Microtubule is one of the key components of the cytoskeleton and plays an important role in the maintenance of cell shape and the process of signal transduction and mitosis. Due to the extreme importance of microtubule in the process of mitosis, tubulin becomes one of the most important targets for development of new anticancer drugs and tubulin inhibitors are used for the treatment of cancer nowadays. These inhibitors have antitumor activity by inhibiting or promoting the assembly of tubulin to microtubules and interfering the process of cell mitosis. This review summarized the research progress of the tubulin inhibitors, especially the introduction of the tubulin inhibitors of pharmacological activities and the progress of clinical research. Also, the development trend of these inhibitors is discussed.
Antineoplastic Agents ; chemical synthesis ; chemistry ; pharmacology ; Humans ; Microtubules ; drug effects ; metabolism ; Mitosis ; drug effects ; Molecular Structure ; Neoplasms ; drug therapy ; Stilbenes ; chemical synthesis ; chemistry ; pharmacology ; Structure-Activity Relationship ; Tubulin ; metabolism ; Tubulin Modulators ; chemical synthesis ; chemistry ; pharmacology

Amino Acids ; isolation & purification ; Animals ; Antineoplastic Agents, Phytogenic ; pharmacology ; Binding Sites ; Colchicine ; pharmacology ; Humans ; Microtubules ; drug effects ; physiology ; Paclitaxel ; pharmacology ; Tubulin ; chemistry ; isolation & purification ; metabolism ; Vinblastine ; pharmacology

New colchicine analogs have been synthesized with the aim of developing stronger potential anticancer activities. Among the analogs, CT20126 has been previously reported to show immunosuppressive activities. Here, we report that CT20126 also shows potential anticancer effects via an unusual mechanism: the modulation of microtubule integrity and cell cycle arrest at the G2/M phase before apoptosis. When we treated COS-7 cells with CT20126 (5 muM), the normal thread-like microtubules were disrupted into tubulin dimers within 10 min and thereafter repolymerized into short, thick filaments. In contrast, cells treated with the same concentration of colchicine exhibited microtubule depolymerization after 20 min and never underwent repolymerization. Furthermore, optical density (OD) analysis (350 nm) with purified tubulin showed that CT20126 had a higher repolymerizing activity than that of Taxol, a potent microtubule-polymerizing agent. These results suggest that the effects of CT20126 on microtubule integrity differ from those of colchicine: the analog first destabilizes microtubules and then stabilizes the disrupted tubulins into short, thick polymers. Furthermore, CT20126 induced a greater level of apoptotic activity in Jurkat T cells than colchicine (assessed by G2/M arrest, caspase-3 activation and cell sorting). At 20 nM, CT20126 induced 47% apoptosis among Jurkat T cells, whereas colchicine induced only 33% apoptosis. Our results suggest that the colchicine analog CT20126 can potently induce apoptosis by disrupting microtubule integrity in a manner that differs from that of colchicine or Taxol.
Acetylation/drug effects ; Animals ; Apoptosis/*drug effects ; COS Cells ; Caspase 3/metabolism ; Cattle ; Cell Division/drug effects ; Cercopithecus aethiops ; Colchicine/*analogs & derivatives/chemistry/pharmacology ; Enzyme Activation/drug effects ; G2 Phase/drug effects ; Humans ; Jurkat Cells ; Microtubules/*metabolism ; Poly(ADP-ribose) Polymerases/metabolism ; Tubulin/metabolism ; Tubulin Modulators/chemistry/*pharmacology

Resveratrol has been reported to possess cancer preventive properties. In this study, we analyzed anti-tumor activity of a newly synthesized resveratrol analog, cis-3,4',5-trimethoxy-3'-hydroxystilbene (hereafter called 11b) towards breast and pancreatic cancer cell lines. 11b treatments reduced the proliferation of human pancreatic and breast cancer cells, arrested cells in the G2/M phase, and increased the percentage of cells in the subG1/G0 fraction. The 11b treatments also increased the total levels of mitotic checkpoint proteins such as BubR1, Aurora B, Cyclin B, and phosphorylated histone H3. Mechanistically, 11b blocks microtubule polymerization in vitro and it disturbed microtubule networks in both pancreatic and breast cancer cell lines. Computational modeling of the 11b-tubulin interaction indicates that the dimethoxyphenyl group of 11b can bind to the colchicine binding site of tubulin. Our studies show that the 11b treatment effects occur at lower concentrations than similar effects associated with resveratrol treatments and that microtubules may be the primary target for the observed effects of 11b. These studies suggest that 11b should be further examined as a potentially potent clinical chemotherapeutic agent for treating pancreatic and breast cancer patients.
Antineoplastic Agents/*pharmacology ; Binding Sites ; Breast Neoplasms ; Cell Cycle/drug effects ; Cell Line, Tumor ; Cell Proliferation/*drug effects ; Colchicine/chemistry/pharmacology ; Cyclin B/metabolism ; G2 Phase/drug effects ; Humans ; Microtubules/drug effects/metabolism ; Models, Molecular ; Pancreatic Neoplasms ; Protein-Serine-Threonine Kinases/metabolism ; Stilbenes/*pharmacology ; Tubulin/metabolism

Phosphoinositide-specific phospholipase C-gamma1 (PLC-gamma1) has two pleckstrin homology (PH) domains: an amino-terminal domain (PH1) and a split PH domain (PH2). Here, we show that overlay assay of bovine brain tubulin pool with glutathione-S-transferase (GST)-PLC-gamma1 PH domain fusion proteins, followed by matrix-assisted laser-desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), identified 68-kDa neurofilament light chain (NF-L) as a binding protein of amino-terminal PH domain of PLC-gamma1. NF-L is known as a component of neuronal intermediate filaments, which are responsible for supporting the structure of myelinated axons in neuron. PLC-gamma1 and NF-L colocalized in the neurite in PC12 cells upon nerve growth factor stimulation. In vitro binding assay and immunoprecipitation analysis also showed a specific interaction of both proteins in differentiated PC12 cells. The phosphatidylinositol 4, 5-bisphosphate [PI(4,5)P2] hydrolyzing activity of PLC-gamma1 was slightly decreased in the presence of purified NF-L in vitro, suggesting that NF-L inhibits PLC-gamma1. Our results suggest that PLC-gamma1-associated NF-L sequesters the phospholipid from the PH domain of PLC-gamma1.
Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization ; Rats ; Protein Interaction Mapping ; Protein Biosynthesis/drug effects ; Protein Binding/drug effects ; Phosphoproteins/chemistry/*metabolism ; Phospholipase C gamma/antagonists & inhibitors/chemistry/*metabolism ; Phosphatidylinositol 4,5-Diphosphate/metabolism ; Peptides/chemistry/metabolism ; PC12 Cells ; Neurofilament Proteins/chemistry/*metabolism ; Nerve Growth Factor/pharmacology ; Molecular Weight ; Molecular Sequence Data ; Microtubules/metabolism ; Microscopy, Fluorescence ; Isoenzymes/metabolism/pharmacology/physiology ; Glutathione Transferase/metabolism ; Blotting, Far-Western ; Blood Proteins/chemistry/*metabolism ; Binding Sites ; Animals ; Amino Acid Sequence

Paclitaxel is a microtubule-targeting agent widely used for the treatment of many solid tumors. However, patients show variable sensitivity to this drug, and effective diagnostic tests predicting drug sensitivity remain to be investigated. Herein, we show that the expression of end-binding protein 1 (EB1), a regulator of microtubule dynamics involved in multiple cellular activities, in breast tumor tissues correlates with the pathological response of tumors to paclitaxel-based chemotherapy. In vitro cell proliferation assays reveal that EB1 stimulates paclitaxel sensitivity in breast cancer cell lines. Our data further demonstrate that EB1 increases the activity of paclitaxel to cause mitotic arrest and apoptosis in cancer cells. In addition, microtubule binding affinity analysis and polymerization/depolymerization assays show that EB1 enhances paclitaxel binding to microtubules and stimulates the ability of paclitaxel to promote microtubule assembly and stabilization. These findings thus reveal EB1 as a critical regulator of paclitaxel sensitivity and have important implications in breast cancer chemotherapy.
Antineoplastic Agents, Phytogenic ; pharmacology ; therapeutic use ; Apoptosis ; drug effects ; Breast Neoplasms ; drug therapy ; metabolism ; pathology ; Cell Cycle Checkpoints ; drug effects ; Cell Line, Tumor ; Female ; Humans ; MCF-7 Cells ; Microtubule-Associated Proteins ; antagonists & inhibitors ; genetics ; metabolism ; Microtubules ; chemistry ; metabolism ; Paclitaxel ; pharmacology ; therapeutic use ; RNA Interference ; RNA, Small Interfering ; metabolism

The massive reorganization of microtubule network involves in transcriptional regulation of several genes by controlling transcriptional factor, nuclear factor-kappa B (NF-kappaB) activity. The exact molecular mechanism by which microtubule rearrangement leads to NF-kappaB activation largely remains to be identified. However microtubule disrupting agents may possibly act in synergy or antagonism against apoptotic cell death in response to conventional chemotherapy targeting DNA damage such as adriamycin or comptothecin in cancer cells. Interestingly pretreatment of microtubule disrupting agents (colchicine, vinblastine and nocodazole) was observed to lead to paradoxical suppression of DNA damage-induced NF-kappaB binding activity, even though these could enhance NF-kappaB signaling in the absence of other stimuli. Moreover this suppressed NF-kappaB binding activity subsequently resulted in synergic apoptotic response, as evident by the combination with Adr and low doses of microtubule disrupting agents was able to potentiate the cytotoxic action through caspase-dependent pathway. Taken together, these results suggested that inhibition of microtubule network chemosensitizes the cancer cells to die by apoptosis through suppressing NF-kappaB DNA binding activity. Therefore, our study provided a possible anti-cancer mechanism of microtubule disrupting agent to overcome resistance against to chemotherapy such as DNA damaging agent.
Animals ; Antibiotics, Antineoplastic/therapeutic use ; *Apoptosis ; Caspases/metabolism ; Cell Line ; Colchicine/pharmacology ; DNA/metabolism ; *DNA Damage ; Doxorubicin/therapeutic use ; Humans ; Mice ; Microtubules/chemistry/*drug effects/metabolism ; NF-kappa B/antagonists & inhibitors/*metabolism ; Neoplasms/drug therapy ; Nocodazole/pharmacology ; Protein Binding ; Signal Transduction ; Tubulin Modulators/*pharmacology ; Vinblastine/pharmacology