POLR3D and cancer: miR‐320a is encoded in the antisense orientation of the cell cycle gene POLR3D and plays a critical role in transcriptional silencing expression of POLR3D.38, 39, 40 Many studies have proved that miR‐320a could inhibit cell proliferation, induces apoptosis, affect cell cycle and plays a critical role of anti‐tumor in many cancers.41, 42, 43, 44 However, the relationship between expression of miR‐320a and osteosarcoma progression remains unclear.45, 46, 47 So, we hypothesized that miR‐320a affects the proliferation and development of osteosarcoma in this research.