Anticancer Mechanism Of Rhein

Rhubarb, an herbal medicine commonly used in China, is believed to possess properties of removing heat from the blood and toxic substances. It has been popularly used for the treatment of several kinds of inflammation. Recent clenical studies have demostrated that rhubarb has potent anticancer activity in many kind of cancers.In this study, we found that rhein, exactive of the rhubarb, had remarkable inhibitory effect on the growth of lung cancer cell A549. Intesetingly, co-treatment with 9-cis-RA significantly reversed the action of rhein in A549 cells. In vitro ligand binding assay showed that rhein can bind with RXRα, which was closely related to the inhibition of RXR transactivation by 9-cis-RA. More importantly, we found the extent of RXR transactivation inhibition by rhein paralleled with the growth inhibition of A549 when treated with rhein. Together, our results strongly suggest the anticancer effect of rhein is through modulating RXR transactivation.It has been widely showed that rhein has remarkable anticancer activity; however the molecular mechanisms remain largely unknown. Our findings provide the first evidence that rhein can induce apoptosis in A549 lung cancer cells by directly binding RXRαand inhibiting RXRαtrasactivation activity, which warrants us to optimize the leads for new drug development.