Carnosic acid inhibits the growth of ER-negative human breast cancer cells and synergizes with curcumin Linda Saxe Einbond a, ⁎, Hsan-au Wu a , Ryota Kashiwazaki a , Kan He b , Marc Roller b , Tao Su a , Xiaomei Wang a , Sarah Goldsberry a a Columbia University College of Physicians and Surgeons, New York, NY 10032, USA b Naturex, South Hackensack, NJ 07606, USA article info abstract Article history: Received 24 April 2012 Accepted in revised form 13 July 2012 Available online 22 July 2012 Background: Studies indicate that extracts and purified components, including carnosic acid, from the herb rosemary display significant growth inhibitory activity on a variety of cancers. Purpose: This paper examines the ability of rosemary/carnosic acid to inhibit the growth of human breast cancer cells and to synergize with curcumin. Materials and methods: To do this, we treated human breast cancer cells with rosemary/ carnosic acid and assessed effects on cell proliferation, cell cycle distribution, gene expression patterns, activity of the purified Na/K ATPase and combinations with curcumin. Results: Rosemary/carnosic acid potently inhibits proliferation of ER-negative human breast cancer cells and induces G1 cell cycle arrest. Further, carnosic acid is selective for MCF7 cells transfected for Her2, indicating that Her2 may function in its action. To reveal primary effects, we treated ER‐negative breast cancer cells with carnosic acid for 6 h. At a low dose, 5 μg/ml (15 μM), carnosic acid activated the expression of 3 genes, induced through the presence of antioxidant response elements, including genes involved in glutathione biosynthesis (CYP4F3, GCLC) and transport (SLC7A11). At a higher dose, 20 μg/ml, carnosic acid activated the expression of antioxidant (AKR1C2, TNXRD1, HMOX1) and apoptosis (GDF15, PHLDA1, DDIT3) genes and suppressed the expression of inhibitor of transcription (ID3) and cell cycle (CDKN2C) genes. Carnosic acid exhibits synergy with turmeric/curcumin. These compounds inhibited the activity of the purified Na-K-ATPase which may contribute to this synergy. Conclusion: Rosemary/carnosic acid, alone or combined with curcumin, may be useful to prevent and treat ER‐negative breast cancer. © 2012 Elsevier B.V. All rights reserved. Keywords: Anti-inflammatory Antioxidant Diterpene Glutathione Rosemary Turmeric 1. Introduction Significant advances have been made in the early detection and treatment of breast cancer, but it is still the most common cancer and the second leading cause of cancer death among women in the U.S. It is thus imperative to develop nontoxic treatments to prevent the development of breast cancer. The use of current chemopreventive agents, tamoxifen and raloxifene, has been limited by toxicity; in addition, they do not reduce the risk of ER‐negative breast cancer, which represents about one-third of invasive breast cancers and the more aggressive triple negative tumors [1]. Rosemary contains multiple components including carnosic acid (CA), rosmarinic acid, carnosol (CS), caffeic acid, and ursolic acid, which contribute to the biological activity of rosemary and could provide effective synergy. Whole extracts and purified components isolated from rosemary have been shown to inhibit the in vitro and in vivo growth of breast cancer cells [2–4]. Fitoterapia 83 (2012) 1160–1168 Abbreviations: CA, carnosic acid;CS, carnosol;CI, combination index. ⁎ Corresponding author at: The Herbert Irving Comprehensive Cancer Center, College of Physicians and Surgeons, Columbia University, HHSC-1518, 701 W. 168th Street, New York, NY 10032, USA. E-mail address: lseinbond@gmail.com (L.S. Einbond). 0367-326X/$ – see front matter © 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.fitote.2012.07.006 Contents lists available at SciVerse ScienceDirect Fitoterapia journal homepage: www.elsevier.com/locate/fitote