Interaction of a new bis-indol derivative, KAR-2 with tubulin and its antimitotic activity.
1. KAR-2 (3"-(beta-chloroethyl)-2",4"-dioxo-3,5"-spiro-oxazolidino- 4-deacetoxy-vinblastine), is a bis-indol derivative; catharantine is coupled with the vindoline moiety which contains a substituted oxazolidino group. Our binding studies showed that KAR-2 exhibited high affinity for bovine purified brain tubulin (Kd-3 microM) and it inhibited microtubule assembly at a concentration of 10 nM. 2. Anti-microtubular activity of KAR-2 was highly dependent on the ultrastructure of microtubules: while the single tubules were sensitive, the tubules cross-linked by phosphofructokinase (ATP: D-fructose-6-phosphate-1-phosphotransferase, EC 2.7.1.11) exhibited significant resistance against KAR-2. 3. The cytoplasmic microtubules of Chinese hamster ovary mammalian and Sf9 insect cells were damaged by 1 microgram ml-1 KAR-2, as observed by indirect immunofluorescence and transmission electron microscopy. Scanning electron microscopy revealed intensive surface blebbing on both types of cells in the presence of KAR-2. 4. KAR-2 was effective in the mouse leukaemia P338 test in vivo without significant toxicity. Studies on a primary cerebro-cortical culture of rat brain and differentiated PC12 cells indicated that the toxicity of KAR-2 was significantly lower than that of vinblastine. The additional property of KAR-2 that distinguishes it from bis-indol derivatives is the lack of anti-calmodulin activity.
Orosz
F
F
Institute of Enzymology, Hungarian Academy of Sciences, Budapest, Hungary.
Kovács
J
J
Löw
P
P
Vértessy
B G
BG
Urbányi
Z
Z
Acs
T
T
Keve
T
T
Ovádi
J
J
D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D016466:CHO Cells; D002147:Calmodulin / Q000037:antagonists & inhibitors; D002417:Cattle; D006224:Cricetinae; D004354:Drug Screening Assays, Antitumor; D007150:Immunohistochemistry; D007313:Insecta; D007941:Leukemia P388 / Q000188:drug therapy; D051379:Mice; D008854:Microscopy, Electron; D011485:Protein Binding; D051381:Rats; D014404:Tubulin / Q000187:drug effects* / Q000648:ultrastructure; D014407:Tumor Cells, Cultured; D014747:Vinblastine / Q000031:analogs & derivatives* / Q000494:pharmacology; D014750:Vincristine / Q000494:pharmacology
D000972:Antineoplastic Agents, Phytogenic; D002147:Calmodulin; D014404:Tubulin; D014750:Vincristine; D014747:Vinblastine; C107832:deacetoxyvinzolidine