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To systematically unveil transcription factors (TFs) that are critical to lung carcinogenesis, here we conducted a genome-wide lethality screening in non-small cell lung cancer (NSCLC) cells and reported that among the 1530 TFs tested, 21 genes were required for NSCLC cell proliferation and were negatively or positively associated with overall survival (OS) of patients with NSCLC. These included 11 potential tumor suppressing genes (AFF3, AhR, AR, CBFA2T3, CHD4, KANK2, NR3C2, PTEN, PRDM16, RB1, and STK11) and 10 potential oncogenic TFs (BARX1, DLX6, ELF3, EN1, ETV1, FOXE1, HOXB7, IRX4, IRX5, and SALL1). The expression levels of IRX5 were positively associated with OS of smoker and inversely associated with OS of non-smoker patients with lung adenocarcinoma. We showed that tobacco carcinogen benzo(a)pyrene (BaP) induced upregulation of IRX5 in lung epithelial cells, and Cyclin D1 was a downstream target of IRX5. Furthermore, silencing of IRX5 by lentivirus mediated transfection of short hairpin RNA significantly inhibited tumor growth in nude mice. These results indicate that tobacco smoke can modulate TFs to facilitate lung carcinogenesis, and inhibition of IRX5 may have therapeutic potentials in NSCLCs. [ABSTRACT FROM AUTHOR]

Abstract: Sonic Hedgehog (Shh) signaling helps pattern the vertebrate neural tube, in part by regulating the dorsal/ventral expression of a number of homeodomain containing transcription factors. These Hh responsive genes have been divided into two classes, with Class II genes being activated by Hh signaling and Class I genes being repressed by Hh signaling. While the transcriptional response to varying Hh levels is well defined in chick and mouse, it is only partially described in zebrafish, despite the fact that zebrafish has emerged as a powerful genetic system for the study of neural patterning. To better characterize the Hh response in the zebrafish neural tube, we cloned the zebrafish Class II Hh target genes nkx2.9 and nkx6.2. We then analyzed the expression of a number of Class I and Class II Hh responsive genes in wild type, Hh mutant, and Hh over-expressing zebrafish embryos. We show that expression of Class I and Class II genes is highly conserved in the vertebrate neural tube. Further, ventral-most Class II gene expression was completely lost in all Hh pathway mutants analyzed, indicating high levels of Hh signaling are blocked in all of these mutants. In contrast, more dorsally expressed genes were variably affected in different Hh pathway mutants, indicating mid-levels of Hh signaling are differentially affected. This comprehensive expression study provides an important tool for the characterization of Hh signaling in zebrafish and provides a sensitive assay for determining the degree to which newly identified zebrafish mutants affect Hh signaling. [Copyright &y& Elsevier]