Plasminogen Activator Receptor and/or Matrix alloproteinase-9 Inhibition Induces Apoptosis Signaling

ownload ll interfering RNA (siRNA)-mediated transcriptional knockdown of urokinase plasminogen activaceptor (uPAR) and matrix metalloproteinase-9 (MMP-9), alone or in combination, inhibits uPAR r MMP-9 expression and induces apoptosis in the human glioblastoma xenograft cell lines 4910 310. siRNA against uPAR (pU-Si), MMP-9 (pM-Si), or both (pUM-Si) induced apoptosis and was ated with the cleavage of caspase-8, caspase-3, and poly(ADP-ribose) polymerase. Furthermore, provels of the Fas receptor (APO-1/CD-95) were increased following transcriptional inactivation of and/or MMP-9. In addition, Fas siRNA against the Fas death receptor blocked apoptosis induced -Si, pM-Si, or pUM-Si, thereby indicating the role for Fas signaling in pU-Si–, pM-Si–, or pUM-Si– ted apoptotic cell death of human glioma xenograft cells. Thus, transcriptional inactivation of uPAR r MMP-9 enhanced localization of Fas death receptor, Fas-associated death domain-containing prond procaspase-8 into lipid rafts. Additionally, disruption of lipid rafts with methyl β cyclodextrin ted Fas clustering and pU-Si–, pM-Si–, or pUM-Si–induced apoptosis, which is indicative of coclusof Fas death receptor into lipid rafts in the glioblastoma xenograft cell lines 4910 and 5310. These ndicate the crucial role of the clusters of apoptotic signaling molecule-enriched rafts in programmed eath, acting as concentrators of death receptors and downstream signaling molecules, and as the cell d linchpin from which a potent death signal is launched in uPARand/or MMP-9–downregulated cells. Mol Cancer Ther; 9(9); OF1–13. ©2010 AACR.