Histone deacetylase inhibitors preferentially augment transient transgene expression in human dermal fibroblasts

Skin is an attractive target for gene therapy. However, low efficiency of gene transfection has been a major problem. Histone deacetylase (HDAC) inhibitors have been reported to increase transgene expression in malignant cells.

We have estimated how much HDAC inhibitors might increase transgene expression in HaCaT cells, normal human epidermal keratinocyte (NHEK) cells, normal human dermal fibroblast (NHDF) cells and also in stratified cultured epidermal sheets that mimic the structure of the skin.

After treatment with each HDAC inhibitor [trichostatin A, FK228 and cyclic hydroxamic acid-containing peptide 31 (CHAP31)], transient transgene expression in HaCaT, NHEK and NHDF cells and stratified cultured epidermal sheets was compared with that of respective controls without treatment. Reactivation of transgene expression using HDAC inhibitors in HaCaT cells stably expressing the transgene was also studied.

All HDAC inhibitors equally increased transient transgene expression by 2-fold in NHEK cells, 20-fold in NHDF cells and 6-fold in HaCaT cells when compared with untreated cells. This augmented expression continued for 72 h in all cell lines maintained under each HDAC inhibitor. In cells stably expressing the transgene, only CHAP31 reactivated transgene expression. In stratified cultured epidermal sheets, CHAP31 most effectively improved transient transgene expression.

HDAC inhibitors are most efficient at amplifying transient transgene expression in NHDF cells. This suggests that NHDF cells may be most suitable as transgene targets for transient gene transfection using HDAC inhibitors. Specific HDAC inhibitors may not prove so useful for treating genetic dermatoses requiring cells stably expressing the correct gene, but may be advantageous in treating nonhealing cutaneous wounds or cancer.