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A spiroligomer α-helix mimic that binds HDM2, penetrates human cells and stabilizes HDM2 in cell culture.

Brown ZZ, Akula K, Arzumanyan A, Alleva J, Jackson M, Bichenkov E, Sheffield JB, Feitelson MA, Schafmeister CE - PLoS ONE (2012)

Bottom Line: Two series of spiroligomers were synthesized, one of structural analogs and one of stereochemical analogs, from which we identified compound 1, that binds HDM2 with a Kd value of 400 nM.This is a biological effect that is not seen with the HDM2 ligand nutlin-3a.We propose that compound 1 modulates the levels of HDM2 by stabilizing it to proteolysis, allowing it to accumulate in the absence of a p53/HDM2 feedback loop.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, Princeton University, Princeton, New Jersey, United States of America.

ABSTRACT
We demonstrate functionalized spiroligomers that mimic the HDM2-bound conformation of the p53 activation domain. Spiroligomers are stereochemically defined, functionalized, spirocyclic monomers coupled through pairs of amide bonds to create spiro-ladder oligomers. Two series of spiroligomers were synthesized, one of structural analogs and one of stereochemical analogs, from which we identified compound 1, that binds HDM2 with a Kd value of 400 nM. The spiroligomer 1 penetrates human liver cancer cells through passive diffusion and in a dose-dependent and time-dependent manner increases the levels of HDM2 more than 30-fold in Huh7 cells in which the p53/HDM2 negative feed-back loop is inoperative. This is a biological effect that is not seen with the HDM2 ligand nutlin-3a. We propose that compound 1 modulates the levels of HDM2 by stabilizing it to proteolysis, allowing it to accumulate in the absence of a p53/HDM2 feedback loop.

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The stereoisomers 8–12 and 1 were suggested by CANDO as being able to mimic the presentation of the side-chains of p53 when bound to HDM2.
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pone-0045948-g004: The stereoisomers 8–12 and 1 were suggested by CANDO as being able to mimic the presentation of the side-chains of p53 when bound to HDM2.

Mentions: Once a set of reasonable mimics of the side chains was determined a second round of optimization was undertaken by changing the stereochemistry of the spiroligomer scaffold to the other stereoisomers suggested by CANDO while keeping the side-chains the same (Figure 1, Figure 4). Examination of the table shows that an ∼60-fold decrease in Kd was achieved by tuning the presentation of the three side chains by changing the stereochemistry of the spiroligomer backbone. Compound 1, the tightest binding spiroligomer identified, had a Kd of 0.4 µM, and bound more tightly than the fluoresceinated derivative of p53 (Flp5314–29). Noteworthy in this stereochemical series of spiroligomers is the subtle relationship between stereochemistry and affinity. For example, compounds 12 and 1 are epimers, with only a minor change in their relative orientation of their side chains by modeling, but they have a four-fold difference in binding. In contrast, the epimeric scaffolds 10 and 11 have nearly identical affinity for HDM2. Finally, spiroligomers 9 and 1 change only the stereocenter of the lysine residue to which the fluorophore is attached and display a nearly 17-fold increase in affinity. Modeling suggests that stereoisomer 1 projects the fluorescein side chain toward the protein surface while 9 projects it away, albeit far from the hydrophobic cleft normally associated with the binding of p53 to HDM2.


A spiroligomer α-helix mimic that binds HDM2, penetrates human cells and stabilizes HDM2 in cell culture.

Brown ZZ, Akula K, Arzumanyan A, Alleva J, Jackson M, Bichenkov E, Sheffield JB, Feitelson MA, Schafmeister CE - PLoS ONE (2012)

The stereoisomers 8–12 and 1 were suggested by CANDO as being able to mimic the presentation of the side-chains of p53 when bound to HDM2.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3475717&req=5

pone-0045948-g004: The stereoisomers 8–12 and 1 were suggested by CANDO as being able to mimic the presentation of the side-chains of p53 when bound to HDM2.
Mentions: Once a set of reasonable mimics of the side chains was determined a second round of optimization was undertaken by changing the stereochemistry of the spiroligomer scaffold to the other stereoisomers suggested by CANDO while keeping the side-chains the same (Figure 1, Figure 4). Examination of the table shows that an ∼60-fold decrease in Kd was achieved by tuning the presentation of the three side chains by changing the stereochemistry of the spiroligomer backbone. Compound 1, the tightest binding spiroligomer identified, had a Kd of 0.4 µM, and bound more tightly than the fluoresceinated derivative of p53 (Flp5314–29). Noteworthy in this stereochemical series of spiroligomers is the subtle relationship between stereochemistry and affinity. For example, compounds 12 and 1 are epimers, with only a minor change in their relative orientation of their side chains by modeling, but they have a four-fold difference in binding. In contrast, the epimeric scaffolds 10 and 11 have nearly identical affinity for HDM2. Finally, spiroligomers 9 and 1 change only the stereocenter of the lysine residue to which the fluorophore is attached and display a nearly 17-fold increase in affinity. Modeling suggests that stereoisomer 1 projects the fluorescein side chain toward the protein surface while 9 projects it away, albeit far from the hydrophobic cleft normally associated with the binding of p53 to HDM2.

Bottom Line: Two series of spiroligomers were synthesized, one of structural analogs and one of stereochemical analogs, from which we identified compound 1, that binds HDM2 with a Kd value of 400 nM.This is a biological effect that is not seen with the HDM2 ligand nutlin-3a.We propose that compound 1 modulates the levels of HDM2 by stabilizing it to proteolysis, allowing it to accumulate in the absence of a p53/HDM2 feedback loop.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, Princeton University, Princeton, New Jersey, United States of America.

ABSTRACT
We demonstrate functionalized spiroligomers that mimic the HDM2-bound conformation of the p53 activation domain. Spiroligomers are stereochemically defined, functionalized, spirocyclic monomers coupled through pairs of amide bonds to create spiro-ladder oligomers. Two series of spiroligomers were synthesized, one of structural analogs and one of stereochemical analogs, from which we identified compound 1, that binds HDM2 with a Kd value of 400 nM. The spiroligomer 1 penetrates human liver cancer cells through passive diffusion and in a dose-dependent and time-dependent manner increases the levels of HDM2 more than 30-fold in Huh7 cells in which the p53/HDM2 negative feed-back loop is inoperative. This is a biological effect that is not seen with the HDM2 ligand nutlin-3a. We propose that compound 1 modulates the levels of HDM2 by stabilizing it to proteolysis, allowing it to accumulate in the absence of a p53/HDM2 feedback loop.

Show MeSH
Related in: MedlinePlus