TY - JOUR
T1 - Identification and characterization of a new tubulin-binding tetrasubstituted brominated pyrrole
AU - Mooberry, Susan L.
AU - Weiderhold, Kimberly N.
AU - Dakshanamurthy, Sivanesan
AU - Hamel, Ernest
AU - Banner, Edith J.
AU - Kharlamova, Anastasia
AU - Hempel, Jonathan
AU - Gupton, John T.
AU - Brown, Milton L.
PY - 2007/7
Y1 - 2007/7
N2 - We studied the mechanism of action of 3,5-dibromo-4-(3,4-dimethoxyphenyl)- 1H-pyrrole-2-carboxylic acid ethyl ester (JG-03-14) and found that it is a potent microtubule depolymerizer. JG-03-14 caused a dose-dependent loss of cellular microtubules, formation of aberrant mitotic spindles, accumulation of cells in the G2/M phase of the cell cycle, and Bcl-2 phosphorylation. These events culminated in the initiation of apoptosis, as evidenced by the caspase 3-dependent cleavage of poly-(ADP-ribose) polymerase (PARP). JG-03-14 has antiproliferative activity against a wide range of cancer cell lines, with an average IC50 value of 62 nM, and it is a poor substrate for transport by P-glycoprotein. JG-03-14 inhibited the polymerization of purified tubulin in vitro, consistent with a direct interaction between the compound and tubulin. JG-03-14 potently inhibited the binding of [3H]colchicine to tubulin, suggesting that it bound to tubulin at a site overlapping the colchicine site. JG-03-14 had antitumor effects in the PC3 xenograft model, in which it caused greater than 50% reduction in tumor burden after 14 days of treatment. Molecular modeling studies indicated that the dimethoxyphenyl group of JG-03-14 occupies a space similar to that of the trimethoxyphenyl group of colchicine. However, the 2,3,5-trisubstituted pyrrole group, which is connected to the dimethoxyphenyl moiety, interacted with both α and β tubulin in space not shared with colchicine, suggesting significant differences compared with colchicine in the mechanism of binding to tubulin. Our results suggest that this tetrasubstituted pyrrole represents a new, biologically active chemotype for the colchicine site on tubulin.
AB - We studied the mechanism of action of 3,5-dibromo-4-(3,4-dimethoxyphenyl)- 1H-pyrrole-2-carboxylic acid ethyl ester (JG-03-14) and found that it is a potent microtubule depolymerizer. JG-03-14 caused a dose-dependent loss of cellular microtubules, formation of aberrant mitotic spindles, accumulation of cells in the G2/M phase of the cell cycle, and Bcl-2 phosphorylation. These events culminated in the initiation of apoptosis, as evidenced by the caspase 3-dependent cleavage of poly-(ADP-ribose) polymerase (PARP). JG-03-14 has antiproliferative activity against a wide range of cancer cell lines, with an average IC50 value of 62 nM, and it is a poor substrate for transport by P-glycoprotein. JG-03-14 inhibited the polymerization of purified tubulin in vitro, consistent with a direct interaction between the compound and tubulin. JG-03-14 potently inhibited the binding of [3H]colchicine to tubulin, suggesting that it bound to tubulin at a site overlapping the colchicine site. JG-03-14 had antitumor effects in the PC3 xenograft model, in which it caused greater than 50% reduction in tumor burden after 14 days of treatment. Molecular modeling studies indicated that the dimethoxyphenyl group of JG-03-14 occupies a space similar to that of the trimethoxyphenyl group of colchicine. However, the 2,3,5-trisubstituted pyrrole group, which is connected to the dimethoxyphenyl moiety, interacted with both α and β tubulin in space not shared with colchicine, suggesting significant differences compared with colchicine in the mechanism of binding to tubulin. Our results suggest that this tetrasubstituted pyrrole represents a new, biologically active chemotype for the colchicine site on tubulin.
UR - http://www.scopus.com/inward/record.url?scp=34347236860&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=34347236860&partnerID=8YFLogxK
U2 - 10.1124/mol.107.034876
DO - 10.1124/mol.107.034876
M3 - Article
C2 - 17456786
AN - SCOPUS:34347236860
VL - 72
SP - 132
EP - 140
JO - Molecular Pharmacology
JF - Molecular Pharmacology
SN - 0026-895X
IS - 1
ER -