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Previous studies have documented that leptin is involved in the pathogenesis of many human cancer types by regulation of numerous signal transduction pathways. The aim of this study was to investigate the biological roles of leptin and the mechanisms attributed to its action in non-small cell lung cancer (NSCLC) cell lines. The expression of leptin was measured by quantitative real-time PCR and western blot in seven NSCLC cell lines. Proliferation and apoptosis of NSCLC cells in response to leptin knockdown were determined by MTT assay and flow cytometry, respectively. The effect of leptin knockdown on the Notch and JAK/STAT3 signaling pathways was further examined by western blot. Leptin expression was significantly increased in NSCLC cell lines compared with normal human bronchial epithelial cell HBE. Leptin knockdown inhibited cell proliferation and induced apoptosis in NSCLC cell lines through inactivation of the Notch and JAK/STAT3 signaling pathways. Furthermore, gene silencing of Notch signaling with Notch-1 siRNA or inhibition of JAK/STAT3 signaling by JSI-124, an inhibitor of STAT3, resulted in proliferation inhibition and apoptosis induction in NSCLC A549 cells. Our findings suggested that leptin knockdown could become a new approach for the prevention of lung cancer progression, which is likely to be mediated at least partially by inactivation of the Notch and JAK/STAT3 signaling pathways.

An efficient and sensitive analytical method for simultaneous determination of trace amounts of a new insecticide broflanilide and its metabolites (S(PFH‐OH)‐8007 and DM‐8007) residues in five typical Chinese soils (red soil, black soil, fluvo‐aquic soil, cinnamon soil and paddy soil) was developed. The samples were prepared by a modified quick, easy, cheap, effective, rugged, and safe method. The determination of broflanilide and its metabolites was conducted by ultra high performance liquid chromatography with tandem mass spectrometry with an electrospray ionization source in the positive ion mode. This is the first report for the determination of broflanilide and its metabolites in different soils. Broflanilide and its metabolites were extracted from all soils with acetonitrile and purified by a mixture of primary secondary amine and graphitized carbon black. The average recoveries of the three compounds in five types of soil ranged from 85.3 to 111.8% and the relative standard deviations were less than 13.6%. The limit of quantification was 0.1 μg/kg for all three compounds. This method was successfully used to determine broflanilide and its metabolites in five types of soil. The method was validated to be simple and effective for the determination of trace residual broflanilide and its metabolites in five types of soil.

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