Abstract
Rhein, a traditional Chinese herbal derived from the rhizome of Rheum palmatum L., is one of the most important active component among the anthraquinones. It has been reported that rhein shows antitumor activity on many types of cancer. However, the mechanism of rhein-induced breast cancer cells death is still unknown. To investigate the cytotoxic effect of rhein on breast cancer cells, we perform lysine-labeling and cysteine-labeling 2D-DIGE combined MALDI-TOF MS to analyze the differentially expressed proteins on rhein-treated breast cancer cells. The multiplex proteomics studies demonstrate that 73 and 9 protein features are significantly changed in protein expression level and thiol reacticity, respectively, in either MCF-7 or MDA-MB-231 cells. Most of the differentially expression proteins involved in protein folding, cytoskeleton regulation and glycolysis. Further study also indicates that rhein may interfere with proper folding of proteins as well as unbalancing of cellular redox status leading to ER-stress. To sum up, our preliminary approach demonstrates that the combined proteomic strategy offers a rapid strategy to study the molecular mechanisms of rhein-induced cytotoxicity in breast cancer cells. The identified target proteins might be useful for further assessment as potential targets in breast cancer therapy.