Reduced or absent TSC-22 expression in hematologic malignant tissue is reversed by the demethylation agent 5-Aza in vitro. (A) Expression of TSC-22 detected by regular RT-PCR in WT, polyclonal IL-15tg (Tg), and primary T or NK LGL leukemia (Leu) mouse splenocytes. (B) RT-PCR of the murine lymphoid tumor cell lines YAC-1 and EL-4 indicated that TSC-22 mRNA was undetectable in untreated cells. Treatment with the demethylation agent 5-Aza restored TSC-22 expression in a dose-dependent fashion. Treatment with trichostatin A (TSA, 300 nM), a histone deacetylase inhibitor, did not have a significant effect on TSC-22 transcription. Amplification of HPRT was included as an internal control.