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Context: Lung cancer, the most common type of cancer, has a high mortality rate. Cucurbitacin B (CuB), a natural compound extracted from Cucurbitaceae plants, has antitumor effects. Objective: We investigated the role of CuB on lung cancer and its potential mechanisms. Materials and methods: A549 cells were treated with 0.1, 0.3, 0.6, and 0.9 lM CuB for 12, 24, and 48 h or untreated. Gene and protein levels were evaluated by quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting. Enzyme-linked immunosorbent assay (ELISA) detected inflammatory factors levels (TNF-a and IL-10). 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), flow cytometry, and colony formation assays measured cell viability, apoptosis, and proliferation. The interaction between miR-let-7c and long non-coding RNA X inactive-specific transcript (XIST) or interleukin-6 (IL-6) was verified by dual-luciferase reporter assays. Results: CuB treatment inhibited the proliferation of lung cancer cells and promoted cell apoptosis, and increased the expression of Bax and cleaved caspase3, decreased cyclin B1 and Bcl-2 expression. CuB suppressed XIST and IL-6 expression, and enhanced miR-let-7c expression. XIST silencing enhanced the inhibitory effect of CuB on cell proliferation and the promotion effect on apoptosis via upregulating miR-let-7c. Moreover, XIST targeted miR-let-7c to activate the IL-6/STAT axis. MiR-let-7c overexpression enhanced the regulatory effect of CuB on proliferation and apoptosis via suppressing the IL-6/STAT3 pathway. Discussion and conclusion: CuB regulated cell proliferation and apoptosis by inhibiting the XIST/miR-let-7c/IL-6/STAT3 axis in lung cancer. These findings indicate CuB may have the possibility of clinical application in lung cancer treatment. [ABSTRACT FROM AUTHOR]

Cordycepin is an active component of the traditional Chinese medicine Cordyceps sinensis and Cordyceps militaris with notable anticancer activity. Though the prominent inhibitory activity was reported in different kinds of cancer cell lines, the concrete mechanisms remain elusive. It was reported that cordycepin could be converted into tri-phosphates in vivo to confuse a number of enzymes and interfere the normal cell function. For the inhibitory mechanism of EGFR inhibitors and the structure similarity of ATP and tri-phosphated cordycepin, human lung cancer cell line H1975 was employed to investigate the inhibitory effect of cordycepin. The results showed that cordycepin could inhibit cell proliferation and induce apoptosis in a dose-dependent manner. Cell cycle analysis revealed that H1975 cells could be arrested at the G0/G1 phase after cordycepin treatment. The expression levels of apoptosis-related protein Caspase-3 and Bcl-2 and phosphorylated expression levels of EGFR, AKT and ERK1/2 were all decreased compared with the control group stimulated with EGF. However, the protein expression levels of proapoptotic protein Bax and cleaved caspase-3 were increased. These results implied that cordycepin could inhibit cell proliferation and induce apoptosis via the EGFR signaling pathway. Our results indicated that there was potential to seek a novel EGFR inhibitor from cordycepin and its chemical derivatives. [ABSTRACT FROM AUTHOR]

Aim: To provide experimental data for further research on the signal transduction of apoptosis in lung adenocarcinoma cells, we examined the effects of exogenous C2-ceramide administration on several members of the mitogen-activated protein kinase (MAPK) superfamily and caspase-3 in A549 cells. Methods: Cell viability and apoptosis were analyzed by cell counting kit-8 assay and flow cytometry. Various MAPK and caspase-3 proteins were detected by Western blotting. Results: C2-ceramide selectively altered the phosphorylation state of members of the MAPK superfamily, causing hyperphosphorylation of mitogen-activated protein kinase kinase (MEK) 1/2 and the p38 MAPK, but not affecting the phosphorylation of extracellular signal-regulated kinase 1/2 and the c-Jun N-terminal kinase. SB-203580 (a p38 MAPK inhibitor) and p38 siRNA, but not U0126 (a MEK inhibitor), partially rescued cell death induced by C2-ceramide. C2-ceramide promoted the activation of caspase-3. Conclusion: Exogenous C2-ceramide induced apoptosis in human lung adenocarcinoma A549 cells. The activation of MAPK and caspase-3 were involved in the mechanisms of C2-ceramide-induced apoptosis in A549 cells. [ABSTRACT FROM AUTHOR]