Epstein-Barr virus oncoprotein LMP1 mediates survivin upregulation by p53 contributing to G1/S cell cycle progression in nasopharyngeal carcinoma

Int J Mol Med. 2012 Apr;29(4):574-80. doi: 10.3892/ijmm.2012.889. Epub 2012 Jan 17.

Abstract

Latent membrane protein 1 (LMP1) is an important oncogenic protein encoded by Epstein-Barr virus (EBV) and plays an important role in the development of nasopharyngeal carcinoma (NPC). Our previous study has shown that p53 protein was accumulated and phosphorylated in NPC, implying its transcription factor activity in NPC tumorigenesis. However, the biological function and potential downstream target of p53 mediated by LMP1 in NPC remain unknown. In this study, we found that LMP1 simultaneously induced upregulation of both p53 and survivin at the protein level, as well as their phosphorylation. Knockdown of p53 by siRNA revealed that LMP1 increased survivin expression by p53 directly. Furthermore, we found that LMP1 upregulated survivin by p53 at the transcriptional level by increasing p53-mediated survivin promoter activity and DNA binding activity. Moreover, LMP1 induced the co-localization of p53 and survivin in the nucleus, conferring to their related functions in NPC tumorigenesis. We further found that p53 promoted G1/S cell cycle progression, but did not induce apoptosis in LMP1-positive NPC cells. Collectively, these findings suggest that p53 acting as a transcription factor promotes the transcriptional activity of survivin, and further increases its protein expression and phosphorylation in the regulation of LMP1, thus, leading to G1/S cell cycle progression with no effect on apoptosis in NPC tumorigenesis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis
  • Carcinoma
  • Cell Division*
  • Cell Line, Tumor
  • Cell Nucleus / genetics
  • Cell Nucleus / metabolism
  • Gene Expression Regulation, Neoplastic
  • Herpesvirus 4, Human / genetics
  • Herpesvirus 4, Human / metabolism
  • Humans
  • Inhibitor of Apoptosis Proteins / genetics
  • Inhibitor of Apoptosis Proteins / metabolism*
  • Nasopharyngeal Carcinoma
  • Nasopharyngeal Neoplasms / genetics*
  • Nasopharyngeal Neoplasms / virology
  • Phosphorylation
  • Survivin
  • Tumor Suppressor Protein p53 / genetics
  • Tumor Suppressor Protein p53 / metabolism*
  • Up-Regulation
  • Viral Matrix Proteins / genetics
  • Viral Matrix Proteins / metabolism*

Substances

  • BIRC5 protein, human
  • EBV-associated membrane antigen, Epstein-Barr virus
  • Inhibitor of Apoptosis Proteins
  • Survivin
  • TP53 protein, human
  • Tumor Suppressor Protein p53
  • Viral Matrix Proteins