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-beta-D-Galp and 1,3,6-linked-beta-D-Galp residues, which was terminated with 1-linked-alpha-Glcp and 1-linked-alpha-L-Araf terminal at O-3 position of 1,3,6-linked-beta-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 mu g/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 mu g/mL) or shMTDH treatment was also repressed after 48 h incubation. Taken together, these findings indicated that SP1 has anticancer potential in the treatment of human breast cancer. (C) 2016 Elsevier Ltd. All rights reserved.