Phenyhexyl Isothiocyanate, a Dual Inhibitor of Histone Deacetylation and Methylation, Inhibit Acute Lymphoblastic Leukemia Cells through Epigenetic Modulation.

We have shown that phenyhexyl isothiocyanate(PHI) is a novel histone deacetylase inhibitor and can also modulate histone methylation. In this study we investigated the effect of PHI on human Acute Lymphoblastic leukemia cell line Molt-4 in vitro. The viability of Molt-4 cells was determined by MTT method. Apoptosis and cell cycle arrest were measured by flow cytometry. The expression of bcl-2, caspase-9, caspase-8, caspase-3, PRAP protein, acetylated H3 and H4, methylated H3K9 and H3K4 were detected by Western Blotting. The results showed that PHI inhibited the cell growth and decreased viability of Molt-4 cells. Cell cycle analysis indicated an arrest in G0/G1 phase. The expression of bcl-2, caspase-9, caspase-3, and PRAP was inhibited by PHI in a dose and time dependent manner. In contrast, there was no significant change in the expression of Caspase-8. PHI also significantly increased the level of acetylated histone H3 as well as H4. Interestingly, PHI increased the level of methylated H3k4, but decreased methylated H3K9. These data suggest that ALL cells are sensitive to the novel HDAC inhibitor, and PHI may become a novel agent in ALL therapy.