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EGF-dependent and independent programmed cell death pathways in NCI-H596 nonsmall cell lung cancer cells
W Lei1, J E Mayotte, M L Levitt
1Lung Cancer Program, Allegheny University of the Health Sciences, Pittsburgh, Pennsylvania 15212, USA.
Abstract:
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.
Insights
Genistein, a tyrosine kinase inhibitor, counteracts EGF-stimulated lung cancer cell growth by blocking EGFR signaling. It also induces apoptosis through a separate pathway, highlighting its potential in cancer therapy.
Area of Science:
- Oncology
- Molecular Biology
- Cell Biology
Background:
- Epidermal Growth Factor Receptor (EGFR) is a key driver in many human cancers, including lung cancer.
- EGFR signaling pathways regulate cell proliferation and survival.
- Understanding EGFR's role in cancer progression and programmed cell death is crucial for developing targeted therapies.
Purpose of the Study:
- To investigate the effects of Epidermal Growth Factor (EGF) and genistein on cell proliferation, EGFR phosphorylation, and downstream signaling in a human pulmonary adenosquamous carcinoma cell line (NCI-H596).
- To elucidate the involvement of these pathways in programmed cell death.
- To determine if genistein antagonizes EGF signaling and/or induces apoptosis.
Main Methods:
- Treatment of NCI-H596 cells with EGF and genistein.
- Assessment of EGFR phosphorylation and MAP kinase activation.
- Evaluation of cell proliferation and induction of cross-linked envelope (CLE) competence.
- Analysis of DNA fragmentation to detect apoptosis.
Main Results:
- EGF treatment increased EGFR phosphorylation, MAP kinase activation, and cell proliferation.
- Genistein inhibited EGF-induced EGFR phosphorylation, MAP kinase activation, and cell proliferation.
- Genistein alone stimulated CLE competence, decreased cell proliferation, and increased DNA fragmentation, suggesting apoptosis induction.
- Genistein's effect on CLE competence differed from EGF's, and it inhibited EGF-stimulated CLE competence.
Conclusions:
- Genistein antagonizes growth-promoting EGF signaling upstream of MAP kinase.
- Genistein may simultaneously activate an apoptotic pathway.
- EGF might induce an alternative programmed cell death pathway linked to proliferation and CLE competence, distinct from DNA fragmentation-induced apoptosis.