Abstract
Background: Epigenetic dysfunction is implicated in many neurologic, psychiatric and oncologic diseases. Consequently, histone deacetylases (HDACs) inhibitors have been developed as therapeutic and imaging agents for these diseases. However, only a few radiotracers have been developed as HDACs imaging agents for the central nervous system (CNS). We report herein the synthesis and evaluation of [18F]INER-1577-3 ([18F]5) as an HDACs imaging agent for CNS.
Methods: [18F]INER-1577-3 ([18F]5) was synthesized by two methods: one-step (A) and two-step (B) methods. Briefly, radiofluorination of the corresponding precursors (11, 12) with K[18F]/K2.2.2 followed by purifications with HPLC gave ([18F]5). The quality of [18F]INER- 1577-3 synthesized by these methods was verified by HPLC and TLC as compared to an authentic sample. The inhibitions of [18F]INER-1577-3 and related HDACs inhibitors on tumor cells growth were carried out with breast cancer cell line 4T1 and MCF-7. The whole-body and brain uptake of [18F]INER-1577-3 in rats and AD mice were determined using a micro-PET scanner and the data was analyzed using PMOD.
Results: The radiochemical yield of [18F]INER-1577-3 synthesized by these two methods was 1.4 % (Method A) and 8.8% (Method B) (EOB), respectively. The synthesis time was 115 min and 100 min, respectively, from EOB. The inhibition studies showed that INER-1577-3 has a significant inhibitory effect in HDAC6 and HDAC8 but not HDAC2. PET studies in rats and AD mice showed a maximum at about 15 min postinjection for the whole brain of a rat (0.47 ± 0.03 %ID/g), SAMP8 mice (5.63 ± 1.09 %ID/g) and SAMR1 mice (7.23 ± 1.21 %ID/g).
Conclusion: This study showed that INER-1577-3 can inhibit tumor cell growth and is one of a few HDACs inhibitors that can penetrate the blood-brain barrier (BBB) and monitor HDAC activities in AD mice. Thus, [18F]INER-1577-3 may be a potent HDACs imaging agent, especially for CNS.
Keywords: Epigenetic modifications, histone deacetylases, [18F]INER-1577-3, histone deacetylases imaging agents, PET imaging, AD mice.
Graphical Abstract
[http://dx.doi.org/10.1038/nrn2132 ] [PMID: 17453016]
[http://dx.doi.org/10.1016/j.neuropharm.2014.01.043 ] [PMID: 24495398]
[http://dx.doi.org/10.1016/j.neuroscience.2012.12.034 ] [PMID: 23291453]
[http://dx.doi.org/10.1007/s12017-014-8306-x ] [PMID: 24777294]
[http://dx.doi.org/10.1038/npp.2012.73 ] [PMID: 22692567]
[http://dx.doi.org/10.1016/j.vascn.2012.08.001 ] [PMID: 22902970]
[http://dx.doi.org/10.1016/j.tins.2009.06.002 ] [PMID: 19775759]
[http://dx.doi.org/10.2217/epi.14.73 ] [PMID: 25942532]
[http://dx.doi.org/10.1038/nrd2681 ] [PMID: 18827828]
[http://dx.doi.org/10.1358/dnp.2009.22.9.1437959 ] [PMID: 20072728]
[http://dx.doi.org/10.1021/jm200620f ] [PMID: 21721525]
[http://dx.doi.org/10.1021/cn9000268 ] [PMID: 20657706]
[http://dx.doi.org/10.1002/jlcr.1122]
[http://dx.doi.org/10.1016/j.nucmedbio.2008.12.005 ] [PMID: 19324270]
[http://dx.doi.org/10.1021/cn500162j ] [PMID: 25188794]
[http://dx.doi.org/10.1021/jm500872p ] [PMID: 25203558]
[http://dx.doi.org/10.1002/jlcr.3219 ] [PMID: 25156811]
[http://dx.doi.org/10.1016/j.bmcl.2013.10.038 ] [PMID: 24210501]
[http://dx.doi.org/10.1016/j.pnpbp.2015.03.010 ] [PMID: 25818247]
[http://dx.doi.org/10.3389/fncel.2015.00042 ] [PMID: 25759639]
[http://dx.doi.org/10.1016/j.pharmthera.2013.05.010 ] [PMID: 23711791]
[http://dx.doi.org/10.1002/acn3.147 ] [PMID: 25642438]
[PMID: 24380043]
[http://dx.doi.org/10.1021/cn500021p ] [PMID: 24780082]
[PMID: 24688469]