FUZ is regarded as a planar cell polarity effector that controls multiple cellular processes during vertebrate development. However, the role of FUZ in tumor biology remains poorly studied. Our purpose of this study is to discover the physiological effects and mechanism of FUZ in non-small-cell lung cancer (NSCLC) in vitro. With the help of bioinformatics analysis, we noticed that the expression level of FUZ negatively correlates with prognosis of NSCLC patients. Exogenous FUZ expression markedly promoted cell proliferation of NSCLC cells. The phosphorylation of Erk1/2, STAT3 and related signaling molecules were induced activated after FUZ over-expression. FUZ also plays an important role in cell motility by regulating cell signaling pathways and inducing epithelial to mesenchymal transition (EMT). FUZ promotes EMT along with the up-regulation of N-cadherin, vimentin, Zeb1, Twist1 and decreased level of E-cadherin. Furthermore, we also carried out FUZ directed siRNA treatments to prove the above observations. Knockdown of FUZ resulted in delayed cell growth as well as impaired cell migration and reversed EMT phonotype. Importantly, we reported for the first time that FUZ is a BNIP3-interacting protein. Loss of FUZ resulted in decreased BNIP3 protein level, but no influence on BNIP3 mRNA level, suggesting weakened stability of BNIP3 protein. Overall, our results in vitro show that FUZ is responsible for NSCLC progression and metastasis, suggesting that FUZ can be a potential therapeutic target for NSCLC.

BACKGROUND: We previously showed that activation of epidermal growth factor receptor (EGFR) induces hypoxia inducible factor-1α (HIF-1α) in head and neck squamous cell carcinoma (HNSCC) cells. In this study, we have furthered this by investigating the mechanism of HIF-1α activation by epidermal growth factor (EGF) and its association with the sensitivity to gefitinib.
METHODS: EGFR/HIF-1α signaling was tested by immunoblot, polymerase chain reaction (PCR), cell proliferation, and apoptosis assays.
RESULTS: HIF-1α accumulated in cells overexpressing EGF and phosphorylated epidermal growth factor receptor (pEGFR), phosphatidylinositol-3-kinase (pPI3K), and mitogen-activated protein kinase (pMAPK). EGF-induced expression of HIF-1α and its targets, vascular endothelial growth factor (VEGF) and BNIP3, were blocked by gefitinib and PI3K-inhibitors and MAPK-inhibitors. HIF-1α-siRNAs abrogated EGF-induced BNIP3 but not VEGF expression. Gefitinib inhibited cell proliferation and induced apoptosis more strongly in cells with constitutively active EGFR/HIF-1α signaling than in cells lacking activation of these pathways. HIF-1α-siRNA treatment reduced sensitivity to gefitinib.
CONCLUSIONS: The search for molecular predictors of sensitivity to gefitinib in HNSCC should be extended to the activation status of EGFR-downstream pathways, phosphorylated protein kinase B, pMAPK, and HIF-1α.