Suchergebnisse

Amanita phalloides is responsible for more than 90 % of mushroom-related fatalities, and no effective antidote is available. a-Amanitin, the main toxin of A. phalloides, inhibits RNA polymerase II (RNAP II), causing hepatic and kidney failure. In silico studies included docking and molecular dynamics simulation coupled to molecular mechanics with generalized Born and surface area method energy decomposition on RNAP II. They were performed with a clinical drug that shares chemical similarities to a-amanitin, polymyxin B. The results show that polymyxin B potentially binds to RNAP II in the same interface of a-amanitin, preventing the toxin from binding to RNAP II. In vivo, the inhibition of the mRNA transcripts elicited by a-amanitin was efficiently reverted by polymyxin B in the kidneys. Moreover, polymyxin B significantly decreased the hepatic and renal a-amanitin-induced injury as seen by the histology and hepatic aminotransferases plasma data. In the survival assay, all animals exposed to a-amanitin died within 5 days, whereas 50 % survived up to 30 days when polymyxin B was administered 4, 8, and 12 h post-a-amanitin. Moreover, a single dose of polymyxin B administered concomitantly with a-amanitin was able to guarantee 100 % survival. Polymyxin B protects RNAP II from inactivation leading to an effective prevention of organ damage and increasing survival in a-amanitin-treated animals. The present use of clinically relevant concentrations of an already human-use-approved drug prompts the use of polymyxin B as an antidote for A. phalloides poisoning in humans. ; Juliana Garcia, Vera Marisa Costa, Ricardo Dinis-Oliveira and Ricardo Silvestre thank FCT-Foundation for Science and Technology-for their PhD grant (SFRH/BD/74979/2010), Post-doc grants (SFRH/BPD/63746/2009 and SFRH/BPD/110001/2015) and Investigator grants (IF/01147/2013) and (IF/00021/2014), respectively. This work was supported by the Fundacao para a Ciencia e Tecnologia (FCT) - project PTDC/DTPFTO/4973/2014 - and the European Union (FEDER funds ...

Background Half of human cancers harbour TP53 mutations that render p53 inactive as a tumor suppressor. As such, reactivation of mutant (mut)p53 through restoration of wild-type (wt)-like function represents one of the most promising therapeutic strategies in cancer treatment. Recently, we have reported the (S)-tryptophanol-derived oxazoloisoindolinone SLMP53-1 as a new reactivator of wt and mutp53 R280K with in vitro and in vivo p53-dependent antitumor activity. The present work aimed a mechanistic elucidation of mutp53 reactivation by SLMP53-1. Methods and results By cellular thermal shift assay (CETSA), it is shown that SLMP53-1 induces wt and mutp53 R280K thermal stabilization, which is indicative of intermolecular interactions with these proteins. Accordingly, in silico studies of wt and mutp53 R280K DNA-binding domain with SLMP53-1 unveiled that the compound binds at the interface of the p53 homodimer with the DNA minor groove. Additionally, using yeast and p53-null tumor cells ectopically expressing distinct highly prevalent mutp53, the ability of SLMP53-1 to reactivate multiple mutp53 is evidenced. Conclusions SLMP53-1 is a p53-activating agent with the ability to directly target wt and a set of hotspot mutp53. General Significance This work reinforces the encouraging application of SLMP53-1 in the personalized treatment of cancer patients harboring distinct p53 status. ; European Union (FEDER funds through Programa Operacional Factores de Competitividade – COMPETE) and National Funds (FCT/MEC, Fundação para a Ciência e Tecnologia and Ministério da Educação e Ciência) through the projects UID/QUI/50006/2019, COMPETE 2020 (POCI-01-0145-FEDER-006684/POCI-01-0145-FEDER-007440) and the BioTecNorte operation (NORTE-01-0145-FEDER-000004), (3599-PPCDT) PTDC/DTP-FTO/1981/2014 – POCI-01-0145-FEDER-016581 and UID/QUI/0081/2013; the Italian Association for Cancer Research, AIRC (IG#5506 to G.F.), Compagnia S. Paolo, Turin, Italy (Project 2017.0526 to G.F.) and Ministry of Health, (Project 5 × 1000, 2013 and 2015; ...