1.A synthetic dolastatin 10 analogue suppresses microtubule dynamics, inhibits cell proliferation, and induces apoptotic cell death.
Gajula PK1, Asthana J, Panda D, Chakraborty TK. J Med Chem. 2013 Mar 28;56(6):2235-45. doi: 10.1021/jm3009629. Epub 2013 Mar 19.
We have synthesized eight analogues (D1-D8) of dolastatin 10 containing several unique amino acid subunits. Of these agents, D5 was found to be most effective in inhibiting both HeLa cell proliferation and microtubule assembly in vitro. At low nanomolar concentrations, D5 inhibited the proliferation of several types of cancer cells in culture. D5 bound to tubulin with a dissociation constant of 29.4 ± 6 μM. D5 depolymerized microtubules in cultured cells and produced mulitpolar spindles. At its half-maximal inhibitory concentration (15 nM), D5 strongly suppressed the dynamics of individual microtubules in live MCF-7 cells. D5 increased the accumulation of checkpoint proteins BubR1 and Mad2 at the kinetochoric region and caused G2/M block in these cells. The blocked cells underwent apoptosis with the activation of Jun N-terminal kinase. The results suggested that D5 exerts its antiproliferative action by dampening microtubule dynamics.
2.Discovery of cytotoxic dolastatin 10 analogues with N-terminal modifications.
Maderna A1, Doroski M, Subramanyam C, Porte A, Leverett CA, Vetelino BC, Chen Z, Risley H, Parris K, Pandit J, Varghese AH, Shanker S, Song C, Sukuru SC, Farley KA, Wagenaar MM, Shapiro MJ, Musto S, Lam MH, Loganzo F, O'Donnell CJ. J Med Chem. 2014 Dec 26;57(24):10527-43. doi: 10.1021/jm501649k. Epub 2014 Dec 9.
Auristatins, synthetic analogues of the antineoplastic natural product Dolastatin 10, are ultrapotent cytotoxic microtubule inhibitors that are clinically used as payloads in antibody-drug conjugates (ADCs). The design and synthesis of several new auristatin analogues with N-terminal modifications that include amino acids with α,α-disubstituted carbon atoms are described, including the discovery of our lead auristatin, PF-06380101. This modification of the peptide structure is unprecedented and led to analogues with excellent potencies in tumor cell proliferation assays and differential ADME properties when compared to other synthetic auristatin analogues that are used in the preparation of ADCs. In addition, auristatin cocrystal structures with tubulin are being presented that allow for the detailed examination of their binding modes. A surprising finding is that all analyzed analogues have a cis-configuration at the Val-Dil amide bond in their functionally relevant tubulin bound state, whereas in solution this bond is exclusively in the trans-configuration.