Objective      To investigate whether down-regulation of c-myc gene with antisense RNA can increase the sensitivity of osteosarcoma cells MG-63 and U2OS to cisplatin-induced apoptosis.       Methods      The recombinant adenovirus (Ad-Asc-myc) encoding antisense RNA targeting c-myc was constructed and used to transfect osteosarcoma cells MG-63 and U2OS. The expression of c-myc gene was analyzed by quantitative real-time PCR and Western blotting. The change of the sensitivity to cisplain-induced apoptosis was assayed by MTT assay. The shape of osteosarcoma cells was observed by Wright’s staining.       Results      Ad-Asc-myc down-regulated the expression of c-myc gene after  transfection of MG-63 and U2OS cells for 48 h

which resulted in an increase of cell proliferation inhibition induced by cisplatin in a dose- and time-dependent manner.       Conclusion      The inhibition of c-myc gene expression increases the chemotherapy sensitivity of osteosarcoma.