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Tan G, Tang X, Huang D, Li Y, Liu N, Peng Z, Zhang Z, Duan C, Lu J, Yan G, Tang F. Dinitrosopiperazine-mediated phosphorylated-proteins are involved in nasopharyngeal carcinoma metastasis. Int J Mol Sci 2014; 15:20054-71. [PMID: 25375189 PMCID: PMC4264155 DOI: 10.3390/ijms151120054] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Revised: 09/12/2014] [Accepted: 10/21/2014] [Indexed: 12/11/2022] Open
Abstract
N,N'-dinitrosopiperazine (DNP) with organ specificity for nasopharyngeal epithelium, is involved in nasopharyngeal carcinoma (NPC) metastasis, though its mechanism is unclear. To reveal the pathogenesis of DNP-induced metastasis, immunoprecipitation was used to identify DNP-mediated phosphoproteins. DNP-mediated NPC cell line (6-10B) motility and invasion was confirmed. Twenty-six phosphoproteins were increased at least 1.5-fold following DNP exposure. Changes in the expression levels of selected phosphoproteins were verified by Western-blotting analysis. DNP treatment altered the phosphorylation of ezrin (threonine 567), vimentin (serine 55), stathmin (serine 25) and STAT3 (serine 727). Furthermore, it was shown that DNP-dependent metastasis is mediated in part through ezrin at threonine 567, as DNP-mediated metastasis was decreased when threonine 567 of ezrin was mutated. Strikingly, NPC metastatic tumors exhibited a higher expression of phosphorylated-ezrin at threonine 567 than the primary tumors. These findings provide novel insight into DNP-induced NPC metastasis and may contribute to a better understanding of the metastatic mechanisms of NPC tumors.
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Affiliation(s)
- Gongjun Tan
- Medical Research Center and Clinical Laboratory, Zhuhai Hospital of Jinan University, 79 Kangning Road, Zhuhai 519000, China.
| | - Xiaowei Tang
- Metallurgical Science and Engineering, Central South University, 21 Lushan South Road, Changsha 410083, China.
| | - Damao Huang
- Clinical Laboratory and Medical Research Center, Xiangya Hospital, Central South University, 87 Xiangya Road, Changsha 410008, China.
| | - Yuejin Li
- Medical Research Center and Clinical Laboratory, Zhuhai Hospital of Jinan University, 79 Kangning Road, Zhuhai 519000, China.
| | - Na Liu
- Clinical Laboratory and Medical Research Center, Xiangya Hospital, Central South University, 87 Xiangya Road, Changsha 410008, China.
| | - Zhengke Peng
- Medical Research Center and Clinical Laboratory, Zhuhai Hospital of Jinan University, 79 Kangning Road, Zhuhai 519000, China.
| | - Zhenlin Zhang
- Medical Research Center and Clinical Laboratory, Zhuhai Hospital of Jinan University, 79 Kangning Road, Zhuhai 519000, China.
| | - Chaojun Duan
- Clinical Laboratory and Medical Research Center, Xiangya Hospital, Central South University, 87 Xiangya Road, Changsha 410008, China.
| | - Jinping Lu
- Medical Research Center and Clinical Laboratory, Zhuhai Hospital of Jinan University, 79 Kangning Road, Zhuhai 519000, China.
| | - Guangrong Yan
- Institute of Life and Health Engineering, National Engineering and Research Center for Genetic Medicine, Jinan University, 601 Huangpu Road West, Guangzhou 510632, China.
| | - Faqing Tang
- Medical Research Center and Clinical Laboratory, Zhuhai Hospital of Jinan University, 79 Kangning Road, Zhuhai 519000, China.
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Epstein-Barr virus EBNA1 protein regulates viral latency through effects on let-7 microRNA and dicer. J Virol 2014; 88:11166-77. [PMID: 25031339 DOI: 10.1128/jvi.01785-14] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
UNLABELLED The EBNA1 protein of Epstein-Barr virus (EBV) plays multiple roles in EBV latent infection, including altering cellular pathways relevant for cancer. Here we used microRNA (miRNA) cloning coupled with high-throughput sequencing to identify the effects of EBNA1 on cellular miRNAs in two nasopharyngeal carcinoma cell lines. EBNA1 affected a small percentage of cellular miRNAs in both cell lines, in particular, upregulating multiple let-7 family miRNAs, including let-7a. The effects of EBNA1 on let-7a were verified by demonstrating that EBNA1 silencing in multiple EBV-positive carcinomas downregulated let-7a. Accordingly, the let-7a target, Dicer, was found to be partially downregulated by EBNA1 expression (at the mRNA and protein levels) and upregulated by EBNA1 silencing in EBV-positive cells. Reporter assays based on the Dicer 3' untranslated region with and without let-7a target sites indicated that the effects of EBNA1 on Dicer were mediated by let-7a. EBNA1 was also found to induce the expression of let-7a primary RNAs in a manner dependent on the EBNA1 transcriptional activation region, suggesting that EBNA1 induces let-7a by transactivating the expression of its primary transcripts. Consistent with previous reports that Dicer promotes EBV reactivation, we found that a let-7a mimic inhibited EBV reactivation to the lytic cycle, while a let-7 sponge increased reactivation. The results provide a mechanism by which EBNA1 could promote EBV latency by inducing let-7 miRNAs. IMPORTANCE The EBNA1 protein of Epstein-Barr virus (EBV) contributes in multiple ways to the latent mode of EBV infection that leads to lifelong infection. In this study, we identify a mechanism by which EBNA1 helps to maintain EBV infection in a latent state. This involves induction of a family of microRNAs (let-7 miRNAs) that in turn decreases the level of the cellular protein Dicer. We demonstrate that let-7 miRNAs inhibit the reactivation of latent EBV, providing an explanation for our previous observation that EBNA1 promotes latency. In addition, since decreased levels of Dicer have been associated with metastatic potential, EBNA1 may increase metastases by downregulating Dicer.
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