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Aspirin, diabetes, and amyloid: re-examination of the inhibition of amyloid formation by aspirin and ketoprofen.

Tu LH, Noor H, Cao P, Raleigh DP - ACS Chem. Biol. (2014)

Bottom Line: The loss of β-cell function and β-cell death are key features of diabetes.There are no therapeutic strategies for the treatment or prevention of islet amyloidosis.Ketoprofen is similarly ineffective at inhibiting amylin amyloid formation.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, Stony Brook University , Stony Brook, New York 11794-3400, United States.

ABSTRACT
The loss of β-cell function and β-cell death are key features of diabetes. A range of mechanisms are thought to contribute to β-cell loss, including islet amyloid formation by the neuropancreatic hormone amylin (islet amyloid polypeptide, IAPP). Islet amyloid deposition also contributes to the failure of islet transplants. There are no therapeutic strategies for the treatment or prevention of islet amyloidosis. Aspirin and the nonsteroid anti-inflammatory drug (NSAID) ketoprofen, at clinically relevant doses, have been proposed to inhibit amyloid formation by amylin and thus may hold promise for treatment of islet amyloidosis. These compounds are potentially attractive given the importance of inflammation in islet amyloidosis and given the fact that there are no anti-islet amyloid agents in the clinic. We show that aspirin, even in 20-fold excess, has no effect on the kinetics of amyloid formation by amylin as judged by thioflavin-T binding, right angle light scattering, and transmission electron microscopy, nor does it alter the morphology of resulting amyloid fibrils. Aspirin showed no ability to disaggregate preformed amylin amyloid fibrils under the conditions of these studies, 25 °C and pH 7.4. Ketoprofen is similarly ineffective at inhibiting amylin amyloid formation. The compounds do, however, interfere with circular dichroism- and Congo Red-based assays of amylin amyloid formation. This study highlights the importance of using multiple methods to follow amyloid formation when screening inhibitors.

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Ketoprofen does not inhibit amyloid formation by human amylin.TEM images of samples recorded after incubating amylin with varyingamount of ketoprofen for 42 h. Scale bars represent 100 nm. (A) Amylinalone. (B) Mixture of amylin with a 20-fold excess of ketoprofen.(C) Mixture of amylin with a 10-fold excess of ketoprofen. (D) Mixtureof amylin with a 5-fold excess of ketoprofen. (E) Mixture of amylinwith a 2-fold excess of ketoprofen. (F) Mixture of amylin with anequimolar amount of ketoprofen. Experiments were conducted at pH 7.4and 25 °C in 20 mM Tris buffer with 0.25% DMSO (v/v) in the absenceof any fluorinated alcohol cosolvent. The concentration of amylinwas 16 μM.
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fig5: Ketoprofen does not inhibit amyloid formation by human amylin.TEM images of samples recorded after incubating amylin with varyingamount of ketoprofen for 42 h. Scale bars represent 100 nm. (A) Amylinalone. (B) Mixture of amylin with a 20-fold excess of ketoprofen.(C) Mixture of amylin with a 10-fold excess of ketoprofen. (D) Mixtureof amylin with a 5-fold excess of ketoprofen. (E) Mixture of amylinwith a 2-fold excess of ketoprofen. (F) Mixture of amylin with anequimolar amount of ketoprofen. Experiments were conducted at pH 7.4and 25 °C in 20 mM Tris buffer with 0.25% DMSO (v/v) in the absenceof any fluorinated alcohol cosolvent. The concentration of amylinwas 16 μM.

Mentions: The NSAID ketoprofen has alsobeen proposed to be an inhibitorof amylin amyloid formation, again on the basis of Congo red assaysand CD spectroscopy. We examined the ability of the compound to inhibitamyloid formation by human amylin using TEM to test its effect onamyloid formation directly (Figure 5). TEManalysis revealed the presence of extensive mats of amyloid fibrilsin all samples, showing that the compound is not an amylin amyloidinhibitor.


Aspirin, diabetes, and amyloid: re-examination of the inhibition of amyloid formation by aspirin and ketoprofen.

Tu LH, Noor H, Cao P, Raleigh DP - ACS Chem. Biol. (2014)

Ketoprofen does not inhibit amyloid formation by human amylin.TEM images of samples recorded after incubating amylin with varyingamount of ketoprofen for 42 h. Scale bars represent 100 nm. (A) Amylinalone. (B) Mixture of amylin with a 20-fold excess of ketoprofen.(C) Mixture of amylin with a 10-fold excess of ketoprofen. (D) Mixtureof amylin with a 5-fold excess of ketoprofen. (E) Mixture of amylinwith a 2-fold excess of ketoprofen. (F) Mixture of amylin with anequimolar amount of ketoprofen. Experiments were conducted at pH 7.4and 25 °C in 20 mM Tris buffer with 0.25% DMSO (v/v) in the absenceof any fluorinated alcohol cosolvent. The concentration of amylinwas 16 μM.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4215902&req=5

fig5: Ketoprofen does not inhibit amyloid formation by human amylin.TEM images of samples recorded after incubating amylin with varyingamount of ketoprofen for 42 h. Scale bars represent 100 nm. (A) Amylinalone. (B) Mixture of amylin with a 20-fold excess of ketoprofen.(C) Mixture of amylin with a 10-fold excess of ketoprofen. (D) Mixtureof amylin with a 5-fold excess of ketoprofen. (E) Mixture of amylinwith a 2-fold excess of ketoprofen. (F) Mixture of amylin with anequimolar amount of ketoprofen. Experiments were conducted at pH 7.4and 25 °C in 20 mM Tris buffer with 0.25% DMSO (v/v) in the absenceof any fluorinated alcohol cosolvent. The concentration of amylinwas 16 μM.
Mentions: The NSAID ketoprofen has alsobeen proposed to be an inhibitorof amylin amyloid formation, again on the basis of Congo red assaysand CD spectroscopy. We examined the ability of the compound to inhibitamyloid formation by human amylin using TEM to test its effect onamyloid formation directly (Figure 5). TEManalysis revealed the presence of extensive mats of amyloid fibrilsin all samples, showing that the compound is not an amylin amyloidinhibitor.

Bottom Line: The loss of β-cell function and β-cell death are key features of diabetes.There are no therapeutic strategies for the treatment or prevention of islet amyloidosis.Ketoprofen is similarly ineffective at inhibiting amylin amyloid formation.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, Stony Brook University , Stony Brook, New York 11794-3400, United States.

ABSTRACT
The loss of β-cell function and β-cell death are key features of diabetes. A range of mechanisms are thought to contribute to β-cell loss, including islet amyloid formation by the neuropancreatic hormone amylin (islet amyloid polypeptide, IAPP). Islet amyloid deposition also contributes to the failure of islet transplants. There are no therapeutic strategies for the treatment or prevention of islet amyloidosis. Aspirin and the nonsteroid anti-inflammatory drug (NSAID) ketoprofen, at clinically relevant doses, have been proposed to inhibit amyloid formation by amylin and thus may hold promise for treatment of islet amyloidosis. These compounds are potentially attractive given the importance of inflammation in islet amyloidosis and given the fact that there are no anti-islet amyloid agents in the clinic. We show that aspirin, even in 20-fold excess, has no effect on the kinetics of amyloid formation by amylin as judged by thioflavin-T binding, right angle light scattering, and transmission electron microscopy, nor does it alter the morphology of resulting amyloid fibrils. Aspirin showed no ability to disaggregate preformed amylin amyloid fibrils under the conditions of these studies, 25 °C and pH 7.4. Ketoprofen is similarly ineffective at inhibiting amylin amyloid formation. The compounds do, however, interfere with circular dichroism- and Congo Red-based assays of amylin amyloid formation. This study highlights the importance of using multiple methods to follow amyloid formation when screening inhibitors.

Show MeSH
Related in: MedlinePlus