EBV-EBNA1 constructs an immunosuppressive microenvironment for nasopharyngeal carcinoma by promoting the chemoattraction of Treg cells.

BACKGROUND: Nasopharyngeal carcinoma (NPC) is primarily caused by the Epstein-Barr virus (EBV) infection in NPC endemic areas. EBNA1 is an EBV-encoded nuclear antigen, which plays a critical role in the maintenance and replication of EBV genome. However, the mechanisms of EBNA1-promoted NPC immune escape are unknown. Regulatory T (Treg) cells are among the key regulators in restraining antitumor responses. However, the mechanisms of accumulation of Treg cells in NPC have not been defined. This study attempted to identify the detailed mechanisms of EBNA1 functions as a tumor accelerator to promote NPC immune escape by enhancing chemoattraction of Treg cells. METHODS: mRNA profiles were determined by next-generation sequencing in NPC cells. In vitro and in vivo assays were performed to analyze the role of EBNA1 in regulation of recruitment of Treg cells. Colocation and coimmunoprecipitation analyzes were used to identify the SMAD3/c-JUN complex. Chromatin immunoprecipitation assay and dual luciferase reporter assays were designed to demonstrate c-JUN binding to miR-200a promoter and miR-200a targeting to CXCL12 3'Untranslated Regions. The hepatocellular carcinoma models were designed to demonstrate universality of the CXCL12-CXCR4-Treg axis in promoting immune evasion of various tumors. RESULT: A novel molecular mechanism was identified that involves EBV-EBNA1-stimulated chemotactic migration of Treg cells toward NPC microenvironment by upregulation of the transforming growth factor-ß1 (TGFß1)-SMAD3-PI3K-AKT-c-JUN-CXCL12-CXCR4 axis and downregulation of miR-200a. EBV-EBNA1 promotes the chemoattraction of Treg cells by governing the protein-protein interactions of the SMAD3/c-JUN complex in a TGFß1-dependent manner in vitro and in vivo. TGFß1 suppresses miR-200a by enhancing the SMAD3/c-JUN complex. miR-200a negatively regulates the CXCL12 chemokine by direct targeting of the CXCL12 3'UTR region. However, CXCL12 acts as the target gene of miR-200a and as an inhibitor of miR-200a transcription, and inhibition of miR-200a by CXCL12 is mediated by c-JUN, which directly binds to the miR-200a promoter and forms a c-JUN-miR-200a-CXCL12-c-JUN feedback loop. In addition, enhanced CXCL12 efficiently attracts CXCR4-positive Treg cells to remodel an immunosuppressive microenvironment. CONCLUSIONS: EBV-EBNA1 promotes chemotactic migration of Treg cells via the TGFß1-SMAD3-PI3K-AKT-c-JUN-miR-200a-CXCL12-CXCR4 axis in the NPC microenvironment. These results suggest that EBV-EBNA1 may serve as a potential therapeutic target to reshape the NPC microenvironment.

Overexpression of ELF3 facilitates cell growth and metastasis through PI3K/Akt and ERK signaling pathways in non-small cell lung cancer.

ELF3 is one of the member of transcription factors from E-twenty-six family, its role varies in different types of cancer. However, the role and specific mechanisms of ELF3 in the development of non-small cell lung cancer (NSCLC) still remains largely unknown. In our study, ELF3 was observed to be upregulated in NSCLC tissues compared to the corresponding normal lung tissue at mRNA and protein levels, and its expression level was correlated with the overall survival of patients with NSCLC. Silencing of the ELF3 gene in NSCLC cells inhibited the proliferation and metastasis significantly in vitro and in vivo. Conversely, overexpression of ELF3 in NSCLC cells promoted cancer growth and metastasis in vitro. Mechanistically, ELF3 activated PI3K/AKT and ERK signaling pathways and its downstream effectors, thus regulating the cell cycle and epithelial-mesenchymal transition (EMT). Furthermore, the promotive effects of ELF3 on cellular proliferation and metastasis could be rescued by Ly294002 (inhibitor of PI3K) and U0126 (inhibitor of MEK1/2). The results show that ELF3 promotes cell growth and metastasis by regulating PI3K/Akt and ERK pathways in NSCLC and that it may be a promising new target for the treatment of NSCLC patients.

Elevated Expression of Zinc Finger Protein 703 Promotes Cell Proliferation and Metastasis through PI3K/AKT/GSK-3ß Signalling in Oral Squamous Cell Carcinoma.

BACKGROUND/AIMS: Zinc finger protein 703 (ZNF703), initially identified as a novel oncogene in human breast cancer, is a member of the NET/NlZ family of zinc finger transcription factors. It is recognized that the overexpression of ZNF703 is associated with various types of human cancers, but the role and molecular mechanism of ZNF703 in oral squamous cell carcinoma (OSCC) are unknown. METHODS: ZNF703 expression levels were examined in OSCC tissues and non-cancerous tissues by qRT-PCR and immunohistochemistry (IHC). The molecular mechanisms of ZNF703 and its effects on cell growth and metastasis were explored in vitro and in vivo using the CCK8 assay, colony formation assay, cell cycle analysis, migration and invasion assays, wound-healing assay, western blotting and xenograft experiments in nude mice. RESULTS: In this study, ZNF703 was found to be upregulated in OSCC tissues compared to that in normal tissues at both mRNA and protein levels, and its expression level was closely correlated with the overall survival of patients with OSCC. Silencing of the ZNF703 gene in OSCC cells significantly inhibited cell growth and metastasis in vitro and in vivo. Conversely, the overexpression of ZNF703 in OSCC cells promoted cancer growth and metastasis in vitro. Mechanistically, ZNF703 activated the PI3K/AKT/GSK-3ß signalling pathway and its downstream effectors, thus regulating the cell cycle and epithelial-mesenchymal transition (EMT). Furthermore, the promotive effects of ZNF703 on cellular proliferation and metastasis could be rescued by LY294002 (a PI3K-specific inhibitor) and MK2206 (an Akt-specific inhibitor). CONCLUSION: The results show that ZNF703 promotes cell growth and metastasis through PI3K/Akt/GSK-3ß signalling in OSCC and that it may be a promising target in the treatment of patients with OSCC.

CDA-2 induces cell differentiation through suppressing Twist/SLUG signaling via miR-124 in glioma.

Cell differentiation agent-2 (CDA-2) is an extraction from healthy human urine consisting of primary organic acids and peptides, and it has been demonstrated to inhibit growth and induce differentiation in glioma and other cell lines. But the mechanism of CDA-2 remains unclear. In this study, we demonstrated that CDA-2 inhibited cell growth and induced differentiation of glioma cells, accompanied with decreased expression of SLUG, Twist and Vimentin in both SWO-38 and U251 cell lines. Overexpression of SLUG or Twist greatly eliminated the efficiency of CDA-2 in inducing differentiation. Further study showed that CDA-2 treatment resulted in great changed microRNAs (miRNAs) detected by quantitative PCR, in which miR-124 was one of the most changed miRNAs and its level was increased by fourfold. The result of miRNA target prediction showed that miR-124 could regulate hundreds of genes which were relative to cell differentiation, such as SLUG, Vimentin, actin cytoskeleton, focal adhesion, tight junction. Inhibition of miR-124 up-regulated SLUG, Twist and Vimentin proteins, and partly eliminated the function of CDA-2 on these mesenchymal markers. Our findings demonstrated for the first time that CDA-2 induced cell differentiation through suppressing Twist and SLUG via miR-124 in glioma cells.