Effects Of Emodin On Apoptosis And Expression Of AIF、and EndoG In Transplanted Tumor Of Hepatocarcinoma Cell In Nude Mice

Backgroud and object:Primary liver cancer is one of the most common malignancies.It is reported that about1million cases are diagnosed each year around the world. With the characteristics of high malignant degree, short survival time and difficult to treat, although liver cancer surgery and intervention chemotherapy get improved, The curative effect of liver cancer is still not satisfied. It is urgent to find out a kind of new effective chemotherapy with low drug toxicity. Emodin, a natural anthraquinone,has been reported to possess antitumor effects in many cancer cell lines including human hepatocellular carcinoma (HCC). further studys found emodin could induce tumor cell apoptosis via Caspase-dependent signaling pathway. However,Our previous studies have found that emodin could increase the intracellular expression and nuclear translocation of apoptosis inducing factor (AIF) and endonuclease G(EndoG) in HepG2cells and SMMC-7721cells. Moreover, inhibitor of caspases (Z-VAD-FMK) can not blocked emodin-induced apoptosis in vitro. These results suggest that the emodin could induce human liver cancer cells apoptosis via a Caspases-independent mitochondrial pathway in vitro. In this study, we investigated whether emodin could exhibit similar anti-cancer effects on hepatocellular cancer in vivo.Methods:The subcutaneously transplanted tumor model of human SMMC-7721cells in nude mice was established.After continuously intraperitoneal injection with different doses of Emodin for14d, the mice were sacrificed. Then the tumor volume were measured and the tumor inhibition rate was calculated. Each group of tumor cells apoptosis were tested by Terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling(TUNEL) assay and the rate of apoptosis were calculated. Detect the expression of AIF and EndoG by Immunohistochemistry respectively, and distribution by immunofluorescence detection.Results:The tumor volumes were significantly smaller in the low-, moderate-, and high-dose Emodin-treated groups(0.86±0.08,0.58±0.12,0.38±0.09) than that in the untreated group(1.37±0.14) and the apoptosis rates(8.23±1.65,34.38±8.73,48.14±9.57,68.71±10.56) was significantly higher. As the effects of increasing doses of Emodin, the expression of AIF, Endo-G protein in tumor tissue increased. Immunofluorescence demonstrated that the location of AIF and EndoG in the tumor has changed obviously in different dose Emodin-treated group. The effect occurred in a dose-and time-dependent manner.But these changes was not significant in untreated group.Conclusions:1.Emodin significantly suppresses the growth of SMMC-7721cells in nude mice with a dose dependent manner.This inhibitory effect is achieved by inducing apoptosis.2.Via the AIF, EndoG mediated Caspase-independent mitochondrial pathway may be one of the mechianism of emodin-induced apoptosis in transplanted tumor of human hepatoma SMMC-7721cells.