Totarol, a natural diterpenoid, induces selective antitumor activity in SGC-7901 human gastric carcinoma cells by triggering apoptosis, cell cycle disruption and suppression of cancer cell migration.

Purpose: Totarol is a plant-derived natural product and has been reported to exhibit important pharmacological activities. However, the anticancer activity of totarol has not been evaluated yet. Therefore, the present research work was designed to evaluate the antitumor effects of totarol in SGC-7901 human gastric cancer cells and human gastric epithelial mucosa cell line GES-I (used as normal cell line model) together with examining its effects on induction of apoptosis, cell cycle phase distribution and cell migration. Methods: The effect of totarol on cell cytotoxicity was evaluated by MTT cell viability assay. Inverted phase contrast microscopy was used to identify the effects on cell morphology, while transmission electron microscopy indicated the apoptosis-driven morphological changes in cancer cells. The effects on cell apoptosis were also evaluated by annexin V/PI staining, while cell cycle analysis was done by flow cytometry. In vitro wound healing assay estimated the effects of totarol on cell migration. Results: The results indicated that totarol induced selective cytotoxic e f fects in SGC-7901 human gastric cancer cells concentration-dependently and exhibited lower toxicity in GES-1 normal cells. The totarol-treated cells showed significant alterations in cell morphology including rounding and cellular shrinkage. Untreated SGC-7901 cells exhibited normal cellular morphology with undamaged plasma membrane. However, treating cells with totarol led to damaged plasma membrane along with appearance of rounded protrusions (apoptotic bodies) containing damaged and broken chromatin material. Treatment with different doses of totarol led to profound suppression of wound healing. Totarol treatment also led to G2/M phase cell cycle arrest in these cells in a concentration-dependent manner. Conclusions: The present study indicated that totarol diterpene has the tendency to show selective anticancer effects in SGC-7901 human gastric cancer cells along with inducing apoptosis, cell cycle arrest and inhibition of cell migration.