An HDAC8-selective fluorescent probe for imaging in living tumor cell lines and tissue slices.

Histone deacetylase 8 (HDAC8) has been used as a therapeutic target for many cancers as it is highly expressed in neuroblastoma cells and breast cancer cells. HDAC8-selective fluorescent probes need to be urgently developed. Herein, two novel fluorescent probes, namely and , based on the conjugation of 1,8-naphthalimide with a highly selective inhibitor of HDAC8 () were reported. Compared with ( = 6.25 × 10 M), ( = 8.05 × 10 M) and ( = 7.42 × 10 M) showed great selectivity toward HDAC8. Two fluorescent probes exhibited high fluorescence intensity under = 450 nm and a large Stokes shift (100 nm). was selected for cell and tissue imaging due to the similarity in the bioactivity of with . The ability of to target imaging HDAC8 in SH-SY5Y and MDA-MB-231 tumor cells was demonstrated. Furthermore, was applied to imaging SH-SY5Y tumor tissue slices to indicate the relative expression level of HDAC8. Therefore, this HDAC8-selective fluorescent probe can be expected for applications in HDAC8-targeted drug screening as well as in pathologic diagnoses.