Abstract 4052: Enhancing estrogen receptor beta mediated tumor suppression by lysine specific demethylase 1A inhibitor for the treatment of ovarian cancer
Authors: Sareddy Gangadhara Reddy R. , Liu Jinyou , Garcia Lauren , Viswanadhapalli Suryavathi , Zhou Mei , Suzuki Takayoshi , Kost Edward , Vadlamudi Ratna K. 
Published: July 2017

Abstract
Ovarian cancer (OCa) is the deadliest of all gynecologic cancers in the United States. Although patients with OCa respond initially to standard combinations of surgical and cytotoxic therapy, nearly 90% will develop recurrence and inevitably succumb to chemotherapy-resistant disease. Estrogen mediates its effects through the estrogen receptor α (ESR1) and estrogen receptor β (ESR2). Recent studies suggest that OCa cells and OCa stem cells express ESR2, which functions as a tumor suppressor and identified synthetic compound LY500307 as a potent ESR2 specific agonist. However, ESR2 expression decreases during tumor progression and under the selection pressure of chemotherapy; this decrease occurs via epigenetic mechanisms. The lysine-specific histone demethylase 1A (KDM1A/LSD1) is overexpressed in OCa and plays a vital role in metastasis and cancer stemness. Our group recently developed a novel KDM1A-specific inhibitor (NCD-38) based on an innovative concept of direct delivery of phenylcyclopropylamine to the KDM1A active site. We reason that agents that restore the expression and functions of ESR2 by increasing active histone marks may provide a novel therapeutic opportunity to reactivate ESR2 for suppression of OCa. The objective of this study is to test whether KDM1A inhibitor could enhance the expression and tumor suppressive functions of ESR2 and to test the combination of KDM1A inhibitor along with ESR2 agonist using in vitro and in vivo preclinical models. Our results demonstrated that combination of ESR2 agonist and KDM1A inhibitor reduces the cell viability of OCa cells synergistically. Further caspase-3/7 activity and Annexin V assays showed synergistic induction of apoptosis upon combination therapy. Matrigel invasion assays revealed reduction in cell invasion of OCa cell lines following ESR2 agonist and KDM1A inhibitor treatment. RT-qPCR analysis demonstrated that KDM1A inhibitor treatment significantly increases the expression of ESR2 and its target genes leading to increased tumor suppression. Further, co-immunoprecipitation analysis revealed that KDM1A interacts with ESR2 and Chromatin immunoprecipitation assays demonstrated that KDM1A inhibition increases the recruitment of active histone methylation mark H3K4-me2 at ESR2 0N promoter. RNA-sequencing analysis demonstrated that ESR2 agonist treatment modulates the several pathways related to cell cycle, apoptosis and DNA damage check point regulation. Finally, ESR2 agonist and KDM1A inhibitor treatment significantly reduced the in vivo tumor growth in orthotopic models. Since ESR2 agonists and KDM1A inhibitors are currently in clinical trials for other clinical indications and are well tolerated, identification of KDM1A inhibitor and ESR2 agonist combination therapy as a novel therapeutic can be readily transferred to clinical use for enhancing survival in OCa patients.
Citation Format: Gangadhara Reddy R. Sareddy, Jinyou Liu, Lauren Garcia, Suryavathi Viswanadhapalli, Mei Zhou, Takayoshi Suzuki, Edward Kost, Ratna K. Vadlamudi. Enhancing estrogen receptor beta mediated tumor suppression by lysine specific demethylase 1A inhibitor for the treatment of ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4052. doi:10.1158/1538-7445.AM2017-4052