title: Synthesis and Superpotent Anticancer Activity of Tubulysins Carrying Non-hydrolysable N-Substituents on Tubuvaline.
abstract: Synthetic tubulysins 24 a-m, containing non-hydrolysable N-substituents on tubuvaline (Tuv), were obtained in high purity and good overall yields using a multistep synthesis. A key step was the formation of differently N-substituted Ile-Tuv fragments 10 by using an aza-Michael reaction of azido-Ile derivatives 8 with the α,β-unsaturated oxo-thiazole 5. A structure-activity relationship study using a panel of human tumour cell lines showed strong anti-proliferative activity for all compounds 24 a-m, with IC50values in the sub-nanomolar range, which were distinctly lower than those of tubulysin A, vinorelbine and paclitaxel. Furthermore, 24 a-m were able to overcome cross-resistance to paclitaxel and vinorelbine in two tumour cell lines with acquired resistance to doxorubicin. Compounds 24 e and 24 g were selected as leads to evaluate their mechanism of action. In vitro assays showed that both 24 e and 24 g interfere with tubulin polymerization in a vinca alkaloid-like manner and prevent paclitaxel-induced assembly of tubulin polymers. Both compounds exerted antimitotic activity and induced apoptosis in cancer cells at very low concentrations. Compound 24 e also exhibited potent antitumor activity at well tolerated doses on in vivo models of diffuse malignant peritoneal mesothelioma, such as MESOII peritoneal mesothelioma xenografts, the growth of which was not significantly affected by vinorelbine. These results indicate that synthetic tubulysins 24 could be used as standalone chemotherapeutic agents in difficult-to-treat cancers.
authors.affiliation: KemoTech Srl, Edificio 3, Località Piscinamanna, 09010, Pula (CA, Italy.|C.N.R., Istituto di Chimica del Riconoscimento Molecolare, Via Mancinelli 7, 20131, Milano (MI), Italy.
authors.forename: Monica
authors.initials: M
authors.lastname: Sani
authors.affiliation: KemoTech Srl, Edificio 3, Località Piscinamanna, 09010, Pula (CA, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Lazzari
authors.affiliation: Fondazione IRCCS Istituto Nazionale dei Tumori, Farmacologia Molecolare, Via Amadeo 42, 20133, Milano (MI), Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Folini
authors.affiliation: KemoTech Srl, Edificio 3, Località Piscinamanna, 09010, Pula (CA, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Spiga
authors.affiliation: Fondazione IRCCS Istituto Nazionale dei Tumori, Farmacologia Molecolare, Via Amadeo 42, 20133, Milano (MI), Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Zuco
authors.affiliation: Fondazione IRCCS Istituto Nazionale dei Tumori, Farmacologia Molecolare, Via Amadeo 42, 20133, Milano (MI), Italy.
authors.forename: Michelandrea
authors.initials: M
authors.lastname: De Cesare
authors.affiliation: C.N.R. Istituto di Farmacologia Traslazionale, UOS di Cagliari, Edificio 5, Località Piscinamanna, 09010, Pula (CA), Italy.
authors.forename: Ilaria
authors.initials: I
authors.lastname: Manca
authors.affiliation: Kosterlitz Centre for Therapeutics, Institute of Medical Sciences, School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Foresterhill, Aberdeen, AB25 2ZD, Scotland, UK.
authors.forename: Sergio
authors.initials: S
authors.lastname: Dall'Angelo
authors.affiliation: Dipartimento di Chimica, Materiali e Ingegneria Chimica, Politecnico di Milano, Via Mancinelli 7, 20131, Milano (MI, Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Frigerio
authors.affiliation: KemoTech Srl, Edificio 3, Località Piscinamanna, 09010, Pula (CA, Italy.
authors.forename: Igor
authors.initials: I
authors.lastname: Usai
authors.affiliation: Kosterlitz Centre for Therapeutics, Institute of Medical Sciences, School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Foresterhill, Aberdeen, AB25 2ZD, Scotland, UK.
authors.forename: Andrea
authors.initials: A
authors.lastname: Testa
authors.affiliation: Fondazione IRCCS Istituto Nazionale dei Tumori, Farmacologia Molecolare, Via Amadeo 42, 20133, Milano (MI), Italy.
authors.forename: Nadia
authors.initials: N
authors.lastname: Zaffaroni
authors.affiliation: Kosterlitz Centre for Therapeutics, Institute of Medical Sciences, School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Foresterhill, Aberdeen, AB25 2ZD, Scotland, UK.|C.N.R., Istituto di Chimica del Riconoscimento Molecolare, Via Mancinelli 7, 20131, Milano (MI), Italy.
authors.forename: Matteo
authors.identifier: http://orcid.org/0000-0002-8257-5232
authors.initials: M
authors.lastname: Zanda
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000138:chemical synthesis* / Q000627:therapeutic use / Q000633:toxicity; D017209:Apoptosis / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004354:Drug Screening Assays, Antitumor; D019073:HT29 Cells; D006801:Humans; D051379:Mice; D008856:Microscopy, Fluorescence; D009369:Neoplasms / Q000188:drug therapy / Q000473:pathology; D017239:Paclitaxel / Q000633:toxicity; D013329:Structure-Activity Relationship; D014183:Transplantation, Heterologous; D014404:Tubulin / Q000737:chemistry / Q000378:metabolism*; D050257:Tubulin Modulators / Q000138:chemical synthesis* / Q000627:therapeutic use / Q000633:toxicity; D014633:Valine / Q000031:analogs & derivatives* / Q000737:chemistry; D014747:Vinblastine / Q000031:analogs & derivatives / Q000627:therapeutic use / Q000633:toxicity; D000077235:Vinorelbine
chemical_list: D000970:Antineoplastic Agents; D014404:Tubulin; D050257:Tubulin Modulators; C000614359:tubuvaline; D014747:Vinblastine; D014633:Valine; D017239:Paclitaxel; D000077235:Vinorelbine
keywords: Michael addition; antitumor agents; peptides; structure-activity relationships; tubulysins