| PART ONE The expression of SKA1 gene in osteosarcoma and the effects of silencing of SKA1 on cell proliferation and cell cycleBackground and purpose: Osteosarcoma is the most common malignant primary bone tumor in adolescent, and is characterized by an extremely high aggressiveness with rapid development of metastasis. In recent years, as one of important subunits of spindle kinetochore associated protein complex, SKA1 has been paid more and more attention. SKA1 is essential for proper chromosome segregation during mitosis. Now, SKA1 has been found expressing in some types of cancers, such as oral squamous carcinoma, hepatocellular carcinoma, gastric cancer and neuronal glioblastoma, and can affect the abnormal proliferation of these malignant tumors. However, the precise role of SKA1 in osteosarcoma remains unknown. The purpose of this study was to investigate whether SKA1 is a key molecule to regulate the proliferation of osteosarcoma.Methods: Real-time PCR and western-blot were used to detect the SKA1 m RNA and protein levels in osteosarcoma cell lines: MG-63, SW1353, U2 OS and SF86. Lv-sh SKA1 and Lv-sh Con were used to transfect osteosarcoma U2 OS cells respectively, the silence efficiency of SKA1 protein levels was detected by western-blot, the effect of Lv-sh SKA1 on cell proliferation, colony formation and cell cycle regulation were investigated by MTT, colony formation assay and flow cytometry respectively.Results: SKA1 m RNA was expressed in osteosarcoma cell lines: MG-63, SW1353, U2 OS and SF86. And SKA1 protein was detected in the MG-63, U2 OS and SF86 cells. After U2 OS cells were transfected by Lv-sh SKA1, the expression of SKA1 protein was reduced significantly. The results of MTT, colony formation assay and flow cytometry showed that U2 OS cells proliferation, clonal growth capacity were significantly decreased, S phase cell and G2/M phase cell were significantly reduced, and G0/G1 phase cell and sub-G1 pahse cell were significantly increased after silencing the target gene SKA1.Conclusion: Silencing SKA1 gene can significantly reduce the osteosarcoma cell proliferation and clone formation ability, and also can affect the cell cycle regulation. SKA1 plays an important role in the process of osteosarcoma malignant proliferation. It is a key molecular in regulating osteosarcoma cells malignant proliferation and may serve as a promising molecular target in osteosarcoma therapy.PART TWO Clinical study on the prognostic factors of osteosarcoma with pulmonary metastasisBackground and purpose: Osteosarcoma is the most common malignant primary bone tumor in adolescent, and is characterized by an extremely high aggressiveness with rapid development of metastasis. It has a high propensity to metastasize to the lungs, and lung metastasis is the main cause of death. The study was to analyze the relationship between the prognosis and the different therapeutic methods in osteosarcoma patients with pulmonary metastasis, and provide the evidences for these patients in clinical decisions.Methods: The clinical data of 87 osteosarcoma patients with pulmonary metastasis admitted in Sixth People’s Hospital from January 2006 to August 2011 were retrospectively reviewed. All patients were followed up. According to the different therapeutic methods for the lung lesions, all the patients were divided into three groups: surgery combined with chemotherapy group(21 cases), gamma-knife radiosurgery combined with chemotherapy group(26 cases), and chemotherapy alone group(40 cases). Kaplan-Meier method was used for survival analysis. The univariate analysis of prognosis was performed by log-rank test, and the multivariate analysis of prognosis was performed by COX regression model.Result: The median progression-free survival(PFS) of patients for the three groups were 8 months in surgery combined with chemotherapy group, 6 months in gamma-knife radiosurgery combined with chemotherapy group and 3 months in the chemotherapy alone group, respectively. The median PFS in surgery combined with chemotherapy group and gamma-knife radiosurgery combined with chemotherapy group were both longer than that in chemotherapy alone group(P < 0.001, P=0.009). Three-year survival rate of osteosarcoma patients in surgery combined with chemotherapy group, gamma-knife radiosurgery combined with chemotherapy group and the chemotherapy alone group were 38.10%, 30.77% and 12.50%, respectively. The univariate analysis showed that unilateral or bilateral lung metastasis, initial treatment or retreatment, the number and distribution type of lung metastatic lesions, metastases of other sites(not lung) and the therapeutic methods for the lung lesions were correlated with prognosis(P<0.05). The COX regression analysis revealed that the therapeutic method for lung metastatic lesions was an independent prognostic factor(P<0.05).Conclusion: Chemotherapy combined with surgery or gamma-knife can effectively improve the survival of osteosarcoma patients, further clinical studies are still needed to confirm our conclusion. |
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