Fibroblast growth factor 8 (FGF8) up-regulates gelatinase expression in chondrocytes through nuclear factor-κB p65

INTRODUCTION

Gelatinases, namely MMP2 and MMP9, are involved in the natural turnover of articular cartilage, as well as the loss of the cartilage matrix in osteoarthritis (OA). Studies have reported that fibroblast growth factor 8 (FGF8) promoted the degradation of cartilage in OA. In the present study, we predicted that FGF8 promoted chondrocyte expression and secretion of gelatinases by activating NF-κB p65 signaling.

MATERIALS AND METHODS

Primary chondrocytes from C57 mice were cultured with recombinant FGF8. RNA sequencing was employed to explore the gene expression changes of gelatinases. Gelatin zymography was used to determine the activation of gelatinases. Western blot was used to investigate the expression of the gelatinases and NF-κB p65 signaling pathways, and immunofluorescence staining and NF-κB inhibitor assays were performed to confirm the activation of NF-κB p65 signaling.

RESULTS

FGF8 could increase the expression and activity of gelatinases in primary chondrocytes. And FGF8-induced expression of gelatinases was regulated through activation of NF-κB signaling with acetylated p65 accumulating in the cell nucleus. We further found that the NF-κB inhibitor, BAY 11-7082, could suppress up-regulation of gelatinase induced by FGF8.

CONCLUSION

FGF8 enhanced the expression and activity of MMP2 and MMP9 in chondrocytes via NF-κB p65 signaling.

The role of fibroblast growth factor 8 in cartilage development and disease

Fibroblast growth factor 8 (FGF‐8), also known as androgen‐induced growth factor (AIGF), is presumed to be a potent mitogenic cytokine that plays important roles in early embryonic development, brain formation and limb development. In the bone environment, FGF‐8 produced or received by chondrocyte precursor cells binds to fibroblast growth factor receptor (FGFR), causing different levels of activation of downstream signalling pathways, such as phospholipase C gamma (PLCγ)/Ca²⁺, RAS/mitogen‐activated protein kinase‐extracellular regulated protein kinases (RAS/MAPK‐MEK‐ERK), and Wnt‐β‐catenin‐Axin2 signalling, and ultimately controlling chondrocyte proliferation, differentiation, cell survival and migration. However, the molecular mechanism of FGF‐8 in normal or pathological cartilage remains unclear, and thus, FGF‐8 represents a novel exploratory target for studies of chondrocyte development and cartilage disease progression. In this review, studies assessing the relationship between FGF‐8 and chondrocytes that have been published in the past 5 years are systematically summarized to determine the probable mechanism and physiological effect of FGF‐8 on chondrocytes. Based on the existing research results, a therapeutic regimen targeting FGF‐8 is proposed to explore the possibility of treating chondrocyte‐related diseases.

The FGF/FGFR system in the physiopathology of the prostate gland

Fibroblast growth factors (FGFs) are a family of proteins possessing paracrine, autocrine, or endocrine functions in a variety of biological processes, including embryonic development, angiogenesis, tissue homeostasis, wound repair, and cancer. Canonical FGFs bind and activate tyrosine kinase FGF receptors (FGFRs), triggering intracellular signaling cascades that mediate their biological activity. Experimental evidence indicates that FGFs play a complex role in the physiopathology of the prostate gland that ranges from essential functions during embryonic development to modulation of neoplastic transformation. The use of ligand- and receptor-deleted mouse models has highlighted the requirement for FGF signaling in the normal development of the prostate gland. In adult prostate, the maintenance of a functional FGF/FGFR signaling axis is critical for organ homeostasis and function, as its disruption leads to prostate hyperplasia and may contribute to cancer progression and metastatic dissemination. Dissection of the molecular landscape modulated by the FGF family will facilitate ongoing translational efforts directed toward prostate cancer therapy.