Journal Article

FGF9/FGFR2 increase cell proliferation by activating ERK1/2, Rb/E2F1, and cell cycle pathways in mouse Leydig tumor cells

Chang, Ming‐Min, Pan, Bo‐Syong, Lai, Meng‐Shao, Wang, Chia‐Yih, Chuang, Jih‐Ing, Sun, H. Sunny, Huang, Bu‐Miin, Yang, Shang‐Hsun, Hong, Siou‐Ying, Wu, Chia‐Ching, Huang, Hsin

2018

Overview

Fibroblast growth factor 9 (FGF9) promotes cancer progression; however, its role in cell proliferation related to tumorigenesis remains elusive. We investigated how FGF9 affected MA‐10 mouse Leydig tumor cell proliferation and found that FGF9 significantly induced cell proliferation by activating ERK1/2 and retinoblastoma (Rb) phosphorylations within 15 minutes. Subsequently, the expressions of E2F1 and the cell cycle regulators: cyclin D1, cyclin E1 and cyclin‐dependent kinase 4 (CDK4) in G1 phase and cyclin A1, CDK2 and CDK1 in S‐G2/M phases were increased at 12 hours after FGF9 treatment; and cyclin B1 in G2/M phases were induced at 24 hours after FGF9 stimulation, whereas the phosphorylations of p53, p21 and p27 were not affected by FGF9. Moreover, FGF9‐induced effects were inhibited by MEK inhibitor PD98059, indicating FGF9 activated the Rb/E2F pathway to accelerate MA‐10 cell proliferation by activating ERK1/2. Immunoprecipitation assay and ChIP‐quantitative PCR results showed that FGF9‐induced Rb phosphorylation led to the dissociation of Rb‐E2F1 complexes and thereby enhanced the transactivations of E2F1 target genes, Cyclin D1, Cyclin E1 and Cyclin A1. Silencing of FGF receptor 2 (FGFR2) using lentiviral shRNA inhibited FGF9‐induced ERK1/2 phosphorylation and cell proliferation, indicating that FGFR2 is the obligate receptor for FGF9 to bind and activate the signaling pathway in MA‐10 cells. Furthermore, in a severe combined immunodeficiency mouse xenograft model, FGF9 significantly promoted MA‐10 tumor growth, a consequence of increased cell proliferation and decreased apoptosis. Conclusively, FGF9 interacts with FGFR2 to activate ERK1/2, Rb/E2F1 and cell cycle pathways to induce MA‐10 cell proliferation in vitro and tumor growth in vivo. Fibroblast growth factor 9 (FGF9) interacts with FGF receptor 2 (FGFR2) to promote the Rb/E2F1 pathway and cell cycle progression by activating the ERK1/2 pathway. The consequence of FGF9‐induced Rb phosphorylation is the dissociation of the Rb‐E2F1 complexes, the transactivation of E2F1 target genes, such as Cyclin D1, Cyclin E1, and Cyclin A1, cell cycle progression and cell proliferation in MA‐10 cells. In summary, FGF9/FGFR2 activates ERK1/2, Rb/E2F and cell cycle pathways to induce MA‐10 cell proliferation in vitro and MA‐10 tumor growth in vivo.

• Publisher: John Wiley and Sons Inc
• Subject: Animals / Cell Cycle / Cell Line, Tumor / Cell Proliferation / E2F1 Transcription Factor - metabolism / ERK1/2 / Extracellular Signal-Regulated MAP Kinases - metabolism / FGF9 / FGFR2 / Fibroblast Growth Factor 9 - metabolism / Gene Expression Regulation, Neoplastic / Leydig Cell Tumor - metabolism / Male / MA‐10 Leydig tumor cell proliferation / Mice / Original / Phosphorylation / Rb/E2F1 / Receptor, Fibroblast Growth Factor, Type 2 - metabolism / Retinoblastoma Protein - metabolism / Signal Transduction / Testicular Neoplasms - metabolism