Class II-specific histone deacetylase inhibitors MC1568 and MC1575 suppress IL-8 expression in human melanoma cells

Here we explored the effects of the novel class II-specific histone deacetylase inhibitors (HDACis) MC1568 and MC1575 on interleukin-8 (IL-8) expression and cell proliferation in cutaneous melanoma cell line GR-M and uveal melanoma cell line OCM-3 upon stimulation with phorbol 12-myristate 13-acetate (PMA). We found that PMA upregulated IL-8 transcription via the AP-1 binding site, and identified c-Jun as the transcription factor involved in this event. MC1568 and MC1575 inhibited IL-8 levels and cell proliferation in either unstimulated or PMA-stimulated melanoma cells. They acted by suppressing: i) c-Jun binding to the IL-8 promoter; ii) recruitment of histones 3 and 4, RNA polymerase II and TFIIB to the c-Jun promoter; iii) c-Jun expression. Our findings provide new insights into mechanisms underlying anti-tumoral activities of class II-specific HDACis in human melanoma and suggest that they may constitute a novel therapeutic strategy for improving the treatment of this cancer.