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Novel Histone Deacetylase Class IIa Selective Substrate Radiotracers for PET Imaging of Epigenetic Regulation in the Brain.

Bonomi R, Mukhopadhyay U, Shavrin A, Yeh HH, Majhi A, Dewage SW, Najjar A, Lu X, Cisneros GA, Tong WP, Alauddin MM, Liu RS, Mangner TJ, Turkman N, Gelovani JG - PLoS ONE (2015)

Bottom Line: Histone deacetylases (HDAC's) became increasingly important targets for therapy of various diseases, resulting in a pressing need to develop HDAC class- and isoform-selective inhibitors.PET imaging with [18F]TFAHA can be used to visualize and quantify spatial distribution and magnitude of HDAC class IIa expression-activity in different organs and tissues in vivo.Furthermore, PET imaging with [18F]TFAHA may advance the understanding of HDACs class IIa mediated epigenetic regulation of normal and pathophysiological processes, and facilitate the development of novel HDAC class IIa-specific inhibitors for therapy of different diseases.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, Wayne State University, Detroit, MI 48202, United States of America.

ABSTRACT
Histone deacetylases (HDAC's) became increasingly important targets for therapy of various diseases, resulting in a pressing need to develop HDAC class- and isoform-selective inhibitors. Class IIa deacetylases possess only minimal deacetylase activity against acetylated histones, but have several other client proteins as substrates through which they participate in epigenetic regulation. Herein, we report the radiosyntheses of the second generation of HDAC class IIa-specific radiotracers: 6-(di-fluoroacetamido)-1-hexanoicanilide (DFAHA) and 6-(tri-fluoroacetamido)-1-hexanoicanilide ([18F]-TFAHA). The selectivity of these radiotracer substrates to HDAC class IIa enzymes was assessed in vitro, in a panel of recombinant HDACs, and in vivo using PET/CT imaging in rats. [18F]TFAHA showed significantly higher selectivity for HDAC class IIa enzymes, as compared to [18F]DFAHA and previously reported [18F]FAHA. PET imaging with [18F]TFAHA can be used to visualize and quantify spatial distribution and magnitude of HDAC class IIa expression-activity in different organs and tissues in vivo. Furthermore, PET imaging with [18F]TFAHA may advance the understanding of HDACs class IIa mediated epigenetic regulation of normal and pathophysiological processes, and facilitate the development of novel HDAC class IIa-specific inhibitors for therapy of different diseases.

No MeSH data available.


Synthesis of DFAHA and TFAHA precursors.Reaction conditions are as follows: c) pyridine, acetyl chloride added drop-wise at 0°C, stirred overnight at RT d) 0.9 eq. SOCl2, 12 hr. stirred under argon at 40°C, catalytic DMF; e) DCM, triethylamine added drop-wise at 0°C, stirred 24 hr. under argon at RT.
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pone.0133512.g002: Synthesis of DFAHA and TFAHA precursors.Reaction conditions are as follows: c) pyridine, acetyl chloride added drop-wise at 0°C, stirred overnight at RT d) 0.9 eq. SOCl2, 12 hr. stirred under argon at 40°C, catalytic DMF; e) DCM, triethylamine added drop-wise at 0°C, stirred 24 hr. under argon at RT.

Mentions: Compound 3a was synthesized from 1 by reacting with difluoroacetic anhydride with no additional solvents in 42% yield. The 1H NMR spectrum of 3a in DMSO-d6 was consistent with the structure and the geminal proton observed at 6.16 ppm as a doublet with a coupling constant of 53.8 Hz. The 19F NMR spectrum showed a doublet at -125.65 ppm with coupling constant 54.93 Hz, matching the coupling seen in the 1H NMR spectrum. Compound 3b was obtained in 51% yield by reacting compound 1 with trifluoroacetic anhydride with only a small amount of DCM (~2 ml). A singlet fluorine peak was observed at -74.32 ppm in the 19F NMR spectrum of 3b, which is consistent with the structure of three fluorines in the trifluoroacetyl moiety. Compounds 3a and 3b were used as non-radioactive standards for HPLC analysis and biochemical assays (Fig 2). Compounds 4a and 4b were synthesized in radiochemical yields of 25% and 22%, respectively (Fig 3). The identity of the radioactive product was confirmed by co-elution with nonradioactive standard as it is not possible to test the purity of radiochemical compounds by NMR. The purity of the compounds was greater than 95%, as assessed by analytical radio-HPLC, and specific activities ranging between 60 and 80 GBq/μmole. The quality control HPLC chromatograms taken for compounds 4a and 4b are shown in Fig 4a and 4b respectively.


Novel Histone Deacetylase Class IIa Selective Substrate Radiotracers for PET Imaging of Epigenetic Regulation in the Brain.

Bonomi R, Mukhopadhyay U, Shavrin A, Yeh HH, Majhi A, Dewage SW, Najjar A, Lu X, Cisneros GA, Tong WP, Alauddin MM, Liu RS, Mangner TJ, Turkman N, Gelovani JG - PLoS ONE (2015)

Synthesis of DFAHA and TFAHA precursors.Reaction conditions are as follows: c) pyridine, acetyl chloride added drop-wise at 0°C, stirred overnight at RT d) 0.9 eq. SOCl2, 12 hr. stirred under argon at 40°C, catalytic DMF; e) DCM, triethylamine added drop-wise at 0°C, stirred 24 hr. under argon at RT.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4526562&req=5

pone.0133512.g002: Synthesis of DFAHA and TFAHA precursors.Reaction conditions are as follows: c) pyridine, acetyl chloride added drop-wise at 0°C, stirred overnight at RT d) 0.9 eq. SOCl2, 12 hr. stirred under argon at 40°C, catalytic DMF; e) DCM, triethylamine added drop-wise at 0°C, stirred 24 hr. under argon at RT.
Mentions: Compound 3a was synthesized from 1 by reacting with difluoroacetic anhydride with no additional solvents in 42% yield. The 1H NMR spectrum of 3a in DMSO-d6 was consistent with the structure and the geminal proton observed at 6.16 ppm as a doublet with a coupling constant of 53.8 Hz. The 19F NMR spectrum showed a doublet at -125.65 ppm with coupling constant 54.93 Hz, matching the coupling seen in the 1H NMR spectrum. Compound 3b was obtained in 51% yield by reacting compound 1 with trifluoroacetic anhydride with only a small amount of DCM (~2 ml). A singlet fluorine peak was observed at -74.32 ppm in the 19F NMR spectrum of 3b, which is consistent with the structure of three fluorines in the trifluoroacetyl moiety. Compounds 3a and 3b were used as non-radioactive standards for HPLC analysis and biochemical assays (Fig 2). Compounds 4a and 4b were synthesized in radiochemical yields of 25% and 22%, respectively (Fig 3). The identity of the radioactive product was confirmed by co-elution with nonradioactive standard as it is not possible to test the purity of radiochemical compounds by NMR. The purity of the compounds was greater than 95%, as assessed by analytical radio-HPLC, and specific activities ranging between 60 and 80 GBq/μmole. The quality control HPLC chromatograms taken for compounds 4a and 4b are shown in Fig 4a and 4b respectively.

Bottom Line: Histone deacetylases (HDAC's) became increasingly important targets for therapy of various diseases, resulting in a pressing need to develop HDAC class- and isoform-selective inhibitors.PET imaging with [18F]TFAHA can be used to visualize and quantify spatial distribution and magnitude of HDAC class IIa expression-activity in different organs and tissues in vivo.Furthermore, PET imaging with [18F]TFAHA may advance the understanding of HDACs class IIa mediated epigenetic regulation of normal and pathophysiological processes, and facilitate the development of novel HDAC class IIa-specific inhibitors for therapy of different diseases.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, Wayne State University, Detroit, MI 48202, United States of America.

ABSTRACT
Histone deacetylases (HDAC's) became increasingly important targets for therapy of various diseases, resulting in a pressing need to develop HDAC class- and isoform-selective inhibitors. Class IIa deacetylases possess only minimal deacetylase activity against acetylated histones, but have several other client proteins as substrates through which they participate in epigenetic regulation. Herein, we report the radiosyntheses of the second generation of HDAC class IIa-specific radiotracers: 6-(di-fluoroacetamido)-1-hexanoicanilide (DFAHA) and 6-(tri-fluoroacetamido)-1-hexanoicanilide ([18F]-TFAHA). The selectivity of these radiotracer substrates to HDAC class IIa enzymes was assessed in vitro, in a panel of recombinant HDACs, and in vivo using PET/CT imaging in rats. [18F]TFAHA showed significantly higher selectivity for HDAC class IIa enzymes, as compared to [18F]DFAHA and previously reported [18F]FAHA. PET imaging with [18F]TFAHA can be used to visualize and quantify spatial distribution and magnitude of HDAC class IIa expression-activity in different organs and tissues in vivo. Furthermore, PET imaging with [18F]TFAHA may advance the understanding of HDACs class IIa mediated epigenetic regulation of normal and pathophysiological processes, and facilitate the development of novel HDAC class IIa-specific inhibitors for therapy of different diseases.

No MeSH data available.