Cloning Of Differentially Expressed Genes In A Nude Mice Metastatic Model Of Human Osteosarcoma

Osteosarcoma is the most common malignant bone tumor in adolescents and young adults, characterized by the proliferation of tumor cells producing osteoid or immature bone matrix. Despite recent advances in surgical techniques and local and systemic adjuvant therapies, pulmonary metastasis occurs in approximately 3040% of patients with osteosarcoma and remains a major cause of fatal outcome. 3 Since most deaths from cancer are due to metastases that are resistant to conventional therapies, there is an urgent need to develop effective regimens against disseminated cancer. A better understanding of the molecular mechanisms that regulate the process of metastasis can provide a biological foundation for the design of more effective therapy for different cancers and new option for oncologists to deal with cancer metastasis. To investigate genetic and biological mechanism involved in metastasis, it is useful to compare cancer cell lines that possess different metastatic abilities. First, we established a metastatic model in nude mice with the method of orthotopically transplanting human osteosarcoma cell line SOSP-9607. Then, the SOSP-M cell line with the high metastatic potential was selected and isolated from its parent cell line SOSP-9607 by using the model. Third, based on two congenial cell lines with the same background and different phenotype related only to metastasis, we chose the two cell lines for attempts to isolate genes related to metastasis by means of suppression subtractive hybridization (5511). In screening for cell lines with high metastatic ability, the spontaneous lung metastasis rate of the SOSP-M cell line was 1000/o after three cycles?selection. In the second part experiment, using SSH method we isolated two possibly metastasis 梤elated gene, TERF2 (Homo sapiens telomeric repeat binding factor 2) and DED (apoptosis antagonizing transcription factor). Northern blot shown that TERF2 4 specifically expressed in SOSP-9607 cell lines and DED highly expressed in SOSP-M cell tine. The RT-PCR shown that TERF2 specifically expressed in SOSP-9607 cell line and its local tumor tissue, and DED expressed highly in SOSP-M cell line and pulmomc metastatic nodules. The results and the data about the two genes? products implied that TERF2 might function as a negative regulator of progression due to stable genome; DED might play a positive role in metastasis according that it could inhibit DAPK which suppressed metastatic process through prompting apoptosis of tumor cells.