7532

YWHAG

epithelial-mesenchymal transition (EMT) is essential for increased invasion and metastasis during cancer progression. Among the candidate EMT-regulating microRNAs that we previously identified, miR-181b-3p was found to induce EMT in MCF7 breast cancer cells, as indicated by an EMT-characteristic morphological change, increased invasiveness, and altered expression of an EMT marker. Transfection with a miR-181b-3p inhibitor reduced the expression of mesenchymal markers and the migration and invasion of highly invasive breast cancer cells. miR-181b-3p induced the upregulation of Snail, a master EMT inducer and transcriptional repressor of E-cadherin, through protein stabilization. YWHAG was identified as a direct target of miR-181b-3p, downregulation of which induced Snail stabilization and EMT phenotypes. Ectopic expression of YWHAG abrogated the effect of miR-181b-3p, including Snail stabilization and the promotion of invasion. In situ hybridization and immunohistochemical analyses indicated that YWHAG expression was inversely correlated with the expression of miR-181b-3p and Snail in human breast cancer tissues. Furthermore, transfection with miR-181b-3p increased the frequency of metastatic nodule formation in the lungs of mice in experimental metastasis assays using MDA-MB-231 cells. Taken together, our data suggest that miR-181b-3p functions as a metastasis activator by promoting Snail-induced EMT, and may therefore be a therapeutic target in metastatic cancers.CI - Copyright (c) 2016 Elsevier B.V. All rights reserved.

Metastatic cancer cells acquire energy-intensive processes including increased invasiveness and chemoresistance. However, how the energy demand is met and the molecular drivers that coordinate an increase in cellular metabolic activity to drive epithelial-mesenchymal transition (EMT), the first step of metastasis, remain unclear. Using different in vitro and in vivo EMT models with clinical patient's samples, we showed that EMT is an energy-demanding process fueled by glucose metabolism-derived adenosine triphosphate (ATP). We identified angiopoietin-like 4 (ANGPTL4) as a key player that coordinates an increase in cellular energy flux crucial for EMT via an ANGPTL4/14-3-3gamma signaling axis. This augmented cellular metabolic activity enhanced metastasis. ANGPTL4 knockdown suppresses an adenylate energy charge elevation, delaying EMT. Using an in vivo dual-inducible EMT model, we found that ANGPTL4 deficiency reduces cancer metastasis to the lung and liver. Unbiased kinase inhibitor screens and Ingenuity pathway Analysis revealed that ANGPTL4 regulates the expression of 14-3-3gamma adaptor protein via the phosphatidylinositol-3-kinase/AKT and mitogen-activated protein kinase signaling pathways that culminate to activation of transcription factors, CREB, cFOS and STAT3. Using a different mode of action, as compared with protein kinases, the ANGPTL4/14-3-3gamma signaling axis consolidated cellular bioenergetics and stabilized critical EMT proteins to coordinate energy demand and enhanced EMT competency and metastasis, through interaction with specific phosphorylation signals on target proteins.

BACKGROUND/AIM: 14-3-3gamma is involved in the metastasis of lung cancer cells. However, its functional roles in tumor cell invasion and the underlying mechanisms are still not understood. In this study, the roles and molecular mechanisms of 14-3-3gamma in epithelial-mesenchymal transition (EMT), migration, and invasion were investigated using A549 and H358 non-small cell lung cancer (NSCLC) cell lines. MATERIALS AND METHODS: siRNA against 14-3-3gamma was used to suppress 14-3-3gamma expression. expression levels of proteins were detected by western blotting. Activity of matrix metalloproteinases (MMP)-2 and MMP9 was determined by gelatin zymography. Cell migration and invasion were analyzed using the Transwell assay. RESULTS: Knockdown of 14-3-3gamma resulted in a significant reduction of expression of EMT-associated proteins in NSCLC cell lines, and led to significant reduction in invasion and migration by approximately 59% and 39% in A549 cells, and 65% and 62% in H358 cells, respectively. In addition, MMP2 and MMP9 activity was significantly reduced in both NSCLC cell lines after down-regulation of 14-3-3gamma. CONCLUSION: Our results suggest that knockdown of 14-3-3gamma may be a potential strategy for suppressing metastasis of lung cancer by inhibiting MMP2 and MMP9 through regulation of EMT.CI - Copyright(c) 2018, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.