PT  - JOURNAL ARTICLE
AU  - Brianne S. Raccor
AU  - Andreas Vogt
AU  - Rachel P. Sikorski
AU  - Charitha Madiraju
AU  - Raghavan Balachandran
AU  - Kia Montgomery
AU  - Youseung Shin
AU  - Yoshikazu Fukui
AU  - Won-Hyuk Jung
AU  - Dennis P. Curran
AU  - Billy W. Day
TI  - Cell-Based and Biochemical Structure-Activity Analyses of Analogs of the Microtubule Stabilizer Dictyostatin
AID  - 10.1124/mol.107.042598
DP  - 2008 Mar 01
TA  - Molecular Pharmacology
PG  - 718--726
VI  - 73
IP  - 3
4099  - http://molpharm.aspetjournals.org/content/73/3/718.short
4100  - http://molpharm.aspetjournals.org/content/73/3/718.full
SO  - Mol Pharmacol2008 Mar 01; 73
AB  - Compounds that bind to microtubules (MTs) and alter their dynamics are highly sought as a result of the clinical success of paclitaxel and docetaxel. The naturally occurring compound (-)-dictyostatin binds to MTs, causes cell cycle arrest in G2/M at nanomolar concentrations, and retains antiproliferative activity in paclitaxel-resistant cell lines, making dictyostatin an attractive candidate for development as an antineoplastic agent. In this study, we examined a series of dictyostatin analogs to probe biological and biochemical structure-activity relationships. We used a high-content multiparameter fluorescence-based cellular assay for MT morphology, chromatin condensation, mitotic arrest, and cellular toxicity to identify regions of dictyostatin that were essential for biological activity. Four analogs (6-epi-dictyostatin, 7-epi-dictyostatin, 16-normethyldictyostatin, and 15Z,16-normethyldictyostatin) retained low nanomolar activity in the cell-based assay and were chosen for analyses with isolated tubulin. All four compounds were potent inducers of MT assembly. Equilibrium binding constant (Ki) determinations using [14C]epothilone B, which has a 3-fold higher affinity for the taxoid binding site than paclitaxel, indicated that 6-epi-dictyostatin and 7-epi-dictyostatin displaced [14C]epothilone B with Ki values of 480 and 930 nM, respectively. 16-Normethyldictyostatin and 15Z,16-normethyldictyostatin had reduced affinity (Ki values of 4.55 and 4.47 μM, respectively), consistent with previous reports showing that C16-normethyldictyostatin loses potency in paclitaxel-resistant cell lines that have a Phe270-to-Val mutation in the taxoid binding site of β-tubulin. Finally, we developed a set of quantitative structure-activity relationship equations correlating structures with antiproliferative activity. The equations accurately predicted biological activity and will help in the design of future analogs. The American Society for Pharmacology and Experimental Therapeutics