Nitric oxide inhibits androgen receptor-mediated collagen production in human gingival fibroblasts

Background and Objective: In our previous study, we found that flutamide [an androgen receptor (AR) antagonist] inhibited the up-regulation of collagen induced by interleukin (IL)-1β and/or nifedipine in gingival fibroblasts. The present study attempted to verify the role of nitric oxide (NO) in the IL-1β/nifedipine-AR pathway in gingival overgrowth. Material and Methods: Confluent gingival fibroblasts derived from healthy individuals (n=4) and those with dihydropyridine-induced gingival overgrowth (DIGO) (n=6) were stimulated for 48h with IL-1β (10ng/mL), nifedipine (0.34μm) or IL-1β + nifedipine. Gene and protein expression were analyzed with real-time RT-PCR and western blot analyses, respectively. Meanwhile, Sircol dye-binding and the Griess reagent were, respectively, used to detect the concentrations of total soluble collagen and nitrite in the medium. Results: IL-1β and nifedipine simultaneously up-regulated the expression of the AR and type-I collagen α1 [Colα1(I)] genes and the total collagen concentration in DIGO cells (p