Cyclophilin A (CypA), the cellular receptor of the immunosuppressant cyclosporin A (CsA), is an abundant cytosolic protein and is involved in a variety of diseases. For example, CypA supports cancer ...proliferation and mediates viral infections, such as the human immunodeficiency virus 1 (HIV-1). Here, we present the design of PROTAC (proteolysis targeting chimera) compounds against CypA to induce its intracellular proteolysis and to investigate their effect on immune cells. Interestingly, upon connecting to E3 ligase ligands, both peptide-based low-affinity binders and CsA-based high-affinity binders can degrade CypA at nM concentration in HeLa cells and fibroblast cells. As the immunosuppressive effect of CsA is not directly associated with the binding of CsA to CypA but the inhibition of phosphatase calcineurin by the CypA:CsA complex, we investigated whether a CsA-based PROTAC compound could induce CypA degradation without affecting the activation of immune cells. P3, the most efficient PROTAC compound discovered from this study, could deplete CypA in lymphocytes without affecting cell proliferation and cytokine production. This work demonstrates the feasibility of the PROTAC approach in depleting the abundant cellular protein CypA at low drug dosage without affecting immune cells, allowing us to investigate the potential therapeutic effects associated with the endogenous protein in the future.
Drug resistance is an important open problem in cancer treatment. In recent years, the heat shock protein HSP27 (HSPB1) was identified as a key player driving resistance development. HSP27 is ...overexpressed in many cancer types and influences cellular processes such as apoptosis, DNA repair, recombination, and formation of metastases. As a result cancer cells are able to suppress apoptosis and develop resistance to cytostatic drugs. To identify HSP27 inhibitors we follow a novel computational drug repositioning approach. We exploit a similarity between a predicted HSP27 binding site to a viral thymidine kinase to generate lead inhibitors for HSP27. Six of these leads were verified experimentally. They bind HSP27 and down-regulate its chaperone activity. Most importantly, all six compounds inhibit development of drug resistance in cellular assays. One of the leads - chlorpromazine - is an antipsychotic, which has a positive effect on survival time in human breast cancer. In summary, we make two important contributions: First, we put forward six novel leads, which inhibit HSP27 and tackle drug resistance. Second, we demonstrate the power of computational drug repositioning.
ABSTRACT
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. FASEB J. 33, 9235–9249 (2019). www.fasebj.org
Based on a parliamentary vote with broad support, the Ministry of Justice of the Netherlands in December 2003 commissioned the development of an examination system to test the Dutch oral language ...skills of foreigners who want to immigrate permanently to the Netherlands for economic or family reasons. This assessment would take place in the country of origin prior to being admitted to the Netherlands. Moreover, the test would also be appropriate for use within the framework of an examination scheme for naturalization within the Netherlands, which would require a higher level of ability than at first entry. The reporting scale for the test would therefore represent reliable measurement at different points on the underlying ability continuum. It was further required by the Ministry of Justice that the reporting scale be related to the scales of the Common European Framework of Reference for Languages (henceforth: CEF;
Council of Europe, 2001
). Furthermore, the test of the Dutch language was to be accompanied by a test assessing knowledge of Dutch society, its political structure, its rules and norms, and some historical and geographical facts.
1
This article reports on some aspects of the production and validation of the language test, i.e., the test of spoken Dutch, henceforth referred to as the TGN (the acronym of the Dutch name: Toets Gesproken Nederlands).
2
Both tests were developed by a consortium with main contractor CINOP (NL) and subcontractors Language Testing Services (NL) and Ordinate Corporation (USA).
1
The specifications for the test of knowledge of Dutch society were defined to take into account the minimal level of ability in the Dutch language of the candidates. For the development of this test, see
De Jong and Tijssen (2005)
.
2
For the full report in Dutch see
Kerkhoff, Poelmans, De Jong, & Lennig (2005)
.
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