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DISCUSSIoN
We demonstrate the development of an exceptionally versatile reac-
tioncascadeofunprecedentedlengthandefficiency, givingaccesstoa
structurally complex natural product–inspired compound collection
that yields new modulators of centrosome integrity and mitotic spin-
dle pole formation by simultaneously targeting NPM and Crm1. On
the basis of the induced phenotype, we term these molecules cen-
trocountins, with compound 16a being centrocountin 1. Although
for chemical-biological analysis of Crm1 function leptomycin B is a
widely used molecular probe30, small molecules influencing NPM
function have rarely been described, with the electrophilic and
thereby nonselective natural product avrainvillamide being the most
prominent case31. A dual NPM–Crm1 ligand is unique, and a molec-
ular probe for the elucidation of NPM or NPM–Crm1 function is not
available yet. NPM is involved in the establishment of many cancers,
although its role is controversial32. In light of the efficient accessibil-
ity of the centrocountins and the fact that treatment of cancer cell
lines with these compounds is antiproliferative and leads to mitotic
arrest and apoptosis, the centrocountins and modulation of the
activity of NPM or the NPM–Crm1 complex might inspire new drug
discovery programs.
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mETHoDS
General procedure for the cascade synthesis of indoloquinolizines 16. The
3-formylchromone (1 eq.) was dissolved in toluene (10 ml mmol−1) by heating to
80 °C, and the acetylenedicarboxylate (1.3 eq.) and triphenylphosphine (0.6 eq.)
were added. After 2–5 min, the tryptamine (1.1 eq.) was added, and, after the
tryptamine dissolved, camphorsulfonic acid (1.5 eq.) was added. After 5–30 min,
the solvent was evaporated, and the remaining residue was subjected to column
chromatography on silica gel to yield the indoloquinolizine 16 as a yellow solid,
which can be further purified by precipitation from methanol. Further details are
available in Supplementary Methods.
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in vitro anticancer activity of the structurally novel and highly potent
antibiotic CI-940 and its hydroxy analog (PD-114,721). Cancer Chemother.
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Other methods. Cell lines and plasmids, imaging protocols, isolation of binding
proteins and other cell-based procedures are detailed in Supplementary Methods.
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target for therapeutic drugs. Curr. Med. Chem. 10, 741–748 (2003).
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binds to the oncoprotein nucleophosmin. J. Am. Chem. Soc. 129,
14444–14451 (2007).
received 9 March 2011; accepted 7 October 2011;
published online 25 December 2011
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acknowledgments
We would like to thank T.U. Mayer (Universität Konstanz) for helpful discussions,
S. Müller and T. Klüßendorf (Max-Planck-Institut Dortmund) for assistance with the
fluorescence lifetime imaging microscopy measurements, C. Nowak for technical
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author contributions
H.D., V.K. and H.B. designed and performed the synthesis experiments. V.P., S.M.,
A.W.B., Z.M. and S.Z. carried out the biological studies. P.J. and A.B. performed MS anal-
ysis. H.W., K.K., K.H., S.Z. and A.H. designed experiments. M.S. and H.P. carried out the
X-ray crystallographic analysis. S.G. determined the absolute configuration of 16a. H.W.,
K.K. and S.Z. supervised the project and wrote the manuscript. All authors discussed the
results and commented on the manuscript.
Competing financial interests
The authors declare no competing financial interests.
additional information
Supplementary information and chemical compound information is available online at
requests for materials should be addressed to K.K. or H.W.
184