Metformin inhibits the proliferation of rheumatoid arthritis fibroblast-like synoviocytes through IGF-IR/PI3K/AKT/m-TOR pathway.

Rheumatoid arthritis (RA) is a chronic autoimmune disease in which synovial fibroblast-like cells (FLSs) play an important role in RA development and is known to be lack of effective therapy. Thus, novel therapeutic strategies are greatly needed for treatment of RA. Metformin, a first-line drug for the treatment of type 2 diabetes, has been reported to inhibit the proliferation of a variety of tumor cells. In this study, we demonstrated that metformin could inhibit the RA-FLS proliferation in dose- and time-dependent manner. Our cell viability MTT test and 5-ethynyl-2-deoxyuridine incorporation assay showed that metformin inhibited the RA-FLSs proliferation with a time- and concentration-dependent increase. More importantly, metformin induced G2/M cell cycle phase arrest in RA-FLS via the IGF-IR/PI3K/AKT/ m-TOR pathway and inhibited m-TOR phosphorylation through both the IGF-IR/PI3K/AKT signaling pathways thereby further upregulating and down-regulating p70s6k and 4E-BP1 phosphorylation, respectively; however, metformin was found not to induce apoptosis in RA-FLSs. In summary, these results demonstrate that metformin can effectively inhibit RA-FLS proliferation through inducing cell cycle and upregulating and down-regulating p70s6k and 4E-BP1 phosphorylation. Moreover, IGF-IR/PI3K/AKT m-TOR signaling pathway can be regulated by metformin. Our results indicate that metformin may provide a new way of thinking for the treatment of RA.

Chen K ，Lin ZW ，He SM ，Wang CQ ，Yang JC ，Lu Y ，Xie XB ，Li Q ... -  《-》

Astragalus polysaccharides inhibits cell growth and pro-inflammatory response in IL-1β-stimulated fibroblast-like synoviocytes by enhancement of autophagy via PI3K/AKT/mTOR inhibition.

Meng Q ，Du X ，Wang H ，Gu H ，Zhan J ，Zhou Z ... -  《-》

IL-22 induced cell proliferation is regulated by PI3K/Akt/mTOR signaling cascade.

Interleukin 22 (IL-22), a relatively new cytokine has been found to induce significant proliferation of human keratinocytes and fibroblast like synoviocytes (FLS) and thus plays an important role in the pathogenesis of autoimmune diseases like psoriasis and rheumatoid arthritis (RA) which are characterized by hyperproliferation of keratinocytes and FLS respectively. PI3K/Akt/mTOR signaling cascade plays crucial role in cell growth and survival. Therefore our objective was to see the regulatory role of PI3K/Akt/mTOR signaling cascade in IL-22 induced proliferation of keratinocytes and FLS. Normal human epidermal keratinocytes (NHEK) and FLS were isolated from skin of healthy volunteer's undergone plastic surgery and synovial tissue of psoriatic arthritis (PsA) and RA patients respectively. IL-22 induced proliferation of NHEK and FLS was measured by MTT assay. Phosphorylation of Akt/mTOR was determined by western blot assay and further confirmed by real time polymerase chain reaction (RT-PCR). We observed that IL-22 induced significant proliferation of NHEK and FLS which was effectively inhibited by dual kinase (PI3K/mTOR) inhibitor, NVP-BEZ235 and specific mTOR inhibitor, Rapamycin. In NHEK and FLS, IL-22 significantly induced phosphorylation of Akt and mTOR which was effectively blocked by Rapamycin and NVP-BEZ235. Further we did RT-PCR in NHEK and found that IL-22 significantly upregulated AKT1 and MTOR gene. These results show that IL-22 induced proliferation of NHEK and FLS is dependent on PI3K/Akt/mTOR signaling pathway. This novel observation provides the scope to develop new therapeutics targeting PI3K/Akt/mTOR signaling pathway in autoimmune diseases like psoriasis and rheumatoid arthritis.

Mitra A ，Raychaudhuri SK ，Raychaudhuri SP 《-》

uPAR promotes tumor-like biologic behaviors of fibroblast-like synoviocytes through PI3K/Akt signaling pathway in patients with rheumatoid arthritis.

Liu Y ，Pan YF ，Xue YQ ，Fang LK ，Guo XH ，Guo X ，Liu M ，Mo BY ，Yang MR ，Liu F ，Wu YT ，Olsen N ，Zheng SG ... -  《-》

Stigmasterol Depresses the Proliferation and Facilitates the Apoptosis of Fibroblast-Like Synoviocytes via the PI3K/AKT Signaling Pathway in Collagen-Induced Arthritis Rats.

Lu D ，Yang Y ，Ma W ，Yao X ，Ling Y ，Huang Y ，Wang Q ，Xia C ，Hou L ... -  《ALTERNATIVE THERAPIES IN HEALTH AND MEDICINE》