RESEARCH Impact of decitabine on im e

Several tumor suppressor genes have now been described, and tumor suppressor gene silencing by mutation, dele-tion, or hypermethylation [1,2] is an important component of tumorigenesis. Treatment of cell lines or xenograft-bearing animals with the demethylating agents decita-bine and 5-azacytidine has been reported to increase expression of a variety of tumor suppressor genes [3-6]. Decitabine may upregulate gene expression through both methylation-dependent and methylation-independent mechanisms [1,2]. Decitabine is active clinically in some hematologic ma-lignancies [7]. Administration of low doses of decitabine daily for multiple successive days may be most effective against hematological malignancies, and is also particularly likely to induce DNA demethylation [7]. In patients with refractory malignancies receiving lo