Abstract
Pseudolaric acid B (PAB) is a diterpene acid isolated from the bark of the root and trunk of Pseudolarix kaempferi Gordon (Pinaceae), which has demonstrated cytotoxic effects against various types of cancer. However, the mechanisms underlying the anticancer effects of PAB have remained to be elucidated. In the present study, the effects of PAB on the viability and apoptosis of HeLa cells were investigated by MTT assay, flow cytometric analysis of Annexin V-fluorescein isothiocyanate/propidium iodide staining, Rhodamine 123 staining and western blot analysis. The results demonstrated that PAB had antiproliferative and apoptosis-inducing effects on HeLa cells. PAB markedly inhibited HeLa cell viability in a time- and concentration-dependent manner. Flow cytometric analysis indicated that PAB induced apoptosis in HeLa cells in a dose-dependent manner. Treatment with PAB suppressed the expression of anti-apoptotic factor B cell lymphoma-2, and promoted the expression of pro-apoptotic factor Bcl-2-associated X protein. In addition, PAB induced an increase in Caspase-3 activity and loss of mitochondrial membrane potential, suggesting that this apoptosis may be mediated by mitochondrial pathways. Furthermore, the results of western blot analysis indicated that PAB was able to reduce Akt phosphorylation, thereby inhibiting the Akt pathway. These results suggested that PAB inhibited cell proliferation and induced apoptosis in HeLa cells, and that the anti-tumor effects of PAB were associated with inhibition of the Akt pathway. In conclusion, the results of the present study suggested that PAB may represent a novel therapeutic strategy for the treatment of human cervical cancer. However, additional studies are required to investigate the underlying apoptotic mechanisms.