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Urokinase-type plasminogen activator receptor (uPAR), is a multifunctional receptor on cell surface, widely present in endothelial cells, fibroblasts, and a variety of malignant cells. Current studies have suggested that uPAR overexpressed on synovial tissues or in synovial fluid or plasma in patients with rheumatoid arthritis (RA). However, there are limited researches regarding the role of uPAR on fibroblast-like synoviocytes of rheumatoid arthritis (RA-FLSs) and its underlying mechanisms. Here, our studies show that the expression of uPAR protein was significantly higher in fibroblast-like synoviocytes (FLSs) from RA than those from osteoarthritis or traumatic injury patients. uPAR gene silencing significantly inhibited RA-FLSs cell proliferation, restrained cell transformation from the G0/G1 phase to S phase, aggravated cell apoptosis, interfered with RA-FLSs cell migration and invasion, and reduced activation of the PI3K/Akt signaling pathway, which may be associated with β1-integrin. Cell supernatants from uPAR gene-silenced RA-FLSs markedly inhibited the migration and tubule formation ability of the HUVECs (a human endothelial cell line). Therefore, we demonstrate that uPAR changes the biological characteristics of RA-FLSs, and affects neoangiogenesis of synovial tissues in patients with RA. All of these may be associated with the β1-integrin/PI3K/Akt signaling pathway. These results imply that targeting uPAR and its downstream signal pathway may provide therapeutic effects in RA.

Fas-associated protein with death domain (FADD), a pivotal adaptor protein transmitting apoptotic signals, is indispensable for the induction of extrinsic apoptosis. However, overexpression of FADD can form large, filamentous aggregates, termed death effector filaments (DEFs) by self-association and initiate apoptosis independent of receptor cross-linking. A mutant of FADD, which is truncated of the C-terminal tail (m-FADD, 182–205 aa) named N-FADD (m-FADD, 1–181 aa), can dramatically up-regulate the strength of FADD self-association and increase apoptosis. In this study, it was found that over-expression of FADD or N-FADD caused apoptosis of B16F10 cells in vitro, even more, N-FADD showed a more potent apoptotic effect than FADD. Meanwhile, Attenuated Salmonella Typhimurium strain VNP20009 was engineered to express FADD or N-FADD under the control of a hypoxia-induced NirB promoter and each named VNP-pN-FADD and VNP-pN-N-FADD. The results showed both VNP-pN-FADD and VNP-pN-N-FADD delayed tumor growth in B16F10 mice model, while VNP-pN-N-FADD suppressed melanoma growth more significantly than VNP-pN-FADD. Additionally, VNP-pN-FADD and VNP-pN-N-FADD induced apoptosis of tumor cells by activating caspase-dependent apoptotic pathway. Our results show that N-FADD is a more potent apoptotic inducer and VNP20009-mediated targeted expression of N-FADD provides a possible cancer gene therapeutic approach for the treatment of melanoma.

Increased plasma creatine kinase-myoglobin (CK-MB) occurs in patients with acute myocardial infarction (AMI), but its underlying relationship with cytosolic phospholipase A2 (cPLA2) is poorly understood. In the present study we sought to determine cPLA2 activation and its relationship with plasma and myocardial CK-MB level and membrane phospholipids (PLs) in an animal model of AMI. AMI was induced in 60 male Sprague-Dawley rats by ligating the left anterior descending of coronary artery. Rats were randomized into six groups at 0 (sham group), 1, 2, 4, 6, and 12 h after AMI onset (ten rats in each group). cPLA2 was detected by reverse transcription polymerase chain reaction and immunohistochemical staining for mRNA and protein expression, respectively. Plasma and myocardial CK-MB activity were measured by inhibition kinetics, and membrane PLs were determined by phosphorus quantitative method. Myocardial cPLA2 expression increased from 1 h and reached a peak at 2 h after AMI onset (p < 0.01) followed by a decrease but still remained high, whereas plasma CK-MB significantly increased in rats from 4 h after the onset of AMI (p < 0.05). During the first 6 h of AMI, a negative correlation existed between myocardial cPLA2 and membrane PLs (r = −0.504, p < 0.01), whereas myocardial cPLA2 levels were positively associated with plasma CK-MB (r = 0.741, p < 0.01) but negatively correlated with myocardial CK-MB in AMI groups (r = −0.785, p < 0.01). Myocardial cPLA2 level increased and is positively correlated with plasma CK-MB activity and negatively correlated with membrane phospholipid content in AMI rats at early stage.