Limits...
18F-glutathione conjugate as a PET tracer for imaging tumors that overexpress L-PGDS enzyme.

Huang HL, Huang YC, Lee WY, Yeh CN, Lin KJ, Yu CS - PLoS ONE (2014)

Bottom Line: The inhibition percentage of the production of PGD2 from PGH2 at the presence of 200 µM of FBuEA-GS and 4-Dibenzo[a,d]cyclohepten-5-ylidene-1-[4-(2H-tetrazol-5-yl)butyl]piperidine (AT-56) were 74.1 ± 4.8% and 97.6 ± 16.0%, respectively. [18F]FBuEA-GS bound L-PGDS (16.3-21.7%) but not the isoform, microsomal prostaglandin E synthase 1.No binding to GST-alpha and GST-pi was observed.The contrasted images indicated that the radiotracer accumulation in tumor lesions is probably related to the overexpression of L-PGDS.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering and Environmental Sciences, National Tsinghua University, Hsinchu, Taiwan.

ABSTRACT
Lipocalin-type prostaglandin D synthase (L-PGDS) has been correlated with the progression of neurological disorders. The present study aimed at evaluating the imaging potency of a glutathione conjugate of fluorine-18-labeled fluorobutyl ethacrynic amide ([18F]FBuEA-GS) for brain tumors. Preparation of [18F]FBuEA-GS has been modified from the -4-tosylate derivative via radiofluorination in 5% radiochemical yield. The mixture of nonradioactive FBuEA-GS derived from a parallel preparation has be resolved to two isomers in a ratio of 9:1 using analytic chiral reversed phase high performance liquid chromatography (RP-HPLC). The two fluorine-18-labeled isomers purified through nonchiral semipreparative RP-HPLC as a mixture were studied by assessing the binding affinity toward L-PGDS through a gel filtration HPLC, by analyzing radiotracer accumulation in C6 glioma cells, and by evaluating the imaging of radiotracer in a C6 glioma rat with positron emission tomography. The inhibition percentage of the production of PGD2 from PGH2 at the presence of 200 µM of FBuEA-GS and 4-Dibenzo[a,d]cyclohepten-5-ylidene-1-[4-(2H-tetrazol-5-yl)butyl]piperidine (AT-56) were 74.1 ± 4.8% and 97.6 ± 16.0%, respectively. [18F]FBuEA-GS bound L-PGDS (16.3-21.7%) but not the isoform, microsomal prostaglandin E synthase 1. No binding to GST-alpha and GST-pi was observed. The binding strength between [18F]FBuEA-GS and L-PGDS has been evaluated using analytic gel filtration HPLC at the presence of various concentrations of the cold competitor FBuEA-GS. The contrasted images indicated that the radiotracer accumulation in tumor lesions is probably related to the overexpression of L-PGDS.

Show MeSH

Related in: MedlinePlus

Inhibition of the formation of PGD2 from PGH2 in the presence of 200 µM of each test compound.Results are the mean of duplicated measurements.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4128654&req=5

pone-0104118-g003: Inhibition of the formation of PGD2 from PGH2 in the presence of 200 µM of each test compound.Results are the mean of duplicated measurements.

Mentions: To date, there is still no effective inhibitor of L-PGDS except AT-56 (IC50 = 95 µM) [25], a dibenzocycloheptenyl tetrazolyl piperidine. This assay was performed via an indirect determination of the formation of PGD2 in the presence of the competitive PGD2- acetylcholineesterase conjugate, which cleaves acetylthiocholine and the substrate 5,5′-dithiobis(2-nitrobenzoic acid) to yield a colored 5-thio-2-nitrobenzoic acid with an absorbance of visible light at a λmax of 412 nm. According to the IC50 value of AT-56 [44], working concentrations of 200 µM of substrates were required to ensure that AT-56 could be used as a positive control (Fig. 3). The relatively large deviation of uridine (5.6±14.3%) reflects the complexity of sequential assays. The observed inhibition was relatively higher than that observed in previous studies. Compared to the AT-56 positive control that, showed complete inhibition (97.6±16.0%), FBuEA-GS 3 (74.1±4.8%) data were significant.


18F-glutathione conjugate as a PET tracer for imaging tumors that overexpress L-PGDS enzyme.

Huang HL, Huang YC, Lee WY, Yeh CN, Lin KJ, Yu CS - PLoS ONE (2014)

Inhibition of the formation of PGD2 from PGH2 in the presence of 200 µM of each test compound.Results are the mean of duplicated measurements.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4128654&req=5

pone-0104118-g003: Inhibition of the formation of PGD2 from PGH2 in the presence of 200 µM of each test compound.Results are the mean of duplicated measurements.
Mentions: To date, there is still no effective inhibitor of L-PGDS except AT-56 (IC50 = 95 µM) [25], a dibenzocycloheptenyl tetrazolyl piperidine. This assay was performed via an indirect determination of the formation of PGD2 in the presence of the competitive PGD2- acetylcholineesterase conjugate, which cleaves acetylthiocholine and the substrate 5,5′-dithiobis(2-nitrobenzoic acid) to yield a colored 5-thio-2-nitrobenzoic acid with an absorbance of visible light at a λmax of 412 nm. According to the IC50 value of AT-56 [44], working concentrations of 200 µM of substrates were required to ensure that AT-56 could be used as a positive control (Fig. 3). The relatively large deviation of uridine (5.6±14.3%) reflects the complexity of sequential assays. The observed inhibition was relatively higher than that observed in previous studies. Compared to the AT-56 positive control that, showed complete inhibition (97.6±16.0%), FBuEA-GS 3 (74.1±4.8%) data were significant.

Bottom Line: The inhibition percentage of the production of PGD2 from PGH2 at the presence of 200 µM of FBuEA-GS and 4-Dibenzo[a,d]cyclohepten-5-ylidene-1-[4-(2H-tetrazol-5-yl)butyl]piperidine (AT-56) were 74.1 ± 4.8% and 97.6 ± 16.0%, respectively. [18F]FBuEA-GS bound L-PGDS (16.3-21.7%) but not the isoform, microsomal prostaglandin E synthase 1.No binding to GST-alpha and GST-pi was observed.The contrasted images indicated that the radiotracer accumulation in tumor lesions is probably related to the overexpression of L-PGDS.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering and Environmental Sciences, National Tsinghua University, Hsinchu, Taiwan.

ABSTRACT
Lipocalin-type prostaglandin D synthase (L-PGDS) has been correlated with the progression of neurological disorders. The present study aimed at evaluating the imaging potency of a glutathione conjugate of fluorine-18-labeled fluorobutyl ethacrynic amide ([18F]FBuEA-GS) for brain tumors. Preparation of [18F]FBuEA-GS has been modified from the -4-tosylate derivative via radiofluorination in 5% radiochemical yield. The mixture of nonradioactive FBuEA-GS derived from a parallel preparation has be resolved to two isomers in a ratio of 9:1 using analytic chiral reversed phase high performance liquid chromatography (RP-HPLC). The two fluorine-18-labeled isomers purified through nonchiral semipreparative RP-HPLC as a mixture were studied by assessing the binding affinity toward L-PGDS through a gel filtration HPLC, by analyzing radiotracer accumulation in C6 glioma cells, and by evaluating the imaging of radiotracer in a C6 glioma rat with positron emission tomography. The inhibition percentage of the production of PGD2 from PGH2 at the presence of 200 µM of FBuEA-GS and 4-Dibenzo[a,d]cyclohepten-5-ylidene-1-[4-(2H-tetrazol-5-yl)butyl]piperidine (AT-56) were 74.1 ± 4.8% and 97.6 ± 16.0%, respectively. [18F]FBuEA-GS bound L-PGDS (16.3-21.7%) but not the isoform, microsomal prostaglandin E synthase 1. No binding to GST-alpha and GST-pi was observed. The binding strength between [18F]FBuEA-GS and L-PGDS has been evaluated using analytic gel filtration HPLC at the presence of various concentrations of the cold competitor FBuEA-GS. The contrasted images indicated that the radiotracer accumulation in tumor lesions is probably related to the overexpression of L-PGDS.

Show MeSH
Related in: MedlinePlus