title: Metalloproteinase dependent reduction of cell surface cluster determinants upon the induction of apoptosis.
abstract: LN18 glioblastoma cells were used as a model to examine changes in surface cluster determinants (CDs) as the cells undergo apoptosis. LN18 cells proceeding through apoptosis manifested a decrease in cell adhesion molecules, growth factor receptors and other surface proteins. Apoptosis was induced by MK886, a known FLAP and PPAR-α inhibitor, or staurosporine, a known inhibitor of protein kinases including protein kinase C (PKC). The detection and decrease of surface CDs were observed by flow cytometry using CD-specific primary antibodies followed by secondary antibodies conjugated to phycoerythrin. It was determined that there was an apoptotic induced decrease of α and β integrin determinants and the growth factor receptors EGFR and IGF1R. The MHC-1 cell surface marker HLA-ABC was also reduced in the apoptotic cells. The level of EGFR, IGF1R and detected α and β integrin determinants dropped dramatically. The degradation takes place in mid to late apoptosis. It was determined by real-time RT-PCR that the decrease in integrins, EGFR, IGF1R and MHC-1 determinants were not due to a reduction in transcription. Inhibitors of metallo-proteinases blocked the apoptotic decrease in cell surface determinants indicating that metalloproteinases mediated the reduction in these CDs in a manner that can reduce growth and survival signals while stimulating the NK surveillance system. Overall, the data indicate that the final stages of the pharmacological induction of apoptosis, while proceeding to a full commitment to non-necrotic cell death, involves the degradation of integrin, insulin and epidermal growth factor receptors caused by a programmed dysregulation of the cell's metalloproteinases.
authors.affiliation: Department of Biology, Fairmont State University, Fairmont, WV, USA.
authors.forename: Albert
authors.initials: A
authors.lastname: Magro
authors.affiliation: Department of Biology, Fairmont State University, Fairmont, WV, USA.
authors.forename: Alice
authors.initials: A
authors.lastname: Magro
authors.affiliation: Department of Statistics, West Virginia University, Morgantown, WV, USA.
authors.forename: Sirish
authors.initials: S
authors.lastname: Shrestha
authors.affiliation: Department of Microbiology, Immunology and Cell Biology, West Virginia University, Morgantown, WV, USA.
authors.forename: Kathy
authors.initials: K
authors.lastname: Brundage
authors.affiliation: Department of Pharmacology, Physiology and Toxicology, Joan C. Edwards School of Medicine, Marshall University, Huntington, WV, USA.
authors.forename: Gary
authors.initials: G
authors.lastname: Rankin
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D002448:Cell Adhesion; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D066246:ErbB Receptors / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D005805:Genes, MHC Class I; D005909:Glioblastoma / Q000378:metabolism*; D006801:Humans; D007211:Indoles / Q000494:pharmacology*; D016023:Integrins / Q000378:metabolism; D008954:Models, Biological; D047493:PPAR alpha / Q000037:antagonists & inhibitors*; D017526:Receptor, IGF Type 1 / Q000378:metabolism; D019311:Staurosporine / Q000494:pharmacology*; D002722:Chlorobenzenes
chemical_list: D004791:Enzyme Inhibitors; D066246:ErbB Receptors; D007211:Indoles; D016023:Integrins; D047493:PPAR alpha; D017526:Receptor, IGF Type 1; D019311:Staurosporine; C060893:MK-886; D002722:Chlorobenzenes