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Methylation-associated silencing of TU3A in human cancers

Yasuo Awakura1, Eijiro Nakamura, Noriyuki Ito

  • 1Department of Urology, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan.

International Journal of Oncology
|September 25, 2008
PubMed

Insights

The tumor suppressor gene TU3A is epigenetically silenced by promoter hypermethylation in renal cell carcinoma (RCC), correlating with advanced stages and poor survival. This methylation was also observed in other cancers, suggesting a broader role in tumorigenesis.

Area of Science:

  • Oncology
  • Epigenetics
  • Molecular Biology

Background:

  • TU3A, a candidate tumor suppressor gene, shows down-regulated expression in various cancers, including renal cell carcinoma (RCC).
  • The mechanisms underlying TU3A inactivation, particularly in RCC, remained largely unexplored prior to this study.

Purpose of the Study:

  • To investigate the expression and promoter CpG island methylation of TU3A in RCC.
  • To determine the association between TU3A hypermethylation and clinicopathological features and survival in RCC patients.
  • To explore TU3A methylation in other cancer types.

Main Methods:

  • Analysis of TU3A mRNA expression in RCC cell lines.
  • Bisulfite sequencing and 5-aza-2'-deoxycytidine/trichostatin A treatment to assess promoter methylation in RCC cell lines.
  • Combined bisulfite restriction analysis (COBRA) to evaluate TU3A methylation in primary RCC and normal kidney tissues.
  • Correlation analysis between TU3A methylation status and clinicopathological data, including tumor stage and patient survival.
  • Examination of TU3A promoter methylation in other cancer cell lines and primary tumors.

Main Results:

  • TU3A mRNA expression was low or absent in examined RCC cell lines.
  • TU3A expression inversely correlated with promoter hypermethylation in RCC cell lines.
  • Hypermethylation of the TU3A promoter was detected in 41.5% of primary RCCs, significantly higher than in normal kidney tissues.
  • TU3A hypermethylation was significantly associated with advanced tumor stage (T stage, N stage, M stage) and poorer disease-specific survival in RCC patients.
  • Promoter hypermethylation of TU3A was also observed in bladder and testis cancer cell lines and primary tumors.

Conclusions:

  • Epigenetic inactivation of TU3A through promoter hypermethylation is a mechanism contributing to RCC development.
  • TU3A hypermethylation serves as a potential biomarker for advanced RCC and poor prognosis.
  • The findings suggest that TU3A epigenetic silencing may play a role in the pathogenesis of multiple human cancers.

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