HOTAIR and osteosarcoma: Nine different long non-coding RNAs were studied in these 10 included articles, with 7 lncRNAs including MALAT1 [12, 15], BCAR4 [13], FGFR3-AS1 [16], HOTAIR [17], TUG1 [18], FOXC2-AS1 [20] and PVT1 [21] were up-regulated in osteosarcoma cells or patients.