Promoter hypermethylation of FBXO32, a novel TGF-Β/SMAD4 target gene and tumor suppressor, is associated with poor prognosis in human ovarian cancer

Jian Liang Chou, Her Young Su, Lin Yu Chen, Yu Ping Liao, Corinna Hartman-Frey, Yi Hui Lai, Hui Wen Yang, Daniel E. Deatherage, Chieh Ti Kuo, Yi Wen Huang, Pearlly S. Yan, Shu Huei Hsiao, Chien Kuo Tai, Huey Jen L Lin, Ramana V. Davuluri, Tai Kuang Chao, Kenneth P. Nephew, Tim H M Huang, Hung Cheng Lai*, Michael W Y Chan

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

113 Scopus citations


Resistance to TGF-Β is frequently observed in ovarian cancer, and disrupted TGF-Β/SMAD4 signaling results in the aberrant expression of downstream target genes in the disease. Our previous study showed that ADAM19, a SMAD4 target gene, is downregulated through epigenetic mechanisms in ovarian cancer with aberrant TGF-Β/SMAD4 signaling. In this study, we investigated the mechanism of downregulation of FBXO32, another SMAD4 target gene, and the clinical significance of the loss of FBXO32 expression in ovarian cancer. Expression of FBXO32 was observed in the normal ovarian surface epithelium, but not in ovarian cancer cell lines. FBXO32 methylation was observed in ovarian cancer cell lines displaying constitutive TGF-Β/SMAD4 signaling, and epigenetic drug treatment restored FBXO32 expression in ovarian cancer cell lines regardless of FBXO32 methylation status, suggesting that epigenetic regulation of this gene in ovarian cancer may be a common event. In advanced-stage ovarian tumors, a significant (29.3%; P0.05) methylation frequency of FBXO32 was observed and the association between FBXO32 methylation and shorter progression-free survival was significant, as determined by both Kaplan-Meier analysis (P0.05) and multivariate Cox regression analysis (hazard ratio: 1.003, P0.05). Reexpression of FBXO32 markedly reduced proliferation of a platinum-resistant ovarian cancer cell line both in vitro and in vivo, due to increased apoptosis of the cells, and resensitized ovarian cancer cells to cisplatin. In conclusion, the novel tumor suppressor FBXO32 is epigenetically silenced in ovarian cancer cell lines with disrupted TGF-Β/SMAD4 signaling, and FBXO32 methylation status predicts survival in patients with ovarian cancer.

Original languageEnglish (US)
Pages (from-to)414-425
Number of pages12
JournalLaboratory Investigation
Issue number3
StatePublished - Mar 2010


  • Epigenetics
  • FBXO32
  • Ovarian cancer
  • TGF-β

ASJC Scopus subject areas

  • Molecular Biology
  • Pathology and Forensic Medicine
  • Cell Biology


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