Hi tytd,
You know no one knows exactely how Vidaza (azacitidine) or Dacogen (decitabine) work but here is a report about some of the effects. The report is very complicated
but at least we can try to understand something about these two drugs. Then we have other epigenic drugs like the histone deacetylase inhibitors (Epival and Zolinza).
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2814859/
Vidaza is incoperated in both DNA and RNA while Dacogen is incorporated solely into DNA. In MDS DNA can be hypermethylated and important tumor supressing genes can be silenced. That is why hypomethylating drugs can have positive effect in MDS (and a lot of other cancers too).
Kind regards
Birgitta-A