Objective  This paper aimed to investigate the effects of isocorydinone on cell proliferation in SiHa human cervical carcinoma cell lines.

  Methods  Different concentrations of isocorydione (100, 200, 400, 800, and 1200 μmol/L) were used to treat SiHa human cervical carcinoma cells in vitro for 24, 48, and 72 h. Methyl thiazolyl tetrazolium (MTT) assays were conducted to determine the inhibitory action of isocorydione. Flow cytometry was performed to detect the cell cycle in SiHa human cervical carcinoma cells after treatment with 400 μmol/L isocorydione. Hoechst 33342 staining was used to observe the micro-morphological changes of SiHa cell nucleus after the treatment. The expression of Bcl-2, Bax, and caspase-3 proteins in cervical carcinoma SiHa cell lines was determined using western blot analysis.

  Results  MTT assays showed that isocorydione inhibits the proliferation of SiHa cells in a dose- and time-dependent manner (P < 0.05). The flow cytometry results showed that SiHa cervical carcinoma cells treated with different concentrations of isocorydione exhibited increased cell cycle. Compared with the control group, Hoechst 33342 staining showed that SiHa cells became narrow, with nuclear pyknosis and fragmentation, and formed an apoptotic body after treatment with 400 μmol/L isocorydione for 48 h. Furthermore, western blot analysis proved that isocorydione significantly inhibited the proliferation of SiHa cell lines, and the expression of Bax protein was increased. By contrast, the expression of Bcl-2 protein decreased gradually. Consequently, the ratio of Bax/Bcl-2 increased, as well as the expression of caspase-3 protein.

  Conclusion  Isocorydione exhibited an overt inhibitory action on SiHa cells. Isocorydione promoted the occurrence of cell apoptosis, which may be associated with related proteins of mitochondrial apoptotic pathway.