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The Journal of Biological Chemistry May 2019Clinical microtubule-targeting drugs are functionally divided into microtubule-destabilizing and microtubule-stabilizing agents. Drugs from both classes achieve...
Clinical microtubule-targeting drugs are functionally divided into microtubule-destabilizing and microtubule-stabilizing agents. Drugs from both classes achieve microtubule inhibition by binding different sites on tubulin and inhibiting or promoting polymerization with no concomitant effects on the protein levels of tubulin heterodimers. Here, we have identified a series of small molecules with diverse structures potentially representing a third class of novel tubulin inhibitors that promote degradation by covalent binding to Cys-239 of β-tubulin. The small molecules highlighted in this study include T0070907 (a peroxisome proliferator-activated receptor γ inhibitor), T007-1 (a T0070907 derivative), T138067, ,'-ethylene-bis(iodoacetamide) (EBI), and allyl isothiocyanate (AITC). Label-free quantitative proteomic analysis revealed that T007-1 promotes tubulin degradation with high selectivity. Mass spectrometry findings showed covalent binding of both T0070907 and T007-01 to Cys-239 of β-tubulin. Furthermore, T007-1 exerted a degradative effect on tubulin isoforms possessing Cys-239 (β2, β4, and β5(β)) but not those containing Ser-239 (β3, β6) or mutant β-tubulin with a C239S substitution. Three small molecules (T138067, EBI, and AITC) also reported to bind covalently to Cys-239 of β-tubulin similarly induced tubulin degradation. Our results strongly suggest that covalent modification of Cys-239 of β-tubulin by small molecules could serve as a novel strategy to promote tubulin heterodimer degradation. We propose that these small molecules represent a third novel class of tubulin inhibitor agents that exert their effects through degradation activity.
Topics: Benzamides; Cysteine; HCT116 Cells; HeLa Cells; Humans; Isothiocyanates; Protein Isoforms; Protein Multimerization; Proteolysis; Pyridines; Sulfonamides; Tubulin
PubMed: 30940730
DOI: 10.1074/jbc.RA118.006325 -
Proceedings of the National Academy of... May 1999Microtubules are linear polymers of alpha- and beta-tubulin heterodimers and are the major constituents of mitotic spindles, which are essential for the separation of... (Comparative Study)
Comparative Study
Microtubules are linear polymers of alpha- and beta-tubulin heterodimers and are the major constituents of mitotic spindles, which are essential for the separation of chromosomes during mitosis. Here we describe a synthetic compound, 2-fluoro-1-methoxy-4-pentafluorophenylsulfonamidobenzene (T138067), which covalently and selectively modifies the beta1, beta2, and beta4 isotypes of beta-tubulin at a conserved cysteine residue, thereby disrupting microtubule polymerization. Cells exposed to T138067 become altered in shape, indicating a collapse of the cytoskeleton, and show an increase in chromosomal ploidy. Subsequently, these cells undergo apoptosis. Furthermore, T138067 exhibits cytotoxicity against tumor cell lines that exhibit substantial resistance to vinblastine, paclitaxel, doxorubicin, and actinomycin D. T138067 is also equally efficacious in inhibiting the growth of sensitive and multidrug-resistant human tumor xenografts in athymic nude mice. These observations suggest that T138067 may be clinically useful for the treatment of multidrug-resistant tumors.
Topics: Animals; Antineoplastic Agents; Apoptosis; Cell Cycle; Cysteine; Cytoskeleton; Drug Resistance, Multiple; Humans; Leukemia, Lymphoid; Mice; Mice, Nude; Microtubules; Molecular Structure; Neoplasm Transplantation; Paclitaxel; Protein Binding; Sulfonamides; Tubulin; Tumor Cells, Cultured; Vinblastine
PubMed: 10318945
DOI: 10.1073/pnas.96.10.5686 -
Neuro-oncology Apr 2005We studied the activity of T138067-sodium in patients with malignant gliomas. T138067-sodium is a unique new chemotherapy agent that inhibits microtubule formation by... (Clinical Trial)
Clinical Trial
We studied the activity of T138067-sodium in patients with malignant gliomas. T138067-sodium is a unique new chemotherapy agent that inhibits microtubule formation by binding irreversibly and specifically to beta(1), beta(2)and beta(4) isotypes of 3-tubulin, causing cell arrest at G(2)/M and inducing apoptosis. Patients with recurrent anaplastic astrocytoma or glioblastoma multiforme were treated intravenously with 330 mg/m(2) of T138067-sodium weekly. Treatment was continued until the patient experienced either unacceptable toxicity or progressive disease. Patients had to have histologically proven glioma, have bidimensionally measurable disease at least 1 cm x 1 cm, and have received no more than one prior adjuvant chemotherapy. No chemotherapy or radiotherapy for recurrent disease was permitted. Nineteen patients entered the trial. One patient was found to be ineligible. There were two patients with anaplastic astrocytoma and 16 with glioblastoma multiforme. Only two patients had received prior adjuvant chemotherapy. The first seven patients had full pharmacokinetic sampling. No dose-limiting toxicity was seen, and pharmacokinetic results were consistent with those from nonglioma patients. The most common drug-related effects were fatigue (33%), nausea (28%), neutropenia (28%), and anorexia (17%). No patients stopped the study because of toxicity. No responses were seen in the 15 eligible patients who completed at least one cycle. Three patients had stable disease with a median duration of 2.6 months. Our results suggest that given in this dose and schedule T138067-sodium does not have activity in this population of anaplastic astrocytoma and glioblastoma multiforme.
Topics: Adult; Aged; Antineoplastic Agents; Brain Neoplasms; Canada; Female; Glioma; Humans; Male; Middle Aged; Sulfonamides; Treatment Outcome
PubMed: 15831236
DOI: 10.1215/S1152851704000602