June 23, 2010
Citation Information: J Clin Invest. 2010;120(7):2319-2330. https://doi.org/10.1172/JCI38291.
View: Text | PDF
Research Article

Non-nuclear estrogen receptor α signaling promotes cardiovascular protection but not uterine or breast cancer growth in mice

Abstract

Steroid hormone receptors function classically in the nucleus as transcription factors. However, recent data indicate that there are also non-nuclear subpopulations of steroid hormone receptors, including estrogen receptors (ERs), that mediate membrane-initiated signaling of unclear basis and significance. Here we have shown that an estrogen-dendrimer conjugate (EDC) that is excluded from the nucleus stimulates endothelial cell proliferation and migration via ERα, direct ERα-Gαi interaction, and endothelial NOS (eNOS) activation. Analysis of mice carrying an estrogen response element luciferase reporter, ER-regulated genes in the mouse uterus, and eNOS enzyme activation further indicated that EDC specifically targets non-nuclear processes in vivo. In mice, estradiol and EDC equally stimulated carotid artery reendothelialization in an ERα- and G protein–dependent manner, and both agents attenuated the development of neointimal hyperplasia following endothelial injury. In contrast, endometrial carcinoma cell growth in vitro and uterine enlargement and MCF-7 cell breast cancer xenograft growth in vivo were stimulated by estradiol but not EDC. Thus, EDC is a non-nuclear selective ER modulator (SERM) in vivo, and in mice, non-nuclear ER signaling promotes cardiovascular protection. These processes potentially could be harnessed to provide vascular benefit without increasing the risk of uterine or breast cancer.

Authors

Ken L. Chambliss, Qian Wu, Sarah Oltmann, Eddy S. Konaniah, Michihisa Umetani, Kenneth S. Korach, Gail D. Thomas, Chieko Mineo, Ivan S. Yuhanna, Sung Hoon Kim, Zeynep Madak-Erdogan, Adriana Maggi, Sean P. Dineen, Christina L. Roland, David Y. Hui, Rolf A. Brekken, John A. Katzenellenbogen, Benita S. Katzenellenbogen, Philip W. Shaul

×

Figure 2

Non-nuclear ERα activation stimulates eNOS via Gαi.

Options: View larger image (or click on image) Download as PowerPoint
Non-nuclear ERα activation stimulates eNOS via Gαi. (A) eNOS activation ...
(A) eNOS activation was assessed in intact BAECs by measuring 14C-l-arginine to 14C-l-citrulline conversion during 15-minute incubations with vehicle (control), 10–8 M E2, EDC at a concentration equivalent to 10–8 M E2, or dendrimer alone at a concentration equivalent to EDC at 10–8 M. EDC at 10–10 M estrogen equivalents did not activate eNOS (data not shown). (B) Parallel experiments were performed in cells incubated with EDC (10–8 M estrogen equivalents) in the absence or presence of 10–5 M ICI 182,780 or 100 ng/ml pertussis toxin (PTX). In A and B, values are mean ± SEM, n = 4. *P < 0.05 versus control. (C) eNOS activation by EDC and VEGF (100 ng/ml) above basal activity (B) was evaluated following siRNA knockdown of ERα. Inset shows ERα abundance in control siRNA cells (lane 1) and ERα siRNA cells (lane 2). Values in C are mean ± SEM, n = 4. *P < 0.05 versus basal; †P < 0.05 versus control.