Ursolic acid induces human hepatoma cell line SMMC-7721 apoptosis via p53-dependent pathway.
BACKGROUND
Ursolic acid (UA) is a ubiquitous molecule in the plant kingdom with specific anticancer effects that have been shown in vitro and in vivo. Although UA can inhibit the proliferation of liver cancer cells and induce apoptosis of many types of tumor cells, the molecular mechanism of its anti-hepatoma activity is still not well defined. The objective of this study was to investigate the inhibitory effect and mechanisms of UA on the human hepatoma cell line SMMC-7721.


METHODS
After treatment with UA, the growth inhibition of SMMC-7721 cells was assessed by MTT assay. Cells were also evaluated by flow cytometric analysis, Wright-Giemasa staining, Hoechst 33258 staining and transmission electron microscope after they were induced by UA. DNA microarray technology was used to investigate the gene expression pattern of SMMC-7721 cells exposed to UA 40 micromol/L. The molecular mechanism of cells death was analyzed by real-time RT-PCR and Western blotting.


RESULTS
The proliferation of SMMC-7721 cells was significantly inhibited in a dose- and time-dependent manner after UA treatment. UA induced cell cycle arrest and apoptosis. The DNA microarray analysis indicated that 64 genes were found to be markedly up- or down-expressed, including GDF15, SOD2, ATF3, and fos. The result of Western blotting showed the apoptotic proteins p53 and Bax were up-regulated while the anti-apoptotic protein Bcl-2 was down-regulated. Real-time RT-PCR confirmed UA could up-regulate the mRNA expressions of GDF15, SOD2, ATF3 and down-regulate the mRAN expression of fos. Meanwhile these effects were partly blocked by pretreatment with the p53 inhibitor Pft-alpha.


CONCLUSIONS
Activation of the p53 pathway is involved in UA inhibition of SMMC-7721 human hepatocellular carcinoma cell growth and induction of apoptosis.
Yu
Yan-Xia
YX
Soochow Institute of Chinese Materia Medica, Suzhou, Suzhou, Jiangsu 215007, China.
Gu
Zhen-Lun
ZL
Yin
Jiang-Lin
JL
Chou
Wen-Hsien
WH
Kwok
Chi-Yi
CY
Qin
Zheng-Hong
ZH
Liang
Zhong-Qin
ZQ
D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy* / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D005434:Flow Cytometry; D006801:Humans; D008113:Liver Neoplasms / Q000188:drug therapy / Q000378:metabolism; D046529:Microscopy, Electron, Transmission; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects; D014315:Triterpenes / Q000627:therapeutic use*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D000097245:Ursolic Acid
D014315:Triterpenes; D016159:Tumor Suppressor Protein p53; D000097245:Ursolic Acid