LncRNA TUG1 promotes the development of osteosarcoma through RUNX2

Abstract

The lncRNA taurine-upregulated gene 1 (TUG1) is known to serve a role as an oncogene in the development of a number of human malignancies. However, the functionality of TUG1 in osteosarcoma remains poorly characterized. Therefore, the aim of the present study was to explore the role of TUG1 in osteosarcoma. TUG1 expression in tumor tissues, adjacent healthy tissues and plasma from 40 osteosarcoma patients and 40 healthy controls was detected using reverse transcription-quantitative PCR. Receiver operating characteristic curves were used to analyze the diagnostic value of TUG1 for osteosarcoma while the prognostic value of TUG1 for osteosarcoma was analyzed using the Kaplan-Meier method. TUG1 expression vectors and siRNAs were transfected into MG-63 and U2OS osteosarcoma cell lines, and the effects on osteosarcoma cell viability, migration and invasion were tested using Cell Counting kit-8 and Transwell assays. The effects of TUG1 overexpression on runt-related transcription factor 2 (RUNX2) expression were also detected using western blotting. TUG1 expression was found to be significantly higher in osteosarcoma tissues compared with adjacent healthy tissues, and in the plasma of osteosarcoma patients compared with healthy controls. TUG1 expression also exhibited significant diagnostic and prognostic value for osteosarcoma. TUG1 overexpression and knockdown respectively increased and reducedosteosarcoma cell viability, migration and invasion. In addition, TUG1 overexpression upregulated RUNX2 expression. These results suggest that lncRNA TUG1 may promote the development of osteosarcoma by modulating RUNX2 and TUG1 expression, which can serve as prognostic and diagnostic markers for this malignancy.

Keywords: long noncoding RNA; osteosarcoma; reverse transcription-quantitative PCR; runt-related transcription factor 2; small interfering RNA silencing; taurine up-regulated gene 1.

Figure 1.

Relative expression of long non-coding RNA TUG1 in osteosarcoma tissues and adjacent healthy tissues. Each experiment was repeated three times. *P<0.05 vs. healthy tissue. TUG1, taurine upregulated gene 1.

Figure 2.

Relative expression levels of lncRNA TUG1 in the plasma samples of osteosarcoma patients and healthy controls, and their diagnostic value for osteosarcoma. (A) Relative expression levels of lncRNA TUG1 in the plasma of osteosarcoma patients and healthy controls. (B) Diagnostic value of TUG1 for osteosarcoma. *P<0.05 vs. Controls. LncRNA, long non-coding RNA; TUG1, taurine upregulated gene 1.

Figure 3.

Kaplan-Meier survival curve of patients with high and low expression of taurine-upregulated gene 1.

Figure 4.

Effects of TUG1 knockdown and overexpression on cell viability. (A) Relative TUG1 expression in normal human bone cell line hFOB and osteosarcoma cell lines MG-63 and U2OS. *P<0.05 vs. hFOB. (B) Relative TUG1 expression in MG-63 and U2OS cells following transfection with plasmid expressing TUG1. *P<0.05 vs. C and NC. (C) Relative TUG1 expression in MG-63 and U2OS cells following transfection with NC or TUG1 siRNA. *P<0.05 vs. C and NC. (D) Effects of TUG1 overexpression on MG-63 and U2OS cell viability. (E) Effects of TUG1 knockdown on MG-63 and U2OS cell viability. *P<0.05 vs. C and NC. Each experiment was repeated three times. For cell viability experiments, all data were normalized to the control group at 96 h. TUG1, taurine upregulated gene 1; siRNA, small interfering RNA; Over, cells transfected with plasmid expressing TUG1; C, controls cells without any transfection; NC, negative control cells transfected with empty vector or negative control siRNA.

Figure 5.

Effects of TUG1 knockdown and overexpression on cell migration and invasion. (A) Migration and (B) invasion of MG-63 and U2OS cells following TUG1 overexpression. (C) Migration and (D) invasion of MG-63 and U2OS cells following TUG1 knockdown. Each experiment was repeated three times, and all data were normalized to C. *P<0.05 vs. C and NC. TUG1, taurine upregulated gene 1; C, control cells without any transfection; NC, negative control cells transfected with empty vector or negative control siRNA; Over, cells transfected with plasmid expressing TUG1.

Figure 6.

LncRNA TUG1 expression correlates positively with RUNX2 expression in osteosarcoma cells. Western blot analysis of RUNX2 in MG-63 and U2OS cells following lncRNA TUG1 overexpression. *P<0.05 vs. NC and C. LncRNA, long non-coding RNA; TUG1, taurine upregulated gene 1; RUNX2, Runt-related transcription factor 2; C, controls cells without any transfection; NC, negative control cells transfected with empty vectors.