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Cancer is a complex multistep process involving genetic and epigenetic changes that eventually result in the activation of oncogenic pathways and/or inactivation of tumor suppressor signals. During cancer progression, cancer cells acquire a number of hallmarks that promote tumor growth and invasion. A crucial mechanism by which carcinoma cells enhance their invasive capacity is the dissolution of intercellular adhesions and the acquisition of a more motile mesenchymal phenotype as part of an epithelial-to-mesenchymal transition (EMT). Although many transcription factors can trigger it, the full molecular reprogramming occurring during an EMT is mainly orchestrated by three major groups of transcription factors: the ZEB, Snail and Twist families. Upregulated expression of these EMT-activating transcription factors (EMT-ATFs) promotes tumor invasiveness in cell lines and xenograft mice models and has been associated with poor clinical prognosis in human cancers. Evidence accumulated in the last few years indicates that EMT-ATFs also regulate an expanding set of cancer cell capabilities beyond tumor invasion. Thus, EMT-ATFs have been shown to cooperate in oncogenic transformation, regulate cancer cell stemness, override safeguard programs against cancer like apoptosis and senescence, determine resistance to chemotherapy and promote tumor angiogenesis. This article reviews the expanding portfolio of functions played by EMT-ATFs in cancer progression.

Leucine-rich repeats and immunoglobulin-like domains 3 (LRIG3) functions as a tumor suppressor in glioma. Although our previous study demonstrated that LRIG3 inhibited angiogenesis via the PI3K/AKT/VEGFA pathway under normoxia, its impact on glioma vascularization under hypoxia remains elusive. Vasculogenic mimicry (VM), an alternative form of neovascularization, plays a pivotal role in glioma progression, particularly within hypoxic tumor microenvironments. This study aimed to investigate the effects of LRIG3 on hypoxia-induced VM in glioma and to elucidate the underlying molecular mechanisms. The effects of LRIG3 on VM were evaluated in vitro using tube formation and 3D spheroid invasion assays. Histological analysis of intracranial xenografts and glioblastoma specimens was performed to assess LRIG3's impact on glioma vascularization in vivo. The underlying mechanisms were investigated using western blot, quantitative real-time PCR (qRT-PCR), and ubiquitination assays. LRIG3 expression was inversely correlated with VM density in the central hypoxic regions of both xenografts and glioblastoma specimens. Under hypoxia, LRIG3 overexpression inhibited the invasion and tube formation capacities of glioma cells, whereas its knockdown promoted these activities. Mechanistically, LRIG3 suppressed VM phenotypes by downregulating Snail2 at the post-translational level, rather than affecting VEGFA. LRIG3 promoted the ubiquitination of Snail2, leading to its proteasomal degradation and destabilization under hypoxia. LRIG3 inhibits hypoxia-induced VM in glioma by facilitating the proteasomal degradation of Snail2 via ubiquitination.

Functional E‐cadherin loss, a hallmark of epithelial‐mesenchymal transition (EMT), is important for metastasis. However, the mechanism of Snail2 in hepatocellular carcinoma (HCC) EMT and metastasis remains unclear. Here, we showed that Snail2 was upregulated in primary HCC, and significantly increased during transforming growth factor‐β‐induced liver cell EMT. Snail2‐overexpressing and knockdown cell lines have been established to determine its function in EMT in HCC. H3K9 methylation was upregulated and H3K4 and H3K56 acetylation were downregulated at the E‐cadherin promoter in Snail2‐overexpressing cancer cells. Furthermore, Snail2 interacted with G9a and histone deacetylases (HDACs) to form a complex to suppress E‐cadherin transcription. Snail2 overexpression enhanced migration and invasion in HCC cells, whereas G9a and HDAC inhibition significantly reversed this effect. Moreover, Snail2 overexpression in cancer cells increased tumor metastasis and shortened survival time in mice, whereas G9a and HDAC inhibitors extended survival. Our study not only reveals a critical mechanism underlying the epigenetic regulation of EMT but also suggests novel treatment strategies for HCC. Snail2 was upregulated in hepatocellular carcinoma and lung cancer tissues, and significantly increased during transforming growth factor‐β‐induced liver cell epithelial‐mesenchymal transition. Snail2 interacted with G9a and histone deacetylases to form a complex to suppress E‐cadherin transcription and enhanced migration and invasion in hepatocellular carcinoma cells. Snail2 overexpression in cancer cells increased tumor metastasis and shortened survival time in mice, whereas G9a and histone deacetylase inhibitors extended survival.

Pancreatic cancer has an extremely poor prognosis because of its resistance to conventional therapies. Cancer stem cell (CSC)‐targeted therapy is considered a promising approach for this disease. Epithelial‐mesenchymal transition‐inducing transcription factors (EMT‐TFs) contribute to CSC properties in some solid tumors; however, this mechanism has not been fully elucidated in pancreatic cancer. Zinc finger protein, SNAIL2 (also known as SLUG), is a member of the SNAIL superfamily of EMT‐TFs and is commonly overexpressed in pancreatic cancer. Patients exhibiting high SNAIL2 expression have a poor prognosis. In this study, we showed that the suppression of SNAIL2 expression using RNA interference decreased tumorigenicity in vitro (sphere formation assay) and in vivo (xenograft assay) in 2 pancreatic cancer cell lines, KLM1 and KMP5. In addition, SNAIL2 suppression resulted in increased sensitivity to gemcitabine and reduced the expression of CD44, a pancreatic CSC marker. Moreover, experiments on tumor spheroids established from surgically resected pancreatic cancer tissues yielded similar results. A microarray analysis revealed that the mechanism was mediated by insulin‐like growth factor (IGF) binding protein 2. These results indicate that IGFBP2 regulated by SNAIL2 may represent an effective therapeutic target for pancreatic cancer. SNAIL2 knockdown reduces tumorigenicity and resistance to gemcitabine in tumor spheroid established from resected tissue of human pancreatic cancer as well as human pancreatic cancer cell lines.

Purpose Long non-coding RNA (LncRNA) urothelial carcinoma-associated 1 (UCA1) is reported to be dysregulated in hepatocellular carcinoma (HCC) progression. However, the functions of UCA1 in HCC still need further study. The aim is to detect the role of UCA1 involving in HCC cells proliferation and invasion, and epithelial–mesenchymal transition (EMT). Methods The quantitative real-time PCR was used to detect the UCA1 and miR-203 expression levels in 60 cases’ HCC tissues and adjacent normal tissues. Western blotting analysis was performed to detect the EMT markers E-cadherin, Vimentin and transcription factor Snail1, Snail2 expression. Luciferase reporter assay, RNA immunoprecipitation (RIP) and pull-down assays were used to evaluate whether miR-203 was a target of UCA1. Results Our results showed that UCA1 was markedly upregulated in HCC tissues and higher UCA1 expression in HCC was positively associated with tumor size, vascular invasion and American Joint Committee on Cancer (AJCC) stage ( P  < 0.05). Furthermore, gain-of-function and loss-of-function analysis showed that UCA1 knockdown inhibited HCC cells proliferation and invasion in vitro and xenograft tumour growth in vivo. Moreover, UCA1 overexpression promoted cell epithelial–mesenchymal transition (EMT) in HCC via effectively sponging to miR-203 and thereby activating the expression of transcription factor Snail2. Conclusions Our results identified that UCA1/miR-203/Snail2 pathway might involve in HCC progression. Inhibition of UCA1 acted as a promising therapeutic target for HCC patients.

Cancer is one of the leading causes of cancer-associated mortality worldwide. Several strategies of treatment, including radiotherapy, have been developed and used to treat this disease. However, post-treatment metastasis and resistance to treatment are two major causes for the limited effectiveness of radiotherapy in cancer patients. Epithelial-mesenchymal transition (EMT) is regulated by SNAIL family transcription factors, including Snail1 and Snail2 (Slug), and serves important roles in progression and cancer resistance to treatment. Snail1 and Slug also have been shown to be implicated in cancer treatment resistance. For resolving the resistance to treatment problems, combining the modulation of gene expression with radiotherapy is a novel strategy to treat patients with cancer. The present review focuses on the effect of Snail1 and Slug on cancer radiosensitivity by targeting cell apoptosis, the cell cycle and cell migration/invasion.

Purpose The Numb protein plays a vital role in tumor development. The main aim of this study was to identify ATP11A, which is associated with the biological behavior of pancreatic cancer, and elucidate its relationship with Numb and the underlying mechanism behind this relationship. Methods First, data retrieved from The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEX) databases was used to investigate the expression of ATP11A mRNA and its relationship with Numb mRNA in pancreatic cancer. Western blot assays on 31 pairs of pancreatic cancer tissues and paracancerous tissues, and immunohistochemical assays on 81 pancreatic cancer specimens were performed in order to verify the expression of ATP11A in pancreatic cancer at the protein level. Next, ATP11A was overexpressed or knocked down to observe its effects on the invasion and migration ability of pancreatic cancer cells and the changes of downstream proteins. Rescue assays were conducted to determine the mechanism through which ATP11A affects Numb, ZEB1, Snail2 and other proteins. Furthermore, immunoprecipitation assays were performed to explore the interaction between ATP11A and Numb. Finally, pancreatic cancer cells were stimulated with TGFB1 and ATP11A expression was examined to explore whether the effect of ATP11A on EMT was TGFB dependent. Results At the mRNA level, the expression of ATP11A in pancreatic cancer tissues was significantly higher than in normal pancreatic tissues (P < 0.001). ATP11A expression was also highly correlated with Numb expression (R = 0.676). At the protein level, ATP11A expression in pancreatic cancer tissues was significantly higher than that in paracancerous tissues (P = 0.0009), and high ATP11A expression was also correlated with a worse prognosis. Moreover, our results showed that ATP11A can promote the invasion and migration of pancreatic cancer cells. Additionally, ATP11A could positively regulate the expression of Numb PRRL, Snail2 and ZEB1 proteins. The rescue experiment results showed that the enhancement effect of ATP11A on ZEB1/Snail2 was suppressed by the specific knockdown of Numb PRRL. In addition, the immunoprecipitation results showed that ATP11A could specifically bind to Numb PRRL. The expression of ATP11A was also upregulated after TGFB stimulation, suggesting that the effect of ATP11A on EMT is TGFB dependent. Conclusion ATP11A is significantly upregulated in pancreatic cancer tissues, where it promotes the invasion and migration ability of pancreatic cancer cells. It is also associated with adverse prognosis in pancreatic cancer. Furthermore, ATP11A affects the epithelial-to-mesenchymal transition (EMT) of pancreatic cancer by regulating the TGFB dependent Numb PRRL-ZEB1/Snail2 pathway.

Background The transcription factor Snail2 is a repressor of E-cadherin expression during carcinogenesis; however, the specific mechanisms involved in this process in human colorectal cancer (CRC) remain largely unknown. Method We checked the expression of Snail2 in several clinical CRC specimens. Then, we established Snail2-overexpressing and knockdown cell lines to determine the function of Snail2 during EMT and metastasis processes in CRC. In addition, we used luciferase reporter assay to explore how Snail2 inhibits the expression of E-cadherin and induces EMT. Results We found that the expression of Snail2 was higher in clinical specimens of colorectal cancer (CRC) compared to non-cancerous tissues. Overexpression of Snail2 induced migration and metastatic properties in CRC cells in vitro and in vivo. Furthermore, overexpression of Snail2 promoted the occurrence of the epithelial–mesenchymal transition (EMT), downregulating the expression of E-cadherin and upregulating that of vimentin. Specifically, Snail2 could interact with HDAC6 and then recruited HDAC6 and PRC2 to the promoter of E-cadherin and thus inhibited the expression of E-cadherin, promoting EMT and inducing invasion and metastasis of CRC. Conclusion Our study reveals that Snail2 might epigenetically suppress the expression of E-cadherin during CRC metastasis.

Increasing evidence shows that Hox transcript antisense RNA (HOTAIR) plays a vital role in liver cancer initiation and progression by affecting the proliferation, invasion, migration, and apoptosis of liver cancer cells. However, the underlying mechanism of how HOTAIR exerts its functions in liver cancer cells remains unclear. Previous studies have shown that HOTAIR affects the invasion and migration of liver cancer cells by regulating the expression of E-cadherin. Snail2, a transcription factor involved in epithelial-mesenchymal transition, directly binds to the E-boxes of the E-cadherin promoter to repress its transcription. The aim of the study was to examine the correlation between HOTAIR and Snail2 in the HOTAIR/Snail2/E-cadherin signal pathway and explore the role of HOTAIR in the proliferation, invasion, migration, and apoptosis of liver cancer cells. Fifty matched normal liver tissues and 373 liver cancer tissues were analysed and evaluated. HepG2 and SNU-387 cells were cultured and transfected with plasmids knocking down HOTAIR to disrupt HOTAIR expression. Cell scratch and transwell assays were performed to examine the migration and invasion of HepG2 and SNU-387 cells; in addition, the expression of MMP2 and MMP9 was detected by immunoblotting analysis, RT-qPCR analysis, immunofluorescence analysis, and bioinformatics analysis, which elucidated the regulatory relationship between HOTAIR and Snail2. We used flow cytometry and JC-1 probe analysis assays to clarify the function of HOTAIR inliver cancer cell apoptosis. The HOTAIR mRNA was upregulated in liver cancer tissues, which was related to worse overall survival. HOTAIR induced the expression of matrix metalloproteinase-9 (MMP9) and metalloproteinase-2 (MMP2), leading to degradation of extracellular matrix. HOTAIR knockdown significantly reduced the doubling time and inhibited cell migration and invasion of liver cancer cells. Furthermore, HOTAIR depletion induced mitochondrial-related apoptosis in HepG2 and SNU-387 cell lines. In this study, we propose a novel mechanism in which HOTAIR promotes invasion and migration of liver cancer cells by regulating the nuclear localisation of Snail2.

Triple-negative breast cancers (TNBCs) are a heterogeneous group of breast tumours that are often associated with adverse pathological characteristics, poorer clinical outcomes and lack of targeted therapeutic options. Epithelial–mesenchymal transition, which plays a crucial role in tumour development and progression, is characterised by a transition from epithelial to mesenchymal phenotype and loss of proteins involved in maintaining cell junctions. We aimed to correlate protein expression of E-cadherin, Snail2 and transforming growth factor beta (TGF-β) with clinicopathological parameters and survivals of a series of patients with TNBC. The study cohort comprised 767 TNBCs diagnosed at the Department of Pathology, Singapore General Hospital from 1994 to 2012. Immunohistochemistry was performed on sections cut from tissue microarrays using the polymeric method. Staining intensity and percentage of positive tumour cells were evaluated and correlated with clinicopathological findings and clinical outcomes. Loss of E-cadherin expression, Snail2 positivity, cytoplasmic and nuclear expression of TGF-β were observed in 265 (35.2 %), 241 (32.0 %), 272 (36.2 %) and 262 (34.8 %) tumours, respectively. Histological grade significantly correlated with Snail2 positivity ( P < 0.001) and loss of membranous E-cadherin expression ( P  = 0.003). Nuclear expression of TGF-β was inversely correlated with histological grade ( P  = 0.010). Median follow-up was 73 months, with a maximum of 236 months. Despite a graphical curve for earlier recurrence in patients with tumours harbouring a combinational phenotype of loss of membranous E-cadherin and positive Snail2 expression, there was no statistical significance. Similarly for women with tumours expressing cytoplasmic TGF-β, graphical representation showed poorer metastasis-free survival but without statistical significance. Loss of membranous E-cadherin and positive Snail2 expression are significantly associated with high-grade TNBCs. More work is needed to improve understanding of the role of TGF-β in TNBC.