MALAT1 knockdown suppresses the viability, migration and invasion of OS cells by downregulation CCND1. (A) CCND1 mRNA expression in OS tissues and normal tissues was detected by RT-qPCR. (B) Correlation between MALAT1 and CCND1 expression in OS tissues. (C) CCND1 mRNA expression in OS cells (Saos-2, MG63 and SOSP-9607) and hFOB cells was evaluated by RT-qPCR. SOSP-9607 cells were transfected with MALAT1, Vector, MALAT1 + si-NC, or MALAT1 + si-CCND1; Saos-2 cells were transfected with si-MALAT1, si-NC, si-MALAT1 + CCND1 or si-MALAT1 + Vector, and subjected to analysis at 48 h post-transfection. (D) Protein expression levels of CCND1 in transfected SOSP-9607 and Saos-2 cells were detected by western blotting. (E) Viability of the transfected SOSP-9607 and Saos-2 cells was assessed by an MTT assay. (F and G) Transwell migration and invasion assays were conducted to evaluate the migration and invasive ability of transfected SOSP-9607 and Saos-2 cells. Scale bar, 100 µm. *P<0.05 vs. normal tissues, hFOB, Vector, si-NC, MALAT1 + si-NC, si-MALAT1 + Vector. CCND1, cyclin D1; MALAT1, metastasis associated lung adenocarcinoma transcript 1; miR, microRNA; NC, negative control; OS, osteosarcoma; RT-qPCR, reverse transcription-quantitative polymerase chain reaction; si,small interfering RNA; Vector, empty vector control.