title: Defective stress kinase and Bak activation in response to ionizing radiation but not cisplatin in a non-small cell lung carcinoma cell line.
abstract: We have here examined ionizing radiation (IR)-induced apoptotic signaling in one IR-sensitive small cell lung carcinoma (SCLC) and one resistant non-small cell lung carcinoma (NSCLC) cell line, both harboring mutant p53. In the sensitive SCLC cell line, IR induced conformational modulation of Bak and Bax, mitochondrial depolarization, and nuclear fragmentation. These events were not observed in the IR-resistant NSCLC cell line. However, in the same cells, cisplatin, a DNA-damaging drug, induced Bak and Bax modulation, mitochondrial depolarization, and nuclear fragmentation. Pre-mitochondrial signaling events were examined in order to further characterize the differing IR response. In the SCLC cell line, IR-induced apoptotic signaling was found to involve a MEKK1-related pathway and activation of the stress-activated kinases JNK and p38. In comparison, the NSCLC cell line had higher basal levels of activity of JNK and p38, and IR treatment did not further activate these kinases. However, NSCLC cells were sensitive to Bak modulation and apoptosis induced by a kinase-active mutant of MEKK1. Together, the results delineate a mechanism of IR resistance in NSCLC cells and indicate that IR and cisplatin induce Bak modulation and apoptosis via different pathways.
mesh_terms: D017209:Apoptosis / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects*; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy / Q000201:enzymology / Q000532:radiotherapy*; D018288:Carcinoma, Small Cell / Q000188:drug therapy / Q000201:enzymology / Q000532:radiotherapy*; D002945:Cisplatin / Q000494:pharmacology*; D053938:DNA Fragmentation / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects; D004789:Enzyme Activation / Q000187:drug effects / Q000528:radiation effects; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases; D008175:Lung Neoplasms / Q000188:drug therapy / Q000201:enzymology / Q000532:radiotherapy*; D048728:MAP Kinase Kinase Kinase 1; D008564:Membrane Potentials / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008928:Mitochondria / Q000187:drug effects / Q000235:genetics; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2; D011836:Radiation Tolerance; D011839:Radiation, Ionizing; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects; D014407:Tumor Cells, Cultured; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: C494772:BAK1 protein, human; C494826:BAX protein, human; D008565:Membrane Proteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein; D017346:Protein Serine-Threonine Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048728:MAP Kinase Kinase Kinase 1; C482576:MAP3K1 protein, human; D002945:Cisplatin