Mitotic arrest and JNK-induced proteasomal degradation of FLIP and Mcl-1 are key events in the sensitization of breast tumor cells to TRAIL by antimicrotubule agents.
Breast tumor cells are often resistant to tumor necrosis factor-related apoptosis-inducing ligand (tumour necrosis factor-related apoptosis-inducing ligand (TRAIL)/APO-2 L). Here, we describe the sensitization by microtubule-interfering agents (MIAs) to TRAIL-induced apoptosis in breast tumor cells through a mitotic arrest and c-Jun N-terminal kinase (JNK)-dependent mechanism. MIA treatment resulted in BubR1-dependent mitotic arrest leading to the sustained activation of JNK and the proteasome-mediated downregulation of cellular FLICE-inhibitory protein (cFLIP) and myeloid cell leukemia-1 (Mcl-1) expression. The JNK inhibitor SP600125 abrogated MIA-induced mitotic arrest and downregulation of cFLIP and Mcl-1 and reduced the apoptosis caused by the combination of MIAs and TRAIL. Silencing of cFLIP and Mcl-1 expression by RNA interference resulted in a marked sensitization to TRAIL-induced apoptosis. Furthermore, in FLIP-overexpressing cells, MIA-induced sensitization to TRAIL-activated apoptosis was markedly reduced. In summary, our results show that mitotic arrest imposed by MIAs activates JNK and facilitates TRAIL-induced activation of an apoptotic pathway in breast tumor cells by promoting the proteasome-mediated degradation of cFLIP and Mcl-1.
Sánchez-Pérez
T
T
Centro Andaluz de Biología Molecular y Medicina Regenerativa, Consejo Superior de Investigaciones Científicas, Sevilla, Spain.
Ortiz-Ferrón
G
G
López-Rivas
A
A
D017209:Apoptosis / Q000187:drug effects*; D001943:Breast Neoplasms / Q000188:drug therapy / Q000378:metabolism; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein / Q000378:metabolism*; D045744:Cell Line, Tumor; D005434:Flow Cytometry; D006801:Humans; D015151:Immunoblotting; D048031:JNK Mitogen-Activated Protein Kinases; D008938:Mitosis / Q000187:drug effects*; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D015739:Nocodazole / Q000494:pharmacology; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D034622:RNA Interference; D020133:Reverse Transcriptase Polymerase Chain Reaction; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000627:therapeutic use*; D050257:Tubulin Modulators / Q000627:therapeutic use*
D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D019253:Proto-Oncogene Proteins c-bcl-2; D053221:TNF-Related Apoptosis-Inducing Ligand; D050257:Tubulin Modulators; D048031:JNK Mitogen-Activated Protein Kinases; D046988:Proteasome Endopeptidase Complex; D015739:Nocodazole