Viscum Album Var Hot Water Extract Mediates Anti-cancer Effects through G1 Phase Cell Cycle Arrest in SK-Hep1 Human Hepatocarcinoma cells

Viscum album var (VAV) also known as mistletoe, has long been categorized as a traditional herbal medicinein Asia. In addition to its immunomodulating activities, mistletoe has also been used in the treatment of chronichepatic disorders in China and Korea. There are numerous reports showing that VAV possesses anti-cancereffects, however influence on human hepatocarcinoma has never been elucidated. In the present study, hot waterextracts of VAV was evaluated for its potential anti-cancer effect in vitro. SK-Hep1 cells were treated with VAV(50-400ug/ml) for both 24 and 48 hours then cell viability was measured by cell counting kit-8 (CCK-8). Flowcytometry analysis was used to measure the proportion of SK-Hep1 in the different stages of cell cycle. RT-PCRand Western blot analysis were conducted to measure expression of cell cycle arrest related genes and proteinsrespectively. VAV dose dependently inhibited the proliferation of SK-Hep1 cells without any cytotoxicity withnormal Chang liver cell (CCL-13). Flow cytometry analysis showed that VAV extract inhibited the cell cycleof SK-Hep1 cells via G1 phase arrest. RT-PCR and Western blot analysis both revealed that cyclin dependentkinase 2 (Cdk2) and cyclin D1 gene expression were significantly down regulated while p21 was upregulated dosedependently by VAV treatment. Combined down regulation of Cdk2, Cyclin D1 and up regulation of p21 canresult in cell death. These results indicate that VAV showed evidence of anti-cancer activity through G1 phasecell cycle arrest in SK-Hep1 cells.