Identification of a CARM1 Inhibitor with Potent In Vitro and In Vivo Activity in Preclinical Models of Multiple Myeloma

Allison E Drew,Suzanne L Jacques,Nigel J Waters,Kenneth W Duncan,Lorna H Mitchell,Christina J Allain ,Gideon Shapiro,Lei Jin,Margaret Porter Scott,Christopher J Sneeringer ,Alejandra Raimondi,Michael T Mccabe,Richard Chesworth,Ryan G Kruger,Mikel P Moyer,Oscar Moradei,Thomas V Riera ,J Joshua Smith ,Robert A Copeland,Nathalie Rioux,Jessica L Handler,Heidi M Ott,Ann Boriack-Sjodin ,Scott Ribich

doi:10.1038/s41598-017-18446-z

Allison E Drew, Suzanne L Jacques + Show 22 more

Open Access

https://doi.org/10.1038/s41598-017-18446-z

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Abstract

CARM1 is an arginine methyltransferase with diverse histone and non-histone substrates implicated in the regulation of cellular processes including transcriptional co-activation and RNA processing. CARM1 overexpression has been reported in multiple cancer types and has been shown to modulate oncogenic pathways in in vitro studies. Detailed understanding of the mechanism of action of CARM1 in oncogenesis has been limited by a lack of selective tool compounds, particularly for in vivo studies. We describe the identification and characterization of, to our knowledge, the first potent and selective inhibitor of CARM1 that exhibits anti-proliferative effects both in vitro and in vivo and, to our knowledge, the first demonstration of a role for CARM1 in multiple myeloma (MM). EZM2302 (GSK3359088) is an inhibitor of CARM1 enzymatic activity in biochemical assays (IC50 = 6 nM) with broad selectivity against other histone methyltransferases. Treatment of MM cell lines with EZM2302 leads to inhibition of PABP1 and SMB methylation and cell stasis with IC50 values in the nanomolar range. Oral dosing of EZM2302 demonstrates dose-dependent in vivo CARM1 inhibition and anti-tumor activity in an MM xenograft model. EZM2302 is a validated chemical probe suitable for further understanding the biological role CARM1 plays in cancer and other diseases.

Highlights

Reversible methylation of histones and other proteins is a key post-translational modification process involved in cellular development and tumorigenesis
Identified as a co-activator of steroid hormone receptor-mediated transcription, CARM1 has been shown to interact with several nuclear receptors including the estrogen and androgen receptors, and it may mediate oncogenic effects in cancers driven by these pathways[17]
A dual CARM1/PRMT6 inhibitor has been shown to inhibit the methylation of the reported CARM1 substrate MED12 with a cellular IC50 value of 1.4 μM28

Summary

Introduction

Reversible methylation of histones and other proteins is a key post-translational modification process involved in cellular development and tumorigenesis. CARM1 (coactivator-associated arginine methyltransferase 1, known as PRMT4), catalyzes the transfer of up to two methyl groups to arginine residues on protein substrates[1]. CARM1 has been reported to methylate over 300 histone and non-histone substrates through which it can mediate effects on many cellular processes including transcriptional co-activation, RNA splicing and processing, control of cell cycle, and cellular differentiation[3]. There have been several publications describing small molecule chemical modulators of CARM120–27 Some of these compounds report inhibition of the CARM1 enzyme with IC50 values in the double-digit nanomolar range, no CARM1-selective compounds exhibited effects in non-engineered cell lines, or at concentrations less than 5 μM. Cell-active CARM1 inhibitors are needed to better understand the implications of pharmacological inhibition of CARM1 and to discover and develop novel agents with potential for anti-cancer therapy

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