GPER is involved in the regulation of the estrogen-metabolizing CYP1B1 enzyme in breast cancer

// Francesca Cirillo 1, * , Michele Pellegrino 1, * , Rocco Malivindi 1 , Vittoria Rago 1 , Silvia Avino 1 , Luigina Muto 1 , Vincenza Dolce 1 , Adele Vivacqua 1 , Damiano Cosimo Rigiracciolo 1 , Paola De Marco 1 , Anna Sebastiani 1 , Sergio Abonante 2 , Miki Nakajima 3 , Rosamaria Lappano 1 and Marcello Maggiolini 1 1 Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Rende, Italy 2 Regional Hospital Cosenza, Cosenza, Italy 3 Faculty of Pharmaceutical Sciences, Kanazawa University, Kanazawa, Japan * These authors have contributed equally to this work Correspondence to: Marcello Maggiolini, email: marcellomaggiolini@yahoo.it , marcello.maggiolini@unical.it Rosamaria Lappano, email: lappanorosamaria@yahoo.it , rosamaria.lappano@unical.it Keywords: breast cancer; cancer-associated fibroblasts; CYP1B1; estrogen; GPER Received: September 07, 2017      Accepted: October 30, 2017      Published: November 20, 2017 ABSTRACT The cytochrome P450 1B1 (CYP1B1) is a heme-thiolate monooxygenase involved in both estrogen biosynthesis and metabolism. For instance, CYP1B1 catalyzes the hydroxylation of E2 leading to the production of 4-hydroxyestradiol that may act as a potent carcinogenic agent. In addition, CYP1B1 is overexpressed in different tumors including breast cancer. In this scenario, it is worth mentioning that CYP1B1 expression is triggered by estrogens through the estrogen receptor (ER)α in breast cancer cells. In the present study, we evaluated whether the G protein estrogen receptor namely GPER may provide an alternate route toward the expression and function of CYP1B1 in ER-negative breast cancer cells, in main players of the tumor microenvironment as cancer associated fibroblasts (CAFs) that were obtained from breast cancer patients, in CAFs derived from a cutaneous metastasis of an invasive mammary ductal carcinoma and in breast tumor xenografts. Our results show that GPER along with the EGFR/ERK/c-Fos transduction pathway can lead to CYP1B1 regulation through the involvement of a half-ERE sequence located within the CYP1B1 promoter region. As a biological counterpart, we found that both GPER and CYP1B1 mediate growth effects in vitro and in vivo . Altogether, our data suggest that estrogens in ER-negative cell contexts may engage the alternate GPER signaling toward CYP1B1 regulation. Estrogen-CYP1B1 landscape via GPER should be taken into account in setting novel pharmacological approaches targeting breast cancer development.