Celastrol inhibits growth and induces apoptotic cell death in melanoma cells via the activation ROS-dependent mitochondrial pathway and the suppression of PI3K/AKT signaling
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Celastrol has been reported to possess anticancer effects in various cancers; however, the precise mechanism underlying ROS-mediated mitochondria-dependent apoptotic cell death triggered by celastrol treatment in melanoma cells remains unknown. We showed that celastrol effectively induced apoptotic cell death and inhibited tumor growth using tissue culture and in vivo models of B16 melanoma. In addition to apoptotic cell death in B16 cells, several apoptotic events such as PARP cleavage and activation of caspase were confirmed. Pretreatment with caspase inhibitor modestly attenuated the celastrol-induced increase in PARP cleavage and sub-G1 cell population, implying that caspases play a partial role in celastrol-induced apoptosis. Moreover, ROS generation was detected following celastrol treatment. Blocking of ROS accumulation with ROS scavengers resulted in inhibition of celastrol-induced Bcl-2 family-mediated apoptosis, indicating that celastrol-induced apoptosis involves ROS generation as well as an increase in the Bax/Bcl-2 ratio leading to release of cytochrome c and AIF. Importantly, silencing of AIF by transfection of siAIF into cells remarkably attenuated celastrol-induced apoptotic cell death. Moreover, celastrol inhibited the activation of PI3K/AKT/mTOR signaling cascade in B16 cells. Our data reveal that celastrol inhibits growth and induces apoptosis in melanoma cells via the activation of ROS-mediated caspase-dependent and -independent pathways and the suppression of PI3K/AKT signaling.
KeywordsCelastrol Reactive oxygen species Apoptosis Apoptosis inducing factor B16 melanoma
This work was supported by National Research Foundation of Korean Grant funded by the Korean Government, Ministry of Education, Science and Technology (NRF-2010-355-F00049).
Conflict of interest
The authors declare that they no conflict of interest.
- 14.Susin SA, Lorenzo HK, Zamzami N, Marzo I, Snow BE, Brothers GM, Mangion J, Jacotot E, Costantini P, Loeffler M, Larochette N, Goodlett DR, Aebersold R, Siderovski DP, Penninger JM, Kroemer G (1999) Molecular characterization of mitochondrial apoptosis-inducing factor. Nature 397:441–446PubMedCrossRefGoogle Scholar
- 24.Kannaiyan R, Manu KA, Chen L, Li F, Rajendran P, Subramaniam A, Lam P, Kumar AP, Sethi G (2011) Celastrol inhibits tumor cell proliferation and promotes apoptosis through the activation of c-Jun N-terminal kinase and suppression of PI3K/Akt signaling pathways. Apoptosis 16:1028–1041PubMedCrossRefGoogle Scholar
- 29.Wan CK, Wang C, Cheung HY, Yang MS, Fong WF (2005) Triptolide induces Bcl-2 cleavage and mitochondria dependent apoptosis in p53-dependent HL-60 cells. Cancer Lett 241:1–11Google Scholar
- 30.Chen CY, Liu TZ, Liu YW, Tseng WC, Liu RH, Lu FJ, Lin YS, Kuo SH, Chen CH (2007) 6-Shogaol (alkanone from ginger) induces apoptotic cell death of human hepatoma p53 mutant Mahlavu subline via an oxidative stress-mediated caspase-dependent mechanism. J Agric Food Chem 55:948–954PubMedCrossRefGoogle Scholar