Danshen (Salvia miltiorrhiza) extract inhibits proliferation of breast cancer cells via modulation of Akt activity and p27 level

Danshen is widely used in traditional Chinese medicine, often in combination with other herbs. To check the effect of Danshen on the proliferation of breast cancer cells, Danshen extract was used to treat MCF‐7 and MCF‐7 HER2 cells, the latter of which overexpresses HER2. HER2 is a receptor tyrosine kinase, and is involved in signal transduction pathways leading to tumor cell proliferation. MTT and cell proliferation assays revealed that Danshen strongly inhibited the proliferation of both MCF‐7 vec cells and MCF‐7 HER2 cells. Flow cytometry analyses indicated that Danshen induced cell cycle delay in the G1 phase. HER2 expression was shown to confer resistance to Danshen‐induced inhibition of proliferation and cell cycle delay, suggesting that HER2 is responsible for the resistance to Danshen. Danshen treatment induced the down‐regulation of Akt phosphorylation and an increase in p27 in MCF‐7 vec and MCF‐7 HER2 cells. Nevertheless, MCF‐7 HER2 cells were more resistant to the Danshen‐induced inhibition of Akt phosphorylation and p27 up‐regulation. Copyright © 2009 John Wiley & Sons, Ltd.