Recent studies have indicated that piperlongumine (PLM) may exert anti-inflammatory effects. In the present study, we determined the effect of PLM on the proliferation, apoptosis, migration and invasion of fibroblast-like synoviocytes (FLS) from patients with rheumatoid arthritis (RA) (referred to herein as RA FLS). We further explored the mechanisms by which the studied compound inhibits the functions of RA FLS.
RA FLS viability and apoptosis were tested using MTT and Annexin V/PI assays, respectively. We performed an EDU assay to examine the proliferation of RA FLS. The migration and invasion of these cells were measured using a transwell chamber method and wound closure assay. The MMP-1, MMP-3, and MMP-13 levels in the culture supernatants of RA FLS were detected using a Luminex Assay kit. The intracellular ROS levels were detected using DCFH-DA. The expression levels of signal transduction proteins were measured using western blot.
We found that PLM induced apoptosis in RA FLS at concentrations of 15 and 20 μM. The proliferation of RA FLS was downregulated by PLM at concentrations of 1, 5 and 10 μM. Migration and invasion of RA FLS were reduced by PLM at concentrations of 1, 5 and 10 μM. PLM also inhibited cytoskeletal reorganization in migrating RA FLS and decreased TNF-α-induced intracellular ROS production. Moreover, we demonstrated the inhibitory effect of PLM on activation of the p38, JNK, NF-κB and STAT3 pathways.
Our findings suggest that PLM can inhibit proliferation, migration and invasion of RA FLS. Moreover, these data suggests that PLM might have therapeutic potential for the treatment of RA.