Unconjugated
Oridonin, a diterpenoid isolated from Rabdosia rubescencs, has been reported to have antitumor effects. However, low solubility has limited its clinical applications. Preparation of drugs in the form of nanosuspensions is an extensively utilized protocol. In this study, we investigated the anticancer activity of oridonin and oridonin nanosuspension on human pancreatic carcinoma PANC-1 cells. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was performed to investigate the effect of oridonin on cell growth. Propidium iodide and Hoechst 33342 staining were used to detect morphologic changes. The percentage of apoptosis and cell cycle progression was determined by flow cytometric method staining with propidium iodide. Annexin V-fluorescein isothiocyanate (FITC)/PI staining was used to evaluate cell apoptosis by flow cytometry. Caspase-3 activity was measured by spectrophotometry. The apoptotic and cell cycle protein expression were determined by Western blot analysis. Both oridonin and oridonin nanosuspension induced apoptosis and G(2)/M phase cell cycle arrest, and the latter had a more significant cytotoxic effect. The ratio of Bcl-2/Bax protein expression was decreased and caspase- 3 activity was stimulated. The expression of cyclin B1 and p-cdc2 (T161) was suppressed. Our results showed that oridonin nanosuspension was more effective than free oridonin on G(2)/M cell cycle arrest and apoptosis in the human pancreatic cancer PANC-1 cell line.
AIM:
To investigate the effects of 1-oxoeudesm-11(13)eno-12,8a-lactone (OEL), a novel eudesmane-type sesquiterpene isolated from Aster himalaicus, on the cell cycle and apoptosis in human glioblastoma cells in vitro.
METHODS:
Human malignant glioblastoma cell lines U87 and A172 were used. The cytotoxicity of OEL was examined using the MTT assay. Cell apoptosis was assessed with DAPI staining and flow cytometry. DNA damage was determined by measuring the phosphorylation of H2AX using immunofluorescence staining and Western blotting. Cell cycle profiles were measured with flow cytometry. The mRNA expression of p53 and p21Waf1/Cip1 was investigated using real-time PCR. The protein expression of γ-H2AX, caspase-9, caspase-3, p53, p21Waf1/Cip1, cyclin B1, and cdc2 was analyzed with Western blotting.
RESULTS:
Treatment of the malignant glioblastoma cells with OEL inhibited the cell growth in dose- and time-dependent manners (the values of IC(50) at 48 and 72 h were 29.5 and 16.99 μmol/L, respectively, in U87 cells; 7.2 and 9.5 μmol/L, respectively, in A172 cells). OEL (10-30 μmol/L) induced apoptosis and G(2)/M phase arrest in both U87 and A172 cells. OEL induced the phosphorylation of cdc2, a G(2)/M phase cyclin-dependent kinase, and decreased the expression of cyclin B1 required for progression through the G(2)/M phase in U87 cells. The compound remarkably increased the phosphorylation of H2AX in U87 cells. Moreover, OEL increased the mRNA and protein levels of p53 and its target gene p21(Waf1/Cip1) in U87 cells. The compound also induced p53 phosphorylation. Pretreatment with PFT-α, a specific inhibitor of p53 transcriptional activity, could partially reverse the inhibition of OEL on the viability of U87 and A172 cells.
CONCLUSION:
OEL suppresses the growth of human glioblastoma cells in vitro via inducing DNA damage, p53-mediated cell cycle arrest and apoptosis, thus warrants further studies as a lead compound of anti-glioblastoma drug.