Vincristine activates c-Jun N-terminal kinase in chronic lymphocytic leukaemia in vivo

Aims The authors' aim was to conduct a proof-of-principle study to test whether c-Jun N-terminal kinase (JNK) phosphorylation and Noxa induction occur in peripheral blood chronic lymphocytic leukaemia (CLL) cells in patients receiving a vincristine infusion. Methods Patients with CLL received 2 mg vincristine by a 5-min intravenous infusion. Blood samples were collected at baseline and up to 6 h after the vincristine infusion, and assayed for JNK activation, Noxa induction and vincristine plasma concentrations. Results Ex vivo treated peripheral CLL cells activated JNK in response to 10-100 nM vincristine in 6 h. Noxa protein expression, while variable, was also observed over this time frame. In CLL patients, vincristine infusion led to rapid (<1 h) JNK phosphorylation in peripheral blood CLL cells which was sustained for at least 4-6 h after the vincristine infusion. Noxa protein expression was not observed in response to vincristine infusion. Conclusions This study confirmed that vincristine can activate JNK but not induce Noxa in CLL cells in vivo. The results suggest that novel JNK-dependent drug combinations with vincristine warrant further investigation.