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Microtubule Binding and Disruption and Induction of Premature Senescence by Disorazole C1S
Disorazoles comprise a family of 29 macrocyclic polyketides isolated from the fermentation broth of the myxobacterium Sorangium cellulosum . The major fermentation product, disorazole A 1 , was found previously to irreversibly bind to tubulin and to have potent cytotoxic activity against tumor cells...
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Published in: | The Journal of pharmacology and experimental therapeutics 2008-12, Vol.328 (3), p.715-722 |
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Main Authors: | , , , , , , , , , , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Online Access: | Get full text |
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Summary: | Disorazoles comprise a family of 29 macrocyclic polyketides isolated from
the fermentation broth of the myxobacterium
Sorangium cellulosum
. The
major fermentation product, disorazole A
1
, was found previously to
irreversibly bind to tubulin and to have potent cytotoxic activity against
tumor cells, possibly because of its highly electrophilic epoxide moiety. To
test this hypothesis, we synthesized the epoxide-free disorazole C
1
and found it retained potent antiproliferative activity against tumor cells,
causing prominent G
2
/M phase arrest and inhibition of in vitro
tubulin polymerization. Furthermore, disorazole C
1
produced
disorganized microtubules at interphase, misaligned chromosomes during
mitosis, apoptosis, and premature senescence in the surviving cell
populations. Using a tubulin polymerization assay, we found disorazole
C
1
inhibited purified bovine tubulin polymerization, with an
IC
50
of 11.8 ± 0.4 μM, and inhibited
[
3
H]vinblastine binding noncompetitively, with a
K
i
of 4.5 ± 0.6 μM. We also found noncompetitive
inhibition of [
3
H]dolastatin 10 binding by disorazole
C
1
, with a
K
i
of 10.6 ± 1.5 μM,
indicating that disorazole C
1
bound tubulin uniquely among known
antimitotic agents. Disorazole C
1
could be a valuable chemical
probe for studying the process of mitotic spindle disruption and its
relationship to premature senescence. |
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ISSN: | 0022-3565 1521-0103 |
DOI: | 10.1124/jpet.108.147330 |