ATO prevents the transcription of GLI target genes.

Human osteosarcoma cells were cultured with or without 1 µM ATO. An equivalent volume of vehicle was used as the control. Total RNA collected from osteosarcoma cell lines was examined by real-time polymerase chain reaction (PCR). A comparative Ct (ΔΔCt) analysis was performed to examine fold changes in mRNA expression compared with β-actin. Real-time PCR showed that ATO decreased the transcription of GLI target genes, including PTCH1, GLI1, and GLI2, in 143B, Saos2, HsOs1, and U2OS cells. The experiment was performed in triplicate with similar results (error bars represent mean [SD]) (*P < 0.01, **P < 0.05).