Effects of diterpenoid pekinenal of Euphorbia pekinensis Rupr. on proliferation, cell cycle and apoptosis of hepatoma cells

Aims: To study the effects of diterpenoid pekinenal of Euphorbia pekinensis Rupr. on cell proliferation, cell cycle phase and apoptosis of hepatoma SMMC-7721 cells and to probe into its anti-cancer mechanisms. Methods: MTT assay was used to investigate the effect of pekinenal on proliferation of SMMC-7721 cells; TUNEL method, Annexin V/PI staining and electron microscopy were employed to observe the cell apoptosis; Flow cytometry was applied to analyze the distribution of cell cycle. Results: Proliferation of SMMC-7721 cells was markedly inhibited by pekinenal in a dose-dependent manner; Annexin V/PI staining showed that with the increase of pekinenal concentration, apoptotic rate of SMMC-7721 cells increased significantly, compared with control group, the difference has significant statistical significance ( P < 0.01 ). TUNEL method test results showed that different concentrations of pekinenal in SMMC-7721 cells could induce liver cancer cell apoptotic and apoptotic index (AI) increased significantly (P< 0.01) with the increase of drug concentration. Compared with control group, electron microscope found that after the treatment, hepatocyte mitochondrial swelling, endoplasmic reticulum expansion, cytoplasm inclusion body formation , part of the nucleus apoptosis, and the more obvious apoptosis appeared with the increase of drug concentration. Flow cytometry analysis showed that different concentrations of pekinenal could all make the cell block in S phase. Conclusion: Pekinenal has an obviously inhibitory effect on the human liver cancer cells, and there is significant concentration dependence; Pekinenal probably inhibits cancer cell DNA synthesis for the human liver cell cycle arrest in S phase and inhibits the proliferation . It plays a role in liver cancer inhibition by inducing liver cancer cells apoptosis, etc.