J Cancer 2020; 11(5):1257-1269. doi:10.7150/jca.37415

Research Paper

LMP1 Up-regulates Calreticulin to Induce Epithelial-mesenchymal Transition via TGF-β/Smad3/NRP1 Pathway in Nasopharyngeal Carcinoma Cells

Dongmei Ye1*, Junhui Zhu1*, Qiang Zhao3*, Wei Ma2, Yiyang Xiao4, Gaosheng Xu2✉, Zhiwei Zhang1✉

1. Cancer Research Institute of Hengyang Medical College, University of South China; Key Laboratory of Cancer Cellular and Molecular Pathology in Hunan Province, Hunan Hengyang 421001, China.
2. Department of Surgery, Innovative Practice Base for Postgraduate Training of Basic Medicine and Clinical Collaboration, University of South China and Yueyang Maternal and Child Health Hospital, Yueyang 414000, Hunan Province, China.
3. Department of Pathology, The First Affiliated Hospital of University of South China, Hunan Hengyang 421001, Hunan Province China.
4. Clinical Medicine of Hengyang Medical College, University of South China, Hengyang 421001, Hunan Province, China.
*Contributed equally.

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Citation:
Ye D, Zhu J, Zhao Q, Ma W, Xiao Y, Xu G, Zhang Z. LMP1 Up-regulates Calreticulin to Induce Epithelial-mesenchymal Transition via TGF-β/Smad3/NRP1 Pathway in Nasopharyngeal Carcinoma Cells. J Cancer 2020; 11(5):1257-1269. doi:10.7150/jca.37415. Available from http://www.jcancer.org/v11p1257.htm

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Abstract

Background: Latent membrane protein 1 (LMP1) is known as an oncogenic protein encoded by the EBV genome. The purpose of this study was to investigate the mechanism of LMP1-induced cell epithelial-mesenchymal transition (EMT).

Methods: The NP69 cell line of nasopharyngeal epithelial cells with high expression of LMP1 was established to observe the effect of high expression of LMP1 on cell growth, proliferation, cycle, apoptosis, migration and invasion. We used proteomics to screen and identify differentially expressed proteins related to LMP1-mediated epithelial cell transformation. Then, we analyzed the expression and significance of differentially expressed calreticulin (CRT) in nasopharyngeal carcinoma (NPC), and observed the effect of CRT expression on EMT in CNE2 cells of NPC. Finally, the expression of neuropilin-1 (NRP1), which is a protein downstream of the EMT-related signaling pathway TGF-β (transforming growth factor β), was detected.

Results: LMP1 promoted NP69 cells proliferation, inhibited apoptosis and induced EMT. We identified 22 differentially expressed proteins associated with LMP1-induced EMT. Among them, CRT expression level was significantly increased in NPC compared with adjacent tissues, and was interrelated with TNM staging and lymph node metastasis of NPC. After knockdown of CRT expression, the phenomenon of cell EMT was reduced and the ability of cell migration and invasion was weakened. CRT regulated NRP1 expression by affecting SMAD3 phosphorylation.

Conclusion: LMP1 induced cell EMT via TGF-β/Smad3/NRP1 pathway, which promoted migration and invasion of NPC cells.

Keywords: nasopharyngeal carcinoma, latent membrane protein 1, calreticulin, Epithelial-mesenchymal transition, TGF-β signaling pathway, Neuropilin-1