Fig. 4

Expression of cell cycle regulator genes and DNMT1 in response to mitogens +/− methotrexate (MTX). Treatment of fibroblast-like synoviocytes (FLS) was performed according to the protocol in Fig. 2a (platelet-derived growth factor (PDGF) 20 ng/mL + IL-1β 2 ng/mL +/− MTX 1 μM). mRNA expression was analyzed by qPCR after 48 h of mitogen stimulation. a Fold change in mRNA levels of the indicated cell cycle regulator genes. b, c Fold change in DNMT1 expression in rheumatoid arthritis (RA) FLS (b) and in osteoarthritis (OA) FLS (c). Values are the mean fold change ± SEM in three to six different FLS lines. *p < 0.05, **p < 0.01. d Correlation between DNMT1 and LBH expression in OA FLS (solid circles; n = 6) and RA FLS (open circles; n = 5). Each dot represents an individual FLS line. Values are fold change in mRNA expression on PDGF + IL-1β + MTX treatment compared to PDGF + IL-1β alone. Lines show fitting of data to a linear regression