Abstract 2957: Inhibition of epigenetic regulator menin is a novel therapeutic approach for high-risk neuroblastoma

Abstract

Abstract Controlling epigenetic factors such as histone methyltransferases and demethylases has recently emerged as an attractive therapeutic approach for different cancers. KMT2 family protein KMT2A or MLL1 is a H3K4 methyltransferase, which is known to play an essential role in cancer development. MLL1 forms a COMPASS complex to function as an epigenetic regulator and Menin is one of the specific and required binding partner for the activation and function of this epigenetic enzyme. Menin acts as a tumor suppressor protein, and inhibition of Menin-MLL1 interaction has been shown to destabilize the MLL1 epigenetic complex, inhibits H3K4 methyltransferase activity, and hinder the oncogenic potential of various cancers. High-risk neuroblastoma (NB) is the most common extracranial solid pediatric tumor and accounts for almost 15% of all pediatric cancer-related deaths. Recent reports indicate that aberrant activation of epigenetic regulators may drive NB progression and relapse. Therefore, in the present study, we used a specific small-molecule inhibitor, MI-503 to disrupt Menin-MLL1 interaction, and to further understand the role of Menin in pediatric NB. We used different NB cell lines including MYCN-non-amplified (SH-SY5Y, SK-N-AS, CHLA-255) and MYCN-amplified (NGP, LAN-5, IMR-32), and performed cytotoxicity and Colonogenic assays to determine the effect of Menin inhibition on NB proliferation. Results showed that MI-503 significantly inhibits NB proliferation and colony formation capacity in a dose-dependent manner in contrast to controls. Further, we performed apoptosis and cell cycle assays and observed that MI-503 significantly induces apoptosis as detected by the increase of Annexin-V positive early apoptotic cells, and blocks cell cycle progression at the S phase in all NB cell lines tested. Additionally, Western blot assays demonstrated an overall inhibition of H3K3me3 levels in NB cells in response to MI-503. To further determine the effects of Menin inhibition on NB tumor growth, we developed a NB 3D spheroid tumor model that recapitulate in vivo tumor growth for solid tumors. Treatment with MI-503 significantly inhibits spheroidal tumor growth by inducing tumor cell death in a dose-dependent manner. Overall, these data highlight the role of epigenetic regulation, MLL1 complex, and of Menin in NB growth and tumorigenicity. In our future efforts, we will further elucidate the effects of MI-503 and the role of Menin in NB by using in vivo tumor models. Epigenetic inhibitor such as MI-503 holds significant potential for further clinical development and as a novel therapeutic approach for NB. Citation Format: Rameswari Chilamakuri, Saurabh Agarwal. Inhibition of epigenetic regulator menin is a novel therapeutic approach for high-risk neuroblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2957.