Abstract Number: 2979 Saponin Polyphyllin D induced apoptosis in human hepatocellular carcinoma and multidrug resistant liver cancer cells Rose C. Y. Ong, Jenny Y. N. Cheung, Henry N. C. Wong, Thomas C. W. Mak, S. K. Kong, Biao Yu, K. P. Fung. CUHK, Hong Kong, China and Chinese Academy of China, Shanghai, China. Saponins are the active components of many medicinal herbs such as Panax ginseng. Polyphyllin D (Figure 1) is a steroidal saponin present in the plant Paris Pollyphylla which has been used in China to treat cancer for many years. As the isolation and purification of saponins from plants had been very difficult, Polyphyllin D was chemically synthesized and purified. By using this synthesized Polyphyllin D, its apoptotic effects in a human hepatocellular carcinoma cell line HepG2 and its doxorubicin resistant derivative RHepG2 cells (with an over-expression of P-glycoprotein) were investigated. As compared to the commonly used anticancer drug doxorubicin (DOX), the IC50 of Polyphyllin D and that of DOX were more or less the same in HepG2 cells after 24 hours treatment (~6ìM). However, the IC50 of Polyphyllin D in RHepG2 cells was 5ìM, and that of DOX was higher than 250ìM. Hallmarks of apoptosis, including externalization of phosphatidylserine, DNA ladder and chromatin condensation were observed in both cell lines after 24 hours treatment with 5ìM Polyphyllin D. Further studies showed that Polyphyllin D induced apoptosis through mitochondrial dysfunction, as evidenced by mitochondrial depolarization and release of cytochrome c, a key protein in mitochondria mediated apoptosis. To demonstrate its direct effects on mitochondria, mitochondria from HepG2 and RHepG2 cells were isolated and treated with Polyphyllin D. Mitochondrial depolarization and cytochrome c release from the isolated mitochondria were again observed. Thus, Polyphyllin D acts directly on mitochondria to cause apoptosis. Furthermore, in a 12 day-treatment of RHepG2 cells with 1.2ìM Polyphyllin D, 27% of cells accumulated more DOX when compared to that of an untreated group. Preliminary assay by Western blot showed that P-glycoprotein expression was down-regulated too. Conclusively, Polyphyllin D is a potent anticancer agent or mitochondrial toxin against "normal" and drug-resistant cancer cells which acts on the mitochondria to trigger apoptosis in HepG2 and RHepG2 cells. More work is needed to confirm its effects in P-glycoprotein expression and the corresponding action mechanism. This work is supported by the Shanghai-Hong Kong Anson Research Foundation. Presenter: Rose C.Y. Ong Affiliation: CUHK, Hong Kong, China; E-mail: rose_ongcy@yahoo.com.hk Proceedings of the AACR, Volume 45, March 2004. Abstract # 2983 AACR, 3/04 Remember we are NOT Doctors and have NO medical training. This site is like an Encylopedia - there are many pages, many links on many topics. Support our work with any size DONATION - see left side of any page - for how to donate. You can help raise awareness of CAM.