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Altered expression of microRNA (miRNA) is associated with lung carcinogenesis and metastasis. Our previous study of lung cancer miRNAs using the gene chip assay demonstrated altered miR-33b expression in lung adenocarcinoma. The present study further investigated miR-33b expression, function, and gene regulation in lung cancer cells in vitro and in nude mouse xenografts. Our data showed that the level of miR-33b expression was dramatically decreased in lung adenocarcinoma cell lines and tissues and that the reduced miR-33b expression was associated with tumor lymph node metastasis. Furthermore, restoration of miR-33b expression inhibited lung adenocarcinoma cell proliferation, migration, and invasion and tumor cell epithelial-mesenchymal transition (EMT) in vitro. Luciferase assay revealed that miR-33b bound to ZEB1 3'-UTR region and inhibited ZEB1 expression, while expression of ZEB1 mRNA and miR-33b was inversely associated with lung adenocarcinoma cell lines and tissues. Subsequently, we found that miR-33b suppressed the activity of WNT/β-catenin signaling in lung adenocarcinoma cells and in turn suppressed tumor cell growth and EMT in vitro and in vivo nude mouse xenografts. In conclusion, the present study provided novel insight into the molecular mechanism of lung adenocarcinoma progression. MicroRNA-33b should be further investigated as a potential therapeutic target in human lung adenocarcinoma.

Neuroimaging evidence suggests that the default mode network (DMN) exhibits antagonistic activity with dorsal attention (DAN) and salience (SN) networks. Here we use human intracranial electroencephalography to investigate the behavioral relevance of fine-grained dynamics within and between these networks. The three networks show dissociable profiles of task-evoked electrophysiological activity, best captured in the high-frequency broadband (HFB; 70-170 Hz) range. On the order of hundreds of milliseconds, HFB responses peak fastest in the DAN, at intermediate speed in the SN, and slowest in the DMN. Lapses of attention (behavioral errors) are marked by distinguishable patterns of both pre-and poststimulus HFB activity within each network. Moreover, the magnitude of temporally lagged, negative HFB coupling between the DAN and DMN (but not SN and DMN) is associated with greater sustained attention performance and is reduced during wakeful rest. These findings underscore the behavioral relevance of temporally delayed coordination between antagonistic brain networks.