ABL-N-induced apoptosis in human breast cancer cells is partially mediated by c-Jun NH2-terminal kinase activation.
BACKGROUND
The present study was designed to determine the possibility of acetylbritannilactone (ABL) derivative 5-(5-(ethylperoxy)pentan-2-yl)-6-methyl-3-methylene-2-oxo-2,3,3a,4,7,7a-hexahydrobenzofuran-4-yl 2-(6-methoxynaphthalen-2-yl)propanoate (ABL-N) as a novel therapeutic agent in human breast cancers.


METHODS
We investigated the effects of ABL-N on the induction of apoptosis in human breast cancer cells and further examined the underlying mechanisms. Moreover, tumor growth inhibition of ABL-N was done in xenograft models.


RESULTS
ABL-N induced the activation of caspase-3 in estrogen receptor (ER)-negative cell lines MDA-MB-231 and MDA-MB-468, as evidenced by the cleavage of endogenous substrate Poly (ADP-ribose) polymerase (PARP). Pretreatment of cells with pan-caspase inhibitor z-VAD-fmk or caspase-3-specific inhibitor z-DEVD-fmk inhibited ABL-N-induced apoptosis. ABL-N treatment also resulted in an increase in the expression of pro-apoptotic members (Bax and Bad) with a concomitant decrease in Bcl-2. Furthermore, c-Jun-NH2-terminal kinase (JNK) and p38 mitogen-activated protein (MAP) kinase (p38) were activated in the apoptosis induced by ABL-N and JNK-specific inhibitor SP600125 and JNK small interfering RNA (siRNA) antagonized ABL-N-mediated apoptosis. However, the p38-specific inhibitor SB203580 had no effect upon these processes. Moreover, neither of the caspase inhibitors prevented ABL-N-induced JNK activation, indicating that JNK is upstream of caspases in ABL-N-initiated apoptosis. Additionally, in a nude mice xenograft experiment, ABL-N significantly inhibited the tumor growth of MDA-MB-231 cells.


CONCLUSIONS
ABL-N induces apoptosis in breast cancer cells through the activation of caspases and JNK signaling pathways. Moreover, ABL-N treatment causes a significant inhibition of tumor growth in vivo. Therefore, it is thought that ABL-N might be a potential drug for use in breast cancer prevention and intervention.
Liu
Bin
B
Department of Biochemistry and Molecular Biology, Institute of Basic Medicine, Hebei Medical University, No,361, Zhongshan East Road, Shijiazhuang, 050017, China.
Han
Mei
M
Sun
Rong-Hua
RH
Wang
Jun-Jie
JJ
Zhang
Yan-Ping
YP
Zhang
Di-Qun
DQ
Wen
Jin-Kun
JK
D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000473:pathology; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004789:Enzyme Activation; D005260:Female; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000502:physiology*; D007783:Lactones / Q000494:pharmacology; D051379:Mice; D008807:Mice, Inbred BALB C; D009281:Naphthalenes / Q000494:pharmacology*; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D012717:Sesquiterpenes / Q000494:pharmacology*; D023041:Xenograft Model Antitumor Assays; D048051:p38 Mitogen-Activated Protein Kinases / Q000502:physiology
C551742:5-(5-(ethylperoxy)pentan-2-yl)-6-methyl-3-methylene-2-oxo-2,3,3a,4,7,7a-hexahydrobenzofuran-4-yl 2-(6-methoxynaphthalen-2-yl)propanoate; D000970:Antineoplastic Agents; D061945:Caspase Inhibitors; D007783:Lactones; D009281:Naphthalenes; D012717:Sesquiterpenes; C487680:acetylbritannilatone; D011065:Poly(ADP-ribose) Polymerases; D048031:JNK Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D020169:Caspases