De novo DNA methyltransferases Dnmt3a and Dnmt3b primarily mediate the cytotoxic effect of 5-aza-2'-deoxycytidine.

Abstract

The deoxycytidine analog 5-aza-2'-deoxycitidine (5-aza-dC) is a potent chemotherapeutic agent effective against selective types of cancer. The molecular mechanism by which 5-aza-dC induces cancer cell death, however, is not fully understood. It has been accepted that the mechanism of toxicity is due to the covalent binding between the DNA methyltransferase (Dnmt) and 5-aza-dC-substituted DNA. In order to define which member of the Dnmt family plays a dominant role in the cytotoxicity, we examined the effect of 5-aza-dC on cell growth and apoptosis in various Dnmt null mutant embryonic stem (ES) cells. Of interest, Dnmt3a-Dnmt3b double null ES cells were highly resistant to 5-aza-dC when compared to wild type, Dnmt3a null, Dnmt3b null, or Dnmt1 null ES cells. The cellular sensitivity to 5-aza-dC correlated well with the expression status of Dnmt3 in both undifferentiated and differentiated ES cells. When exogenous Dnmt3a or Dnmt3b was expressed in double null ES cells, the sensitivity to 5-aza-dC was partially restored. These results suggest that the cytotoxic effect of 5-aza-dC may be mediated primarily through Dnmt3a and Dnmt3b de novo DNA methyltransferases. Further, the ability to form Dnmt-DNA adducts was similar in Dnmt1 and Dnmt3, and the expression level of Dnmt3 was not higher than that of Dnmt1 in ES cells. Therefore, Dnmt3-DNA adducts may be more effective for inducing apoptosis than Dnmt1-DNA adducts. These results imply a therapeutic potential of 5-aza-dC to cancers expressing Dnmt3.

• Authors: Masahiro Oka, Amy M Meacham, Takashi Hamazaki, Nemanja Rodić, Lung-Ji Chang, Naohiro Terada
• Journal: Oncogene (Oncogene) Vol. 24 Issue 19 Pg. 3091-9 (Apr 28 2005) ISSN: 0950-9232 [Print] England
• PMID: 15735669 (Publication Type: Journal Article)

Chemical References

• DNA Adducts
• Dnmt3a protein, mouse
• Decitabine
• DNA
• DNA Modification Methylases
• DNA (Cytosine-5-)-Methyltransferase 1
• DNA (Cytosine-5-)-Methyltransferases
• DNA Methyltransferase 3A
• DNA methyltransferase 3B
• Dnmt1 protein, mouse
• Azacitidine

Topics

• Animals
• Apoptosis
• Azacitidine (analogs & derivatives, pharmacology)
• COS Cells
• Cell Death
• Cell Differentiation
• Cell Line
• DNA (metabolism)
• DNA (Cytosine-5-)-Methyltransferase 1
• DNA (Cytosine-5-)-Methyltransferases (metabolism, physiology)
• DNA Adducts (metabolism)
• DNA Fragmentation
• DNA Methyltransferase 3A
• DNA Modification Methylases (metabolism)
• Decitabine
• Dose-Response Relationship, Drug
• Embryo, Mammalian (cytology)
• Immunoblotting
• Lentivirus (genetics)
• Mice
• Mice, Knockout
• Microscopy, Fluorescence
• Mutation
• Stem Cells (cytology)