dinoprost and benzyloxycarbonylleucyl-leucyl-leucine-aldehyde

We have previously shown that nuclear factor-kappaB inhibition by adenovirus expressing mutated IkappaB-alpha or by proteasome inhibitor increases human articular chondrocytes sensibility to apoptosis. Moreover, the nuclear factor-kappaB inhibitor BAY11-7085, a potent anti-inflammatory drug in rat adjuvant arthritis, is itself a proapoptotic agent for chondrocytes. In this work, we show that BAY 11-7085 but not the proteasome inhibitor MG-132 induced a rapid and sustained phosphorylation of extracellular signal-regulated kinases (ERK1/2) in human articular chondrocytes. The level of ERK1/2 phosphorylation correlated with BAY 11-7085 concentration and chondrocyte apoptosis. 15-Deoxy-delta(12,14)-prostaglandin J2 (15d-PGJ2) and its precursor prostaglandin (PG) D2 but not PGE2 and PGF2alpha rescued chondrocytes from BAY 11-7085-induced apoptosis. 15d-PGJ2 markedly inhibited BAY 11-7085-induced phosphorylation of ERK1/2. BAY 11-7085 also induced ERK1/2 phosphorylation and apoptosis in human synovial fibroblasts, and these reactions were down-regulated by 15d-PGJ2. Further analysis in synovial fibroblasts showed that only molecules that suppressed BAY 11-7085-induced phosphorylation of ERK1/2 (i.e. 15d-PGJ2, PGD2, and to a lesser extent, MEK1/2 inhibitor UO126, but not prostaglandins E2 and F2alpha or peroxisome proliferator-activated receptor-gamma agonist ciglitazone) were able protect cells from apoptosis. These results suggested that the antiapoptotic effect of 15d-PGJ2 on chondrocytes and synovial fibroblasts might involve inhibition of ERK1/2 phosphorylation.

Topics: Annexin A5; Anti-Infective Agents; Apoptosis; Blotting, Western; Cartilage; Cartilage, Articular; Cell Survival; Cells, Cultured; Chondrocytes; Coloring Agents; Cysteine Endopeptidases; Dinoprost; Dinoprostone; Down-Regulation; Fibroblasts; Humans; I-kappa B Proteins; Immunologic Factors; Leupeptins; Mitogen-Activated Protein Kinases; Multienzyme Complexes; Mutation; NF-kappa B; NF-KappaB Inhibitor alpha; Nitriles; Phosphorylation; Prostaglandin D2; Proteasome Endopeptidase Complex; Receptors, Cytoplasmic and Nuclear; Sulfones; Synovial Membrane; Thiazolidinediones; Transcription Factors

The present study was undertaken to investigate whether withdrawal of estrogen and progesterone (EP-withdrawal) stimulates prostaglandin F2alpha (PGF2alpha) production through oxygen radical (ROS)-induced NF-kappaB activation in human endometrial stromal cells (ESC). To study the EP-withdrawal, ESC that had been treated with estradiol (E, 10(-8) M) and medroxyprogesterone acetate (MPA, 10(-6) M) for 12 days were then incubated with or without E+MPA for a further 11 days. PGF2alpha concentrations in the medium and cyclooxygenase-2 (COX-2) mRNA levels were significantly increased after EP-withdrawal, while they were unchanged by the continuous treatment with E+MPA. When ESC were incubated with N-acetyl-L-cysteine (Nac, 50 mM), an antioxidant, during EP-withdrawal, Nac blocked the increases in PGF2alpha production and COX-2 mRNA expression caused by EP-withdrawal. Next, we examined whether ROS generated in response to EP-withdrawal acted through NF-kappaB activation. Electrophoretic mobility shift assay revealed that EP-withdrawal caused marked increases in NF-kappaB DNA binding activity, which was completely suppressed by Nac. Furthermore, when ESC were incubated with MG132 (3 microM), which inhibits NF-kappaB activation, during EP-withdrawal, MG132 blocked the increases in PGF2alpha production and COX-2 mRNA expression caused by EP-withdrawal. In conclusion, EP-withdrawal stimulates COX-2 expression and PGF2alpha production through ROS-induced NF-kappaB activation, suggesting a possible mechanism for menstruation.

Topics: Acetylcysteine; Adult; Antioxidants; Cells, Cultured; Cyclooxygenase 2; Cysteine Endopeptidases; Dinoprost; Endometrium; Enzyme Activation; Estradiol; Female; Free Radicals; Humans; Isoenzymes; Leupeptins; Medroxyprogesterone Acetate; Membrane Proteins; Menstruation; Multienzyme Complexes; NF-kappa B; Ovary; Oxygen; Progesterone; Prostaglandin-Endoperoxide Synthases; Proteasome Endopeptidase Complex; Reactive Oxygen Species; Reverse Transcriptase Polymerase Chain Reaction; RNA; RNA, Messenger; Steroids; Stromal Cells; Superoxide Dismutase; Superoxides; Time Factors