Natalia Ogrodnik

Canada

Discovering small molecule inhibitors of a novel dual-specificity phosphatase to treat inflammatory bowel disease

Natalia Ogrodnik1, Saurav Roy Choudhury1, Eva Warwick1, Daniel Mao2, Zemin Zhang2, Jason Yang1, Frank Sicheri2,3,4, Alberto Martin1

1. Department of Immunology, University of Toronto, Toronto, ON, Canada
2. Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, ON, Canada
3. Department of Biochemistry, University of Toronto, Toronto, ON, Canada
4. Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada

Abstract

Background

Canada has one of the highest rates of inflammatory bowel disease (IBD) worldwide, affecting nearly 1% of Canadians. IBD is a burden on patients, healthcare and society, and with many patients not responding to and/or having adverse side effects to current treatments, novel therapeutics are needed. Consisting of Crohn’s disease and ulcerative colitis, IBD is characterized by chronic, recurrent inflammation of the gastrointestinal tract. Although various genetic and environmental factors have been implicated, the cause of IBD is unknown. Numerous genes are associated with IBD, but many have yet to be explored, such as the DUSPX* locus. Unpublished work from our lab shows that the DUSPX phosphatase promotes IBD in pre-clinical mouse models, supporting GWAS studies linking this gene to IBD. Thus, our work identified DUSPX as a novel therapeutic target for IBD. Historically, phosphatases were deemed ‘undruggable’, however, recent developments in orally deliverable small molecule inhibitors that selectively target phosphatases in cancer and autoimmune diseases has spurred renewed interest in these enzymes. This has initiated our lab to discover potent and selective small molecule inhibitors of DUSPX and assess whether these inhibitors can reproduce the biological findings observed in mice deficient in DUSPX.

*Target protein undisclosed for proprietary purposes

Methods

To identify and develop small molecule inhibitors, an excellent 384-well biochemical high-throughput screening assay for DUSPX activity was developed (Z’-factor >0.7) using DiFMUP as a substrate. 85,440 structurally diverse compounds from 10 compound libraries at the S.M.A.R.T Laboratory for High-Throughput Programs were screened to identify any hit compounds that exhibited inhibitory effects against DUSPX.

Results

Using a hit cut-off of <74.6% activity (4 σ below the mean compound % activity), 52 compounds were identified, 32 of which are being validated in secondary assays.

Conclusions

A potent and selective small molecule inhibitor of DUSPX has the potential of being developed into a novel treatment for IBD patients.