zerumbone and Carcinoma--Non-Small-Cell-Lung

Lung cancer is the most frequently diagnosed cancer and the leading cause of cancer deaths in the United States and Korea. We have previously demonstrated that osteopontin (OPN) induces cell invasion through inactivating cofilin. Inactivation of cofilin is mediated by the FAK/AKT/Rho-associated kinase (ROCK) pathway in human nonsmall cell lung cancer (NSCLC) cells. Zerumbone (1) has been shown to exert anticancer activities. In this study, whether and how 1 affects OPN-induced cell invasion was determined in NSCLC A549 cells. Results from Boyden chamber assays suggested that OPN induced invasion of A549 cells and that 1 strongly suppressed this activity without affecting cell viability. Compound 1 effectively inhibited OPN-induced protein expression of ROCK1, the phosphorylation of LIM kinase 1 and 2 (LIMK1/2), and cofilin. In addition, immunofluorescence staining showed that OPN caused a significant increase in lamellipodia formation at the leading edge of cells. However, 1 dramatically decreased OPN-induced lamellipodia formation. Compound 1 impaired OPN-induced phosphorylation of FAK and AKT, as determined by Western blot analysis. Taken together, these results suggest that 1 causes considerable suppression of OPN-induced cell invasion through inhibiting the FAK/AKT/ROCK pathway in NSCLC A549 cells.

Topics: Blotting, Western; Carcinoma, Non-Small-Cell Lung; Humans; Molecular Structure; Osteopontin; Phosphorylation; Republic of Korea; rho-Associated Kinases; Sesquiterpenes; Zingiber officinale

p53 signaling plays an important role in cell death. Zerumbone, a natural cyclic sesquiterpene, has shown cytotoxic activity against many cancers. This study was done to investigate the anticancer effects of zerumbone on non-small cell lung cancer (NSCLC) cells and explored the involvement of p53 signaling. Cell viability was assessed by 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium assay. Apoptosis was confirmed by annexin-V/propidium iodide staining and caspase activity assay. Mitochondrial membrane potential (Δφm) and reactive oxygen species (ROS) production were measured by flow cytometry. Depletion of p53 was achieved by transfection of specific small interfering RNA. Gene expression changes were determined by Western blot analysis. Zerumbone treatment caused a dose-dependent inhibition of A549 and H460 NSCLC cell viability. Zerumbone-induced mitochondrial apoptosis of NSCLC cells, evidenced loss of Δφm, release of mitochondrial cytochrome c, and activation of caspase-9 and -3. There was increased p53 and Bax expression and ROS production in zerumbone-treated cells. Downregulation of p53 or scavenging ROS interfered with the pro-apoptotic action of zerumbone. Combinational treatment with zerumbone and cisplatin significantly accelerated apoptosis and promoted p53 expression and ROS production in NSCLC cells, compared with each alone. These findings demonstrate that zerumbone induces mitochondrial apoptosis and enhances the susceptibility to cisplatin in NSCLC cells, which are, at least partially, mediated through activation of p53 signaling and promotion of ROS generation. This study may provide a rationale for the potential clinical application of zerumbone as a chemotherapeutic agent against NSCLC.

Topics: Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Carcinoma, Non-Small-Cell Lung; Cell Line, Tumor; Cisplatin; Drug Synergism; Humans; Lung Neoplasms; Membrane Potential, Mitochondrial; Oxidative Stress; Reactive Oxygen Species; Sesquiterpenes; Signal Transduction; Tumor Suppressor Protein p53