Urokinase plasminogen activator receptor and/or matrix metalloproteinase-9 inhibition induces apoptosis signaling through lipid rafts in glioblastoma xenograft cells.
Small interfering RNA (siRNA)-mediated transcriptional knockdown of urokinase plasminogen activator receptor (uPAR) and matrix metalloproteinase-9 (MMP-9), alone or in combination, inhibits uPAR and/or MMP-9 expression and induces apoptosis in the human glioblastoma xenograft cell lines 4910 and 5310. siRNA against uPAR (pU-Si), MMP-9 (pM-Si), or both (pUM-Si) induced apoptosis and was associated with the cleavage of caspase-8, caspase-3, and poly(ADP-ribose) polymerase. Furthermore, protein levels of the Fas receptor (APO-1/CD-95) were increased following transcriptional inactivation of uPAR and/or MMP-9. In addition, Fas siRNA against the Fas death receptor blocked apoptosis induced by pU-Si, pM-Si, or pUM-Si, thereby indicating the role for Fas signaling in pU-Si-, pM-Si-, or pUM-Si-mediated apoptotic cell death of human glioma xenograft cells. Thus, transcriptional inactivation of uPAR and/or MMP-9 enhanced localization of Fas death receptor, Fas-associated death domain-containing protein, and procaspase-8 into lipid rafts. Additionally, disruption of lipid rafts with methyl β cyclodextrin prevented Fas clustering and pU-Si-, pM-Si-, or pUM-Si-induced apoptosis, which is indicative of coclustering of Fas death receptor into lipid rafts in the glioblastoma xenograft cell lines 4910 and 5310. These data indicate the crucial role of the clusters of apoptotic signaling molecule-enriched rafts in programmed cell death, acting as concentrators of death receptors and downstream signaling molecules, and as the linchpin from which a potent death signal is launched in uPAR- and/or MMP-9-downregulated cells.
Chetty
Chandramu
C
Department of Cancer Biology and Pharmacology, University of Illinois College of Medicine at Peoria, Peoria, Illinois 61605, USA.
Lakka
Sajani S
SS
Bhoopathi
Praveen
P
Gondi
Christopher S
CS
Veeravalli
Krishna Kumar
KK
Fassett
Daniel
D
Klopfenstein
Jeffrey D
JD
Dinh
Dzung H
DH
Gujrati
Meena
M
Rao
Jasti S
JS
D000818:Animals; D017209:Apoptosis / Q000235:genetics; D001932:Brain Neoplasms / Q000201:enzymology / Q000235:genetics / Q000473:pathology / Q000628:therapy*; D053181:Caspase 8 / Q000378:metabolism; D045744:Cell Line, Tumor; D015536:Down-Regulation; D005909:Glioblastoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology / Q000628:therapy*; D006801:Humans; D020780:Matrix Metalloproteinase 9 / Q000235:genetics / Q000378:metabolism; D061965:Matrix Metalloproteinase Inhibitors; D021962:Membrane Microdomains / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008819:Mice, Nude; D034741:RNA, Small Interfering / Q000008:administration & dosage* / Q000235:genetics; D055293:Receptors, Urokinase Plasminogen Activator / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D015533:Transcriptional Activation; D014162:Transfection; D014183:Transplantation, Heterologous; D023041:Xenograft Model Antitumor Assays; D019014:fas Receptor / Q000378:metabolism
D061965:Matrix Metalloproteinase Inhibitors; D034741:RNA, Small Interfering; D055293:Receptors, Urokinase Plasminogen Activator; D019014:fas Receptor; D053181:Caspase 8; D020780:Matrix Metalloproteinase 9