Upregulating Noxa by ER stress, celastrol exerts synergistic anti-cancer activity in combination with ABT-737 in human hepatocellular carcinoma cells.

Autor: Hong Zhu, Wei Yang, Ling-juan He, Wan-jing Ding, Lin Zheng, Si-da Liao, Ping Huang, Wei Lu, Qiao-jun He, Bo Yang
Jazyk: angličtina
Rok vydání: 2012
Předmět:
Zdroj: PLoS ONE, Vol 7, Iss 12, p e52333 (2012)
Druh dokumentu: article
ISSN: 1932-6203
DOI: 10.1371/journal.pone.0052333
Popis: The human hepatocellular carcinoma (HCC) represents biologically aggressive and chemo-resistant cancers. Owing to the low affinity with the apoptotic factor Mcl-1, the BH3 mimetic drug ABT-737 failed to exert potent cancer-killing activities in variety of cancer models including HCC. The current study demonstrated that combining ABT-737 and Celastrol synergistically suppressed HCC cell proliferation, and induced apoptosis which was accompanied with the activation of caspase cascade and release of cytochrome c from mitochondria. Further study revealed that the enhanced Noxa caused by Celastrol was the key factor for the synergy, since small interfering RNA-mediated knockdown of Noxa expression in HCC cells resulted in decreased apoptosis and attenuated anti-proliferative effects of the combination. In addition, our study unraveled that, upon Celastrol exposure, the activation of endoplasmic reticulum (ER) stress, specifically, the eIF2α-ATF4 pathway played indispensable roles in the activation of Noxa, which was validated by the observation that depletion of ATF4 significantly abrogated the Noxa elevation by Celastrol. Our findings highlight a novel signaling pathway through which Celastrol increase Noxa expression, and suggest the potential use of ATF4-mediated regulation of Noxa as a promising strategy to improve the anti-cancer activities of ABT-737.
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