Fibulin-5 inhibits Wnt/?-catenin signaling in lung cancer.
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ABSTRACT: Metastatic lung cancer is incurable and a leading cause of cancer death in the United States. However, the molecular mechanism by which lung cancer cells invade other tissues has remained unclear. We previously identified fibulin-5, an extracellular matrix protein, as a frequently silenced gene in lung cancer and a suppressor of cell invasion. In this study, we found fibulin-5 functions by inhibiting the Wnt/?-catenin pathway. The Cancer Genome Atlas (TCGA) datasets show a strong association between loss of fibulin-5 expression and poor outcomes of lung cancer patients, and also activation of the Wnt target genes MMP-7 and c-Myc. Fibulin-5 impedes Wnt/?-catenin signaling by inhibiting extracellular signal-regulated kinase (ERK) to activate glycogen synthase kinase-3 ? (GSK3?), which downregulates ?-catenin and prevents its nuclear accumulation, leading to suppression of MMP-7 and c-Myc expression. These effects of fibulin-5 are mediated by its amino-terminal integrin-binding RGD motif. Fibulin-5 also blocks Wnt/?-catenin signaling in vivo in H460 metastasis and H1299 tumor models. Furthermore, knockdown of ?-catenin suppresses metastasis of H460 tumors, while knockdown of GSK3? promotes metastasis of fibulin-5-expressing H1752 tumors. Together, our results suggest that fibulin-5 functions as a metastasis suppressor in lung cancer by modulating tumor microenvironment to suppress Wnt/?-catenin signaling.
SUBMITTER: Chen X
PROVIDER: S-EPMC4558133 | biostudies-literature | 2015 Jun
REPOSITORIES: biostudies-literature
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