Combination therapy of BCR-ABL-positive B cell acute lymphoblastic leukemia by tyrosine kinase inhibitor dasatinib and c-JUN N-terminal kinase inhibition
Xinhua Xiao, Ping Liu, Donghe Li, Zhizhou Xia, Peihong Wang, Xiuli Zhang, Mingzhu Liu, Lujian Liao, Bo Jiao, Ruibao Ren
Abstract
Abstract Background The Philadelphia chromosome (Ph), which leads to the creation and expression of the fusion gene product BCR-ABL, underlines the pathogenesis of chronic myelogenous leukemia (CML) and a fraction of adult and pediatric acute B-lymphoblastic leukemia (B-ALL). The BCR-ABL tyrosine kinase inhibitors (TKIs) have shown a remarkable clinical activity in patients with CML, but their efficacy in treating Ph + B-ALL is limited. Identifying additional therapeutic targets is important for the effective treatment of Ph + B-ALL. Methods Activation of the JNK signaling pathway in human and mouse BCR-ABL + B-ALL cells with or without dasatinib treatment was analyzed by Western blotting. JNK was inhibited either by RNA interference or chemical inhibitors, such as JNK-IN-8. The effect of JNK inhibition with or without BCR-ABL TKI dasatinib on BCR-ABL + B-ALL cells was analyzed by the CellTiter-Glo® Luminescent Cell Viability Assay. The in vivo effects of JNK-IN-8 and dasatinib alone or in combination were tested using a BCR-ABL induced B-ALL mouse model. Results We found that the c-JUN N-terminal kinase (JNK) signaling pathway is abnormally activated in both human and mouse BCR-ABL + B-ALL cells, but the BCR-ABL TKI does not inhibit JNK activation in these cells. Inhibition of JNK, either by RNAi-mediated downregulation or by JNK inhibitors, could significantly reduce viability of Ph + B-ALL cells. JNK inhibition by RNAi-mediated downregulation or JNK inhibitors also showed a synergistic effect with the BCR-ABL TKI, dasatinib, in killing Ph + B-ALL cells in vitro. Furthermore, a potent JNK inhibitor, JNK-IN-8, in combination with dasatinib markedly improved the survival of mice with BCR-ABL induced B-ALL, as compared to the treatment with dasatinib alone. Conclusions Our findings indicate that simultaneously targeting both BCR-ABL and JNK kinase might serve as a promising therapeutic strategy for Ph + B-ALL.