Establishment and characterization of a novel human rheumatoid fibroblast-like synoviocyte line, MH7A, immortalized with SV40 T antigen

A novel immortalized rheumatoid fibroblast-like synoviocyte (FLS) line, MH7A, was established by stably transfecting FLS cells with SV40 T antigen gene. MH7A cells expressed SV40-specific small t and large T antigens as well as an elevated level of p53 protein. They have already reached over 150 population doublings through culture crisis, and have been growing rapidly compared with the parental FLSs, Constitutive activation of p42/p44 mitogen-activated protein (MAP) kinase was detected in MH7A cells. Serum requirements for the growth of MH7A were markedly decreased compared with those for the parental FLSs, MH7A cells were stained positively for interleukin (IL)-1R, intercellular adhesion molecule-1 (ICAM-1), CD16, CD40, CD80, and CD95, IL-1 beta enhanced the production of IL-6 and stromelysin-l, and the surface expression of ICAM-1, in a manner similar to that in the parental FLSs. SB203580, a specific inhibitor of p38 MAP kinase, significantly inhibited IL-1 beta-induced IL-6 and stromelysin-l production by both parental FLSs and MH7A cells; although PD098059, an inhibitor of the p42/p44 MAP kinase pathway, did not affect it. Our results clearly indicate the usefulness of MH7A cells for investigating the regulation of rheumatoid FLSs and the IL-1 signal transduction pathway to develop future RA therapy.