Ent-11α-Hydroxy-15-oxo-kaur-16-en-19-oic-acid Inhibits Growth of Human Lung Cancer A549 Cells by Arresting Cell Cycle and Triggering Apoptosis.
OBJECTIVE
To examine the apoptotic effect of ent-11α-hydroxy-15-oxo-kaur-16-en-19-oic-acid (5F), a compound isolated from Pteris semipinnata L (PsL), in human lung cancer A549 cells.


METHODS
A549 cells were treated with 5F (0-80 μg/ml) for different time periods. Cytotoxicity was examined using a MTT method. Cell cycle was examined using propidium iodide staining. Apoptosis was examined using Hoechst 33258 staining, enzyme-linked immunosorbent assay (ELISA) and caspase-3 activity analysis. Expression of representative apoptosis-related proteins was evaluated by Western blot analysis. Reactive oxygen species (ROS) level was measured using standard protocols. Potential interaction of 5F with cisplatin was also examined.


RESULTS
5F inhibited the proliferation of A549 cells in a concentration- and time-dependent manner. 5F increased the accumulation of cells in sub-G1 phase and arrested the cells in the G2 phase. Exposure to 5F induced morphological changes and DNA fragmentation that are characteristic of apoptosis. The expression of p21 was increased. 5F exposure also increased Bax expression, release of cytochrome c and apoptosis inducing factor (AIF), and activation of caspase-3. 5F significantly sensitized the cells to cisplatin toxicity. Interestingly, treatment with 5F did not increase ROS, but reduced ROS production induced by cisplatin.


CONCLUSIONS
5F could inhibit the proliferation of A549 cells by arresting the cells in G2 phase and by inducing mitochondrial-mediated apoptosis.
Guangdong Key Laboratory for Research and Development of Natural Drugs, Guangdong Medical College, Zhanjiang 524023, China.
Li
L
Li
George G
GG
Chen
Ying-Nian
YN
Lu
Yi
Y
Liu
Ke-Feng
KF
Wu
Xian-Ling
XL
Gong
Zhan-Ping
ZP
Gou
Ming-Yue
MY
Li
Nian-Ci
NC
Liang
Apoptosis; G2 cell cycle arrest; Lung cancer; Pteris semipinnata L; Reactive oxygen species