The Nonsteroidal Anti-Inflammatory Drug Exisulind Selectively Induces Apoptosis via JNK in Secondary Acute Myeloid Leukemia after Myelodysplastic Syndrome

Treatment of patients suffering from myelodysplastic syndromes and secondary acutemyeloid leukemia after MDS is often unsuccessful. Pro-apoptosis with arsenic trioxide hasrecently been proposed as a novel therapeutic approach. Exisulind is another potentially proapoptoticagent, and therefore, we investigated its influence on proliferation, differentiation,cell cycle and apoptosis in two sAML/MDS cell lines, one de-novo AML cell line and healthyCD34+ bone marrow cells. Treatment of sAML/MDS cells with Exisulind clearly inhibitedcolony formation in the CFU-assays. Interestingly, Exisulind did not alter the percentages ofsAML/MDS cells in G1-, G2-, M- or S-phase, but reduced proliferation and inducedapoptosis in this cell type. Exisulind had no effect on de-novo AML or normal CD34+ cells.We detected increased c-Jun NH2-terminal kinase activity in sAML/MDS cells treated withExisulind. Adding a specific JNK-inhibitor to Exisulind-treated sAML/MDS cells partiallyabrogated apoptosis, thus proving that Exisulind-mediated apoptosis in sAML/MDS cells isdependent on JNK activation. We conclude that JNK is one mediator of apoptosis insAML/MDS cells treated with Exisulind. Moreover, our data strongly suggests to explore thepotential use of Exisulind as a novel, pro-apoptotic therapy for patients with MDS andsAML/MDS.