Aim:To characterize and compare the different biological behaviors of 2 novel human osteosarcoma cell lines,Zos and Zos-M,established respectively from the primary tumor and the skip metastasis of an osteosarcoma patient.Methods:In vitro studies included morphological observations,karyotype analysis,3-(4,5-dimethylthiazol-2-y1)-2,5-diphenyltetrazolium bromide cell proliferation assay,and cell sensitivity to chemotherapeutic drugs.Subcutaneous and intravenous in-oculations into nude mice were carried out to study the tumorigenicity and the metastatic potential.RT-PCR was performed to assess the expression of the os-teoblastic markers and some metastasis-related genes.Results:Both cell lines remained stable for more than 100 passages in vitro without interruption.The RT-PCR examination indicated that they retained the molecular characteristics of an osteoblastic lineage.The karyotype analysis displayed aneuploidy and various structural abnormalities.Both cell lines are tumorigenic;Zos-M differs from Zos by the former’s ability to develop lung metastasis after intravenous injection.The comparison of the expression patts of some metastasis-related genes revealed that the decreased expression of cadherin-11 in Zos-M may correlate with a high potential of metastases.Moreover,both cell lines are less sensitive to the current chemotherapy protocols.Conclusion:The establishment of osteosarcoma cell lines,Zos and Zos-M,and related animal models provide a useful resource for studying the aggressive behavior of osteosarcoma and will be helpful for screen-ing effective treatment strategies.