JNK and NFκB dependence of apoptosis induced by vinblastine in human acute promyelocytic leukaemia cells.

The relationship between the mitogen-activated protein kinase response, nuclear factor-κB (NFκB) expression and the apoptosis in human acute promyelocytic leukaemia NB4 cells treated with vinblastine was investigated in this work. Cell viability, subdiploid DNA and cell cycle were analysed by propidium iodide permeability and flow cytometry analyses. Apoptosis was determined by annexin V-Fluorescein isothiocyanate assays. Western-blot analysis was used for determination of expression levels of apoptotic factors (p53, Bax and Bcl2), intracellular kinases [serine/threonine-specific protein kinase, extracellular signal-regulated kinase and c-Jun N-terminal kinase (JNK)], NFκB factor and caspases. Electrophoretic mobility shift assay was usefully applied to study DNA-NFκB interaction. In NB4 cells, vinblastine produces alteration of p53 and DNA fragmentation. Vinblastine treatment had an antiproliferative effect via the induction of apoptosis producing Bax/Bcl-2 imbalance. Vinblastine treatment suppressed NFκB expression and depressed NFκB-DNA binding activity while maintaining JNK activation that subsequently resulted in apoptotic response through caspase-dependent pathway. Our study provides a possible anti-cancer mechanism of vinblastine action on NB4 cells by deregulation of the intracellular signalling cascade affecting to JNK activation and NFκB expression. Moreover, JNK activation and NFκB depression can be very significant factors in apoptosis induction by vinblastine.