Objective      To investigate the effect of inhibitor of differentiation factor 1 (Id1) on reversing the malignant biological behaviors and inducing osteogenic differentiation of human osteosarcoma cells.       Methods      Human osteosarcoma cell line MG63 was infected with recombinant adenoviruses AdId1

AdsiId1 and AdGFP separately. RT-PCR and Western blot assay were used to determine the expression of Id1 in MG63 cells

and the cell proliferation

migration and invasion were detected by CCK-8 assay

scratch wound ass

ay

and Transwell assay

respectively. Alkaline phosphatase (ALP) numeration was used to detect the early osteogenic potential of MG63 cells

and the cell cycle was detected by flow cytometry.       Results      The mRNA and protein expression of Id1 gene was increased after infection with AdId1 and decreased after infection with AdsiId1 (P0.05). CCK-8 assay

scratch wound assay and Transwell assay results showed that the malignant behaviors including cell proliferation

migration and invasion were significantly increased after AdId1 infection

and significantly decreased after AdsiId1 infection (P0.05). The percentage of G

1

-phase cells was decreased after infection with AdId1 and increased after infection with AdsiId1 (P0.05). AdsiId1 infection could enhance the activity of ALP in MG63 cells (P0.05).       Conclusion      Inhibiting the expression of Id1 gene can reverse the malignant biological behaviors and induce the osteogenic differentiation of human osteosarcoma cells.