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IPP51, a chalcone acting as a microtubule inhibitor with in vivo antitumor activity against bladder carcinoma.

Martel-Frachet V, Keramidas M, Nurisso A, DeBonis S, Rome C, Coll JL, Boumendjel A, Skoufias DA, Ronot X - Oncotarget (2015)

Bottom Line: The antimitotic actions of other chalcones are often associated with microtubule disruption.Finally, in a human bladder xenograft mouse model, IPP51 inhibited tumor growth without signs of toxicity.Altogether, these findings suggest that IPP51 is an attractive new microtubule-targeting agent with potential chemotherapeutic value.

View Article: PubMed Central - PubMed

Affiliation: Université Joseph Fourier, AGIM CNRS FRE, EPHE, GRENOBLE Cedex 9. Université Joseph Fourier, Grenoble, France.

ABSTRACT
We previously identified 1-(2,4-dimethoxyphenyl)-3-(1-methylindolyl) propenone (IPP51), a new chalcone derivative that is capable of inducing prometaphase arrest and subsequent apoptosis of bladder cancer cells. Here, we demonstrate that IPP51 selectively inhibits proliferation of tumor-derived cells versus normal non-tumor cells. IPP51 interfered with spindle formation and mitotic chromosome alignment. Accumulation of cyclin B1 and mitotic checkpoint proteins Bub1 and BubR1 on chromosomes in IPP51 treated cells indicated the activation of spindle-assembly checkpoint, which is consistent with the mitotic arrest. The antimitotic actions of other chalcones are often associated with microtubule disruption. Indeed, IPP51 inhibited tubulin polymerization in an in vitro assay with purified tubulin. In cells, IPP51 induced an increase in soluble tubulin. Furthermore, IPP51 inhibited in vitro capillary-like tube formation by endothelial cells, indicating that it has anti-angiogenic activity. Molecular docking showed that the indol group of IPP51 can be accommodated in the colchicine binding site of tubulin. This characteristic was confirmed by an in vitro competition assay demonstrating that IPP51 can compete for colchicine binding to soluble tubulin. Finally, in a human bladder xenograft mouse model, IPP51 inhibited tumor growth without signs of toxicity. Altogether, these findings suggest that IPP51 is an attractive new microtubule-targeting agent with potential chemotherapeutic value.

No MeSH data available.


Related in: MedlinePlus

IPP51 binds at the colchicine binding domain of tubulinA. Chemical structures of colchicine compared to IPP51. B. The β-subunit of tubulin is represented as purple ribbons whereas the α-subunit of the same heterodimer is represented as orange ribbons. Residues interacting with the ligand are in sticks and labeled in black whereas IPP51 best-ranked pose (GOLD score 56.9) according to docking calculation is represented in black ball and stick. Snapshots extracted from MD simulation are also reported as blue lines indicating the stability of the complex (ΔGMM-GBSA −37.2 +/− 1.8 kcal/mol). Hydrophobic fitting points calculated by using the GOLD-MLP approach are visualized as green dots. C. Competitive binding assay of colchicine. The decreased stable fluorescence ratio of colchicine (F) at each IPP51 concentration to the original fluorescence intensity of tubulin (F0) in the absence of IPP51 was plotted and fitted.
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Figure 5: IPP51 binds at the colchicine binding domain of tubulinA. Chemical structures of colchicine compared to IPP51. B. The β-subunit of tubulin is represented as purple ribbons whereas the α-subunit of the same heterodimer is represented as orange ribbons. Residues interacting with the ligand are in sticks and labeled in black whereas IPP51 best-ranked pose (GOLD score 56.9) according to docking calculation is represented in black ball and stick. Snapshots extracted from MD simulation are also reported as blue lines indicating the stability of the complex (ΔGMM-GBSA −37.2 +/− 1.8 kcal/mol). Hydrophobic fitting points calculated by using the GOLD-MLP approach are visualized as green dots. C. Competitive binding assay of colchicine. The decreased stable fluorescence ratio of colchicine (F) at each IPP51 concentration to the original fluorescence intensity of tubulin (F0) in the absence of IPP51 was plotted and fitted.

Mentions: Numerous chalcone compounds that inhibit the assembly of tubulin into microtubules bind to the colchicine-binding site of tubulin [51]. Colchicine (Figure 5A) binding to tubulin causes tubulin to acquire a straight structure, which prevents it from polymerizing into microtubules. To determine whether IP551 can bind to the colchicine-binding site of tubulin, a computational study was performed. The crystallographic structure of tubulin in complex with DAMA colchicine from Bos Taurus (99% identity with human tubulin for which no X-ray information is available, Supplementary Figure S1) was used as a starting point for molecular docking calculations [52]. Due to the hydrophobic properties of the colchicine binding domain (lipophilic index of 11), a GOLD-MLP approach was used for the molecular docking calculations [39, 40]. Hydrophobicity was described by the molecular lipophilicity potential (MLP), a molecular interaction field that relies on an atomic fragmental system based on 1-octanol/water experimental partition coefficients. The docking protocol was able to position the best-ranked DAMA colchicine in the niche localized between the two α and β tubulin subunits with a RMSD value of 1.0 Å with respect to crystallographic information (Supplementary Figure S2). Following this successful strategy, IPP51 was docked in the colchicine binding site of β-tubulin (Figure 5B). The best ranked pose for the indol group of IPP51 was found to be trapped between helices H7 (Val238, Cys241, and Leu242) and H8 (Leu248, Ala250, and Leu255), whereas the aromatic moiety of IPP51 formed hydrophobic interactions with Leu242 (H7), Ala316 and Ala354 (S8-S10). No hydrogen bonds were observed between IPP51 and the protein. MD simulation for 1 ns confirmed the stability of the complex in explicit water molecules, with a RMSD value of 0.9 +/− 0.2 for the ligand atoms. Moreover, MM-GBSA thermodynamic calculations confirmed a favorable binding mode for IP551, with a ΔGMM-GBSA value of −37.2 +/− 1.8 kcal/mol.


IPP51, a chalcone acting as a microtubule inhibitor with in vivo antitumor activity against bladder carcinoma.

Martel-Frachet V, Keramidas M, Nurisso A, DeBonis S, Rome C, Coll JL, Boumendjel A, Skoufias DA, Ronot X - Oncotarget (2015)

IPP51 binds at the colchicine binding domain of tubulinA. Chemical structures of colchicine compared to IPP51. B. The β-subunit of tubulin is represented as purple ribbons whereas the α-subunit of the same heterodimer is represented as orange ribbons. Residues interacting with the ligand are in sticks and labeled in black whereas IPP51 best-ranked pose (GOLD score 56.9) according to docking calculation is represented in black ball and stick. Snapshots extracted from MD simulation are also reported as blue lines indicating the stability of the complex (ΔGMM-GBSA −37.2 +/− 1.8 kcal/mol). Hydrophobic fitting points calculated by using the GOLD-MLP approach are visualized as green dots. C. Competitive binding assay of colchicine. The decreased stable fluorescence ratio of colchicine (F) at each IPP51 concentration to the original fluorescence intensity of tubulin (F0) in the absence of IPP51 was plotted and fitted.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4546496&req=5

Figure 5: IPP51 binds at the colchicine binding domain of tubulinA. Chemical structures of colchicine compared to IPP51. B. The β-subunit of tubulin is represented as purple ribbons whereas the α-subunit of the same heterodimer is represented as orange ribbons. Residues interacting with the ligand are in sticks and labeled in black whereas IPP51 best-ranked pose (GOLD score 56.9) according to docking calculation is represented in black ball and stick. Snapshots extracted from MD simulation are also reported as blue lines indicating the stability of the complex (ΔGMM-GBSA −37.2 +/− 1.8 kcal/mol). Hydrophobic fitting points calculated by using the GOLD-MLP approach are visualized as green dots. C. Competitive binding assay of colchicine. The decreased stable fluorescence ratio of colchicine (F) at each IPP51 concentration to the original fluorescence intensity of tubulin (F0) in the absence of IPP51 was plotted and fitted.
Mentions: Numerous chalcone compounds that inhibit the assembly of tubulin into microtubules bind to the colchicine-binding site of tubulin [51]. Colchicine (Figure 5A) binding to tubulin causes tubulin to acquire a straight structure, which prevents it from polymerizing into microtubules. To determine whether IP551 can bind to the colchicine-binding site of tubulin, a computational study was performed. The crystallographic structure of tubulin in complex with DAMA colchicine from Bos Taurus (99% identity with human tubulin for which no X-ray information is available, Supplementary Figure S1) was used as a starting point for molecular docking calculations [52]. Due to the hydrophobic properties of the colchicine binding domain (lipophilic index of 11), a GOLD-MLP approach was used for the molecular docking calculations [39, 40]. Hydrophobicity was described by the molecular lipophilicity potential (MLP), a molecular interaction field that relies on an atomic fragmental system based on 1-octanol/water experimental partition coefficients. The docking protocol was able to position the best-ranked DAMA colchicine in the niche localized between the two α and β tubulin subunits with a RMSD value of 1.0 Å with respect to crystallographic information (Supplementary Figure S2). Following this successful strategy, IPP51 was docked in the colchicine binding site of β-tubulin (Figure 5B). The best ranked pose for the indol group of IPP51 was found to be trapped between helices H7 (Val238, Cys241, and Leu242) and H8 (Leu248, Ala250, and Leu255), whereas the aromatic moiety of IPP51 formed hydrophobic interactions with Leu242 (H7), Ala316 and Ala354 (S8-S10). No hydrogen bonds were observed between IPP51 and the protein. MD simulation for 1 ns confirmed the stability of the complex in explicit water molecules, with a RMSD value of 0.9 +/− 0.2 for the ligand atoms. Moreover, MM-GBSA thermodynamic calculations confirmed a favorable binding mode for IP551, with a ΔGMM-GBSA value of −37.2 +/− 1.8 kcal/mol.

Bottom Line: The antimitotic actions of other chalcones are often associated with microtubule disruption.Finally, in a human bladder xenograft mouse model, IPP51 inhibited tumor growth without signs of toxicity.Altogether, these findings suggest that IPP51 is an attractive new microtubule-targeting agent with potential chemotherapeutic value.

View Article: PubMed Central - PubMed

Affiliation: Université Joseph Fourier, AGIM CNRS FRE, EPHE, GRENOBLE Cedex 9. Université Joseph Fourier, Grenoble, France.

ABSTRACT
We previously identified 1-(2,4-dimethoxyphenyl)-3-(1-methylindolyl) propenone (IPP51), a new chalcone derivative that is capable of inducing prometaphase arrest and subsequent apoptosis of bladder cancer cells. Here, we demonstrate that IPP51 selectively inhibits proliferation of tumor-derived cells versus normal non-tumor cells. IPP51 interfered with spindle formation and mitotic chromosome alignment. Accumulation of cyclin B1 and mitotic checkpoint proteins Bub1 and BubR1 on chromosomes in IPP51 treated cells indicated the activation of spindle-assembly checkpoint, which is consistent with the mitotic arrest. The antimitotic actions of other chalcones are often associated with microtubule disruption. Indeed, IPP51 inhibited tubulin polymerization in an in vitro assay with purified tubulin. In cells, IPP51 induced an increase in soluble tubulin. Furthermore, IPP51 inhibited in vitro capillary-like tube formation by endothelial cells, indicating that it has anti-angiogenic activity. Molecular docking showed that the indol group of IPP51 can be accommodated in the colchicine binding site of tubulin. This characteristic was confirmed by an in vitro competition assay demonstrating that IPP51 can compete for colchicine binding to soluble tubulin. Finally, in a human bladder xenograft mouse model, IPP51 inhibited tumor growth without signs of toxicity. Altogether, these findings suggest that IPP51 is an attractive new microtubule-targeting agent with potential chemotherapeutic value.

No MeSH data available.


Related in: MedlinePlus