Title: A polysaccharide from Huaier induced apoptosis in MCF-7 breast cancer cells via down-regulation of MTDH protein Author:

In this study, one homogeneous polysaccharide (SP1), with a molecular weight of 56 kDa, was isolated from the Huaier fruiting bodies. It had a backbone consisting of 1, 4-linked-β-D-Galp and 1, 3, 6-linked-β-D-Galp residues, which was terminated with 1-linked-α-D-Glcp and 1-linked-α-L-Araf terminal at O-3 position of 1, 3, 6-linked-β-D-Galp unit along the main chain in the ratio of 1.1: 2.0: 1.1: 1.1. MTT assay showed that shMTDH or SP1 (100, 200 and 400 μg/ml) was able to suppress the proliferation of MCF-7 cells, due to a significant increase in the number of apoptotic cells as determined by flow cytometric analysis. Furthermore, Western blot analysis revealed that SP1 or shMTDH treatment led to a rise of ratio between proapoptotic Bax and antiapoptotic Bcl-2 protein in MCF-7 cells. In addition, carcinogene MTDH protein expression in MCF-7 cells received SP1 (100, 200 and 400 μg/ml) or shMTDH treatment was also repressed after 48h incubation. Taken together, these findings indicated that SP1 has anticancer potential in the treatment of human breast cancer.