Background Gambogic acid (AG) is believed to be a potent anti-cancer agent. ER (endoplasmic reticulum) stress-induced cell apoptosis was identified as one of the anti-proliferative mechanisms of several anti-cancer agents. In this study, we investigated the involvement of ER stress-induced apoptosis in the anti-proliferative effect of GA on NSCLC (non-small cell lung cancer) cells. Material/Methods GA at 0, 0.5, and 1.0 μmol/l was used to treat A549 cells. We also used the ER stress-specific inhibitor 4-PBA (4-phenylbutyric acid) (1 μmol/l) to co-treat the cells incubated with GA. Cell viability was assessed by MTT (methyl thiazolyl tetrazolium) assay. Cell apoptosis was evaluated by MTT (methyl thiazolyl tetrazolium) assay. Intracellular ROS (reactive oxygen species) production was detected by DCFH-DA (2,7- dichloro-dihydrofluorescein diacetate) florescent staining. Western blotting was used to assess the expression and phosphorylation levels of protein. Results GA treatment significantly reduced cell viabilities of NSCLC cells in a concentration-dependent manner. GA treatment increased intracellular ROS level, expression levels of GRP (glucose-regulated protein) 78, CHOP (C/EBP-homologous protein), ATF (activating transcription factor) 6 and caspase 12, as well as the phosphorylation levels of PERK (protein kinase R-like ER kinase) and IRE (inositol-requiring enzyme) 1α. Co-treatment of 4-PBA dramatically impaired the inhibitory effect of GA on cell viability. 4PBA co-treatment also decreased expression levels of GRP78, CHOP, ATF6, and caspase12, as well as the phosphorylation levels of PERK and IRE1α, in GA-treated NSCLC cells, without affecting ROS levels. Conclusions GA inhibited NSCLC cell proliferation by inducing ROS-induced ER stress-medicated apoptosis of NSCLC cells.

BackgroundActivation of Notch signaling was found to be associated with cancer. Gambogic acid (GA) was reported to be an anti-cancer agent. This study investigated the anti-cancer effect of GA on human non-small cell lung cancer (NSCLC) cells. Involvement of the Notch pathway was also studied.Matreial/MethodsGA at 0, 0.5, 0.75, and 1.0 μmol/l was used to incubate A549 and SPC-A1 cells. MTT assay was used to determine the cell viability. TUNEL assay was used to detect the apoptosis. Western blotting was used to evaluate protein expression levels, protein phosphorylation levels, and nuclear translocation levels.ResultsNotch signaling pathway was activated in NSCLC cells. GA treatment significantly inhibited NSCLC cell viability and increased cell apoptosis. GA treatment significantly decreased the expression levels of DLL1, DLL3, DLL4, Jagged1, Jagged2, Bcl2, and PK3K, inhibited NICD nuclear translocation and Akt phosphorylation, and increased expression level of active caspase3.ConclusionsGA inhibited NSCLC cell viability by inducing apoptosis. Inhibition of the Notch signaling pathway was the mechanism involved in the anti-proliferation effect of GA on NSCLC.

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MicroRNAs are small non-coding RNAs that regulate gene expression at the post-transcriptional level which have been reported to be involved in the pathogenesis of various cancers. In the present study, we found that miR-497 was downregulated in osteosarcoma tissues. Gain and loss of function studies were carried out to investigate the e ect of miR-497 on the growth of osteosarcoma cells. e results indicated that miR-497 inhibited the growth of osteosarcoma cells. Furthermore, bioinformatics analysis predicted plexinA4 and CDK6 as targets of miR-497, which was a erward con rmed by luciferase activity assay and rescue experiments. ese ndings suggested that miR-497, plexinA4, and CDK6 may serve as novel potential makers for osteosarcoma diagnostics and therapy.