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Bis-indole derivatives with antitumor activity turn out to be specific ligands of human telomeric G-quadruplex.

Amato J, Iaccarino N, Pagano B, Morigi R, Locatelli A, Leoni A, Rambaldi M, Zizza P, Biroccio A, Novellino E, Randazzo A - Front Chem (2014)

Bottom Line: Bis-indolinone derivatives having either 2,6-disubstituted pyridine core (1a and 1b) or 1,10-disubstituted phenanthroline core (2a and 2b), already known to have antitumor activity, have been tested as potential G-quadruplex binders.Compounds 2a and 2b are able to selectively stabilize G-quadruplex over duplex DNA, and also to discriminate among different G-quadruplex structures, having a particular affinity for the parallel form of the human telomeric G-quadruplex.Both compounds are also able to induce telomeric DNA damage that may explain the activity of these compounds.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacy, University of Naples "Federico II" Naples, Italy.

ABSTRACT
Bis-indolinone derivatives having either 2,6-disubstituted pyridine core (1a and 1b) or 1,10-disubstituted phenanthroline core (2a and 2b), already known to have antitumor activity, have been tested as potential G-quadruplex binders. Compounds 2a and 2b are able to selectively stabilize G-quadruplex over duplex DNA, and also to discriminate among different G-quadruplex structures, having a particular affinity for the parallel form of the human telomeric G-quadruplex. Both compounds are also able to induce telomeric DNA damage that may explain the activity of these compounds.

No MeSH data available.


Related in: MedlinePlus

Analysis of DNA damage response by bis-indole derivatives 2a and 2b. Transformed BJ-EHLT fibroblasts were grown for 24 h in absence (−) or in presence of the indicated concentrations of compound 2a or 2b. DNA damage response was evaluated by immunofluorescence (IF) analysis by using an anti-γH2AX antibody (green) and DAPI (blue) was used to mark nuclei. (A) Representative images of IF analysis. Images were acquired by using a Leica Deconvolution microscope (magnification 20×). (B) Quantification of γH2AX-positive BJ-EHLT fibroblasto from (A). Histograms show the mean values ± SD of at least three independent experiments. p-values were calculated using the student t-test (*p < 0.05; **p < 0.005).
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Figure 5: Analysis of DNA damage response by bis-indole derivatives 2a and 2b. Transformed BJ-EHLT fibroblasts were grown for 24 h in absence (−) or in presence of the indicated concentrations of compound 2a or 2b. DNA damage response was evaluated by immunofluorescence (IF) analysis by using an anti-γH2AX antibody (green) and DAPI (blue) was used to mark nuclei. (A) Representative images of IF analysis. Images were acquired by using a Leica Deconvolution microscope (magnification 20×). (B) Quantification of γH2AX-positive BJ-EHLT fibroblasto from (A). Histograms show the mean values ± SD of at least three independent experiments. p-values were calculated using the student t-test (*p < 0.05; **p < 0.005).

Mentions: The two molecules that were able to significantly increase the thermal stability of the telomeric G4 were further investigated from biological point of view. In particular, we evaluated if the mechanism through which the two bis-indole derivatives 2a and 2b exert their antitumor activity is due to their ability to bind the G4 DNA structures. Thus, human transformed fibroblasts (BJ-EHLT) were exposed for 24 h to different concentrations of the two compounds and activation of DNA damage response (DDR) was evaluated by immunofluorescence. As shown in Figure 5, both ligands, even if at different extents, induced the phosphorylation of H2AX, a hallmark of DDR at almost all the drug doses tested (Thiriet and Hayes, 2005). Specifically, treatment with compound 2a produced a dose-dependent effect with an induction of γH2AX-positive cells starting from 1 μM (about 30%) and reaching about 70% of positive cells at 5 μM concentration (Figure 5). Interestingly, exposure of BJ-EHLT to 0.5 μM of 2b was already sufficient to induce a potent phosphorylation of H2AX (more than 50% of positive cells), percentage that does not further enhanced with the increase of the dosage (Figure 5). Altogether, these results suggest that the chemical substituents introduced in the tested molecules can determine a different affinity of the two ligands for the target.


Bis-indole derivatives with antitumor activity turn out to be specific ligands of human telomeric G-quadruplex.

Amato J, Iaccarino N, Pagano B, Morigi R, Locatelli A, Leoni A, Rambaldi M, Zizza P, Biroccio A, Novellino E, Randazzo A - Front Chem (2014)

Analysis of DNA damage response by bis-indole derivatives 2a and 2b. Transformed BJ-EHLT fibroblasts were grown for 24 h in absence (−) or in presence of the indicated concentrations of compound 2a or 2b. DNA damage response was evaluated by immunofluorescence (IF) analysis by using an anti-γH2AX antibody (green) and DAPI (blue) was used to mark nuclei. (A) Representative images of IF analysis. Images were acquired by using a Leica Deconvolution microscope (magnification 20×). (B) Quantification of γH2AX-positive BJ-EHLT fibroblasto from (A). Histograms show the mean values ± SD of at least three independent experiments. p-values were calculated using the student t-test (*p < 0.05; **p < 0.005).
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4109613&req=5

Figure 5: Analysis of DNA damage response by bis-indole derivatives 2a and 2b. Transformed BJ-EHLT fibroblasts were grown for 24 h in absence (−) or in presence of the indicated concentrations of compound 2a or 2b. DNA damage response was evaluated by immunofluorescence (IF) analysis by using an anti-γH2AX antibody (green) and DAPI (blue) was used to mark nuclei. (A) Representative images of IF analysis. Images were acquired by using a Leica Deconvolution microscope (magnification 20×). (B) Quantification of γH2AX-positive BJ-EHLT fibroblasto from (A). Histograms show the mean values ± SD of at least three independent experiments. p-values were calculated using the student t-test (*p < 0.05; **p < 0.005).
Mentions: The two molecules that were able to significantly increase the thermal stability of the telomeric G4 were further investigated from biological point of view. In particular, we evaluated if the mechanism through which the two bis-indole derivatives 2a and 2b exert their antitumor activity is due to their ability to bind the G4 DNA structures. Thus, human transformed fibroblasts (BJ-EHLT) were exposed for 24 h to different concentrations of the two compounds and activation of DNA damage response (DDR) was evaluated by immunofluorescence. As shown in Figure 5, both ligands, even if at different extents, induced the phosphorylation of H2AX, a hallmark of DDR at almost all the drug doses tested (Thiriet and Hayes, 2005). Specifically, treatment with compound 2a produced a dose-dependent effect with an induction of γH2AX-positive cells starting from 1 μM (about 30%) and reaching about 70% of positive cells at 5 μM concentration (Figure 5). Interestingly, exposure of BJ-EHLT to 0.5 μM of 2b was already sufficient to induce a potent phosphorylation of H2AX (more than 50% of positive cells), percentage that does not further enhanced with the increase of the dosage (Figure 5). Altogether, these results suggest that the chemical substituents introduced in the tested molecules can determine a different affinity of the two ligands for the target.

Bottom Line: Bis-indolinone derivatives having either 2,6-disubstituted pyridine core (1a and 1b) or 1,10-disubstituted phenanthroline core (2a and 2b), already known to have antitumor activity, have been tested as potential G-quadruplex binders.Compounds 2a and 2b are able to selectively stabilize G-quadruplex over duplex DNA, and also to discriminate among different G-quadruplex structures, having a particular affinity for the parallel form of the human telomeric G-quadruplex.Both compounds are also able to induce telomeric DNA damage that may explain the activity of these compounds.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacy, University of Naples "Federico II" Naples, Italy.

ABSTRACT
Bis-indolinone derivatives having either 2,6-disubstituted pyridine core (1a and 1b) or 1,10-disubstituted phenanthroline core (2a and 2b), already known to have antitumor activity, have been tested as potential G-quadruplex binders. Compounds 2a and 2b are able to selectively stabilize G-quadruplex over duplex DNA, and also to discriminate among different G-quadruplex structures, having a particular affinity for the parallel form of the human telomeric G-quadruplex. Both compounds are also able to induce telomeric DNA damage that may explain the activity of these compounds.

No MeSH data available.


Related in: MedlinePlus