Fig 6. Histone deacetylase (HDAC) inhibitor assessment.

(A) Dose-response of HDAC inhibitors on NDST1 promoter. HeLa cells stably expressing the NDST1 promoter—luciferase reporter gene were treated with serially diluted selected HDAC inhibitors. ITF 2357, an HDAC inhibitor which is structurally and functionally similar to SAHA, produced a dose-response curve with IC₅₀ of 0.2 μM. Experiments were performed in duplicates. (B) NDST1 mRNA level after treatment with ITF 2357. Normal human fibroblast cells were treated with 2x IC₅₀ (0.4 μM) of ITF 2357 for 5 days. Level of NDST1 mRNA was reduced by 40% after the treatment. Expression of NDST1 mRNA level was normalized to 18S rRNA level. Experiments were conducted in duplicates. (C) Western blot densitometry analysis of NDST1 protein expression after treatment with ITF 2357. Normal human fibroblast, MPS I patient, and MPS IIIA patient cells were treated with ITF 2357 at its calculated 2x IC₅₀. The effect of the compound on the NDST1 expression was evaluated using densitometry analysis of NDST1 band normalized to its corresponding actin band. Significant decrease in NDST1 expression was observed in all treated cells. l.u.–luminescence units. r.u.–relative units.