Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Tubulin Modulators”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 289 records · Page 16Linked to original sources
PubMed2004

A tale of two tumor targets: topoisomerase I and tubulin. The Wall and Wani contribution to cancer chemotherapy.

The seminal discoveries of camptothecin and Taxol by Wall and Wani are discussed in a manner that demonstrates the influence that these two compounds has had on the further development of natural product, natural product-derived, and (some) synthetic entities as potential drug leads that interact either with tubulin or with topoisomerase I. The major categories of tubulin interactive agents in terms of inhibition and promotion of tubulin polymerization are briefly discussed. Likewise, a brief discussion of topoisomerase I inhibitors is presented. Lists of tubulin interactive agents and topoisomerase I inhibitors in preclinical and clinical development are given in Tables 2 and 3, respectively. This review is not meant to be exhaustive, but does illustrate the profound impact that these two plant-derived agents have had on cancer chemotherapy.

Antineoplastic Agents, Phytogenic↗
PubMed2004

Scleritodermin A, a cytotoxic cyclic peptide from the lithistid sponge Scleritoderma nodosum.

The lithistid sponge Scleritoderma nodosum contains a new cyclic peptide, scleritodermin A (1), the structure of which incorporates l-proline, l-serine, and keto-allo-isoleucine units as well as a novel conjugated thiazole moiety (ACT) and O-methyl-N-sulfoserine. Scleritodermin A (1) inhibited tubulin polymerization and showed significant in vitro cytotoxicity against human tumor cell lines.

Animals↗
PubMed2004

Biosynthetic pathway and gene cluster analysis of curacin A, an antitubulin natural product from the tropical marine cyanobacterium Lyngbya majuscula.

Curacin A (1) is a potent cancer cell toxin obtained from strains of the tropical marine cyanobacterium Lyngbya majuscula found in Curaçao. Its structure is unique in that it contains the sequential positioning of a thiazoline and cyclopropyl ring, and it exerts its potent cell toxicity through interaction with the colchicine drug binding site on microtubules. A series of stable isotope-labeled precursors were fed to cultures of curacin A-producing strains and, following NMR analysis, allowed determination of the metabolic origin of all atoms in the natural product (one cysteine, 10 acetate units, two S-adenosyl methionine-derived methyl groups) as well as several unique mechanistic insights. Moreover, these incorporation experiments facilitated an effective gene cloning strategy that allowed identification and sequencing of the approximately 64 kb putative curacin A gene cluster. The metabolic system is comprised of a nonribosomal peptide synthetase (NRPS) and multiple polyketide synthases (PKSs) and shows a very high level of collinearity between genes in the cluster and the predicted biochemical steps required for curacin biosynthesis. Unique features of the cluster include (1) all but one of the PKSs are monomodular multifunctional proteins, (2) a unique gene cassette that contains an HMG-CoA synthase likely responsible for formation of the cyclopropyl ring, and (3) a terminating motif that is predicted to function in both product release and terminal dehydrative decarboxylation.

Amino Acid Sequence↗
PubMed2003

Novel orthogonal strategy toward solid-phase synthesis of 1,3,5-substituted triazines.

[reaction: see text] To improve upon the previous orthogonal method for synthesis of a triazine library, an alternative strategy has been developed via oxidation-activation of the thioether to the sulfone. Through a comparison between these two methods, the sulfone strategy was demonstrated as an enhanced method in the generation of highly pure triazine library compounds.

Combinatorial Chemistry Techniques↗
PubMed2003

Toward the synthesis of peloruside a: fragment synthesis and coupling studies.

[reaction: see text] The asymmetric synthesis of building blocks 3, 4, and 5, corresponding to C(12)-C(19), C(7)-C(11), and C(1)-C(6) segments of peloruside A, is reported, along with boron-mediated aldol coupling studies directed toward the assembly of the complete carbon skeleton of this microtubule-stabilizing macrolide.

Animals↗
PubMed2004

Synthesis, modeling, and anti-tubulin activity of a D-seco paclitaxel analogue.

[reaction: see text] We have previously described a model of paclitaxel-microtubule binding that led to the prediction that analogues of paclitaxel lacking any D ring could stabilize microtubules as well as paclitaxel if the substituent present at C4 did not have unfavorable steric interactions with the binding pocket. We report the synthesis of a 4-methyl paclitaxel analogue, compound 1, which bears this prediction out. Compound 1 is as potent as paclitaxel at microtubule stabilization in vitro; however, it has only about one-four-hundredth the cytotoxicity of paclitaxel.

Antineoplastic Agents, Phytogenic↗
PubMed2006

Synthesis of the celogentin C right-hand ring.

[reaction: see text] Synthesis of the cyclic tetrapeptide comprising the right-hand ring of celogentin C, a potent inhibitor of tubulin polymerization, has been accomplished. A mild oxidative coupling reaction permitted construction of the indole-imidazole linkage via a convergent union of two fully functionalized dipeptides. A high-yielding macrolactamization and subsequent deprotection of the N-terminus furnished the target compound.

Celosia↗
PubMed2001

Comparative molecular field analysis (coMFA) study of epothilones-tubulin depolymerization inhibitors: pharmacophore development using 3D QSAR methods.

A three-dimensional quantitative structure-activity relationship (3D QSAR) study has been carried out on epothilones based on comparative molecular field analyses (CoMFA) using a large data set of epothilone analogs, which are potent inhibitors of tubulin depolymerization. Microtubules, which are polymers of the a/beta-tubulin heterodimer, need to dissociate in order to form the mitotic spindle, a structure required for cell division. A rational pharmacophore searching method using 3D QSAR procedures was carried out and the results for the epothilones are described herein. One-hundred and sixty-six epothilone analogs and their depolymerization inhibition properties with tubulin were used as a training set. Over a thousand molecular field energies were generated and applied to generate the descriptors of QSAR equations. Using a genetic function algorithm (GFA) method, combined with a least square approach, multiple QSAR models were considered during the search for pharmacophore elements. Each GFA run resulted in 100 QSAR models, which were ranked according to their lack of fit (LOF) scores, with a total of 40 GFA runs having been performed. The 40 best QSAR equations from each run had adequate fitted correlation coefficients (R from 0.813 to 0.863) and were of sufficient statistical significance (F value from 7.2 to 10.9). The pharmacophore elements for epothilones were studied by investigating the hit frequency of descriptors (i.e. the sampling probabilities of grid points from the GFA studies) from the set of the 4,000 top scoring QSAR equations. By comparing the frequency with which each grid point appeared in the QSAR equations, three candidate regions in the epothilones were proposed to be pharmacophore elements. Two of them are completely compatible with the recent model proposed by Ojima et al. [Proc. Natl. Acad. Sci. USA, 96 (1999) 4256], however, one is quite different and is necessary to accurately predict the activities of all 166 epothilone molecules used in our training set. Finally, by visualizing the 35 most probable grid points, it was found that changes related to the C6, C7, C8, C 12, S20, and C21 atoms of the epothilones were highly correlated to their activity.

Algorithms↗
PubMed2003

Antimicrotubular drugs binding to vinca domain of tubulin.

Studies on vinca domain binding drugs were done in great details by a number of workers as it is recognized as a potential target for anticancer drug development. Their structures, properties, mode of action, success and failures as potential anticancer drug have been discussed in short details in this review. Among these drugs rhizoxin and maytansine are competitive inhibitors, and bind at the vinblastine binding site of tubulin where as others are non-competitive inhibitors. Besides binding, these drugs also differ in the extent of GTP hydrolysis, GTP exchange and in the stabilization of colchicine binding site. The toxicity level of these drugs towards the host cells and the extent of efflux of drugs by the P-glycoprotein mediated pump are also discussed.

Animals↗
PubMed2003

Calprotectin release from human neutrophils is induced by Porphyromonas gingivalis lipopolysaccharide via the CD-14-Toll-like receptor-nuclear factor kappaB pathway.

OBJECTIVES: Calprotectin is a cytosolic protein with antibacterial action in leukocytes and its level increases in some inflammatory diseases, including periodontal diseases, rheumatoid arthritis and ulcerative colitis. Recently, we found that the lipopolysaccharide of Porphyromonas gingivalis (P-LPS) induced calprotectin release from human neutrophils. P-LPS, a major virulence factor of periodontal pathogens, is known to induce the production and release of inflammatory cytokines through CD14, Toll-like receptor (TLR) and nuclear factor kappaB (NF-kappaB). In the present study, we investigated whether calprotectin release by P-LPS is induced via the CD14-TLR-NF-kappaB pathway and the cellular mechanism of calprotectin release in human neutrophils. MATERIAL AND METHODS: Human neutrophils were isolated from the peripheral blood of healthy donors and pre-incubated in medium containing antibodies against CD14, TLR2 and TLR4, or several inhibitors of NF-kappaB, microtubules and microfilaments, and then incubated with P-LPS. The calprotectin amount in the culture medium was determined using ELISA, and the nuclear extracts from cells were used for the examination of NF-kappaB binding activity using electrophoretic mobility shift assays. RESULTS: P-LPS increased calprotectin release from neutrophils and its induction was inhibited by anti-CD14 and anti-TLR2 antibodies, but not by two anti-TLR4 antibodies. NF-kappaB inhibitors suppressed P-LPS-induced NF-kappaB binding activity and calprotectin release. The inhibitors of microtubule and microfilament polymerization significantly decreased P-LPS-induced calprotectin release. CONCLUSION: These results suggest that calprotectin release is induced by P-LPS via the CD14-TLR2-NF-kappaB signal pathway in human neutrophils and may be dependent on microtubule and microfilament systems.

Actin Cytoskeleton↗
PubMed2004

Insight into tubulin regulation from a complex with colchicine and a stathmin-like domain.

Microtubules are cytoskeletal polymers of tubulin involved in many cellular functions. Their dynamic instability is controlled by numerous compounds and proteins, including colchicine and stathmin family proteins. The way in which microtubule instability is regulated at the molecular level has remained elusive, mainly because of the lack of appropriate structural data. Here, we present the structure, at 3.5 A resolution, of tubulin in complex with colchicine and with the stathmin-like domain (SLD) of RB3. It shows the interaction of RB3-SLD with two tubulin heterodimers in a curved complex capped by the SLD amino-terminal domain, which prevents the incorporation of the complexed tubulin into microtubules. A comparison with the structure of tubulin in protofilaments shows changes in the subunits of tubulin as it switches from its straight conformation to a curved one. These changes correlate with the loss of lateral contacts and provide a rationale for the rapid microtubule depolymerization characteristic of dynamic instability. Moreover, the tubulin-colchicine complex sheds light on the mechanism of colchicine's activity: we show that colchicine binds at a location where it prevents curved tubulin from adopting a straight structure, which inhibits assembly.

Amino Acid Sequence↗
PubMed2007

Cyclostreptin binds covalently to microtubule pores and lumenal taxoid binding sites.

Cyclostreptin (1), a natural product from Streptomyces sp. 9885, irreversibly stabilizes cellular microtubules, causes cell cycle arrest, evades drug resistance mediated by P-glycoprotein in a tumor cell line and potently inhibits paclitaxel binding to microtubules, yet it only weakly induces tubulin assembly. In trying to understand this paradox, we observed irreversible binding of synthetic cyclostreptin to tubulin. This results from formation of covalent crosslinks to beta-tubulin in cellular microtubules and microtubules formed from purified tubulin in a 1:1 total stoichiometry distributed between Thr220 (at the outer surface of a pore in the microtubule wall) and Asn228 (at the lumenal paclitaxel site). Unpolymerized tubulin was only labeled at Thr220. Thus, the pore region of beta-tubulin is an undescribed binding site that (i) elucidates the mechanism by which taxoid-site compounds reach the kinetically unfavorable lumenal site and (ii) explains how taxoid-site drugs induce microtubule formation from dimeric and oligomeric tubulin.

Alkanes↗
PubMed1999

Antisense oligonucleotides to class III beta-tubulin sensitize drug-resistant cells to Taxol.

A major impediment to the successful use of Taxol in the treatment of cancer is the development of drug resistance. The major cellular target of Taxol is the microtubule that is comprised of alpha- and beta-tubulin heterodimers. Binding sites for Taxol have been delineated on the beta-tubulin subunit that has six isotypes. We have recently described increased expression of the brain-specific human class III beta-tubulin isotype, encoded by the Hbeta4 gene, in both Taxol-resistant ovarian tumours and non-small-cell lung cancer cell lines. To evaluate directly the role of the class III beta-tubulin isotype in mediating Taxol resistance, antisense phosphorothioate oligodeoxynucleotides (ODN) targeted against various regions of the Hbeta4 gene have been designed and examined for their efficacy in reducing Hbeta4 gene and protein expression. Taxol-resistant lung cancer cells, A549-T24, which are 17-fold resistant to Taxol and display a fourfold increase in Hbeta4 expression compared to the parental A549 cells, were treated with 1 microM antisense ODNs. Two ODNs, AS1 and AS3, were found to reduce mRNA expression by 40-50%, as determined by reverse transcription polymerase chain reaction. A concentration-dependent reduction in Hbeta4 mRNA expression was demonstrated with AS1 ODN. Immunofluorescence staining of cells treated with AS1 ODN revealed a decrease in class III protein expression which corresponded to a 39% increase in sensitivity to Taxol (P < 0.005). These findings support an important role for Hbeta4 (class III) beta-tubulin expression in Taxol resistance and have potential implications for the treatment of Taxol-resistant tumours.

Carcinoma, Non-Small-Cell Lung↗
PubMed2006

Synthesis of (S)-(-)-N-acetylcolchinol using intramolecular biaryl oxidative coupling.

An asymmetric synthesis of the tubulin polymerisation inhibitor (S)-(-)-N-acetylcolchinol is reported based on an intramolecular biaryl oxidative coupling of a 1,3-diarylpropyl acetamide intermediate using phenyliodonium bis(trifluoroacetate) as the final step. Three syntheses of the penultimate 1,3-diarylpropyl acetamide intermediate (S)-(-)-N-[1-[3-(tert-butyldimethylsilyloxy)phenyl)]-3-(3,4,5-trimethoxyphenyl)propyl] acetamide are described which differ in the means by which the stereogenic centre was introduced.

Acetamides↗
PubMed2007

Disassembly of actin filaments by botulinum C2 toxin and actin-filament-disrupting agents induces assembly of microtubules in human leukaemia cell lines.

BACKGROUND INFORMATION: C(2) toxin produced by Clostridium botulinum types C and D ADP-ribosylates actin monomers and inactivates their polymerization activities. The disassembly of actin filaments by C(2) toxin induces a polarization of cultured human leukaemia cell lines. RESULTS: The polarization induced by C(2) toxin was temperature dependent and was prevented by nocodazole, a microtubule-disrupting agent, whereas it was promoted by paclitaxel, a microtubule-stabilizing agent. The fluorescence staining of polarized cells indicated an increase in microtubule assembly accompanying disassembly of actin filaments. Furthermore, several actin-filament-disrupting agents, other than C(2) toxin, also induced microtubule assembly and cell polarization, irrespective of their different mechanisms of action. The effects induced by some of the agents, which have lower binding affinities for actin, were reversible in response to the re-assembly of actin filaments. CONCLUSIONS: Thus the disassembly of actin filaments by C(2) toxin and actin-filament-disrupting agents induces assembly of microtubules followed by polarization of human leukaemia cell lines, indicating that the assembly/disassembly equilibrium of actin filaments influences the dynamics of microtubules, which control cell morphology and, in turn, diverse cellular processes.

Actin Cytoskeleton↗
PubMed2006

Biological evaluation of tubulysin A: a potential anticancer and antiangiogenic natural product.

Tubulysin A (tubA) is a natural product isolated from a strain of myxobacteria that has been shown to depolymerize microtubules and induce mitotic arrest. The potential of tubA as an anticancer and antiangiogenic agent is explored in the present study. tubA shows potent antiproliferative activity in a panel of human cancer cell lines irrespective of their multidrug resistance properties. It induces apoptosis in cancer cells but not in normal cells and shows significant potential antiangiogenic properties in several in vitro assays. It is efficacious in initial animal studies using a hollow fibre assay with 12 different human tumour cell lines. This study suggests that both in vitro and preclinical profiles of tubA may translate into clinically useful anticancer properties.

ATP Binding Cassette Transporter, Subfamily B, Mem↗