Labd-14-ene-8,13-diol (sclareol) induces cell cycle arrest and apoptosis in human breast cancer cells and enhances the activity of anticancer drugs

Sclareol is a labdane-type diterpene that has demonstrated a significant cytotoxic activity against human leukemic cell lines. Here, we report the effect of sclareol against the human breast cancer cell lines MN1 and MDD2 derived from the parental cell line, MCF7. MN1 cells express functional p53, whereas MDD2 cells do not express p53. Flow cytometry analysis of the cell cycle indicated that sclareol was able to inhibit DNA synthesis induce arrest at the G0/1 phase of the cycle apoptosis independent of p53. Sclareol-induced apoptosis was further assessed by detection of fragmented DNA in the cells. Furthermore, sclareol enhanced the activity of known anticancer drugs, doxorubicin, etoposide and cisplatinum, against MDD2 breast cancer cell line.