cytochrome-c-t and zerumbone

Gastric cancer is one of the leading causes for cancer death. There is an urgent need to develop new therapeutic approaches targeting metastatic gastric cancer. It has been reported that zerumbone has the anti-cancer effects in various malignant cells. However, the effect and the mechanism of zerumbone on melanoma cells is still largely unknown. In the study, we determined the actions of zerumbone on the human gastric cancer cell line SGC-7901.We also observed the mechanism by which zerumbone induced gastric cancer cell apoptosis. Our data indicated that zerumbone significantly inhibited the growth of human gastric cancer cells in a dose-dependent manner and apoptosis was the main cause of decreased cell viability in zerumbone -treated cells. The treatment with zerumbone downregulated Cyp A and Bcl-2 levels, upregulated Bax levels, and caused Cytochrome c (Cyt-C) to release, activating Caspase-3. In summary, our study suggests that zerumbone mightinduced human gastric cancer cells apoptosis through down-regulating Cyp A and mitochondria-mediated pathways.

Topics: Apoptosis; bcl-2-Associated X Protein; Caspase 3; Cell Line, Tumor; Cell Survival; Cyclophilin A; Cytochromes c; Enzyme Activation; Gene Expression Regulation, Neoplastic; Humans; Mitochondria; Sesquiterpenes; Signal Transduction; Stomach Neoplasms

Fluorescent protein based signaling probes are emerging as valuable tools to study cell signaling because of their ability to provide spatio- temporal information in non invasive live cell mode. Previously, multiple fluorescent protein probes were employed to characterize key events of apoptosis in diverse experimental systems. We have employed a live cell image based approach to visualize the key events of apoptosis signaling induced by zerumbone, the active principle from ginger Zingiber zerumbet, in cancer cells that enabled us to analyze prominent apoptotic changes in a hierarchical manner with temporal resolution. Our studies substantiate that mitochondrial permeabilisation and cytochrome c dependent caspase activation dominate in zerumbone induced cell death. Bax activation, the essential and early event of cell death, is independently activated by reactive oxygen species as well as calpains. Zerumbone failed to induce apoptosis or mitochondrial permeabilisation in Bax knockout cells and over-expression of Bax enhanced cell death induced by zerumbone confirming the essential role of Bax for mitochondrial permeabilsation. Simultaneous inhibition of reactive oxygen species and calpain is required for preventing Bax activation and cell death. However, apoptosis induced by zerumbone was prevented in Bcl 2 and Bcl-XL over-expressing cells, whereas more protection was afforded by Bcl 2 specifically targeted to endoplasmic reticulum. Even though zerumbone treatment down-regulated survival proteins such as XIAP, Survivin and Akt, it failed to affect the pro-apoptotic proteins such as PUMA and BIM. Multiple normal diploid cell lines were employed to address cytotoxic activity of zerumbone and, in general, mammary epithelial cells, endothelial progenitor cells and smooth muscle cells were relatively resistant to zerumbone induced cell death with lesser ROS accumulation than cancer cells.

Topics: Apoptosis; bcl-2-Associated X Protein; Calcium; Calpain; Caspases; Cell Line; Chromatin; Cytochromes c; Endoplasmic Reticulum; Enzyme Activation; Humans; Membrane Potential, Mitochondrial; Mitochondria; Permeability; Proto-Oncogene Proteins c-bcl-2; Reactive Oxygen Species; Sesquiterpenes

HSP27 or HSP25 negatively regulates apoptosis pathways after radiation or chemotherapeutic agents. Abrogation of HSP27 function may be a candidate target for overcoming radio- and chemoresistance.. Zerumbone (ZER), a cytotoxic component isolated from Zingiber zerumbet smith. Clonogenic survival assay and flow cytometry after Annexin V staining were performed to determine in vitro sensitization effects of ZER with ionizing radiation. A nude mouse xenografting system was also applied to detect in vivo radiosensitizing effects of ZER.. ZER produced cross-linking of HSP27, which was dependent on inhibition of the monomeric form of HSP27. ZER was directly inserted between the disulfide bond in the HSP27 dimer and modified normal HSP27 dimerization. Pretreatment with ZER before radiation inhibited the binding affinity between HSP27 and apoptotic molecules, such as cytochrome c and PKCδ, and induced sensitization in vitro and in an in vivo xenografted nude mouse system. Structural analogs lacking only the carbonyl group in ZER, such as α-humulene (HUM) and 8-hydroxy-humulen (8-OH-HUM), did not affect normal cross-linking of HSP27 and did not induce radiosensitization.. We suggest that altered cross-linking of HSP27 by ZER is a good strategy for abolishing HSP27-mediated resistance.

Topics: Animals; Blotting, Western; Cell Line, Tumor; Cross-Linking Reagents; Cytochromes c; Electrophoresis, Polyacrylamide Gel; HSP27 Heat-Shock Proteins; Humans; Mass Spectrometry; Mice; Mice, Inbred BALB C; Mice, Nude; Monocyclic Sesquiterpenes; Protein Kinase C-delta; Radiation Tolerance; Radiation-Sensitizing Agents; Sesquiterpenes; Transplantation, Heterologous