Induction of differentiation in human hepatocarcinoma cells by isoverbascoside

Isoverbascoside, a phenylethanoid glycoside, was isolated from Chinese folk medicine herb Pedicularis striata Pall. Here we report that isoverbascoside is capable of inducing differentiation in human hepatocellular carcinoma (HCC) cell line SMMC-7721. When treated with isoverbascoside, the proliferation of SMMC-7721 cells was markedly inhibited in a dose- and time-dependent manner, and the average cell population doubling time was delayed. Exposure of cells to 20 micromol/l isoverbascoside led to the decline of colony formation efficiency on soft agar, induced G0/G1 arresting, and resulted in the decrease of gamma-glutamyltransferase (gamma-GT) activity and the increase of tyrosine aminotransferase (TAT) activity, two marker enzymes, respectively, representing HCC malignance and differentiation stage. These results suggest that isoverbascoside possess the activity of inducing differentiation in SMMC-7721 cells.