5747

PTK2

Emerging evidence has shown that caveolin-1 is up-regulated in a number of metastatic cancers and can influence various aspects of cell migration. However, in general, the role of caveolin-1 in cancer progression is poorly understood. In the present study, we examined alterations in caveolin-1 expression during epithelial-to-mesenchymal transition (EMT) and the ability of caveolin-1 to alter cancer cell adhesion, an aspect of cell motility. We employed two EMT cell models, the human embryonic carcinoma cell line NT2/D1, and TGF-beta1-treated NMuMG cells, which are derived from normal mouse mammary epithelia. Caveolin-1 expression was substantially up-regulated in both cell lines following the induction of EMT and was preceded by increased activation of focal adhesion kinase (FAK) and Src, two known tyrosine kinases involved in EMT. We hypothesized that caveolin-1 expression could be influenced by increased FAK phosphorylation, to which Src is a known contributor. Examination of FAK+/+ and FAK-/- mouse embryonic fibroblasts revealed that in cells devoid of FAK, caveolin-1 expression is strikingly diminished. Using FAK and superFAK constructs and the novel FAK inhibitor PF-228, we were able to demonstrate that indeed, FAK can regulate caveolin-1 expression. We also found that Src can contribute to increases in caveolin-1 expression, however, only in the presence of FAK. From the culmination of this data and our functional analyses, we conclude that caveolin-1 expression can be up-regulated during EMT, and further, once expressed, caveolin-1 can greatly influence cancer cell adhesion.

epithelial-mesenchymal transition (EMT) contributes to the occurrence and development of tumors, particularly to the promotion of tumor invasion and metastasis. As a newly discovered ubiquitin hydrolase family member, USP22 plays a key role in the malignant transformation of tumors and the regulation of the cell cycle. However, recent studies on USP22 have primarily focused on its role in cell cycle regulation, and the potential mechanism underlying the promotion of tumor invasion and metastasis by abnormal USP22 expression has not been reported. Our studies revealed that the overexpression of USP22 in PANC-1 cells promoted Ezrin redistribution and phosphorylation and cytoskeletal remodeling, upregulated expression of the transcription factors Snail and ZEB1 to promote EMT, and increased cellular invasion and migration. In contrast, blockade of USP22 expression resulted in the opposite effects. In addition, the focal adhesion kinase (FAK) signaling pathway was shown to play a key role in the process of EMT induction in PANC-1 cells by USP22. Thus, the present study suggests that USP22 acts as a regulatory protein for EMT in pancreatic cancer, which may provide a new approach for the targeted therapy of pancreatic cancer.

Laryngeal squamous cell carcinoma (LSCC) is one of the most common malignant tumors, and the main cause of death is metastasis. Overexpression of aurora kinase A (AURKA) plays an important role in the metastasis of LSCC. However, the mechanism by which AURKA promotes the metastasis of LSCC is poorly understood. Recent accumulating evidence indicates that epithelial-mesenchymal transition (EMT) may be one of the mechanisms of tumor metastasis. In the present study, we studied whether AURKA may induce EMT to promote the metastasis of LSCC. CCK-8 and plate colony-formation assays were carried out to show that AURKA significantly promoted the proliferation of Hep2 cells. Immunofluorescence staining and western blotting showed that EMT-related proteins changed in a time-dependent manner along with the alteration of AURKA, with decreased expression of N-cadherin, vimentin and slug and increased expression of E-cadherin. Additionally, downregulation of the expression of AURKA inhibited FAK/PI3K pathway activity. Inhibition of the FAK/PI3K pathway caused less mesenchymal-like characteristics and reduced the mobility, migration and invasion of Hep2 cells. In conclusion, AURKA may induce EMT to promote metastasis via activation of the FAK/PI3K pathway in LSCC. Those regulatory factors may present new diagnostic biomarkers and potential therapeutic targets for LSCC.

AIM: To investigate the possibility of enhancing an anti-metastatic effect of 5-fluorouracil (5-FU) on colorectal cancer (CRC) cells by combining it with continuous calcium supplementation. MATERIALS AND METHODS: Optimal doses of 5-FU with/without lactate salt (CaLa) were determined via clonogenicity and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays using human CRC cells cultured on normal or low-attachment plates. Invasion and migration assays confirmed the enhanced anti-metastatic effect of combining 5-FU and CaLa. Western blot analysis for elements of the focal adhesion kinase (FAK) signaling cascade and epithelial-mesenchymal transition (EMT) markers was used to investigate the underlying mechanism. RESULTS: 5-FU (2.5 muM) had no antitumor activity against unanchored CRC cells, while it significantly suppressed anchorage-dependent cell proliferation. In contrast, treatment with CaLa (2.5 mM), alone and in combination with 5-FU, exerted antitumor activity against both anchored and unanchored CRC cells via calcium-mediated FAK proteolysis and inhibition of EMT markers, such as vimentin and SNAIL. CONCLUSION: Calcium supplementation represents a method of enhancing the potency of existing antitumor agents such as 5-FU, augmenting their clinical effectiveness.CI - Copyright(c) 2017 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

Accumulating evidence demonstrates that aberrant miRNAs contribute to gastric cancer (GC) development and progression. However, the roles of various miRNAs in GC remain to be determined. In the present study, we confirmed that a reduced miR-379 expression was present in GC tissues and cell lines. Our clinical analysis revealed that the downregulated miR-379 expression was significantly correlated with poor prognostic features including lymph node metastasis and advanced TNM stage. Moreover, we confirmed that miR-379 was a novel independent prognostic marker for predicting 5-year survival of GC patients. The ectopic overexpression of miR-379 inhibited cell migration, invasion and EMT progress, while downregulated miR-379 reversed the effect. In addition, miR-379 regulated the focal adhesion kinase (FAK) by directly binding to its 3'-UTR, resulting in suppression of AKT signaling. In clinical samples of GC, miR-379 inversely correlated with FAK, which was upregulated in GC. Alteration of FAK expression or activating AKT signaling at least partially abolished the migration, invasion and EMT progress effects of miR-379 on GC cells. In conclusion, our results indicated that miR-379 functioned as a tumor suppressor gene in regulating the EMT and metastasis of GC via targeting FAK/AKT signaling, and may represent a novel potential therapeutic target and prognostic marker for GC.

BACKGROUND: TGF-beta promotes tumor invasion and metastasis through inducing epithelial-mesenchymal transition (EMT) in non-small cell lung cancer (NSCLC). Circular RNAs (circRNAs) are recognized as functional non-coding RNAs involved in human cancers. However, whether and how circRNAs contribute to TGF-beta-induced EMT and metastasis in NSCLC remain vague. Here, we investigated the regulation and function of Circular RNA hsa_circ_0008305 (circPTK2) in TGF-beta-induced EMT and tumor metastasis, as well as a link between circPTK2 and transcriptional intermediary factor 1 gamma (TIF1gamma) in NSCLC. METHODS: Circular RNAs were determined by human circRNA Array analysis, real-time quantitative reverse transcriptase PCR and northern blot. Luciferase reporter, RNA-binding protein immunoprecipitation (RIP), RNA pull-down and fluorescence in situ hybridization (FISH) assays were employed to test the interaction between circPTK2 and miR-429/miR-200b-3p. Ectopic overexpression and siRNA-mediated knockdown of circPTK2, TGF-beta-induced EMT, Transwell migration and invasion in vitro, and in vivo experiment of metastasis were used to evaluate the function of circPTK2. Transcription and prognosis analyses were done in public databases. RESULTS: CircPTK2 and TIF1gamma were significantly down-regulated in NSCLC cells undergoing EMT induced by TGF-beta. CircPTK2 overexpression augmented TIF1gamma expression, inhibited TGF-beta-induced EMT and NSCLC cell invasion, whereas circPTK2 knockdown had the opposite effects. CircPTK2 functions as a sponge of miR-429/miR-200b-3p, and miR-429/miR-200b-3p promote TGF-beta-induced EMT and NSCLC cell invasion by targeting TIF1gamma. CircPTK2 overexpression inhibited the invasion-promoting phenotype of endogenous miR-429/miR-200b-3p in NSCLC cells in response to TGF-beta. CircPTK2 overexpression significantly decreased the expression of Snail, an important downstream transcriptional activator of TGF-beta/Smad signaling. In an in vivo experiment of metastasis, circPTK2 overexpression suppressed NSCLC cell metastasis. Moreover, circPTK2 expression was dramatically down-regulated and positively correlated with TIF1gamma expression in human NSCLC tissues. Especially, circPTK2 was significantly lower in metastatic NSCLC tissues than non-metastatic counterparts. CONCLUSION: Our findings show that circPTK2 (hsa_circ_0008305) inhibits TGF-beta-induced EMT and metastasis by controlling TIF1gamma in NSCLC, revealing a novel mechanism by which circRNA regulates TGF-beta-induced EMT and tumor metastasis, and suggesting that circPTK2 overexpression could provide a therapeutic strategy for advanced NSCLC.

Mouse embryonic cells isolated from focal adhesion kinase (FAK)-null animals at embryonic day 7.5 display multiple defects in focal adhesion remodeling, microtubule dynamics, mechanotransduction, proliferation, directional motility, and invasion. To date, the ability of FAK to modulate cell function has been ascribed largely to its control of posttranscriptional signaling cascades in this embryonic cell population. In this paper, we demonstrate that FAK unexpectedly exerts control over an epithelial-mesenchymal transition (EMT) program that commits embryonic FAK-null cells to an epithelial status highlighted by the expression of E-cadherin, desmoplakin, and cytokeratins. FAK rescue reestablished the mesenchymal characteristics of FAK-null embryonic cells to generate committed mouse embryonic fibroblasts via an extracellular signal-related kinase- and Akt-dependent signaling cascade that triggered Snail1 gene expression and Snail1 protein stabilization. These findings indentify FAK as a novel regulator of Snail1-dependent EMT in embryonic cells and suggest that multiple defects in FAK(-/-) cell behavior can be attributed to an inappropriate commitment of these cells to an epithelial, rather than fibroblastic, phenotype.

The microRNA miR-17-92 cluster plays a fundamental role in heart development. The aim of this study was to investigate the effect of a member of this cluster, miR-17, on cardiac senescence. We examined the roles of miR-17 in senescence and demonstrated that miR-17-3p attenuates cardiac aging in the myocardium by targeting Par4 (also known as PAWR). This upregulates the downstream proteins CEBPB, FAK, N-cadherin, vimentin, Oct4 and Sca-1 (also known as stem cell antigen-1), and downregulates E-cadherin. Par4 has been reported as a tumor suppressor gene that induces apoptosis in cancer cells, but not in normal cells. Repression of Par4 by miR-17-3p enhances the transcription of CEBPB and FAK, which promotes mouse cardiac fibroblast (MCF) epithelial-to-mesenchymal transition (EMT) and self-renewal, resulting in cellular senescence and apoptosis resistance. We conclude that Par4 can bind to the CEBPB promoter and inhibit its transcription. Decreased Par4 expression increases the amount of CEBPB, which binds to the FAK promoter and enhances FAK transcription. Par4, CEBPB and FAK form a senescence signaling pathway, playing roles in modulating cell survival, growth, apoptosis, EMT and self-renewal. Through this novel senescence signaling axis, miR-17-3p represses Par4 expression, acting pleiotropically as a negative modulator of cardiac aging and cardiac fibroblast cellular senescence.CI - (c) 2015. Published by The Company of Biologists Ltd.