Potential role of β-elemene on histone H1 in the H22 ascites hepatoma cell line

beta-elemene is extracted from the Chinese medicinal herb Curcuma Wenyujin. It has a broad-spectrum antitumor effect on many types of cancer. However, the exact mechanism of action of beta-elemene in hepatocellular carcinoma (HCC) remains unknown. Histone H1 is thought to act as a repressor of transcription by promoting the compaction of chromatin into higher order structures. We found that histone H1 plays an important role in the antitumor function of beta-elemene. In this study, histone H1 expression in the H22 murine hepatocellular carcinoma cell line was confirmed, with P388D1 cells serving as a positive control. Furthermore, H22 cells were cultured with beta-elemene for different time-points in vitro and treated with different dose-dependent beta-elemene in an experimental H22 HCC xenograft transplantation model to confirm whether beta-elemene inhibited the growth of H22 tumor cells. In addition, measurements of histone H1 expression both in vitro and in vivo enabled us to demonstrate that beta-elemene affects the expression of histone H1 only at the protein level, but is not involved in regulation at the gene level. Our results clearly show that the effect of beta-elemene on inhibiting the growth of H22 tumor cells is time- and dose-dependent. In conclusion, beta-elemene inhibits the growth of H22 cells by enhancing the expression of histone H1 only at the protein level. This finding may provide insight into a new mechanism of the antitumor action of beta-elemene.