Lexibulin (CYT997)

For research use only.

Catalog No.S2195 Synonyms: SRI-32007

8 publications

Lexibulin (CYT997) Chemical Structure

CAS No. 917111-44-5

Lexibulin (CYT997, SRI-32007) is a potent microtubule polymerization inhibitor with IC50 of 10-100 nM in cancer cell lines. Phase 2.

Selleck's Lexibulin (CYT997) has been cited by 8 publications

4 Customer Reviews

  • CYT997 inhibits cellular proliferation in acute myeloid leukemia (AML) cell lines. Cell viability was measured by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay in 96-well plates in the presence of increasing concentrations of CYT997 for 24 h.The results represent the mean ?SD of four replicates.

    Exp Ther Med 2013 6(2), 299-304. Lexibulin (CYT997) purchased from Selleck.

    CYT997 induces apoptosis in acute myeloid leukemia (AML) cell lines. HL-60 cells were treated with CYT997 (0, 50, 100, and 200 nM) for 24 h, resuspended in propidium iodide (PI)-containing hypotonic buffer, and then the percentage of apoptotic cells was analyzed by flow cytometry.

    Exp Ther Med 2013 6(2), 299-304. Lexibulin (CYT997) purchased from Selleck.

  • Activation of caspases by CYT997. (A) Immunoblotting analysis for caspase-9, -8 and -3 and poly ADP-ribose polymerase (PARP), was performed in lysates of HL-60 cells treated with CYT997 (0, 50, 100 or 200 nM) for 24 h. (B) Annexin V-propidium iodide (PI) staining was performed to quantify phospha- tidylserine externalization in HL-60 cells treated with CYT997 (200 nM) or untreated for 24 h, in the presence or absence of the caspase-8 inhibitor. * P<0.05.

    Exp Ther Med 2013 6(2), 299-304. Lexibulin (CYT997) purchased from Selleck.

    Effects of CYT997 on the cell cycle. HL-60 cells were treated with CT997 (0, 50, 100 or 200 nM) for 24 h. The cell cycle was analyzed using propidium iodide (PI) staining followed by flow cytometry analysis.

    Exp Ther Med 2013 6(2), 299-304. Lexibulin (CYT997) purchased from Selleck.

Purity & Quality Control

Choose Selective Microtubule Associated Inhibitors

Biological Activity

Description Lexibulin (CYT997, SRI-32007) is a potent microtubule polymerization inhibitor with IC50 of 10-100 nM in cancer cell lines. Phase 2.
Microtubules (cancer cell lines) [1]
10 nM-100 nM
In vitro

CYT997 (1 μM) treatment for 24 hours in A549 cells induces rapid reorganization of microtubules including the destruction of the existing microtubule network and accumulation of tubulin in plaques within the cytoplasm of some cells, leading to significant cell morphology alterations including the loss of adhesion and cell rounding. CYT997 displays potent cytotoxic activity against a range of 16 cancer cells with IC50 ranging from 9 nM for HepG2 to 101 nM for KHOS/NP. Especially, CYT997 exhibits potent activity against HCT15 cells, known to possess the multidrug resistance mechanism Pgp (MDR+), with IC50 of 52 nM. Through inhibition of microtubule polymerization, CYT997 blocks the cell cycle at the G2-M boundary, and induces an increase in phosphorylated Bcl-2 and increased expression of cyclin B1, as well as caspase-3 activation and the generation of poly (ADP-ribose) polymerase. CYT997 treatment causes a rapid and reversible increase in the permeability of HUVEC monolayers with IC50 of ~80 nM at 1 hour of exposure. [1] Consistent with the disruption of cellular tubulin, CYT997 potently inhibits proliferation, induces cell cycle arrest and most importantly apoptosis of both human myeloma cell lines (HMCLs) and primary MM cells. [2]

In vivo The half-life of CYT997 for oral administration (2.5 hours) to rats is slightly longer than that for intravenous administration (1.5 hours), with the absolute oral bioavailability being 50% to 70%. Oral administration of CYT997 induces dose-dependent inhibition of tumor growth of PC3 xenografts in mice, more potently compared with paclitaxel. CYT997 is also effective in an orthotopic syngeneic model using the mouse breast cancer 4T1 cells, which are some refractory to Paclitaxel treatment. A single dose of CYT997 (7.5 mg/kg, i.p.) reduces tumor blood flow significantly at 6 hours in liver metastases, to a similar extent as the positive control CA4P dosed at 100 mg/kg. [1] CYT997 treatment (15 mg/kg/day) significantly prolongs the survival in a murine model of aggressive systemic myelomatosis. [2]


Kinase Assay:[1]
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Turbidimetric assay for tubulin polymerization:

The effect of CYT997 on microtubule polymerization is determined using conventional turbidimetric assay using bovine neuronal tubulin in which the assembly of microtubules is monitored by an increase in absorbance at 340 nm. Increasing concentrations of CYT997 is added to 100 μL of tubulin/GTP/glycerol. Turbidimetric assays of microtubule assembly is done by incubating bovine microtubule protein in cuvettes at 37 °C in a thermostatically controlled spectrophotometer measuring the change in absorbance at 340 nm over time in PEM buffer [80 nM PIPES (pH 6.9), 2 mM MgCl2, 0.5 mM EGTA, and 5% glycerol].
Cell Research:[1]
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  • Cell lines: DU145, A549, Ramos, KHOS/NP, A375, HCT-15, HT1376, BT-20, A431, PA-1, U937, HepG2, TF-1, Baf3/TelJAK2, PC3, and K562
  • Concentrations: Dissolved in DMSO, final concentrations ~1 μM
  • Incubation Time: ~72 hours
  • Method: Cells are exposed to various concentrations of CYT997 for ~72 hours. Cell proliferation is assessed with either the Alamar blue or MTT assays. For MTT assays, 5 mg/mL of MTT is added to all wells, plates are incubated for 6 hours at 37 °C, and then lysis buffer is added (10% SDS in 0.01 N HCl) and absorbance is measured at 620 nm in a BMG Technologies Lumistar or Polarstar plate reader. For Alamar blue assays, Alamar blue (10 μL/well) is added to each well and the plates are incubated at 37 °C for 4 hours. The fluorescence is then measured using a fluorescence plate reader with an excitation filter at 544 nm and an emission filter at 590 nm. For cell cycle analysis, cells are fixed and permeabilized with 70% ethanol in PBS and incubated at 4 °C overnight. RNase-treated samples (10 μg RNase/mL for 20 minutes at 37 °C) are stained with propidium iodide (5 μg/mL) at 4 °C for a minimum of 10 minutes. Cell cycle variables are determined by fluorescence-activated cell sorting (FACS) analysis using a Beckman-Coulter Quanta SC MPL system and analyzed using CXP Software. For apoptosis analysis, cells are detached and collected. Annexin staining is done using the Vybrant Apoptosis Assay Kit. Cells are stored on ice and analyzed on a Beckman Coulter Quanta MPL within 1 hour of preparation. Annexin V–positive cells are determined using two-channel analysis.
    (Only for Reference)
Animal Research:[1]
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  • Animal Models: Male nude mice inoculated s.c. with PC3 cells, and female BALB/c mice inoculated with 4T1 cells
  • Dosages: ~30 mg/kg/day
  • Administration: Oral gavage thrice a day
    (Only for Reference)

Solubility (25°C)

In vitro DMSO 86 mg/mL (197.91 mM)
Ethanol 20 mg/mL (46.02 mM)
Water Insoluble

* Please note that Selleck tests the solubility of all compounds in-house, and the actual solubility may differ slightly from published values. This is normal and is due to slight batch-to-batch variations.

Chemical Information

Molecular Weight 434.53


CAS No. 917111-44-5
Storage powder
in solvent
Synonyms SRI-32007

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Clinical Trial Information

NCT Number Recruitment interventions Conditions Sponsor/Collaborators Start Date Phases
NCT00650949 Terminated Drug: CYT997|Drug: Carboplatin Glioblastoma Multiforme Gilead Sciences November 2009 Phase 1|Phase 2
NCT00664378 Terminated Drug: CYT997 Relapsed and Refractory Multiple Myeloma Gilead Sciences January 2008 Phase 2

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Microtubule Associated Signaling Pathway Map

Related Microtubule Associated Products

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Cell Lines Assay Type Concentration Incubation Time Formulation Activity Description PMID