Heinrich, T. | Search bioRxiv

bioRxiv2025

Disrupting Notch signalling by a small molecule inhibiting dihydroorotate dehydrogenase activity

The Notch signalling pathway is highly evolutionarily conserved and regulates differentiation and homeostasis in most organs. Given the critical role of Notch signalling for normal development, dysregulated Notch signalling is frequently linked to pathogenesis of disease and cancer. Hence, developing Notch-targeting therapeutics is warranted but has been challenging and Notch inhibitors have not yet reached broad clinical use. In this report, we identify potential Notch inhibitors, using a novel cell-based Notch reporter system for unbiased screening of compounds reducing Notch signalling. A library of 37.966 small organic compounds was screened for inhibitor candidates, followed by a counter screen to eliminate {gamma}-secretase inhibitor-like compounds and an orthogonal screen based on the role of Notch signalling in myogenic differentiation. This triage led to the identification of five Notch inhibitor candidate hits with different chemical backbones and unrelated to previous Notch antagonists. One candidate hit showed structural similarities to dihydroorotate dehydrogenase (DHODH) inhibitors, and we provide evidence that inhibition of DHODH activity reduces Notch signalling. In conclusion, our data support the notion that DHODH inhibition may be an interesting avenue to explore for the development of novel Notch inhibitors.

cancer biology↗

bioRxiv2023

Novel YAP1/TAZ pathway inhibitors identified through phenotypic screening with potent anti-tumor activity via blockade of GGTase-I / Rho-GTPase signaling

This study describes the identification and target deconvolution of novel small molecule inhibitors of oncogenic YAP1/TAZ activity with potent anti-tumor activity in vivo. A high-throughput screen (HTS) of 3.8 million compounds was conducted using a cellular YAP1/TAZ reporter assay. Target deconvolution studies identified the geranylgeranyltransferase-I (GGTase-I) complex, as the direct target of YAP1/TAZ pathway inhibitors. The novel small molecule inhibitors block the activation of Rho-GTPases, leading to subsequent inactivation of YAP1/TAZ and inhibition of cancer cell proliferation in vitro. Multi-parameter optimization resulted in BAY-593, an in vivo probe with favorable PK properties, which demonstrated anti-tumor activity and blockade of YAP1/TAZ signaling in vivo. SIGNIFICANCEYAP1/TAZ have been shown to be aberrantly activated oncogenes in several human solid tumors, resulting in enhanced cell proliferation, metastasis and provision of a pro-tumorigenic microenvironment, making YAP1/TAZ targets for novel cancer therapies. Yet, the development of effective inhibitors of these potent oncogenes has been challenging. In this work, we break new ground in this direction through the identification of novel inhibitors of YAP1/TAZ activity. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=192 HEIGHT=200 SRC="FIGDIR/small/555331v2_ufig1.gif" ALT="Figure 1"> View larger version (33K): org.highwire.dtl.DTLVardef@4aac3forg.highwire.dtl.DTLVardef@728b6forg.highwire.dtl.DTLVardef@203a2eorg.highwire.dtl.DTLVardef@1cbc5f9_HPS_FORMAT_FIGEXP M_FIG C_FIG HIGHLIGHTSO_LINovel YAP1/TAZ pathway inhibitors identified by phenotypic high-throughput screen C_LIO_LITarget deconvolution identifies GGTase-I as the direct target of the novel YAP1/TAZ pathway inhibitors C_LIO_LIGGTase-I inhibitors block Rho-GTPase signaling and downstream YAP1/TAZ C_LIO_LIGGTase-I inhibitor BAY-593 demonstrates potent anti-tumor activity in vivo C_LI

cancer biology↗