Transcriptional regulation of livin by beta-catenin/TCF signaling in human lung cancer cell lines.

Wnt/beta-catenin signaling emerged as a critical pathway in human lung carcinogenesis by regulating the livin promoter activity. This study clarified that livin was a direct target gene of beta-catenin/TCF signaling pathway in non-small cell lung cancer (NSCLC) cells. First, we observed that livin mRNA was up-regulated by LiCl treatment in culture of A549 and 103H cell lines. In addition we found that the activity of livin promoter is increased considerably by activation of beta-catenin and could be blocked by a dominant negative form of DeltaTCF4. Furthermore, we identified a TCF binding site located at -1476/-1470 of the livin promoter which is crucial to the response of beta-catenin. At last, chromatin immunoprecipitation (ChIP) assay was performed and the result indicated that beta-catenin/TCF complex binds to the putative TCF binding site of the livin promoter in A549 and 103H cell lines. Our results suggest that livin is transcriptionally regulated by beta-catenin/TCF signaling in human NSCLC cell lines.