Selective estrogen receptor modulator: A novel polysaccharide from Sparganii Rhizoma induces apoptosis in breast cancer cells

A polysaccharide named SpaTA, as novel selective estrogen receptor modulator, was isolated from water extraction of traditional Chinese herbal medicine Sparganii Rhizoma. SpaTA had a backbone consisting of 2-O-grailsine-β-xylose (4 → 6)-α-glucose (1 → 4) −β-mannose osamine. There is an aluminium element combined with nitrogen on both grailsine and mannose osamine in repeating unit of SpaTA. The anticancer effect of SpaTA was assessed using ZR-75-1 human breast cancer cells. The results showed that SpaTA induced sequential increases in proliferation and apoptosis through a time- and concentration-dependent manner. Further studies revealed that SpaTA regulated the expression and nuclear translocation of ERα, then modulated the downstream estrogen signaling pathway. Moreover, knock-down ERα in ZR-75-1 cells and overexpress ERα in MDA-MB-231 cells also provided evidences that SpaTA activated the apoptosis-related caspase −3, −8, −9 and PARP in an ERα-dependent manner. Taken together, these results indicated that SpaTA can induce the apoptosis of breast cancer cells through regulating ERα. Therefore, SpaTA may be considered as an effective agent against human breast cancer.