Sprouty2 Inhibits Migration and Invasion of Fibroblast-Like Synoviocytes in Rheumatoid Arthritis by Down-regulating ATF2 Expression and Phosphorylation

Activating transcription factor 2(ATF2), a transcription factor belonging to the AP-1 family, plays an important role in inflammation. However, its biological functions and underlying molecular mechanisms in rheumatoid arthritis (RA) remain unclear. Western blot and immunohistochemistry were used to identify the expression of ATF2 and Sprouty2(SPRY2) in RA synovial tissues. SW982 cells were stimulated by TNF-α to establish an in vitro RA fibroblast-like synoviocyte (RA-FLS) model. Transwell and monolayer wound-healing were used to detect cell migration and invasion. RNA interference (si-ATF2) and adenovirus vector (Ad-SPRY2) methods were employed to manipulate ATF2 or SPRY2 expression in SW982 cells. The protein expression and phosphorylation levels in SW982 cells were evaluated by western blot. ATF2 expression and phosphorylation were upregulated in the RA synovial tissues. In RA-FLS model, ATF2 expression and phosphorylation were increased in a time-dependent manner. ATF2 knockdown inhibited the migration and invasion of RA-FLS model, reducing the inflammatory factors, which was consistent with the influence on cell behaviors caused by SPRY2 overexpression. Moreover, SPRY2 overexpression inhibited the TNF-α-induced phosphorylation of ERK and ATF2 in SW982 cells. The high expression and phosphorylation of ATF2 promoted migration and invasion of RA-FLSs. SPRY2 might inhibited the inflammatory responses of RA-FLSs via suppressing ERK-ATF2 pathway.