Early upregulation of cyclooxygenase-2 in human papillomavirus type 16 and telomerase-induced immortalization of human esophageal epithelial cells

J Gastroenterol Hepatol. 2008 Oct;23(10):1613-20. doi: 10.1111/j.1440-1746.2008.05509.x. Epub 2008 Aug 20.


Background and aim: Cyclooxygenase-2 (COX-2) plays an important role in the carcinogenesis of esophageal squamous cell carcinoma (ESCC). However, it is not clear whether COX-2 is involved in the early or late stage of the development of ESCC. The aim of this study was to investigate the role of COX-2 in the carcinogenesis of ESCC by an immortalized esophageal epithelial cell line.

Methods: Human papillomavirus type 16 (HPV16)-E6/E7 and human telomerase reverse transcriptase (hTERT) transfection were used for immortalization of esophageal epithelial cells. COX-2-specific RNA interference was used for the inhibition of COX-2 expression.

Results: An immortalized esophageal epithelial cell line, NE6-E6E7/hTERT, was established, which had high proliferation activity but failed to induce colony formation in soft agar. COX-2 expression was upregulated in the early process of immortalization, while COX-2 small interfering RNA (siRNA) decreased the Bcl-2 expression, increased the expression of Bax, and induced cell-cycle arrest at the G0/G1 phase in NE6-E6E7/hTERT cells. Expressions of p53, cyclinD1, and the ratio of hyperphosphorylated-RB/hypophosphorylated-RB were progressively increased after E6E7 and the subsequent hTERT transfections. These changes were accompanied by the alteration of COX-2 expression, but could be reversed by COX-2 siRNA (P < 0.05). P16 expression was significantly downregulated in NE6-E6E7 or NE6-E6E7/hTERT cells (P < 0.05), and was not affected by COX-2 siRNA.

Conclusions: Our results suggest that induction of cyclooxygenase-2 is essential in the human papillomavirus type 16 and hTERT-induced immortalization of human esophageal epithelial cells, and that COX-2 inhibition may be a potential target to block the carcinogenesis of ESCC at the precancerous stage.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis
  • Cell Cycle
  • Cell Line
  • Cell Proliferation
  • Cell Transformation, Neoplastic / genetics
  • Cell Transformation, Neoplastic / metabolism*
  • Cell Transformation, Neoplastic / pathology
  • Cell Transformation, Viral*
  • Cyclooxygenase 2 / genetics
  • Cyclooxygenase 2 / metabolism*
  • Dinoprostone / metabolism
  • Epithelial Cells / enzymology*
  • Epithelial Cells / pathology
  • Epithelial Cells / virology
  • Esophagus / enzymology*
  • Esophagus / pathology
  • Esophagus / virology
  • Humans
  • Karyotyping
  • Neoplastic Stem Cells / enzymology
  • Oncogene Proteins, Viral / genetics*
  • Oncogene Proteins, Viral / metabolism
  • Papillomavirus E7 Proteins
  • Proto-Oncogene Proteins c-bcl-2 / metabolism
  • RNA Interference
  • RNA, Small Interfering / metabolism
  • Repressor Proteins / genetics*
  • Repressor Proteins / metabolism
  • Retinoblastoma Protein / metabolism
  • Telomerase / genetics*
  • Telomerase / metabolism
  • Time Factors
  • Transfection
  • Tumor Suppressor Protein p53 / metabolism
  • Up-Regulation
  • bcl-2-Associated X Protein / metabolism


  • BAX protein, human
  • E6 protein, Human papillomavirus type 16
  • Oncogene Proteins, Viral
  • Papillomavirus E7 Proteins
  • Proto-Oncogene Proteins c-bcl-2
  • RNA, Small Interfering
  • Repressor Proteins
  • Retinoblastoma Protein
  • TP53 protein, human
  • Tumor Suppressor Protein p53
  • bcl-2-Associated X Protein
  • oncogene protein E7, Human papillomavirus type 16
  • Cyclooxygenase 2
  • PTGS2 protein, human
  • TERT protein, human
  • Telomerase
  • Dinoprostone