Cyclostreptin Derivatives Specifically Target Cellular Tubulin and Further Map the Paclitaxel Site

13 páginas, 7 figuras, 1 tabla -- PAGS nros. 329-341Cyclostreptin is the first microtubule-stabilizing agent whose mechanism of action was discovered to involve formation of a covalent bond with tubulin. Treatment of cells with cyclostreptin irreversibly stabilizes their microtubules because cyclostreptin forms a covalent bond to β-tubulin at either the T220 or the N228 residue, located at the microtubule pore or luminal taxoid binding site, respectively. Because of its unique mechanism of action, cyclostreptin overcomes P-glycoprotein-mediated multidrug resistance in tumor cells. We used a series of reactive cyclostreptin analogues, 6-chloroacetyl-cyclostreptin, 8-chloroacetyl-cyclostreptin, and [14C-acetyl]-8-acetyl-cyclostreptin, to characterize the cellular target of the compound and to map the binding site. The three analogues were cytotoxic and stabilized microtubules in both sensitive and multidrug resistant tumor cells. In both types of cells, we identified β-tubulin as the only or the predominantly labeled cellular protein, indicating that covalent binding to microtubules is sufficient to prevent drug efflux mediated by P-glycoprotein. 6-Chloroacetyl-cyclostreptin, 8-chloroacetyl-cyclostreptin, and 8-acetyl-cyclostreptin labeled both microtubules and unassembled tubulin at a single residue of the same tryptic peptide of β-tubulin as was labeled by cyclostreptin (219-LTTPTYGDLNHLVSATMSGVTTCLR-243), but labeling with the analogues occurred at different positions of the peptide. 8-Acetyl-cyclostreptin reacted with either T220 or N228, as did the natural product, while 8-chloroacetyl-cyclostreptin formed a cross-link to C241. Finally, 6-chloroacetyl-cyclostreptin reacted with any of the three residues, thus labeling the pathway for cyclostreptin-like compounds, leading from the pore where these compounds enter the microtubule to the luminal binding pocketThis work was supported in part by Grant BIO2010-16351 from Ministerio de Ciencia e Innovacioń (to J.F.D.) and grant BIPPED2 from Comunidad Autónoma de Madrid. The CNIC is supported by the Ministerio de Ciencia e Innovación and the Fundación Pro CNICPeer reviewe

Epidemiological and clinical features of Kawasaki disease in Spain over 5 years and risk factors for aneurysm development. (2011-2016): KAWA-RACE study group

BACKGROUND: Kawasaki disease (KD) is an acute self-limited systemic vasculitis of unknown etiology affecting mainly children less than 5 years of age. Risk factors for cardiac involvement and resistance to treatment are insufficiently studied in non-Japanese children. OBJECTIVE: This study aimed to investigate the epidemiology, clinical features and risk factors for resistance to treatment and coronary artery lesions (CAL) in KD in Spain. METHODS: Retrospective study (May 2011-June 2016) of all patients less than 16 years of age diagnosed with KD included in KAWA-RACE network (84 Spanish hospitals). RESULTS: A total of 625 cases were analyzed, 63% were males, 79% under 5 year-olds and 16.8% younger than 12 months. On echocardiographic examination CAL were the most frequent findings (23%) being ectasia the most common (12%). Coronary aneurysms were diagnosed in 9.6%, reaching 20% in infants under 12 months (p 900,000 cells/mm3, maximum temperature 10 days and fever before treatment >/= 8 days as independent risk factors for developing coronary aneurysms. CONCLUSIONS: In our population, children under 12 months develop coronary aneurysms more frequently and children with KD with anemia and leukocytosis have high risk of cardiac involvement. Adding steroids early should be considered in those patients, especially if the treatment is not started before 8 days of fever. A score applicable to non-Japanese children able to predict the risk of aneurysm development and IVIG resistance is necessary