2319

FLOT2

Transforming growth factor-beta (TGF-beta) promotes cancer metastasis via the epithelial-mesenchymal transition (EMT) but the underlying mechanisms in nasopharyngeal carcinoma (NPC) remain unclear. Flotillin-2 (Flot2), a specialized lipid raft domain in cellular membrane, was reported to promote cancer metastasis. Recently, in neuropathy, it was also suggested that Flot2 was involved in Src activation, which is known as the downstream signal of TGF-beta. Therefore, we intended to find out the relationship between Flot2 and TGF-beta in the process of nasopharyngeal carcinoma (NPC) metastasis. In this study, we found that Flot2 expression level positively correlated with the cancer stage in NPC tissues. Elevated Flot2 in tumor tissue was an independent prognostic marker, and higher Flot2 expression level showed shorter overall survival time in 181 NPC patients. In NPC cells, silencing Flot2 reversed the metastatic effect induced by TGF-beta. Moreover, TGF-beta-induced Src phosphorylation was significantly inhibited by Flot2 knocking down. As the consequence of Flot2 inhibition, the expression of the epithelial biomarker E-cadherin was upregulated, while the mesenchymal marker vimentin and signaling transducer beta-catenin was suppressed. In conclusions, Flot2 is an indispensable member for TGF-beta signaling, which is essential for the EMT process in NPC metastasis. Suppressing Flot2 may be a novel way against TGF-beta-induced EMT.

BACKGROUND: Flot2, a highly conserved protein of the SPFH domain containing proteins family, has recently been identified as oncogene to be involved in the tumorigenesis and metastasis of several cancers including gastric cancer. However, the underlying molecular mechanism of Flot2 in gastric cancer (GC) is largely unknown. METHODS: qRT-PCR and western blot was performed to detect miR-449a and Flot2 expression in GC cell lines and Normal human gastric epithelial cells. Then, luciferase reporter assay was used to elucidate whether Flot2 is a target gene of miR-449a. Finally, the roles and mechanism of miR-449a in regulation of tumor invasion were further investigated. RESULTS: In this study, miR-449a expression was downregulated and Flot2 was upregulated in all GC cell lines as compared with that in GES-1. luciferase reporter assay identified Flot2 as a novel direct target of miR-449a. miR-449a regulated GC cell invasion by suppressing Flot2 expression. expression analysis of a set of epithelial-mesenchymal transition (EMT) markers showed that miR-449a reduced the expression of mesenchymal markers (vimentin and N-cadherin) and induced the expression of epithelial marker (E-cadherin), which was consistent with silenced Flot2. Moreover, Flot2 is necessary for TGF-beta-induced EMT in GC cells. CONCLUSIONS: Our results demonstrated that miR-449a suppressed Flot2 expression results in decreased cell invasion through repressing TGF-beta-mediated-EMT, and provides a new theoretical basis to further investigate miR-449a-regulated Flot2 as a potential biomarker and a promising approach for GC treatment.

Lung adenocarcinoma, as a common form of non-small cell lung cancer, poses a significant threat to public health worldwide. Previous studies have reported that flotillin-2 (Flot2) is often overexpressed in various tumors and is h correlated with tumor progression and patient survival. Dysregulated microRNA (miRNA) is associated with various cancers, including lung adenocarcinoma. However, little is known about the miRNAs targeting Flot2 in lung adenocarcinoma. In this study, we found that the expression level of miR-485 was downregulated in four lung adenocarcinoma cell lines and tissues and that the reduced miR-485 expression was associated with tumor metastasis. Luciferase assay revealed that Flot2 is direct target of miR-485, while the expression levels of Flot2 were inversely correlated with the expression levels of miR-485 in lung adenocarcinoma tissues. Ectopic Flot2 could significantly reverse miR-485-mediated inhibition of metastasis and EMT, demonstrating Flot2 downregulation is involved in function of miR-485. Subsequently, we found that miR-485 suppressed the activity of PI3K/AKT/mTOR signaling in lung adenocarcinoma cells. In conclusion, the present study provided novel insight into the molecular mechanism of lung adenocarcinoma progression and demonstrating miR-485 as a potential therapeutic target in human lung adenocarcinoma.CI - Copyright (c) 2016. Published by Elsevier Inc.

miRNAs are a class of non-coding RNAs that exert critical roles in various biological processes. The aim of the present study was to identify the functional roles of miR-802 in regulating epithelial-mesenchymal transition (EMT) in prostate cancer (PCa). miR-802 expression was detected in 73 pairs of PCa samples and PCa cell lines (PC3 and DU145 cells) by qRT-PCR. Cell proliferation was detected using MTT assay, and cell apoptosis was evaluated using flow cytometry. Transwell assay was conducted to investigate cell migration and invasion. expression analysis of a set of EMT markers was performed to explore whether miR-802 is involved in EMT program. Xenograft model was established to investigate the function of miR-802 in carcinogenesis in vivo The direct regulation of Flotillin-2 (Flot2) by miR-802 was identified using luciferase reporter assay. miR-802 was remarkably down-regulated in PCa tissues and cell lines. Gain-of-function trails showed that miR-802 serves as an 'oncosuppressor' in PCa through inhibiting cell proliferation and promoting cell apoptosis in vitro Overexpression of miR-802 significantly suppressed in vivo PCa tumor growth. Luciferase reporter analysis identified Flot2 as a direct target of miR-802 in PCa cells. Overexpressed miR-802 significantly suppressed EMT, migration and invasion in PCa cells by regulating Flot2. We identified miR-802 as a novel tumor suppressor in PCa progression and elucidated a novel mechanism of the miR-802/Flot2 axis in the regulation of EMT, which may be a potential therapeutic target.CI - (c) 2017 The Author(s).