Quantitative analysis of the effect of tubulin isotype expression on sensitivity of cancer cell lines to a set of novel colchicine derivatives

<p>Abstract</p> <p>Background</p> <p>A maximum entropy approach is proposed to predict the cytotoxic effects of a panel of colchicine derivatives in several human cancer cell lines. Data was obtained from cytotoxicity assays performed with 21 drug molecules from the same family of colchicine compounds and correlate these results with independent tubulin isoform expression measurements for several cancer cell lines. The maximum entropy method is then used in conjunction with computed relative binding energy values for each of the drug molecules against tubulin isotypes to which these compounds bind with different affinities.</p> <p>Results</p> <p>We have found by using our analysis that <it>αβ</it>I and <it>αβ</it>III tubulin isoforms are the most important isoforms in establishing predictive response of cancer cell sensitivity to colchicine derivatives. However, since <it>αβ</it>I tubulin is widely distributed in the human body, targeting it would lead to severe adverse side effects. Consequently, we have identified tubulin isotype <it>αβ</it>III as the most important molecular target for inhibition of microtubule polymerization and hence cancer cell cytotoxicity. Tubulin isotypes <it>αβ</it>I and <it>αβ</it>II are concluded to be secondary targets.</p> <p>Conclusions</p> <p>The benefit of being able to correlate expression levels of specific tubulin isotypes and the resultant cell death effect is that it will enable us to better understand the origin of drug resistance and hence design optimal structures for the elimination of cancer cells. The conclusion of the study described herein identifies tubulin isotype <it>αβ</it>III as a target for optimized chemotherapy drug design.</p

Paclitaxel resistance by random mutagenesis of α‐tubulin

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/102075/1/cm21154-sup-0001-suppfig1.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/102075/2/cm21154-sup-0002-suppfig2.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/102075/3/cm21154.pd

Drug-tubulin interactions interrogated by transient absorption spectroscopy

[EN] Colchicine (COL) is a bioactive molecule with antitumor properties. When COL binds to tubulin (TU), it inhibits microtubule assembly dynamics. We have investigated COL-TU interactions using laser flash photolysis (LFP) technique and performing fully flexible molecular dynamics simulations. Excitation of COL at 355 nm in aqueous medium did not lead to any transient absorption spectrum. By contrast, in the presence of TU a transient peaking at lambda(max) ca. 420 nm was registered and assigned as triplet excited COL complexed with TU ((COL)-C-3*@TU). In aerated medium, the lifetime was tau ca. 160 mu s and the quantum yield was 0.138. Likewise, when the bicyclic COL analog MTC was submitted to LFP in the presence of TU, (MTC)-M-3@TU* was detected with a lifetime of ca. 62 ms and a quantum yield of 0.296, Aqueous solutions of MTC did not produce any signal in the microsecond timescale. The triplet energy of MTC was obtained by means of emission measurements and found to be ca. 200 kJ mol(-1), a value that matches with that previously reported for COL (188 kJ mol(-1)). Molecular dynamic simulations, both with the ground and triplet excited state, reveal a strong interaction between COL and TU to give stabilized complexes with restricted mobility inside the protein binding site. These results demonstrate that LFP is a useful methodology to study the binding of COL derivatives to TU and open a new way to evaluate the interactions of non-fluorescent anticancer drugs with this protein.Financial support from the Spanish Government (grants CTQ2010-19909; BFU2011-23416 and SEV 2012-0267), the Generalitat Valenciana (Prometeo II/2013/005) and Comunidad de Madrid (S2010/BMD-2353) is gratefully acknowledged. G.S. thanks ASIC-UPV for computing time.Bosca Mayans, F.; Sastre Navarro, GI.; Andreu, JM.; Jornet, D.; Tormos Faus, RE.; Miranda Alonso, MÁ. (2015). 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Microtubule-Stabilizing Drugs from Marine Sponges: Focus on Peloruside A and Zampanolide

Marine sponges are an excellent source of bioactive secondary metabolites with potential therapeutic value in the treatment of diseases. One group of compounds of particular interest is the microtubule-stabilizing agents, the most well-known compound of this group being paclitaxel (Taxol®), an anti-cancer compound isolated from the bark and leaves of the Pacific yew tree. This review focuses on two of the more recent additions to this important class of drugs, peloruside A and zampanolide, both isolated from marine sponges. Peloruside A was isolated from Mycale hentscheli collected in New Zealand coastal waters, and it already shows promising anti-cancer activity. Two other potent bioactive compounds with different modes of action but isolated from the same sponge, mycalamide A and pateamine, will also be discussed. The fourth compound, zampanolide, most recently isolated from the Tongan sponge Cacospongia mycofijiensis, has only recently been added to the microtubule-stabilizing group of compounds, and further work is in progress to determine its activity profile relative to peloruside A and other drugs of this class

The Carpathian Euroregion as an example of the oldest plane for regional cooperation in Central Europe

Tematem pracy jest Euroregion Karpaty jako przykład najstarszej płaszczyzny współpracy regionalnej w Europie Środkowej. Rozwój obszarów przygranicznych oraz ich wzajemna, ścisła współpraca odgrywa kluczową rolę dla kształtowania się harmonijnego rozwoju społeczno-gospodarczego regionów, stając się jednocześnie płaszczyzną dla pogłębiania współpracy pomiędzy sąsiednimi krajami.The subject of the work is the Carpathian Euroregion as an example of the oldest plane of regional cooperation in Central Europe. The development of border areas and their mutual, close cooperation plays a key role in shaping the harmonious socio-economic development of regions, at the same time becoming a platform for deepening cooperation between neighboring countries

Pharmaceutical characterization of solid and dispersed carbon nanotubes as nanoexcipients

Marina V Ivanova1, Constanze Lamprecht1, M Jimena Loureiro1, J Torin Huzil1,2, Marianna Foldvari11School of Pharmacy, 2Faculty of Applied Mathematics, University of Waterloo, Waterloo, ON, CanadaBackground: Carbon nanotubes (CNTs) are novel materials with considerable potential in many areas related to nanomedicine. However, a major limitation in the development of CNT-based therapeutic nanomaterials is a lack of reliable and reproducible data describing their chemical and structural composition. Knowledge of properties including purity, structural quality, dispersion state, and concentration are essential before CNTs see widespread use in in vitro and in vivo experiments. In this work, we describe the characterization of several commercially available and two in-house-produced CNT samples and discuss the physicochemical profiles that will support their use in nanomedicine.Methods: Eighteen single-walled and multi-walled CNT raw materials were characterized using established analytical techniques. Solid CNT powders were analyzed for purity and structural quality using thermogravimetric analysis and Raman spectroscopy. Extinction coefficients for each CNT sample were determined by ultraviolet-visible near infrared absorption spectroscopy. Standard curves for each CNT sample were generated in the 0&amp;ndash;5 &amp;micro;g/mL concentration range for dispersions prepared in 1,2-dichlorobenzene.Results: Raman spectroscopy and thermogravimetric analysis results demonstrated that CNT purity and overall quality differed substantially between samples and manufacturer sources, and were not always in agreement with purity levels claimed by suppliers. Absorbance values for individual dispersions were found to have significant variation between individual single-walled CNTs and multi-walled CNTs and sources supplying the same type of CNT. Significant differences (P &amp;lt; 0.01) in extinction coefficients were observed between and within single-walled CNTs (24.9&amp;ndash;53.1 mL&amp;bull;cm-1&amp;bull;mg-1) and multi-walled CNTs (49.0&amp;ndash;68.3 mL&amp;bull;cm-1&amp;bull;mg-1). The results described here suggest a considerable role for impurities and structural inhomogeneities within individual CNT preparations and the resulting spectroscopic properties of their dispersions.Conclusion: Raw CNT materials require thorough analytical workup before they can be used as nanoexcipients. This applies especially to the determination of CNT purity, structure, and concentration. The results presented here clearly demonstrate that extinction coefficients must be determined for individual CNT preparations prior to their use.Keywords: carbon nanotubes, pharmaceutical characterization, Raman spectroscopy, thermogravimetric analysis, ultraviolet-visible near infrared spectroscop

Discovery and Characterization of the Laulimalide-Microtubule Binding Mode by Mass Shift Perturbation Mapping

SummaryConventional approaches to site mapping have so far failed to identify the laulimalide binding site on microtubules. Using mass shift perturbation analysis and data-directed docking, we demonstrate that laulimalide binds to the exterior of the microtubule on β-tubulin, in a region previously unknown to support ligand binding and well removed from the paclitaxel site. Shift maps for docetaxel and laulimalide are otherwise identical, indicating a common state of microtubule stability induced by occupancy of the distinct sites. The preferred binding mode highlights the penetration of the laulimalide side chain into a deep, narrow cavity through a unique conformation not strongly populated in solution, akin to a “striking cobra.” This mode supports the development of a pharmacophore model and reveals the importance of the C1–C15 axis in the macrocycle