Intracellular FGF1 promotes invasion and migration in thyroid carcinoma via HMGA1 independent of FGF receptors

BACKGROUND: Fibroblast growth factor 1 (FGF1) is extensively amplified in many tumors and accelerates tumor invasion and metastasis. However, the role and precise molecular mechanism by which FGF1 participates in thyroid cancer (TC) are still unclear. METHODS: Quantitative real-time polymerase chain reaction- and western blotting were used to detect the mRNA and protein levels of FGF1, high mobility group A (HMGA1), epithelial-to-mesenchymal transition (EMT)-related factors, and FGFs in both TC tissues and cell lines. Immunohistochemistry was conducted to examine the expression of FGF1 and HMGA1. Immunofluorescence staining was used to detect the coexpression of FGF1 and HMGA1. Transwell and wound healing assays were conducted to evaluate the effects of FGF1 on the capacity of invasion and migration in cells. RESULTS: FGF1 was upregulated in papillary thyroid carcinoma (PTC) tissues and cell lines and was relatively higher in PTC tissues with cervical lymph node metastasis. Furthermore, FGF1 promotes invasion and metastasis through the EMT pathway. Mechanistically, FGF1 promotes EMT through intracellular function independent of FGF receptors. Interestingly, we demonstrated that FGF1 could upregulate HMGA1 in TC cells, and the correlation of FGF1 and HMGA1 was positive in PTC tissues. FGF1 and HMGA1 had obvious colocalization in the nucleus. We further revealed that FGF1 promotes the invasion and migration of TC cells through the upregulation of HMGA1. CONCLUSION: Intracellular FGF1 could promote invasion and migration in TC by mediating the expression of HMGA1 independent of FGF receptors, and FGF1 may be an effective therapeutic target in TC.