RESUMO
FGFR1 is a receptor tyrosine kinase deregulated in certain breast cancers (BCs) with a poor prognosis. Although FGFR1-activated phosphorylation cascades have been mapped, the key genes regulated by FGFR1 in BC are largely unclear. FOXQ1 is an oncogenic transcription factor. Although we found that activation of FGFR1 robustly upregulated FOXQ1 mRNA, how FGFR1 regulates FOXQ1 gene expression and whether FOXQ1 is essential for FGFR1-stimulated cell proliferation are unknown. Herein, we confirmed that activation of FGFR1 robustly upregulated FOXQ1 mRNA and protein in BC cells. Knockdown of FOXQ1 blocked the FGFR1 signaling-stimulated BC cell proliferation, colony formation, and xenograft tumor growth. Inhibition of MEK or ERK1/2 activities, or knockout of ERK2 but not ERK1 suppressed the FGFR1 signaling-promoted FOXQ1 gene expression. Inhibition of ERK2 in ERK1 knockout cells blocked, while ectopic expression of FOXQ1 in ERK2 knockout cells rescued the FGFR1-signaling-promoted cell growth. Mechanistically, c-FOS, an early response transcription factor upregulated by the FGFR1-MEK-ERK2 pathway, bound to the FOXQ1 promoter to mediate the FGFR1 signaling-promoted FOXQ1 expression. These results indicate that the FGFR1-ERK2-c-FOS-FOXQ1 regulatory axis plays an essential role in the FGFR1 signaling-promoted BC growth. Targeting ERK2 and FOXQ1 should block BC growth caused by a deregulated FGFR1 signaling.
Assuntos
Neoplasias da Mama , Humanos , Feminino , Neoplasias da Mama/metabolismo , Transdução de Sinais/genética , Mama/metabolismo , Proteínas Proto-Oncogênicas c-fos/metabolismo , Quinases de Proteína Quinase Ativadas por Mitógeno/metabolismo , Linhagem Celular Tumoral , Fatores de Transcrição Forkhead/metabolismo , Receptor Tipo 1 de Fator de Crescimento de Fibroblastos/genética , Receptor Tipo 1 de Fator de Crescimento de Fibroblastos/metabolismoRESUMO
BACKGROUND: As a type of breast cancer that has relatively strong invasiveness, triple negative breast cancer (TNBC) seriously affects the survival of patients. microRNAs (miRNAs) have been shown to exert a prominent regulatory effect on the disease, among which miR-133b is reported to be involved in the pathological mechanism of breast cancer, but its role in TNBC remains unclear. METHODS: In this study, real-time quantitative PCR (RT-qPCR) and Western blotting (WB) were performed for detecting the expressions of miR-133b, fibroblast growth factor receptor 1 (FGFR1), and Wingless/Integrated (Wnt)-ß-catenin pathway markers (Wnt1, ß-catenin, nuclear-ß-catenin, p-GSK-3ß, GSK-3ß, cyclinD1, and FOXQ1). With TNBC cells and DDP-resistant TNBC cells (TNBC/DDP cells) used as research objects, their proliferation and apoptosis were measured by Cell Counting Kit-8 (CCK-8) assays and Flow cytometry, respectively. Then, the targeted relationship between miR-133b and FGFR1 was verified by Dual luciferase reporter gene assay (DLRGA). RESULTS: In our study, miR-133b was down-regulated while FGFR1 up-regulated in TNBC. The ectopic expression of miR-133b remarkably inhibited the proliferation and colony formation but induced apoptosis of TNBC cells, and inactivated the Wnt-ß-catenin pathway. The knockdown of FGFR1 had similar effects. Additionally, miR-133b targeted and negatively regulated FGFR1. Up-regulating miR-133b or down-regulating FGFR1 could enhance the proliferation and DDP sensitivity of TNBC cells or TNBC/DDP cells. Up-regulating FGFR1 could offset the anti-TNBC cell survival and DDP sensitization shown by ectopic expression of miR-133b. CONCLUSION: To sum up, miR-133b can inhibit the growth and DDP resistance of TNBC cells by targeting FGFR1 and inactivating the Wnt-ß-catenin pathway.