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Cancer cells can switch between signaling pathways to regulate growth under different conditions. In the tumor microenvironment, this likely helps them evade therapies that target specific pathways. We must identify all possible states and utilize them in drug screening programs. One such state is characterized by expression of the transcription factor Hairy and Enhancer of Split 3 (HES3) and sensitivity to HES3 knockdown, and it can be modeled in vitro. Here, we cultured 3 primary human brain cancer cell lines under 3 different culture conditions that maintain low, medium, and high HES3 expression and characterized gene regulation and mechanical phenotype in these states. We assessed gene expression regulation following HES3 knockdown in the HES3-high conditions. We then employed a commonly used human brain tumor cell line to screen Food and Drug Administration (FDA)-approved compounds that specifically target the HES3-high state. We report that cells from multiple patients behave similarly when placed under distinct culture conditions. We identified 37 FDA-approved compounds that specifically kill cancer cells in the high-HES3-expression conditions. Our work reveals a novel signaling state in cancer, biomarkers, a strategy to identify treatments against it, and a set of putative drugs for potential repurposing.-Poser, S. W., Otto, O., Arps-Forker, C., Ge, Y., Herbig, M., Andree, C., Gruetzmann, K., Adasme, M. F., Stodolak, S., Nikolakopoulou, P., Park, D. M., Mcintyre, A., Lesche, M., Dahl, A., Lennig, P., Bornstein, S. R., Schroeck, E., Klink, B., Leker, R. R., Bickle, M., Chrousos, G. P., Schroeder, M., Cannistraci, C. V., Guck, J., Androutsellis-Theotokis, A. Controlling distinct signaling states in cultured cancer cells provides a new platform for drug discovery.

Fibrosis and inflammation promote atrial fibrillation (AF) and worsen its clinical outcome. The underlying molecular mechanisms, that are relevant for effective antifibrotic drug development, are still under debate. This study deciphers a novel mechanistic interplay between polo-like kinase 2 (PLK2) and the pro-inflammatory cytokine osteopontin (OPN) in the pathogenesis of atrial fibrosis. Compared to sinus rhythm (SR) controls, right atrial appendages and isolated right atrial fibroblasts from AF patients showed downregulation ofPLK2mRNA and protein levels, which were accompanied by remarkable hypoxia-sensitive DNA-methylation of thePLK2promotor. In an experimental setting, both, genetic deletion and pharmacological inhibition of PLK2 induced myofibroblast differentiation and reduced fibroblast proliferation. Notably, proteomics fromPLK2-deleted fibroblasts revealedde novosecretion of OPN. Accordingly, we observed higher OPN plasma levels in AF patients with atrial fibrosis compared to non-fibrosis AF patients. Hence, we provide evidence for PLK2 reactivation and/or OPN inhibition as potential novel targets to prevent fibrosis progression in AF.

Introductory paragraphUntil recently missense germ-line mutations inACTB, encoding the ubiquitously expressed β-cytoplasmic actin (CYA), were exclusively associated with Baraitser-Winter Cerebrofrontofacial syndrome (BWCFF), a complex developmental disorder1,2. Here, we report six patients with previously undescribed heterozygous variants clustered in the 3’-coding region ofACTB. These patients present with clinical features different from BWCFF, including thrombocytopenia, microcephaly, and mild developmental disability. Patient derived cells are morphologically and functionally distinct from controls. Assessment of cytoskeletal constituents identified a discrete filament population altered in these cells, which comprises force generating and transmitting actin binding proteins (ABP) known to be associated with thrombocytopenia3–8.In silicomodelling and molecular dynamics (MD)-simulations support altered interactions between these ABP and mutant β-CYA. Our results describe a new clinical syndrome associated withACTBmutations with a distinct genotype-phenotype correlation, identify a cytoskeletal protein interaction network crucial for thrombopoiesis, and provide support for the hypomorphic nature of these actinopathy mutations.