Abstract: BACKGROUND AND AIM: The suppressive effects of cortex periplocae on human breast cancer BT_549 cells and the expressions of p16 and p27 were analyzed to demonstrate the possible mechanisms. MATERIALS AND METHODS: The suppressive effects of Cortex periplocae on proliferation of BT_549 cells was analyzed with MTT method. The cell cycle and apoptosis rate of BT_549 cells treated with Cortex periplocae were examined by flow cytometry. Expressions of p16 and p27 mRNA and proteins were assessed by semiquauntitative RT_PCR and flow cytometry. RESULTS: Cortex periplocae could obviously inhibit proliferation of BT_549 cells (P<0.01). Compared to control group, after treatment with Cortex periplocae, the cell number in G0/G1 phase of BT_549 cells was increased(P<0.01), the apoptosis rate was also increased significantly(P<0.01) as well as the expression of p16 and p27(P<0.05). CONCLUSION: Cortex periplocae exerted significant inhibitory effects on BT_549 cells in vitro which was probably related to improving the expressions of p16 and p27.

Key words: cortex periplocae, breast cancer, p16, p27