Sinulariolide induced hepatocellular carcinoma apoptosis through activation of mitochondrial-related apoptotic and PERK/eIF2α/ATF4/CHOP pathway.

Abstract

Sinulariolide, an active compound isolated from the cultured soft coral Sinularia flexibilis, has potent anti-microbial and anti-tumorigenesis effects towards melanoma and bladder cancer cells. In this study, we investigated the effects of sinulariolide on hepatocellular carcinoma (HCC) cell growth and protein expression. Sinulariolide suppressed the proliferation and colony formation of HCC HA22T cells in a dose-dependent manner and induced both early and late apoptosis according to flow cytometry, Annexin V/PI stain and TUNEL/DAPI stain analyses. A mechanistic analysis demonstrated that sinulariolide-induced apoptosis was activated through a mitochondria-related pathway, showing up-regulation of Bax, Bad and AIF, and down- regulation of Bcl-2, Bcl-xL, MCl-1 and p-Bad. Sinulariolide treatment led to loss of the mitochondrial membrane potential, release of mitochondrial cytochrome c to the cytosol, and activation of both caspase-9 and caspase-3. Sinulariolide-induced apoptosis was significantly blocked by the caspase inhibitors Z-VAD-FMK and Z-DEVD-FMK. The increased expression of cleaved PARP also suggested that caspase-independent apoptotic pathway was involved. In the western blotting; the elevation of ER chaperones GRP78; GRP94; and CALR; as well as up-regulations of PERK/eIF2α/ATF4/CHOP; and diminished cell death with pre-treatment of eIF2α phosphatase inhibitor; salubrinal; implicated the involvement of ER stress-mediated PERK/eIF2α/ATF4/CHOP apoptotic pathway following sinulariolide treatment in hepatoma cells. The current study suggested sinulariolide-induced hepatoma cell cytotoxicity involved multiple apoptotic signal pathways. This may implicate that sinulariolide is a potential compound for the treatment of hepatocellular carcinoma.

• Authors: Yi-Jen Chen, Jui-Hsin Su, Chia-Yu Tsao, Chun-Tzu Hung, Hsiang-Hao Chao, Jen-Jie Lin, Ming-Hui Liao, Zih-Yan Yang, Han Hisang Huang, Feng-Jen Tsai, Shun-Hsiang Weng, Yu-Jen Wu
• Journal: Molecules (Basel, Switzerland) (Molecules) Vol. 18 Issue 9 Pg. 10146-61 (Aug 22 2013) ISSN: 1420-3049 [Electronic] Switzerland
• PMID: 23973991 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• ATF4 protein, human
• Antineoplastic Agents
• DDIT3 protein, human
• Diterpenes
• Endoplasmic Reticulum Chaperone BiP
• Eukaryotic Initiation Factor-2
• HSPA5 protein, human
• Activating Transcription Factor 4
• Transcription Factor CHOP
• sinulariolide
• Extracellular Signal-Regulated MAP Kinases
• Caspases

Topics

• Activating Transcription Factor 4 (metabolism)
• Antineoplastic Agents (pharmacology)
• Apoptosis (drug effects)
• Carcinoma, Hepatocellular
• Caspases (metabolism)
• Cell Survival (drug effects)
• Diterpenes (pharmacology)
• Drug Screening Assays, Antitumor
• Endoplasmic Reticulum Chaperone BiP
• Endoplasmic Reticulum Stress (drug effects)
• Eukaryotic Initiation Factor-2 (metabolism)
• Extracellular Signal-Regulated MAP Kinases (metabolism)
• Hep G2 Cells
• Humans
• Inhibitory Concentration 50
• Liver Neoplasms
• MAP Kinase Signaling System
• Membrane Potential, Mitochondrial (drug effects)
• Mitochondria (drug effects, metabolism)
• Transcription Factor CHOP (metabolism)