Abstract 215: Aminoflavone exhibits in vivo efficacy on cancer stem cells in a spontaneous estrogen-dependent breast cancer murine model

Abstract

Abstract Stem-cell populations have been identified in a range of solid tumors and possess the capacity to self renew. It is thought that these cancer stem cells (CSCs) play an important role in cancer establishment, progression, and resistance to current treatments. CSCs have been identified in primary breast cancer tissues and cell lines derived from metastatic tumors. Traditional cancer therapies are effective at debulking some tumors but often fail to produce long-term clinical remissions, presumably due to their inability to eradicate the cancer stem cell population. Therefore, novel treatments aimed at targeting this population can potentially enhance treatment of both primary and metastatic tumors. Aminoflavone (AF; NSC 686288) is a novel anticancer agent. Previous work from our research group demonstrated that AF is a ligand of the aryl hydrocarbon receptor (AhR) and displays cytotoxicity in the MCF-7 breast cancer cell line. A prodrug formulation of AF (AFP464, NSC710464), recently entered phase II clinical trials. Moreover, we previously found that AF disrupts MCF-7 mammosphere formation via AhR signaling activation to inhibit alpha 6-integrin expression. To investigate the efficacy of AF in vivo, we used an estrogen dependent, Tamoxifen-sensitive spontaneous M05 model system involving 1-year-old virgin female BALB/c mice developed in our animal facility. The M05 tumor is a semi-differentiated adenocarcinoma that expresses estrogen and progesterone receptors. After AF treatment (12 mg/kg, i.p., QD × 5 days) tumor size and growth rate decreased substantially compared to control animals. Cytometric analyses of cells obtained from AF-treated and control animals revealed that Lin (-)/ CD29 (Hi)/CD24 (+) cancer stem cells were lower in animals treated with AF than in the vehicle control group. We also observed a diminished capacity for mammosphere formation in cells obtained from tumors treated with AF. These data suggest AF diminishes the quantity of breast cancer stem cells as well as their integrity and capacity to form mammospheres in vitro and in vivo. These findings shed additional insight into the molecular mechanism of anticancer action for this novel anticancer agent to strengthen the rationale for its inclusion in breast cancer treatment regimens. Citation Format: Mariana Callero, Damian Berardi, Laura Todaro, Marina Simian, Eileen J. Brantley, Ubaldo Soto, Andrea Loaiza-Perez. Aminoflavone exhibits in vivo efficacy on cancer stem cells in a spontaneous estrogen-dependent breast cancer murine model. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 215. doi:10.1158/1538-7445.AM2014-215