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Regulation of matrix metalloproteinase-1 by Epstein-Barr virus proteins
Jean Lu1, Huey-Huey Chua, Shao-Yin Chen
1Graduate Institute of Microbiology, College of Medicine, National Taiwan University, Taipei, Taiwan.
Abstract:
Matrix metalloproteinases (MMPs) play crucial roles in tumor progression. To investigate the roles of MMPs in the progression of nasopharyngeal carcinoma (NPC), the expression of MMP-1, MMP-2, MMP-3, MMP-7, MMP-12, MMP-13, MMP-14, and MMP-19 was explored by microarray assay. Among them, MMP-1 was significantly up-regulated in NPC biopsies. These results were confirmed further by real-time quantitative PCR in additional NPC biopsies and comparison with normal tissues and other head and neck cancers. Moreover, the use of RNA from different cellular constituents of NPC biopsies revealed that MMP-1 was detected predominantly in epithelial cells. Immunohistochemical staining of paraffin-fixed NPC sections confirmed that MMP-1 protein was expressed in the epithelial tumor cells. Because EBV is strongly associated with NPC formation, we sought a correlation between viral gene expression and MMP-1 up-regulation. The results showed clearly that the amounts of transcripts, proteins, and enzyme activities of MMP-1 were increased in cells expressing EBV proteins, LMP1 (latent membrane protein 1) and Zta (Z transactivator; also named as BZLF1 or ZEBRA) but not EBNA-1 (EBV nuclear antigen-1). Additionally, the mobility of LMP1 and Zta transfectants was increased in scrape-wound migration assays. The invasiveness and ability to survive in a three-dimensional collagen gel also were enhanced in LMP1- and Zta-expressing cells. Furthermore, anti-MMP-1 antibody and peptide inhibitors could block the invasiveness and survival properties of LMP1 and Zta transfectants, suggesting a real contribution of MMP-1 to cell mobility and survival. Taken together, our data show that the viral LMP1 and Zta proteins regulate the expression and activity of MMP-1, and thereby confer the invasive properties of the cells. This study presents the first evidence that viral proteins are capable of regulating MMP-1 and also provides clues for the role of EBV in NPC progression.
Insights
Matrix metalloproteinase-1 (MMP-1) is upregulated in nasopharyngeal carcinoma (NPC) and its expression is driven by Epstein-Barr virus (EBV) proteins LMP1 and Zta, promoting tumor cell invasion and survival.
Area of Science:
- Oncology
- Virology
- Biochemistry
Background:
- Matrix metalloproteinases (MMPs) are implicated in tumor progression.
- Nasopharyngeal carcinoma (NPC) is a malignancy with a strong association with Epstein-Barr virus (EBV).
Purpose of the Study:
- To investigate the role of MMPs, particularly MMP-1, in NPC progression.
- To explore the correlation between EBV gene expression and MMP-1 up-regulation in NPC.
Main Methods:
- Microarray assay and real-time quantitative PCR to assess MMP expression in NPC biopsies.
- Immunohistochemical staining to localize MMP-1 expression.
- Analysis of MMP-1 levels in cells expressing EBV proteins (LMP1, Zta, EBNA-1).
- Cell migration and invasion assays, including 3D collagen gel invasion and scrape-wound assays.
Main Results:
- MMP-1 was significantly up-regulated in NPC tissues, predominantly in epithelial tumor cells.
- Expression of EBV proteins LMP1 and Zta, but not EBNA-1, correlated with increased MMP-1 transcripts, protein, and enzyme activity.
- LMP1 and Zta expression enhanced cell migration, invasiveness, and survival.
- Inhibition of MMP-1 blocked the invasive properties of LMP1 and Zta transfectants.
Conclusions:
- EBV-encoded proteins LMP1 and Zta regulate MMP-1 expression and activity in NPC.
- MMP-1 contributes to the invasive phenotype of NPC cells.
- This study provides evidence for viral protein regulation of MMP-1 and its role in NPC pathogenesis.