Arsenic trioxide inhibits proliferation of rat synoviocyte line stimulated with TNF-α and its mechanism

Objective To investigate the effect and possible mechanism of arsenic trioxid(As2O3)on proliferation of RSC-364 synoviocyte lines stimulated with TNF-α.Methods RSC-364 synoviocytes were cultured with standard medium as control group or medium supplemented with 10 μg/LTNF-α and different concentrations of As2O3 respectively. MTT assay were carried out to study cell proliferation. Proliferation index (PI) and cell cycle were detected by flow cytometry (FCM). RT-PCR was used to detect the mRNA expression of High mobility group box chromosomal protein (HMGB)1. HMGB-1 and proliferation cell nuclear antigen (PCNA) proteins were detected by immunocytochemistry and FCM. Results (1)As2O3 inhibited proliferation of cell lines stimulated by TNF-α time-dependently and dose-dependently. (2)Compared with normal group, TNF-α up-regulated HMGB-1 protein and mRNA as well as PCNA protein. HMGB-1 protein was not only in nuclear but also in cytoplasm by immunocy-tochemistry. As2O3 down-regulated mRNA and protein of HMGB-1 in a dose-dependent manner; so did PCNA proteins (P0.01). (3)Compared with TNF-α stimulation group, G0/G1 phase cell percentage increased and G2/ M phase decreased with the increasing As2O3 concentrations. PI also remarkably decreased (P0.01). (4)There was a positive correlation between HMGB-1 and PCNA(r=0.946, P0.001). Moreover both of them were also with positive correlation to PI (r=0.731, P0.001; r=0.706 P0.001). Conclusion Arsenic trioxide may inhibit synoviocyte proliferation stimulated with TNF-α. which maybe explained by down-regulating expression of HMGB-1 and blocking cell cycle.