Su Jui-Hsin 1, 2, Shih Shou-Ping 1, 2, Chen Yu-Cheng 1, 2, Sung Ping-Jyun 1, 2, Lu Mei-Chin 1, 2, Chiu Ching-Wen 3, Wu Yang-Chang 4
1 Graduate Institute of Marine Biology, National Dong Hwa University, Pingtung, Taiwan
2 National Museum of Marine Biology and Aquarium, Pingtung, Taiwan
3 Department of Marine Biotechnology and Resources, National Sun Yat-sen University, Kaohsiung, Taiwan
4 Graduate Institute of Natural Products, Kaohsiung Medical University, Kaohsiung, Taiwan
Bioactivity-guided fractionation of the marine sponge
Aaptos sp. extract led to the isolation of aaptamine (
1), demethyloxyaaptamine (
2) and isoaaptamine (
3). The cytotoxic activity of the isolated compounds (
1-
3) was evaluated revealing that compound
3 was the most potent cytotoxic against breast cancer T47D cells. In a dose dependent manner,
3 inhibited the growth of T47D cells as indicated by the short- (MTT) and long-term (colony formation) assays. The cytotoxic effect of
3 was mediated through apoptosis which was suggested by DNA ladder formation, caspase-7 activation, XIAP inhibition and PARP cleavage. Furthermore, TEM and flow cytometric analysis using acridine orange dye indicated that that
3 treatment could induce t-47D cells autophagy. Immunoblot assays demonstrated that
3 treatment significantly activated autophagy marker proteins such as the increase in Type II LC-3. In addition,
3 treatment enhanced the activation of DNA damage (γH2AX) and ER stress-related proteins (IRE1αand BiP). Moreover, the use of
3 resulted in a significant increase in the generation of reactive oxygen species (ROS) as well as in the disruption of mitochondrial membrane potential (MMP). The pretreatment of t-47D cells with an ROS scavenger, NAC, attenuated apoptosis- and MMP disruption-induced by
3 up to 90%.Taken together, these findings suggest that the anticancer effect of
3 is associated with the induction of apoptosis and autophagy through oxidative stress. Accordingly, our data indicated that
3 exhibited as an outstanding lead for the development of marine derived anti-breast cancer agent.
