Hydroxynonenal-induced 5-lipoxygenase and 5-lipoxygenase-activating protein expression is prostaglandin E
-dependent and TGF-β-dependent in human osteoarthritis chondrocytes. Cells were treated with 50 μM naproxen, 10 μM 4-hydroxynonenal (HNE) and 50 μM naproxen + 10 μM HNE for 24 or 72 hours. (a), (b) 5-Lipoxygenase-activating protein (FLAP) and (c), (d) 5-lipoxygenase (5-LOX) mRNA expression at 24 and 72 hours was evaluated by real-time RT-PCR. (e) Cells were treated with single addition of 10 μM HNE for 72 hours in the presence or absence of anti-TGF-β1 antibody, and 5-LOX and FLAP mRNA levels were then assessed by real-time RT-PCR (#P < 0.01 and &P < 0.05, respectively). (f) Cells were treated with single addition of 10 μM HNE for 24, 48, and 72 hours, and the transforming growth factor-beta 1 (TGF-β1) level was measured with ELISA commercial kits and expressed as picograms per milliliter. Data are means ± standard errors of the mean, n = 4, expressed as percentages of untreated cells. Student's unpaired t test: ***P < 0.001. Ab: antibody; CTL: control.