Double blockade of cell cycle at g(1)-s transition and m phase by 3-iodoacetamido benzoyl ethyl ester, a new type of tubulin ligand.
3-Iodoacetamido benzoyl ethyl ester (3-IAABE) is a new compound synthesized in our laboratory. The primary action of 3-IAABE is to inhibit microtubule assembly by interacting with -SH groups on tubulin. In contrast to other known microtubule disrupters, 3-IAABE caused a double blockade in the cell cycle at G(1)-S transition and in M phase. The blockade was determined by cell cycle analysis and chromosome distribution. Kinase activities of cyclin E and cyclin-dependent kinase 2 responsible for the G(1)-S transition were increased, as were the activities of mitotic cyclin B and cdc2. 3-IAABE treatment also increased p53 expression and dephosphorylated (or activated) retinoblastoma protein. Investigation of the signal transduction pathway showed that 3-IAABE induced bcl-2 phosphorylation, followed by activation of caspase-9, -3, and -6, but not caspase-8. DNA fragmentation factor and poly(ADP-ribose) polymerase, the downstream substrates of caspase-3 and -6, were cleaved after 3 h of exposure to 3-IAABE, followed by DNA fragmentation. Pretreatment of the cells with inhibitors of caspase-9, -3, or -6, respectively, inhibited the cleavage of DNA fragmentation factor and poly(ADP-ribose) polymerase and thus inhibited the onset of apoptosis. 3-IAABE showed antitumor activities in the panel of 60 National Cancer Institute human tumor cell lines with total growth inhibition in the range of 0.22-4.3 micro M for solid tumor lines and 0.025-0.22 micro M for leukemia/lymphoma cell lines. The 3-IAABU total growth inhibition of phytohemagglutinin-stimulated healthy human lymphocytes was 450-fold greater than that of leukemic cells. 3-IAABE significantly inhibited the growth of human hepatocarcinoma (BEL-7402) in nude mice by 72% in tumor volume, more strongly than did vincristine (43 percent inhibition). Besides being a novel lead for the design of new anticancer tubulin ligands, the activity of 3-IAABE in the cell cycle may also help us to understand the molecular pharmacology of microtubule-active drugs.
Jiang
Jian-Dong
JD
Division of Medical Oncology, Mount Sinai School of Medicine-New York University, New York 10029, USA.
Denner
Larry
L
Ling
Yi-He
YH
Li
Jian-Nong
JN
Davis
Ashley
A
Wang
Yue
Y
Li
Yan
Y
Roboz
Julia
J
Wang
Long-Gui
LG
Perez-Soler
Roman
R
Marcelli
Marco
M
Bekesi
George
G
Holland
James F
JF
D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy / Q000473:pathology; D002453:Cell Cycle / Q000187:drug effects*; D004354:Drug Screening Assays, Antitumor; D006801:Humans; D007460:Iodoacetamide / Q000031:analogs & derivatives / Q000494:pharmacology*; D008024:Ligands; D008113:Liver Neoplasms / Q000188:drug therapy / Q000473:pathology; D008297:Male; D051379:Mice; D008819:Mice, Nude; D008870:Microtubules / Q000187:drug effects; D010766:Phosphorylation / Q000187:drug effects; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D014404:Tubulin / Q000378:metabolism; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000096:biosynthesis; D020298:U937 Cells / Q000187:drug effects; D014750:Vincristine / Q000494:pharmacology; D023041:Xenograft Model Antitumor Assays
C468871:3-iodoacetamido benzoyl ethyl ester; D000970:Antineoplastic Agents; D008024:Ligands; D019253:Proto-Oncogene Proteins c-bcl-2; D014404:Tubulin; D016159:Tumor Suppressor Protein p53; D014750:Vincristine; D007460:Iodoacetamide