Activity of taspine isolated from Radix et Rhizoma Leonticis against estrogen-receptor-positive breast cancer.

The aim of our study was to investigate the effect of taspine isolated from Radix et Rhizoma Leonticis on the growth of oestrogen-receptor-positive breast cancer xenografts in vivo and the possible mechanism for this action. In vivo taspine studies were conducted with ZR-75-30 human breast cancer xenografts in athymic mice, and then tumors tissue lysates were subjected to Western blotting analysis of estrogen receptor (ER) and progesterone receptor (PR), which was related to inhibition of tumor growth. For in vitro study, cell proliferation, cell cycle and apoptosis of ZR-75-30 cell treated with or without taspine were detected. ER and PR expression were detected by Western blotting, ER and PR mRNA were verified by reverse transcription polymerase chain reaction (RT-PCR). The results showed that treatment over 14 days resulted in a sustained and significant reduction in xenograft weight compared with untreated controls. Cell cycle and apoptosis analysis documented that taspine could change cell cycle and induce cell apoptosis. There was a significant decrease observed in the expression of ER and PR both in tumor tissue and cells after treatment with taspine, RT-PCR also showed a reduction in the expression of mRNA for ER and PR in the group treated with taspine. Taken together, these results suggested that taspine might serve as a promising candidate of ER antagonist in the treatment of oestrogen-independent breast cancer.