MDM2 overexpression deregulates the transcriptional control of RB/E2F leading to DNA methyltransferase 3A overexpression in lung cancer

Yen An Tang, Ruo Kai Lin, Yo Ting Tsai, Han Shui Hsu, Yi Chieh Yang, Chih Yi Chen, Yi Ching Wang

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32 Citations (Scopus)

Abstract

Purpose: Overexpression of DNA 5′-cytosine-methyltransferase 3A (DNMT3A), which silences genes including tumor suppressor genes (TSG), is involved in many cancers. Therefore, we examined whether the transcriptional deregulation of RB/MDM2 pathway was responsible for DNMT3A overexpression and analyzed the therapeutic potential of MDM2 antagonist for reversing aberrant DNA methylation status in lung cancer. Experimental Design: The regulation of DNMT3A expression and TSG methylation status by RB/MDM2 was assessed in cancer cell lines and patients. The effects of Nutlin-3, an MDM2 antagonist, on tumor growth in relation to DNMT3A expression and TSG methylation status were examined by xenograft model. Results: We found that RB suppressed DNMT3A promoter activity and mRNA/protein expression through binding with E2F1 protein to the DNMT3A promoter, leading to the decrease of methylation level globally and TSG specifically. In addition, MDM2 dramatically induced DNMT3A expression by negative control over RB. In clinical study, MDM2 overexpression inversely correlated with RB expression, while positively associating with overexpression of DNMT3A in samples from patients with lung cancer. Patients with high MDM2 and low RB expression showed DNMT3A overexpression with promoter hypermethylation in TSGs. Treatment with Nutlin-3, an MDM2 antagonist, significantly suppressed tumor growth and reduced DNA methylation level of TSGs through downregulation of DNMT3A expression in xenograft studies. Conclusions: This study provides the first cell, animal, and clinical evidence that DNMT3A is transcriptionally repressed, in part, by RB/E2F pathway and that the repression could be attenuated by MDM2 overexpression. MDM2 is a potent target for anticancer therapy to reverse aberrant epigenetic status in cancers.

Original languageEnglish
Pages (from-to)4325-4333
Number of pages9
JournalClinical Cancer Research
Volume18
Issue number16
DOIs
Publication statusPublished - Aug 15 2012

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ASJC Scopus subject areas

  • Cancer Research
  • Oncology

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