Optimization of taxane binding to microtubules: binding affinity dissection and incremental construction of a high-affinity analog of paclitaxel.

The microtubule binding affinities of a series of synthetic taxanes have been measured with the aims of dissecting individual group contributions and obtaining a rationale for the design of novel compounds with the ability to overcome drug resistance. As previously observed for epothilones, the positive and negative contributions of the different substituents to the binding free energies are cumulative. By combining the most favorable substitutions we increased the binding affinity of paclitaxel 500-fold. Insight into the structural basis for this improvement was gained with molecular modeling and NMR data obtained for microtubule-bound docetaxel. Taxanes with affinities for microtubules well above their affinities for P-glycoprotein are shown not to be affected by multidrug resistance. This finding strongly indicates that optimization of the ligand-target interaction is a good strategy to overcome multidrug resistance mediated by efflux pumps.

[1]  J. Snyder,et al.  The binding conformation of Taxol in β-tubulin: A model based on electron crystallographic density , 2001, Proceedings of the National Academy of Sciences of the United States of America.

[2]  E. Nogales,et al.  Refined structure of alpha beta-tubulin at 3.5 A resolution. , 2001, Journal of molecular biology.

[3]  D. Kingston,et al.  Taxoids: cancer-fighting compounds from nature. , 2007, Current opinion in drug discovery & development.

[4]  J. Manfredi,et al.  Taxol binds to cellular microtubules , 1982, The Journal of cell biology.

[5]  P. Kollman,et al.  A Second Generation Force Field for the Simulation of Proteins, Nucleic Acids, and Organic Molecules , 1995 .

[6]  P. Kollman,et al.  A Second Generation Force Field for the Simulation of Proteins, Nucleic Acids, and Organic Molecules J. Am. Chem. Soc. 1995, 117, 5179−5197 , 1996 .

[7]  G. Georg,et al.  Hydrophobic collapse of taxol and taxotere solution conformations in mixtures of water and organic solvent , 1993 .

[8]  B. Mitchell,et al.  Transcriptional regulation of the c-myc protooncogene by 1,25-dihydroxyvitamin D3 in HL-60 promyelocytic leukemia cells. , 1987, The Journal of biological chemistry.

[9]  I. Barasoain,et al.  Inhibition of microtubules and cell cycle arrest by a new 1-deaza-7,8-dihydropteridine antitumor drug, CI 980, and by its chiral isomer, NSC 613863. , 1994, Cancer research.

[10]  D. Agard,et al.  Insights into microtubule nucleation from the crystal structure of human gamma-tubulin. , 2005, Nature.

[11]  Lenwood S. Heath,et al.  H++: a server for estimating pKas and adding missing hydrogens to macromolecules , 2005, Nucleic Acids Res..

[12]  L. Ratner,et al.  Multidrug resistance transporters and modulation , 2000, Current opinion in oncology.

[13]  J. Díaz,et al.  Characterizing ligand-microtubule binding by competition methods. , 2007, Methods in molecular medicine.

[14]  J. Snyder,et al.  Synthesis, biological evaluations, and tubulin binding poses of C-2alpha sulfur linked taxol analogues. , 2007, Bioorganic & Medicinal Chemistry Letters.

[15]  P. Giannakakou,et al.  Synthesis and biological evaluation of 2-acyl analogues of paclitaxel (Taxol). , 1998, Journal of medicinal chemistry.

[16]  A. Ritzén,et al.  Interaction of epothilone analogs with the paclitaxel binding site: relationship between binding affinity, microtubule stabilization, and cytotoxicity. , 2004, Chemistry & biology.

[17]  Jianmei Wei,et al.  Taxol structure-activity relationships: Synthesis and biological evaluation of 2-deoxytaxol , 1993 .

[18]  P. Vrignaud,et al.  Synthesis and structure-activity relationships of new antitumor taxoids. Effects of cyclohexyl substitution at the C-3' and/or C-2 of taxotere (docetaxel). , 1994, Journal of medicinal chemistry.

[19]  S. Kuduk,et al.  Synthesis and Structure−Activity Relationships of Nonaromatic Taxoids: Effects of Alkyl and Alkenyl Ester Groups on Cytotoxicity , 1997 .

[20]  J. A. Shabbits,et al.  Molecular and pharmacological strategies to overcome multidrug resistance , 2001, Expert review of anticancer therapy.

[21]  C. Geroni,et al.  Isolation and characterization of a human colon adenocarcinoma cell line resistant to doxorubicin. , 1986, British Journal of Cancer.

[22]  Y. Engelborghs,et al.  Molecular Recognition of Taxol by Microtubules , 2000, The Journal of Biological Chemistry.

[23]  David S. Goodsell,et al.  Automated docking using a Lamarckian genetic algorithm and an empirical binding free energy function , 1998, J. Comput. Chem..

[24]  Qi Gao,et al.  An unprecedented side chain conformation of paclitaxel (Taxol®): Crystal structure of 7-Mesylpaclitaxel , 1996 .

[25]  I. Barasoain,et al.  Overcoming Tumor Drug Resistance with High‐Affinity Taxanes: A SAR Study of C2‐Modified 7‐Acyl‐10‐Deacetyl Cephalomannines , 2007, ChemMedChem.

[26]  D. Agard,et al.  Insights into microtubule nucleation from the crystal structure of human γ-tubulin , 2005, Nature.

[27]  K. Nicolaou,et al.  Chemical Synthesis and Biological Evaluation of C-2 Taxoids , 1995 .

[28]  H. Minderman,et al.  Taxane-based reversal agents modulate drug resistance mediated by P-glycoprotein, multidrug resistance protein, and breast cancer resistance protein. , 2003, Molecular cancer therapeutics.

[29]  I. Barasoain,et al.  Fast Kinetics of Taxol Binding to Microtubules , 2003, The Journal of Biological Chemistry.

[30]  I. Barasoain,et al.  Cyclostreptin binds covalently to microtubule pores and lumenal taxoid binding sites. , 2007, Nature chemical biology.

[31]  Jesús Jiménez-Barbero,et al.  NMR determination of the bioactive conformation of peloruside A bound to microtubules. , 2006, Journal of the American Chemical Society.

[32]  J. Díaz,et al.  Assembly of purified GDP-tubulin into microtubules induced by taxol and taxotere: reversibility, ligand stoichiometry, and competition. , 1993, Biochemistry.

[33]  N. Zefirov,et al.  Taxol: Synthesis, Bioactive Conformations, and Structure-Activity Relationships in Its Analogs , 2005 .

[34]  R. Ozols,et al.  Reversal of adriamycin resistance by verapamil in human ovarian cancer. , 1984, Science.

[35]  K. Nicolaou,et al.  Synthesis of C-2 taxol analogues , 1994 .

[36]  M Pastor,et al.  Comparative binding energy analysis of HIV-1 protease inhibitors: incorporation of solvent effects and validation as a powerful tool in receptor-based drug design. , 1998, Journal of medicinal chemistry.

[37]  I. Barasoain,et al.  Microtubule interactions with chemically diverse stabilizing agents: thermodynamics of binding to the paclitaxel site predicts cytotoxicity. , 2005, Chemistry & biology.