EGF-dependent and independent programmed cell death pathways in NCI-H596 nonsmall cell lung cancer cells.
EGF receptor (EGFR) is a transmembrane glycoprotein with trosine kinase activity that is overexpressed in many human cancers, including lung. In the present study, we evaluated the effect of EGF and genistein, a tyrosine kinase inhibitor, on cell proliferation, EGFR phosphorylation and its downstream signal MAP kinase activation and investigated the involvement of these processes in programmed cell death in a human pulmonary adenosquamous carcinoma cell line, NCI-H596. Treatment with EGF resulted in phosphorylation of EGFR, activation of MAP kinase, phosphorylation of ERK 2 (an isoform of MAP kinase), increased cell proliferation and induction of cross-linked envelope (CLE) competence. Genistein abolished the ability of EGF to induce EGFR phosphorylation, to activate MAP kinase and to increase cell proliferation. Genistein alone stimulated CLE competence, but apparently by a different mechanism than EGF since genistein prevented EGF-stimulated CLE competence. The genistein-stimulated CLE competence was accompanied by a decrease in cell proliferation and increased DNA fragmentation. These results demonstrate that genistein antagonizes growth stimulatory EGF signaling upstream of MAP kinase and may simultaneously stimulate an apoptotic pathway. Furthermore, EGF appears to stimulate an alternate, growth related programmed cell death pathway, not involving DNA fragmentation, but characterized by rapid proliferation and genistein-sensitive CLE competence.
Lei
W
W
Lung Cancer Program, Allegheny University of the Health Sciences, Pittsburgh, Pennsylvania 15212, USA.
Mayotte
J E
JE
Levitt
M L
ML
D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D002289:Carcinoma, Non-Small-Cell Lung / Q000473:pathology*; D002455:Cell Division; D053938:DNA Fragmentation; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004815:Epidermal Growth Factor / Q000378:metabolism*; D066246:ErbB Receptors / Q000378:metabolism*; D019833:Genistein / Q000494:pharmacology; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D010766:Phosphorylation; D015398:Signal Transduction; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000378:metabolism
D000970:Antineoplastic Agents; D004791:Enzyme Inhibitors; D014443:Tyrosine; D004815:Epidermal Growth Factor; D019833:Genistein; D066246:ErbB Receptors; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases