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.
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.
Department of Food and Nutrition, Sunchon National University, Jungangno, Suncheon, Jeonnam 540-742, Republic of Korea.
Ju-Hye
JH
Lee
Yeong-Seon
YS
Won
Ki-Hun
KH
Park
Mi-Kyung
MK
Lee
Hirofumi
H
Tachibana
Koji
K
Yamada
Kwon-Il
KI
Seo
D017209:Apoptosis / Q000187:drug effects*; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D015536:Down-Regulation / Q000187:drug effects; D006801:Humans; D008545:Melanoma / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology*; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism; D053978:Pentacyclic Triterpenes; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D014315:Triterpenes / Q000494:pharmacology*
D053978:Pentacyclic Triterpenes; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D019253:Proto-Oncogene Proteins c-bcl-2; D017382:Reactive Oxygen Species; D014315:Triterpenes; C050414:celastrol