CARM1 Is Essential for Myeloid Leukemogenesis but Dispensable for Normal Hematopoiesis

Abstract

Chromatin-modifying enzymes, and specifically the protein arginine methyltransferases (PRMTs), have emerged as important targets in cancer. Here, we investigated the role of CARM1 in normal and malignant hematopoiesis. Using conditional knockout mice, we show that loss of CARM1 has little effect on normal hematopoiesis. Strikingly, knockout of Carm1 abrogates both the initiation and maintenance of acute myeloid leukemia (AML) driven by oncogenic transcription factors. We show that CARM1 knockdown impairs cell-cycle progression, promotes myeloid differentiation, and ultimately induces apoptosis. Finally, we utilize a selective, small-molecule inhibitor of CARM1 to validate the efficacy of CARM1 inhibition in leukemia cells in vitro and in vivo. Collectively, this work suggests that targeting CARM1 may be an effective therapeutic strategy for AML.

A Chemical Probe of CARM1 Alters Epigenetic Plasticity against Breast Cancer Cell Invasion

“…In comparison to SKI-73, the CARM1 inhibitors EZM2302 and TP-064 demonstrated the anti-proliferation effects on hematopoietic cancer cells, in particular multiple myeloma. (Drew et al, 2017;Greenblatt et al, 2018;Nakayama et al, 2018) Mechanistically, genetic perturbation of CARM1 in the context of leukemia impairs cell-cycle progression, promotes myeloid differentiation, and ultimately induces apoptosis, likely via targeting pathways of proliferation and cell-cycle progression---E2F-, MYC-, and mTOR-regulated processes. (Greenblatt et al, 2018) In comparison, CARM1 inhibition with EZM2302 led to a slightly different phenotype, including reduction of RNA stability, E2F target downregulation, and induction of a p53 response signature featured for senescence.…”

“…(Blanc and Richard, 2017;Yang and Bedford, 2013) The requirement of CARM1 is implicated in multiple cancers with its methyltransferase activity particularly addicted by hematopoietic malignancies and metastatic breast cancer. (Drew et al, 2017;Greenblatt et al, 2018;Nakayama et al, 2018;Wang et al, 2014) Our prior efforts using in vivo mouse and in vitro cell models uncovered the role of CARM1 in promoting breast cancer metastasis. (Wang et al, 2014) Mechanistically, CARM1 methylates Arg1064 of BAF155 and thus facilitates the recruitment of the BAF155-containing SWI/SNF complex to a specific subset of gene loci essential for breast cancer metastasis.…”

“…(Wang et al, 2014) While this cancer relevance inspired the development of CARM1 inhibitors, (Kaniskan et al, 2018;Scheer et al, 2019) many small-molecule CARM1 inhibitors lack target selectivity or cellular activity (Kaniskan et al, 2018)---two essential criteria of chemical probes. (Frye, 2010) To the best of our knowledge, EZM2302, (Drew et al, 2017;Greenblatt et al, 2018) TP-064 (Nakayama et al, 2018) and SKI-73 (www.thesgc.org/chemical-probes/SKI-73) are the only selective and cell-active CARM1 chemical probes, which were developed by Epizyme, Takeda/SGC(Structural Genomic Consortium), and our team, respectively. EZM2302 and TP-064 were developed through conventional small-molecule scaffolds occupying the substrate-binding pocket of CARM1.…”

“…(Drew et al, 2017;Greenblatt et al, 2018;Nakayama et al, 2018) The potential utility of EZM2302 and TP-064 is implicated by their selective anti-proliferative effects on hematopoietic cancer cells, in particular multiple myeloma cells. (Drew et al, 2017;Greenblatt et al, 2018;Nakayama et al, 2018) However, definitive molecular mechanisms of the CARM1 addiction in these contexts remain elusive. (Greenblatt et al, 2018) Here we report the characterization and novel utility of SKI-73---a chemical probe of CARM1 with pro-drug properties.…”

“…(Drew et al, 2017;Greenblatt et al, 2018;Nakayama et al, 2018) However, definitive molecular mechanisms of the CARM1 addiction in these contexts remain elusive. (Greenblatt et al, 2018) Here we report the characterization and novel utility of SKI-73---a chemical probe of CARM1 with pro-drug properties. SKI-73 can readily penetrate cell membranes and then be processed into two active CARM1 inhibitors containing 6′−homosinefungin (HSF) as their core scaffold.…”