Abstract 1628: A small-molecule inhibitor of WRN selectively kills MSI-H cancer cells and phenocopies WRN genetic defects

Werner syndrome protein (WRN) is a RecQ-family helicase involved in the maintenance of genome integrity. Germline mutations in WRN cause premature aging and cancer predisposition. Analysis of systematic RNAi and CRISPR screening data has previously revealed that WRN is essential for the survival of cancer cell lines with high microsatellite instability (MSI-H). We have developed potent and selective small-molecule inhibitors of WRN helicase (WRNi) and showed that pharmacological inhibition of WRN causes lethality and induction of DNA damage markers selectively in MSI-H cancer cell lines compared to microsatellite-stable (MSS) cell lines. Screening of WRNi across a large panel of pooled, barcoded cell lines in the PRISM format revealed selective sensitivity in MSI-H cell lines and showed that pharmacological inhibition of WRN is highly correlated with genetic ablation of WRN across this panel, confirming selectivity for WRN. In vivo evaluation demonstrated robust and MSI-selective tumor regressions. These data provide pharmacological proof-of-concept for the WRN/MSI-H synthetic lethal relationship and support WRN inhibition as a novel therapeutic approach for the treatment of MSI-H cancers.

Citation Format: Yanhua Rao, Anjana Srivatsan, Marya Liimatta, Diana Munoz, Jeanne Quirit, Jianxia Shi, An Nguyen, Xin Linghu, Federowicz Federowicz, Brian Jones, Melissa Fleury, Zach Newby, Michael P. Dillon, Paul A. Barsanti, Mark R. Lackner, Michael A. White, Yang Lee, Phil Landis, Yang Peng, Michelle Cicchini, Josh Cottom, Leng Nickels, Ed Brnardic, Michael DeMartino, Josh Taygerly. A small-molecule inhibitor of WRN selectively kills MSI-H cancer cells and phenocopies WRN genetic defects [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1628.

Targeting the Regulatory Site of ER Aminopeptidase 1 Leads to the Discovery of a Natural Product Modulator of Antigen Presentation

ER aminopeptidase 1 (ERAP1) is an intracellular enzyme that generates antigenic peptides and is an emerging target for cancer immunotherapy and the control of autoimmunity. ERAP1 inhibitors described previously target the active site and are limited in selectivity, minimizing their clinical potential. To address this, we targeted the regulatory site of ERAP1 using a high-throughput screen and discovered a small molecule hit that is highly selective for ERAP1. (4aR,5S,6R,8S,8aR)-5-(2-(Furan-3-yl)ethyl)-8-hydroxy-5,6,8a-trimethyl-3,4,4a,5,6,7,8,8a-octahydronaphthalene-1-carboxylic acid is a natural product found in Dodonaea viscosa that constitutes a submicromolar, highly selective, and cell-active modulator of ERAP1. Although the compound activates hydrolysis of small model substrates, it is a competitive inhibitor for physiologically relevant longer peptides. Crystallographic analysis confirmed that the compound targets the regulatory site of the enzyme that normally binds the C-terminus of the peptide substrate. Our findings constitute a novel starting point for the development of selective ERAP1 modulators that have potential for further clinical development.

Discovery of a Novel 2,6-Disubstituted Glucosamine Series of Potent and Selective Hexokinase 2 Inhibitors

A novel series of potent and selective hexokinase 2 (HK2) inhibitors, 2,6-disubstituted glucosamines, has been identified based on HTS hits, exemplified by compound 1. Inhibitor-bound crystal structures revealed that the HK2 enzyme could adopt an "induced-fit" conformation. The SAR study led to the identification of potent HK2 inhibitors, such as compound 34 with greater than 100-fold selectivity over HK1. Compound 25 inhibits in situ glycolysis in a UM-UC-3 bladder tumor cell line via (13)CNMR measurement of [3-(13)C]lactate produced from [1,6-(13)C2]glucose added to the cell culture.

High throughput screening identifies ATP-competitive inhibitors of the NLRP1 inflammasome

Nod-like receptors (NLRs) are cytoplasmic pattern recognition receptors that are promising targets for the development of anti-inflammatory therapeutics. Drug discovery efforts targeting NLRs have been hampered by their inherent tendency to form aggregates making protein generation and the development of screening assays very challenging. Herein we report the results of an HTS screen of NLR family member NLRP1 (NLR family, pyrin domain-containing 1) which was achieved through the large scale generation of recombinant GST-His-Thrombin-NLRP1 protein. The screen led to the identification of a diverse set of ATP competitive inhibitors with micromolar potencies. Activity of these hits was confirmed in a FP binding assay, and two homology models were employed to predict the possible binding mode of the leading series and facilitate further lead-optimization. These results highlight a promising strategy for the identification of inhibitors of NLR family members which are rapidly emerging as key drivers of inflammation in human disease.

Fractionating the articulatory loop: dissociations and associations in phonological recoding in aphasia

This paper uses neuropsychological data to differentiate between three models of verbal short-term memory (Baddeley, 1983, 1986; Besner, 1987; Monsell, 1987). The focus is on three tasks: homophone judgments, rhyme judgments and pseudohomophone detection. When lesioned each model predicts characteristic patterns of impairment across these tasks. Thirteen span impaired aphasic subjects were assessed on all three tasks. The patterns of performance unequivocally supported the model proposed by Monsell (1987) which distinguishes input and output phonological buffers. Implications for further research are discussed.

Aphasic naming: what matters?

This paper investigates the factors which affect naming performance for two groups of aphasic subjects. The effects of word age-of-acquisition, operativity, frequency, familiarity, imageability, concreteness, length and the visual complexity of the stimulus picture were examined. In contrast to previous studies, we found remarkably small effects of word frequency on naming performance; these studies, we argue, have failed to control sufficiently for the effects of variables which intercorrelate with frequency. However, many patients were significantly affected by age-of-acquisition even when any effects of frequency and familiarity had been accounted for. Operativity, imageability and word length were also predictive of naming performance for some of the patients investigated, unlike visual complexity. The applicability of conclusions drawn from groups of aphasics is again thrown into doubt, as these two groups showed different patterns of predictor variables, and the variables affecting the performance of individuals could be different from those affecting the group.

Phonological errors in aphasic naming: comprehension, monitoring and lexicality

This paper investigates the production of phonological errors in aphasic naming, examining the relationship between these errors and deficits in comprehension. The predictions of Dell and O'Seaghda's (1991) computational model of speech production were tested by lesioning. The set of lesioned models demonstrated a strong correlation between proportion of phonologically related errors in naming and comprehension accuracy. In contrast, no correlation between proportion of phonological errors in naming and comprehension accuracy was found for a group of fifteen aphasics. This paper also examines monitoring behaviours, such as the presence of self-corrections and interrupted responses, again finding no relationship with auditory comprehension. There was also no evidence for a lexical bias in the phonological errors for these aphasic subjects. Phonologically related errors were argued to be words only by chance; this was supported by the fact that they occurred more frequently on short words than long words, and that the proportion of real word errors was not significantly different to that observed in a pseudocorpus of errors. We conclude that a production-based monitor would be compatible with these results but that any comprehension-based monitor is not reliably employed by some or all of the aphasic subjects examined here. Additionally, these data are incompatible with models of language processing where speech input and output share the same processing components.

Reading too little into reading?: strategies in the rehabilitation of acquired dyslexia

This paper examines four recent therapy studies, two involving deep dyslexic patients and two involving surface dyslexic patients. These studies illustrate that remediation of aspects of acquired dyslexia can have positive benefits for the patients concerned which often extend beyond an improvement in reading aloud. It is argued that, although it may not be immediately apparent, the remediation of acquired reading impairments (and even of reading aloud) can be of functional significance for an aphasic subject.