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Beta-Catenin in complex with compound 6Beta-Catenin in complex with compound 6
Structural highlights
DiseaseCTNB1_HUMAN Defects in CTNNB1 are associated with colorectal cancer (CRC) [MIM:114500. Note=Activating mutations in CTNNB1 have oncogenic activity resulting in tumor development. Somatic mutations are found in various tumor types, including colon cancers, ovarian and prostate carcinomas, hepatoblastoma (HB), hepatocellular carcinoma (HCC). HBs are malignant embryonal tumors mainly affecting young children in the first three years of life. Defects in CTNNB1 are a cause of pilomatrixoma (PTR) [MIM:132600; a common benign skin tumor.[1] [2] [3] Defects in CTNNB1 are a cause of medulloblastoma (MDB) [MIM:155255. MDB is a malignant, invasive embryonal tumor of the cerebellum with a preferential manifestation in children.[4] [5] Defects in CTNNB1 are a cause of susceptibility to ovarian cancer (OC) [MIM:167000. Ovarian cancer common malignancy originating from ovarian tissue. Although many histologic types of ovarian neoplasms have been described, epithelial ovarian carcinoma is the most common form. Ovarian cancers are often asymptomatic and the recognized signs and symptoms, even of late-stage disease, are vague. Consequently, most patients are diagnosed with advanced disease. Note=A chromosomal aberration involving CTNNB1 is found in salivary gland pleiomorphic adenomas, the most common benign epithelial tumors of the salivary gland. Translocation t(3;8)(p21;q12) with PLAG1. Defects in CTNNB1 may be a cause of mesothelioma malignant (MESOM) [MIM:156240. An aggressive neoplasm of the serosal lining of the chest. It appears as broad sheets of cells, with some regions containing spindle-shaped, sarcoma-like cells and other regions showing adenomatous patterns. Pleural mesotheliomas have been linked to exposure to asbestos.[6] FunctionCTNB1_HUMAN Key downstream component of the canonical Wnt signaling pathway. In the absence of Wnt, forms a complex with AXIN1, AXIN2, APC, CSNK1A1 and GSK3B that promotes phosphorylation on N-terminal Ser and Thr residues and ubiquitination of CTNNB1 via BTRC and its subsequent degradation by the proteasome. In the presence of Wnt ligand, CTNNB1 is not ubiquitinated and accumulates in the nucleus, where it acts as a coactivator for transcription factors of the TCF/LEF family, leading to activate Wnt responsive genes. Involved in the regulation of cell adhesion. Acts as a negative regulator of centrosome cohesion. Involved in the CDK2/PTPN6/CTNNB1/CEACAM1 pathway of insulin internalization. Blocks anoikis of malignant kidney and intestinal epithelial cells and promotes their anchorage-independent growth by down-regulating DAPK2.[7] [8] [9] [10] Publication Abstract from PubMedAberrant WNT pathway activation, leading to nuclear accumulation of beta-catenin, is a key oncogenic driver event. Mutations in the tumor suppressor gene APC lead to impaired proteasomal degradation of beta-catenin and subsequent nuclear translocation. Restoring cellular degradation of beta-catenin represents a potential therapeutic strategy. Here, we report the fragment-based discovery of a small molecule binder to beta-catenin, including the structural elucidation of the binding mode by x-ray crystallography. The difficulty in drugging beta-catenin was confirmed as the primary screening campaigns identified only few and very weak hits. Iterative virtual and NMR screening techniques were required to discover a compound (6) with sufficient potency to be able to obtain an x-ray co-crystal structure. The binding site is located between armadillo repeats two and three, adjacent to the BCL9 and TCF4 binding sites. Genetic studies show that it is unlikely to be useful for the development of protein-protein-interaction inhibitors but structural information and established assays provide a solid basis for a prospective optimization towards beta-catenin proteolysis targeting chimeras (PROTACs) as alternative modality. Getting a Grip on the Undrugged: Targeting beta-Catenin with Fragment-Based Methods.,Kessler D, Mayer M, Zahn S, Zeeb M, Wohrle S, Bergner A, Bruchhaus J, Ciftci T, Dahmann G, Dettling M, Dobel S, Fuchs JE, Geist L, Hela W, Kofink C, Kousek R, Moser F, Puchner T, Rumpel K, Scharnweber M, Werni P, Wolkerstorfer B, Breitsprecher D, Baaske P, Pearson M, McConnell DB, Bottcher J ChemMedChem. 2020 Dec 4. doi: 10.1002/cmdc.202000839. PMID:33275320[11] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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