G. Bounda, F. Yu, W. Zhou, D. Wang; China Pharmaceutical University, Nanjing, China

BACKGROUND: Rhein (4, 5-dihydroxyanthraquinone-2-carboxylic acid) is a natural anthraquinone molecule enriched in the rhizome of Polygonum multiflorum, a traditional Chinese medicine herb with the abilities of pharmacological effect such as anti-tumor, antibacterial, anti-inflammation and anti-aging. However, liver injuries induced by Polygonum multiflorum have been raising serious concerns in recent years, and the mechanisms are still not fully elucidated.
OBJECTIVE: The aim of this study was to assess rhein-induced apoptosis and to investigate its molecular mechanisms in primary human hepatic cells.
METHODS: The cell viability of L-02 (HL-7702) cells treated with different rhein concentrations showed significant decrease in dose-dependent manner. After exposure cells to rhein (25μM, 50μM, 100μM) for 12 h, the detection of apoptotic cells were significantly analyzed by flow cytometry analysis and nuclear morphological changes by Hoechst 33258 staining, respectively.
RESULTS: Caspase activities expressed significant up-regulation of caspase-3, -9 and -8. Moreover, overproduction of reactive oxygen species and the loss of mitochondrial membrane potential were detected by fluorometry (p<0.001). Furthermore, real-time qPCR results showed significant up-regulation of p53 and PUMA mRNA, with no significant changes of Fas and cytochrome c. Western blotting study revealed significant cytochrome c release from mitochondria into cytosol, and no change in Fas expression.
CONCLUSION: Taken together, these observations suggested that rhein could induce apoptosis in L-02 (HL-7702) cells via mitochondria-mediated signal pathway but not through Fas death-receptor-dependent apoptotic pathway.