Taxol produced from endophytic fungi induces apoptosis in human breast, cervical and ovarian cancer cells

Abstract

Currently, taxol is mainly extracted from the bark of yews; however, this method can not meet its increasing demand on the market because yews grow very slowly and are a rare and endangered species belonging to firstlevel conservation plants. Recently, increasing efforts have been made to develop alternative means of taxol production; microbe fermentation would be a very promising method to increase the production scale of taxol. To determine the activities of the taxol extracted from endophytic fungus N. sylviforme HDFS4-26 in inhibiting the growth and causing the apoptosis of cancer cells, on comparison with the taxol extracted from the bark of yew, we used cellular morphology, cell counting kit (CCK-8) assay, staining (HO33258/PI and Giemsa), DNA agarose gel electrophoresis and flow cytometry (FCM) analyses to determine the apoptosis status of breast cancer MCF-7 cells, cervical cancer HeLa cells and ovarian cancer HO8910 cells. Our results showed that the fungal taxol inhibited the growth of MCF-7, HeLa and HO8910 cells in a dose-and time-dependent manner. IC50 values of fungal taxol for HeLa, MCF-7 and HO8910 cells were 0.1-1.0 μg/ml, 0.001-0.01 μg/ml and 0.01- 0.1 μg/ml, respectively. The fungal taxol induced these tumor cells to undergo apoptosis with typical apoptotic characteristics, including morphological changes for chromatin condensation, chromatin crescent formation, nucleus fragmentation, apoptotic body formation and G2/M cell cycle arrest. The fungal taxol at the 0.01-1.0 μg/ ml had significant effects of inducing apoptosis between 24-48 h, which was the same as that of taxol extracted from yews. This study offers important information and a new resource for the production of an important anticancer drug by endofungus fermentation.