BMI1 and osteosarcoma: Accumulating evidence has indicated that lncRNA acts as a competing endogenous RNA or miRNA sponge, thereby modulating a variety of cellular biological activities.20 For example, the lncRNA CCAT1 promoted gall bladder cancer progression by acting as miR‐218‐5p sponge and increasing the expression of its target gene Bmi1. 21 The lncRNA DANCR competitively binds to miR‐335‐5p and miR‐1972 to regulate the expression of ROCK1, thereby promoting the malignant behaviour of osteosarcoma.22 TUG1 is also involved in many diseases by virtue of acting as a competing endogenous RNA or miRNA sponge.