HUWE1 inhibition as a therapeutic strategy to target MYC in MM Lisa Crawford 14th March 2018

The ubiquitin proteasome system as a molecular target in Multiple Myeloma

Huwe1 482 kDa HECT domain E3 ligase Intrinsic catalytic activity to directly transfer ubiquitin to target protein Involved in the regulation of DNA damage response, core histones, p53 and MYC Involved in the regulation of B cell differentiation and function - implicated in B cell transformation Small molecule inhibitors of HUWE1 inhibit MYC function in colorectal cancer cells HUWE1 Qi et al., Int J Mol Sci, 2012;13: 6204-19

HUWE1 Inhibitors (BI8622 and BI8626) Peter et al., EMBO Mol Med, 2014;6: 1525-41 BI8622 and BI8626 decrease viability of MM cell lines, including those resistant to dexamethasome and bortezomib

No significant effect on normal bone marrow BI8622/BI8626 inhibit the proliferation of MM cell lines Control BI8622 BI8626 No significant effect on normal bone marrow

HUWE1 inhibition leads to a reduction of DNA synthesis Control BI8622 Control Control BI8622 BI8626 HUWE1 inhibition leads to a reduction of DNA synthesis Control BI8622 BI8626 HUWE1 inhibitors induce cellular senescence

HUWE1 exerts a cell type-dependent effect on MYC HUWE1 inhibition decreases MYC expression Peter et al, 2014, EMBO HUWE1 inhibition leads to decreased expression of MYC-dependent target genes Myant et al, 2017, EMBO

Identification of candidate substrates of HUWE1 Snapshot proteomics TM NTC HUWE1 KD HuProt Protein Arrays 2314 changes in protein ubiquitination

Ingenuity Pathway Analysis Input UbiQapture HUWE1 inhibition induces degradation of MYC

Combination of HUWE1 inhibitors with conventional MM therapies is synergistic Carfilzomib Dexamethasone Pomalidomide

Summary Inhibitors of HUWE1 lead to growth arrest of MM cell lines. HUWE1 inhibitors act in synergy with conventional MM therapies. HUWE1 inhibitors decrease expression of MYC and MYC-dependent target genes. Studies are ongoing to elucidate the molecular mechanism of MYC downregulation following HUWE1 inhibition.

Acknowledgements CCRCB Blood Cancer Research Group Collaborators Dr. Sandra Irvine Prof. Ken Mills Cliona Johnston Jonathan Morgan Claudia Hamilton Collaborators Dr. Dharminder Chauhan Dana Farber Cancer Institute, Harvard Dr. Andrew Chantry Dr. Michelle Lawson University of Sheffield Professor Krishnaraj Rajalingam Mainz University Medical Centre Professor Martin Eilers University of Wurzberg