Positive regulation of deoxycytidine kinase activity by phosphorylation of Ser-74 in B-cell chronic lymphocytic leukaemia lymphocytes.

Deoxycytidine kinase (dCK) activates several antileukaemic nucleoside analogues. We have recently reported that the activity of dCK, overexpressed in HEK 293T cells, correlates with its phosphorylation level on Ser-74. Here, we show that dCK from B-cell chronic lymphocytic leukaemia (B-CLL) lymphocytes can be detected by an anti-phospho-Ser-74 antibody and that interindividual variability in dCK activity is related to its phosphorylation level on Ser-74. Moreover, pharmacological intervention modified Ser-74 phosphorylation, in close parallel with changes in dCK activity. These results suggest that activation of dCK via phosphorylation of Ser-74 might constitute a new therapeutic strategy to enhance activation and efficacy of nucleoside analogues.