C1q/TNF-related protein-3 exerts the chondroprotective effects in IL-1β-treated SW1353 cells by regulating the FGFR1 signaling.

Cartilage degeneration is known as a major cause of osteoarthritis (OA). C1q/TNF-related protein-3 (CTRP3) is an adipokine relative to chondrogenesis in vitro. However, its effect on cartilage degeneration in OA remains unclearly. In the present study, SW1353 cells were treated with IL-1β to imitate the microenvironment of OA for vitro research. Then, an obvious down-regulation of CTRP3 were validated in IL-1β-treated SW1353 cells. In addition, CTRP3 overexpression significantly attenuated the decrease in cell proliferation and increase in cell apoptosis triggered by IL-1β. Moreover, CTRP3 up-regulation significantly inhibited the expression of FGFR1, but with slight decrease in FGFR3 levels. Further analysis corroborated that FGFR1 overexpression markedly ameliorated the pro-proliferation and anti-apoptotic effects of CTRP3 elevation in cells upon IL-1β. Down-regulation of FGFR1 attenuated the increase in Ras-GTP expression caused by IL-1β stimulation. Moreover, EGFR1 elevation also abated the inhibitory effect of CTRP3 on Ras expression and the CRTP3-induced activation of PI3K/AKT in cells upon IL-1β. Furthermore, Ras inhibitor manumycin A antagonized the decrease in phosphorylation of PI3K and Akt caused by IL-1β treatment. Both Manumycin A and PI3K/Akt agonist FGF-1 attenuated the inhibitory effect of IL-1β on cell growth. Together, this research suggested that CTRP3 might protect chondrocytes against IL-1β-induced injury by suppressing the FGFR1- Ras/PI3K/Akt signaling-mediated growth inhibitory pathway, indicating a potential agent against osteoarthritis.