Inhibition of DNA methyltransferase activity upregulates Fyn tyrosine kinase expression in Hut-78 T-lymphoma cells

Tyrosine kinase Fyn, the expression of which is epigenetically regulated, has been proposed to be a tumour suppressor gene. A frequent deletion at the 6q chromosomal region encoding the Fyn gene in lymphomas has been reported. Therefore, we assessed the impact of 5-Aza-2'-deoxycytidine (5-dAzaC), a DNA methyltransferase (DNMTs) inhibitor on Fyn expression in Hut-78 T-lymphoma cells. Using reverse transcription, real-time quantitative PCR (RQ-PCR), and western blot analyses, we found that 5-dAzaC significantly increased transcript and protein levels of Fyn in Hut-78 T-lymphoma cells. However, bisulfite sequencing revealed that Hut-78 T-lymphoma cells cultured in the absence of 5-dAzaC contained unmethylated cytosine in the cytosine-guanosine dinucleotide island of the Fyn promoter. Our results suggest that the DNMTs activity may have an indirect influence on the expression of Fyn without altering the methylation level of its promoter in Hut-78 T-lymphoma cells. (c) 2008 Elsevier Masson SAS. All rights reserved.