The root bark of Paeonia moutan is a potential anticancer agent in human oral squamous cell carcinoma cells.

Currently there is growing use of complementary and alternative anticancer medicines worldwide, and considerable interest in finding anticancer drugs among Chinese medicinal herbs. The aim of this study was to determine the antitumor activity of the root bark of Paeonia moutan (RBPM) in human squamous cell carcinoma (OSCC) cells. Cell lines derived from human oral squamous cell carcinoma (HSC2, 3, 4, SAS) were tested with different concentrations of RBPM (1-100 μg/ml) using a series of in vitro assay systems. RBPM at a concentration of 100 μg/ml inhibited monolayer and anchorage-independent growth, and interrupted coordinated migration. RBPM activated the phosphorylation of extracellular signal-regulated kinase (ERK) and serine/threonine kinase AKT in 30 min; then, at a later stage (after 6 hours) exhibited potent cytostatic, pro-apoptotic effects through the down-regulation of the expression of cyclin-dependent kinase 4 and its partner cyclin D1, and poly(ADP-ribose) polymerase cleavage. We found direct evidence that RBPM induces apoptotic cell death via DNA fragmentation. Taken together, the antitumor activity of RBPM was demonstrated through antiproliferative and apoptotic effects.