Imperial College London

MrRyanHoward

Faculty of Natural SciencesDepartment of Chemistry

Research Postgraduate
 
 
 
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r.howard16

 
 
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Location

 

302Molecular Sciences Research HubWhite City Campus

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Summary

 

Publications

Publication Type
Year
to

3 results found

Howard RT, Hemsley P, Petteruti P, Saunders CN, Molina Bermejo JA, Scott JS, Johannes JW, Tate EWet al., 2020, Structure-guided design and in-cell target profiling of a cell-active target engagement probe for PARP inhibitors, ACS Chemical Biology, Vol: 15, Pages: 325-333, ISSN: 1554-8929

Inhibition of the poly(ADP-ribose) polymerase (PARP) family of enzymes has become an attractive therapeutic strategy in oncology and beyond; however, chemical tools to profile PARP engagement in live cells are lacking. Herein, we report the design and application of PARPYnD, the first photoaffinity probe (AfBP) for PARP enzymes based on triple PARP1/2/6 inhibitor AZ9482, which induces multipolar spindle (MPS) formation in breast cancer cells. PARPYnD is a robust tool for profiling PARP1/2 and is used to profile clinical PARP inhibitor olaparib, identifying several novel off-target proteins. Surprisingly, while PARPYnD can enrich recombinant PARP6 spiked into cellular lysates and inhibits PARP6 in cell-free assays, it does not label PARP6 in intact cells. These data highlight an intriguing biomolecular disparity between recombinant and endogenous PARP6. PARPYnD provides a new approach to expand our knowledge of the targets of this class of compounds and the mechanisms of action of PARP inhibitors in cancer.

Journal article

Kennedy C, Howard R, Panyain N, Tate Eet al., 2019, Activity-Based Protein Profiling, Target Discovery and Validation, Publisher: John Wiley & Sons, ISBN: 9783527345298

Additionally, the book highlights techologies that are applicable to ?difficult? targets and drugs directed at multiple targets, including chemoproteomics, activity-based protein profiling, pathway mapping, genome-wide association studies, ...

Book chapter

Wang Z, Grosskurth SE, Cheung T, Petteruti P, Zhang J, Wang X, Wang W, Gharahdaghi F, Wu J, Su N, Howard RT, Mayo M, Widzowski D, Scott DA, Johannes JW, Lamb ML, Lawson D, Dry JR, Lyne PD, Tate EW, Zinda M, Mikule K, Fawell SE, Reimer C, Chen Het al., Pharmacological inhibition of PARP6 triggers multipolar spindle formation and demonstrates therapeutic effects in breast cancer, Cancer Research, Vol: 78, Pages: 6691-6702, ISSN: 1538-7445

PARP proteins represent a class of post-translational modification enzymes with diverse cellular functions. Targeting PARPs has proven to be efficacious clinically, but exploration of the therapeutic potential of PARP inhibition has been limited to targeting poly(ADP-ribose) generating PARP, including PARP1/2/3 and tankyrases. The cancer-related functions of mono(ADP-ribose) generating PARP, including PARP6, remain largely uncharacterized. Here, we report a novel therapeutic strategy targeting PARP6 using the first reported PARP6 inhibitors. By screening a collection of PARP compounds for their ability to induce mitotic defects, we uncovered a robust correlation between PARP6 inhibition and induction of multipolar spindle (MPS) formation, which was phenocopied by PARP6 knockdown. Treatment with AZ0108, a PARP6 inhibitor with a favorable pharmacokinetic profile, potently induced the MPS phenotype, leading to apoptosis in a subset of breast cancer cells in vitro and antitumor effects in vivo. In addition, Chk1 was identified as a specific substrate of PARP6 and was further confirmed by enzymatic assays and by mass spectrometry. Furthermore, when modification of Chk1 was inhibited with AZ0108 in breast cancer cells, we observed marked upregulation of p-S345 Chk1 accompanied by defects in mitotic signaling. Together, these results establish proof-of-concept antitumor efficacy through PARP6 inhibition and highlight a novel function of PARP6 in maintaining centrosome integrity via direct ADP-ribosylation of Chk1 and modulation of its activity.

Journal article

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