Epigenetic silencing of TCEAL7 (Bex4) in ovarian cancer

Jeremy Chien, Julie Staub, Rajeswari Avula, Heyu Zhang, Wanguo Liu, Lynn C. Hartmann, Scott H Kaufmann, David I Smith, Vijayalakshmi Shridhar

Research output: Contribution to journalArticle

42 Citations (Scopus)

Abstract

Epigenetic silencing by hypermethylation of CpGs represents a mechanism of inactivation of tumor suppressors. Here we report on the cloning of a novel candidate tumor suppressor gene TCEAL7 inactivated by methylation in ovarian cancer. TCEAL codes for a 1.35kb transcript that was previously reported to be downregulated in ovarian cancer by cDNA microarray and suppression subtraction cDNA (SSH) analyses. This report focuses on the elucidation of mechanisms associated with TCEAL7 downregulation. Expression of TCEAL7 is downregulated in a majority of ovarian tumors and cancer cell lines but induced by 5-aza-2′-deoxycytidine treatment in a dose-dependant manner, implicating methylation as a mechanism of TCEAL7 inactivation. Sequence analyses of bisufite-modified genomic DNA from somatic cell hybrids with either the active or the inactive human X chromosome reveal that TCEAL7 is subjected to X chromosome inactivation. Loss of TCEAL7 expression in primary tumors and cell lines correlates with methylation of a CpG site within the promoter. In vitro methylation of the CpG site suppresses promoter activity whereas selective demethylation of the SmaI site attenuates the suppression. Finally, re-expression of TCEAL7 in cancer cell lines induces cell death and reduces colony formation efficiency. These data implicate TCEAL7 as a cell death regulatory protein that is frequently inactivated in ovarian cancers, and suggest that it may function as a tumor suppressor.

Original languageEnglish (US)
Pages (from-to)5089-5100
Number of pages12
JournalOncogene
Volume24
Issue number32
DOIs
StatePublished - Jul 28 2005

Fingerprint

Epigenomics
Ovarian Neoplasms
Methylation
Down-Regulation
decitabine
Tumor Cell Line
Cell Death
Chromosomes, Human, X
X Chromosome Inactivation
Neoplasms
Hybrid Cells
Oligonucleotide Array Sequence Analysis
Tumor Suppressor Genes
Sequence Analysis
Organism Cloning
Complementary DNA
Cell Line
DNA
Proteins
Therapeutics

Keywords

  • Apoptosis
  • Methylation
  • Ovarian cancer
  • Proliferation
  • Tumor suppressor

ASJC Scopus subject areas

  • Molecular Biology
  • Cancer Research
  • Genetics

Cite this

Chien, J., Staub, J., Avula, R., Zhang, H., Liu, W., Hartmann, L. C., ... Shridhar, V. (2005). Epigenetic silencing of TCEAL7 (Bex4) in ovarian cancer. Oncogene, 24(32), 5089-5100. https://doi.org/10.1038/sj.onc.1208700

Epigenetic silencing of TCEAL7 (Bex4) in ovarian cancer. / Chien, Jeremy; Staub, Julie; Avula, Rajeswari; Zhang, Heyu; Liu, Wanguo; Hartmann, Lynn C.; Kaufmann, Scott H; Smith, David I; Shridhar, Vijayalakshmi.

In: Oncogene, Vol. 24, No. 32, 28.07.2005, p. 5089-5100.

Research output: Contribution to journalArticle

Chien, J, Staub, J, Avula, R, Zhang, H, Liu, W, Hartmann, LC, Kaufmann, SH, Smith, DI & Shridhar, V 2005, 'Epigenetic silencing of TCEAL7 (Bex4) in ovarian cancer', Oncogene, vol. 24, no. 32, pp. 5089-5100. https://doi.org/10.1038/sj.onc.1208700
Chien J, Staub J, Avula R, Zhang H, Liu W, Hartmann LC et al. Epigenetic silencing of TCEAL7 (Bex4) in ovarian cancer. Oncogene. 2005 Jul 28;24(32):5089-5100. https://doi.org/10.1038/sj.onc.1208700
Chien, Jeremy ; Staub, Julie ; Avula, Rajeswari ; Zhang, Heyu ; Liu, Wanguo ; Hartmann, Lynn C. ; Kaufmann, Scott H ; Smith, David I ; Shridhar, Vijayalakshmi. / Epigenetic silencing of TCEAL7 (Bex4) in ovarian cancer. In: Oncogene. 2005 ; Vol. 24, No. 32. pp. 5089-5100.
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