title: Mcl-1 regulates survival and sensitivity to diverse apoptotic stimuli in human non-small cell lung cancer cells.
abstract: Overexpression of anti-apoptotic Bcl-2 family members and deregulation of the pathways that regulate pro-apoptotic family members have been observed in non-small cell lung cancers (NSCLC). Previous reports have identified both Bcl-2 and Bcl-x(L) proteins as survival factors in lung cancer cells since reductions in these proteins can induce apoptosis and sensitize lung cancer cells to apoptosis induced by chemotherapy agents. Myeloid cell leukemia-1 (Mcl-1), another member of the Bcl-2 family, has been found to be a critical survival factor in hematopoietic cells, yet little data exists for a role of Mcl-1 in human lung cancers. We used NSCLC cell lines to explore how Mcl-1 levels affect lung cancer cell survival and studied tumors from patients to determine expression patterns of Mcl-1. NSCLC cells express abundant Mcl-1 protein and depletion of Mcl-1 levels by antisense Mcl-1 oligonucleotides induces apoptosis in A549 and H1299 lung cancer cells. Reduction in Mcl-1 levels can sensitize lung cancer cells to apoptosis induced by cytotoxic agents as well as by ionizing radiation. Lung cancer cells overexpressing Mcl-1 are less sensitive to apoptosis induced by chemotherapeutic agents, ZD1839 (an inhibitor of EGFR tyrosine kinase) and Bcl-2 or Bcl-x(L) antisense oligonucleotides. We find that epidermal growth factor (EGF) can enhance Mcl-1 protein levels in an ERK-dependent manner. Signal transduction agents that reduce Mcl-1 levels correlated with their individual ability to induce apoptosis in lung cancer cells. Finally, NSCLC tumors taken directly from patients have elevated levels of Mcl-1 protein compared with normal adjacent lung tissue. Therefore, agents that target Mcl-1 can induce apoptosis and sensitize cells to apoptosis induced by cytotoxic agents. Mcl-1 protein is overexpressed in a subset of human NSCLC and enhanced levels of Mcl-1 may protect lung cancer cells from death induced by a variety of pro-apoptotic stimuli.
authors.affiliation: Thoracic Oncology/Experimental Therapeutics, University of South Florida College of Medicine, Tampa, Florida, USA.
authors.forename: Lanxi
authors.initials: L
authors.lastname: Song
authors.forename: Domenico
authors.initials: D
authors.lastname: Coppola
authors.forename: Sandy
authors.initials: S
authors.lastname: Livingston
authors.forename: Doug
authors.initials: D
authors.lastname: Cress
authors.forename: Eric B
authors.initials: EB
authors.lastname: Haura
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis; D002289:Carcinoma, Non-Small-Cell Lung / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm; D066246:ErbB Receptors / Q000037:antagonists & inhibitors; D000077156:Gefitinib; D006801:Humans; D008175:Lung Neoplasms / Q000235:genetics / Q000378:metabolism*; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology*; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology*; D011799:Quinazolines / Q000494:pharmacology; D011836:Radiation Tolerance; D015533:Transcriptional Activation; D051020:bcl-X Protein / Q000037:antagonists & inhibitors / Q000235:genetics
chemical_list: D000970:Antineoplastic Agents; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D009363:Neoplasm Proteins; D016376:Oligonucleotides, Antisense; D019253:Proto-Oncogene Proteins c-bcl-2; D011799:Quinazolines; D051020:bcl-X Protein; D066246:ErbB Receptors; D000077156:Gefitinib