5-demethylnobiletin and Lung-Neoplasms

Lung cancer remains a highly prevalent disease and a leading cause of cancer-related deaths worldwide. Currently, exploring antitumor drugs derived from herbs used in traditional Chinese medicine is increasingly becoming an attractive area of research. Paclitaxel (PTX), a highly effective chemotherapeutic drug, is widely used for treating different cancers; however, the clinical use of PTX is dose limited because of its adverse side effects. Chemotherapeutic agents are being developed to enhance the anticancer activity of PTX, particularly for use in combination therapy. 5-Demethylnobiletin (5-DMN), a natural, active compound isolated from orange peel, has been reported to induce apoptosis in several cancer cell lines. In this study, we tested the synergistic anticancer antiproliferative effects of combinations of PTX and 5-DMN on CL1-5 lung cancer cells through the MTT and propidium iodide assays. After low-dose combination treatments (PTX and 5-DMN), a reduction in cell viability and a concomitant increase in apoptosis were observed in the CL1-5 cells. We propose that 5-DMN cooperates with PTX to induce apoptosis via the caspase pathway (by modulating caspase-3, caspase-8, and caspase-9 activities). Furthermore, we observed that the combination treatment significantly suppressed tumor growth in the nude mouse xenograft model. The results suggest that the synergistic effects of PTX and 5-DMN in lung cancer cells deserve particular attention and indicate the possibility of developing additional new strategies for treating lung cancer.

Topics: Animals; Antineoplastic Agents; Apoptosis; Caspases; Cell Cycle; Cell Line, Tumor; Cell Proliferation; Cell Survival; Drug Synergism; Flavones; Humans; Lung Neoplasms; Mice; Paclitaxel; Xenograft Model Antitumor Assays

Topics: A549 Cells; Animals; Antineoplastic Combined Chemotherapy Protocols; Cell Survival; Cetuximab; Drug Delivery Systems; Drug Liberation; Drug Synergism; Female; Flavones; Humans; Lipids; Lung Neoplasms; Mice, Inbred BALB C; Mice, Nude; Nanostructures; Paclitaxel; Particle Size; Tissue Distribution

5-Demethylnobiletin (5DN) is a unique citrus flavonoid with various beneficial bioactivities. In this study, we determined the inhibitory effects of 5DN and its two major metabolites in the 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced lung tumorigenesis mouse model as well as in human and mouse lung cancer cell models. In NNK-treated female A/J mice, dietary administration of 5DN (0.025% or 0.05% w/w in the diet) significantly decreased both lung tumor multiplicity and tumor volume. Immunohistochemical analysis showed strong anti-proliferative effects of 5DN in lung tumors. Two major metabolites of 5DN, named 5,3'-didemethylnobiletin (M1) and 5,4'-didemethylnobiletin (M2), were found in the lung tissue of 5DN-fed mice. Cell culture studies demonstrated that 5DN, M1 and M2 significantly inhibited the growth of human and mouse lung cancer cells by causing cell cycle arrest, inducing apoptosis and modulating key signaling proteins related to cell proliferation and cell death. Interestingly, the metabolites of 5DN, especially M1 produced much stronger inhibitory effects on both human and mouse lung cancer cells than those produced by 5DN itself. Our results demonstrated that dietary administration of 5DN significantly inhibited NNK-induced tumorigenesis in mice, and this effect may be partially associated with the metabolites of 5DN in lung tissues.

Topics: Animals; Anticarcinogenic Agents; Apoptosis; Carcinogenesis; Carcinogens; Citrus; Female; Flavones; Humans; Lung; Lung Neoplasms; Mice; Nitrosamines; Tobacco Products

5-Demethylnobiletin is a unique flavonoid found in citrus fruits with potential chemopreventive effects against human cancers. We previously identified three metabolites of 5DN, namely 5,4'-didemethylnobiletin (M1), 5,3',4'- tridemethylnobiletin (M2), and 5,3'-didemethylnobiletin (M3) in mice fed 5DN. Herein, we investigated the inhibitory effects of these three metabolites on NSCLC cells. Our results demonstrated that M1, M2, and especially M3 showed stronger inhibition on the growth and colony formation of H460 and H1299 cells compared to 5DN. Three metabolites significantly inhibited the tumorsphere formation of A549 cells. Flow cytometry analysis showed that all metabolites induced cell cycle arrest and cellular apoptosis, and these effects were also stronger than that of 5DN. The inhibitory effects of these metabolites were associated with their ability to modulate the key signaling proteins related to cell proliferation and apoptosis. Overall, our results provided a basis for utilizing 5DN and its metabolites for chemoprevention of lung cancer.

Topics: Animals; Apoptosis; Carcinoma, Non-Small-Cell Lung; Cell Cycle Checkpoints; Cell Line, Tumor; Cell Proliferation; Citrus; Flavones; Humans; Lung Neoplasms; Mice; Plant Extracts

5-Demethylnobiletin is a hydroxylated polymethoxyflavone found in citrus plants that shows antiproliferative activities in several cancer cell lines. In this study, we investigated the effects and underlying molecular mechanisms of 5-demethylnobiletin on inhibition of cell growth, apoptosis, cell cycle and autophagy in A549 and CL1-5 lung cancer cells. The results of the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay suggested that 5-demethylnobiletin inhibited cell growth in a dose- and time-dependent manner. Flow cytometry results suggested that 5-demethylnobiletin inhibited proliferation in lung cancer cells by inducing G2/M cell cycle phase arrest but predominantly not through apoptosis. Western blot results illustrated that the blockade of the cell cycle was associated with reduced levels of cdc25 and cdc2. Notably, our results indicated that 5-demethylnobiletin induced significant abnormal microtubule dynamics in A549 and CL1-5 cells, a novel finding. Studies conducted with isolated tubulin and docking models suggest that 5-demethylnobiletin promoted the polymerization of microtubules and bound to the taxol site. Additionally, 5-demethylnobiletin might also induce autophagy via activation of the JNK signaling pathway in A549 and CL1-5 cells. Pretreatment of the cells with the autophagy inhibitor 3-methyladenine significantly potentiated 5-demethylnobiletin-induced apoptosis, suggesting that 5-demethylnobiletin-induced autophagy mitigated cell apoptosis. Further investigation revealed that 5-demethylnobiletin inhibition of CL1-5 lung cancer cell growth was reproducible in a nude mouse model. Taken together, these studies suggest that 5-demethylnobiletin has anti-lung cancer efficacy both in vitro and in vivo possibly through induction of G2/M arrest, autophagy and apoptosis.

Topics: Autophagy; Cell Division; Cell Line, Tumor; DNA Damage; Flavones; G2 Phase; Humans; Lung Neoplasms; Polymerization; Tubulin