The Dolastatins 16. Synthesis of Dolaphenine

Pettit, George R.; Hogan, Fiona; Burkett, Douglas D.; Singh, Sheo B.; Kantoci, Darko; Srirangam, Jayaram K.; Williams, M. D.

doi:10.3987/com-93-s(b)2

Cited by 17 publications

(14 citation statements)

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“…[ 3 H]dolastatin 1073 enabled us to examine interactions of the peptide with tubulin in detail. The binding of dolastatin 10 was strongly inhibited by (19a R )‐isodolastatin 10,103 a highly active chiral isomer of the peptide, and by phomopsin A and spongistatin 1; moderately inhibited by halichondrin B, maytansine, and vincristine; and weakly inhibited by rhizoxin and vinblastine 73. Dolastatin 10 binding to tubulin was not inhibited by dolastatin 15,73 but binding was also inhibited by three additional antimitotic peptides to be discussed below (cryptophycin 1, hemiasterlin, vitilevuamide).…”

Section: Dolastatins 10 and 15mentioning

confidence: 99%

Interactions of antimitotic peptides and depsipeptides with tubulin

Hamel

2002

Biopolymers

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Tubulin is the target for an ever increasing number of structurally unusual peptides and depsipeptides isolated from a wide range of organisms. Since tubulin is the subunit protein of microtubules, the compounds are usually potently toxic to mammalian cells. Without exception, these (depsi)peptides disrupt cellular microtubules and prevent spindle formation. This causes cells to accumulate at the G2/M phase of the cell cycle through inhibition of mitosis. In biochemical assays, the compounds inhibit microtubule assembly from tubulin and suppress microtubule dynamics at low concentrations. Most of the (depsi)peptides inhibit the binding of Catharanthus alkaloids to tubulin in a noncompetitive manner, GTP hydrolysis by tubulin, and nucleotide turnover at the exchangeable GTP site on beta-tubulin. In general, the (depsi)peptides induce the formation of tubulin oligomers of aberrant morphology. In all cases tubulin rings appear to be formed, but these rings differ in diameter, depending on the (depsi)peptide present during their formation.

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Section: Dolastatins 10 and 15mentioning

confidence: 99%

Interactions of antimitotic peptides and depsipeptides with tubulin

Hamel

2002

Biopolymers

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“…Auristatin PHE (M r ϭ 760) was synthesized and purified by standard purification procedures as previously described (41,42). Aliquots were stored desiccated in the dark at room temperature.…”

Section: Methodsmentioning

confidence: 99%

Differential Gene Expression in Auristatin PHE-Treated Cryptococcus neoformans

Woyke

Berens

Hoelzinger

et al. 2004

Antimicrob Agents Chemother

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The antifungal pentapeptide auristatin PHE was recently shown to interfere with microtubule dynamics and nuclear and cellular division in the opportunistic pathogen Cryptococcus neoformans. To gain a broader understanding of the cellular response of C. neoformans to auristatin PHE, mRNA differential display (DD) and reverse transcriptase PCR (RT-PCR) were applied. Examination of approximately 60% of the cell transcriptome from cells treated with 1.5 times the MIC (7.89 M) of auristatin PHE for 90 min revealed 29 transcript expression differences between control and drug-treated populations. Differential expression of seven of the transcripts was confirmed by RT-PCR, as was drug-dependent modulation of an additional seven transcripts by RT-PCR only. Among genes found to be differentially expressed were those encoding proteins involved in transport, cell cycle regulation, signal transduction, cell stress, DNA repair, nucleotide metabolism, and capsule production. For example, RHO1 and an open reading frame (ORF) encoding a protein with 91% similarity to the Schizophyllum commune 14-3-3 protein, both involved in cell cycle regulation, were down-regulated, as was the gene encoding the multidrug efflux pump Afr1p. An ORF encoding a protein with 57% identity to the heat shock protein HSP104 in Pleurotus sajor-caju was up-regulated. Also, three transcripts of unknown function were responsive to auristatin PHE, which may eventually contribute to the elucidation of the function of their gene products. Further study of these differentially expressed genes and expression of their corresponding proteins are warranted to evaluate how they may be involved in the mechanism of action of auristatin PHE. This information may also contribute to an explanation of the selectivity of auristatin PHE for C. neoformans. This is the first report of drug action using DD in C. neoformans.

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“…Auristatin PHE (M r ϭ760) was synthesized and purified using standard purification procedures as previously described (37,38). Aliquots were stored desiccated in the dark at room temperature.…”

Section: Methodsmentioning

confidence: 99%

Effect of Auristatin PHE on Microtubule Integrity and Nuclear Localization in Cryptococcus neoformans

Woyke

Roberson

Pettit³

et al. 2002

Antimicrob Agents Chemother

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The mechanism of action of the fungicidal peptide auristatin PHE was investigated in Cryptococcus neoformans. Since auristatin PHE causes budding arrest in C. neoformans (T. Woyke, G. R. Pettit, G. Winkelmann, and R. K. Pettit, Antimicrob. Agents Chemother. 45:3580-3584, 2001), microtubule integrity and nuclear localization in auristatin PHE-treated cells were examined. Iterative deconvolution in conjunction with an optimized C. neoformans microtubule immunolabeling procedure enabled detailed visualization of the microtubule cytoskeleton in auristatin PHE-treated C. neoformans. The effect of auristatin PHE on C. neoformans microtubule organization was compared with that of the tubulin-binding agent nocodazole. Both drugs produced complete disruption first of cytoplasmic and then of spindle microtubules in a time-and concentrationdependent manner. Sub-MICs of auristatin PHE caused complete microtubule disruption within 4.5 h, while 1.5 times the nocodazole MIC was required for the same effect. For both drugs, disruption of microtubules was accompanied by blockage of nuclear migration and of nuclear and cellular division, resulting in cells arrested in a uninucleate, large-budded stage. Nocodazole and the linear peptide auristatin PHE are remarkably different in structure and spectrum of activity, yet on the cellular level, they have similar effects.The basidiomycetous budding yeast Cryptococcus neoformans was identified as a human pathogen more than 100 years ago (5). Due to the growing number of immunocompromised patients worldwide, the number of invasive infections caused by this encapsulated yeast has been increasing dramatically (6,15,29,42). The most frequent clinical manifestation of cryptococcal infection is meningoencephalitis, which is fatal if left untreated. Existing therapies, including polyene and azole antifungals (11,29,42,49), are limited by host toxicities (42) and the emergence of drug-resistant strains (18,20).The pentapeptide auristatin PHE (dovaline-valine-dolaisoleunine-dolaproine-phenylalanine-methyl-ester) is a synthetic modification of the natural marine product dolastatin 10 (37, 38), which is currently undergoing phase I and phase II cancer clinical trials. Auristatin PHE has fungicidal activity against C. neoformans and fungicidal or fungistatic activity against various species of Trichosporon (39, 50). Auristatin PHE caused C. neoformans cells to arrest in a large-budded stage (50), suggesting that it might interfere with the microtubule dynamics in a manner similar to that of nocodazole in Saccharomyces cerevisiae (17).To investigate this possibility, we optimized cell wall digestion and microtubule labeling conditions for C. neoformans. This procedure, in conjunction with iterative deconvolution microscopy, allowed detailed visualization of the C. neoformans microtubule network. In iterative deconvolution, the focal Z plane sections are digitally captured and out-of-focus light in each section is mathematically removed and/or reduced by examination of neighboring sections (2, 43). T...

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The Dolastatins 16. Synthesis of Dolaphenine

Cited by 17 publications

References 0 publications

Interactions of antimitotic peptides and depsipeptides with tubulin

Interactions of antimitotic peptides and depsipeptides with tubulin

Differential Gene Expression in Auristatin PHE-Treated Cryptococcus neoformans

Effect of Auristatin PHE on Microtubule Integrity and Nuclear Localization in Cryptococcus neoformans

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