miR-210 promotes human osteosarcoma cell migration and invasion by targeting FGFRL1

Abstract

Osteosarcoma is a common bone tumor and a frequently occuring cancer-associated threat to children. Notably, the prognosis of osteosarcoma is very poor when it is diagnosed with metastasis. A growing number of studies have indicated that various microRNAs (miRs) serve important regulatory roles in the pathogeny of different types of cancer. However, the functions of miR-210 in osteosarcoma need to be elucidated comprehensively. The aim of the present study was to investigate the potential roles of miR-210 in osteosarcoma by targeting fibroblast growth factor receptor-like 1 (FGFRL1). Reverse transcription-quantitative polymerase chain reaction results revealed that the expression of miR-210 was highly elevated while FGFRL1 expression was reduced inversely in osteosarcoma tissues compared with matched normal tissues. The results of Transwell assays showed that miR-210 promoted osteosarcoma cell migration and invasion. Furthermore, the luciferase reporter assay results suggested that miR-210 could directly bind to FGFRL1 in osteosarcoma cells. In addition, the present findings demonstrated that miR-210 could negatively regulate FGFRL1 expression by targeting the 3'untranslated region. In conclusion, the findings of the present study suggested that miR-210 exerted tumor carcinogenic functions in osteosarcoma by targeting FGFRL1. The findings of this study demonstrated that FGFRL1 was a direct target of miR-210 in osteosarcoma involved in the promoting functions mediated by miR-210 in the invasion and migration of osteosarcoma, suggesting that miR-210/FGFRL1 may be promising for discovering diagnostic and prognostic biomarkers for the therapies of osteosarcoma.

Keywords: FGFRL1; human osteosarcoma; invasion; miR-210; migration.

Figure 1.

miR-210 expression elevated and FGFRL1 expression reduced in osteosarcoma. (A) RT-qPCR analysis was applied to measure the miR-210 expression in osteosarcoma tissues (n=54) and matched normal tissues (n=54). (B) FGFRL1 expressions in osteosarcoma tissues (n=54) and matched normal tissues (n=54) were measured by RT-qPCR. (C) miR-210 expression in osteosarcoma cells was detected by RT-qPCR. (D) The FGFRL1 expression was measured using RT-qPCR in MG63 and Saos-2 cells (**P<0.01 as indicated). (E) Correlation between miR-210 and FGFRL1 expressions. (F) miR-210 expression level in osteosarcoma was associated with overall survival. miR, microRNA; FGFRL1, fibroblast growth factor receptor-like 1; RT-qPCR, reverse transcription-quantitative polymerase chain reaction.

Figure 2.

miR-210 accelerates osteosarcoma cell invasion and migration. (A) The miR-210 expressions in transfected MG63 and Saos-2 cells were detected using RT-qPCR (**P<0.01). (B) The migration cell numbers of osteosarcoma cells were counted (**P<0.01). (C) The invasion cell numbers of osteosarcoma cells were counted (**P<0.01). (D) Cell invasion was observed by the Transwell assay in transfected osteosarcoma cells (magnification, ×100). (E) The Transwell assay was conducted to detect cell migration in transfected osteosarcoma cells (magnification, ×100). miR, microRNA; RT-qPCR, reverse transcription-quantitative polymerase chain reaction.

Figure 3.

miR-210 de-regulated FGFRL1 expression via binding to the 3′-UTR of FGFRL1 directly. (A) The miR-210 binding sequence in the 3′-UTR of FGFRL1. (B and C) The luciferase reporter gene assays were performed to detect the fluorescence activities of the FGFRL1 3′UTR in MG63 cells (B) and Saos-2 cells (C) which were cotransfected with wild-type FGFRL1 3′UTR or mutational type FGFRL1 3′UTR and miR-210, respectively (**P<0.01). (D and E) RT-qPCR results of the FGFRL1 mRNA level in MG63 cells (D) and Saos-2 cells (E) with different transfections (**P<0.01 as indicated). (F) Western blot results of the FGFRL1 expression in osteosarcoma cells with different transfections. miR, microRNA; FGFRL1, fibroblast growth factor receptor-like 1; 3′-UTR, 3′untranslated region; RT-qPCR, reverse transcription-quantitative polymerase chain reaction.

Figure 4.

Restoration of FGFRL1 could reverse partial function of miR-210 in osteosarcoma cells. (A) RT-qPCR and western blot analyses of the (B) FGFRL1 expressions in osteosarcoma cells with different transfections (**P<0.01). (C) Transwell assay was performed to observe migration of MG63 cells with different transfection treatments (magnification, ×100) (**P<0.01). (D) Transwell assay was performed to observe invasion of MG63 cells with different transfection treatments (magnification, ×100) (**P<0.01). One-way ANOVA and Scheffe's post-hoc test were utilized to analyze the data. FGFRL1, fibroblast growth factor receptor-like 1; RT-qPCR, reverse transcription-quantitative polymerase chain reaction.