Effects of Ganoderic acid Me on inhibiting multidrug resistance and inducing apoptosis in multidrug resistant colon cancer cells

Ganoderma lucidum is known as a valuable herb in the search for anticancer lead compounds because it has been used for thousands of years as a traditional medication. Triterpenoids are the principal active components in this fungus. Ganoderic acid Me (GA-Me), a pure lanostane triterpene, was isolated from G. lucidum. Our study showed that GA-Me could reverse the multidrug resistance (MDR) in multidrug resistant clone cancer cells. We investigated that GA-Me enhanced the chemosensitivities of anticancer agents in MDR cells. Furthermore. GA-Me inhibited the activity of hMDR1 promoter and this transcriptional suppression was consistent with the inhibitory effect of GA-Me on the mRNA and protein expression level of MDR1. Meanwhile, the expression levels of MRP1 and MRP2 were also inhibited by GA-Me. GA-Me could induce apoptosis in MDR cells via up-regulation of p-p53, p53, Bax, caspase-3, caspase-9 and down-regulation of Bcl-2. In addition, GA-Me stimulated the decline in mitochondrial membrane potential and cytochrome release into cytosol. We concluded that GA-Me could effectively reverse multidrug resistance in MDR colon cancer cells, via repressing expression levels of MDR1, MRPs and regulating apoptosis-related pathways. These results suggested that GA-Me had therapeutic potential against multiclrug resistance as a new agent. (C) 2011 Elsevier Ltd. All rights reserved.