The Biological Character Of Anoikis Resistance Variant Of Human Osteosarcoma Cell And Preliminary Research Of It's Molecular Mechanisms

osteosarcoma is one of the most common primary malignant tumour of bone. It often happens in teenager, and is of high malignance. Lung metastasis lesion can be found at the early stage. Nearly 15%～20% patients have lung metastasis when diagnosis as osteosarcoma ,nearly 50% patients develop lung metastasis during every stage of therapy, so the investigation of the mechanism of osteosarcoma metastasis is meaningful. The metastasis of tumor is a cascade including many steps. First, the tumor cell should leave the primary tumor, and live in an anchorage-independence way and then breakthrough the immune surveillance and enter the system of blood and lymph system. After entering the blood system the malignant cell should invade distant organ, live on the tissue of it and generate a new tumor. These are all important steps in tumor metastasis,of which anchorage-independence growth is an important precondition of it,and anoikis resistance serves as the precondition of anchorage-independence growth. So this examination selects anoikis-resistance as the entry point. Anoikis is a special kind of program cell death caused by losing connects with ECM or neighboring cell. In normal circumstance, cell connects with cells around it; the signals generated from the ECM let them know that they are on the homeground. When the connection is disrupted, cells will die of anoikis. In contrast tumor cell are not so"homesick"as normal cells, they hold the ability to leave the primary tumor and survive, even proliferation in the new circumstance. All these provide a precondition of malignant cell invasion. Apoptosis resistance, including anoikis resistant are thought to be early events in tumor metastasis. In many in vivo experiments malignant cells with high ability of metastasis tend to be have stronger ability in anoikis resistance than their parental cell. Since the distribution of malignant cell is fatal to patients, it is meaningful to investigate the mechanism of anoikis resistance. Now the investigation of anoikis resistance focuses mostly in tumor generated from epithelial tissue such as prostate cancer, oesophagus squamous cell carcinoma and so on. And there are few investigation of tumor generate from non-epithelial cell .Since there are difference in the source of tumor, difference in places tumor cell tend to invade, so there maybe difference between epithelial-derive tumor and non-epithelial derive tumor in mechanism of anoikis resistance. Douma's work reveal that TrkB connection closely with rat intestinal epithelial cell in anoikis resistance . But whether TrkB connected with the anoikis resistance of osteosarcoma is not reported. This experiment was done as two successive parts. The first part was to acquire anoikis resistance model maligmant transformant of( hFOB1.19) osteoblast cell line . The second part was to use fluorescent quantitation PCR and immunechemistry to analyse the mRNA of TrkB gene and protein level of TrkB .To discuss the relationship of TrkB and the anoikis resistance of human osteosarcoma .Main results and conclusions:1. Establish the human osteosarcoma anoikis resistance model.2. The anoikis resistant variants of the transforman show characters different from the transformant.It has stronger ability in proliferation ability,nude mice tumor generation ability,migration ability.When transferd into anoikis inducing circumstances, they have a lower apoptosis rate .3.The expression of TrkB have connection with osteosarcoma anoikis resistance, The anoikis resistant variants have stronger TrkB expression than the transformant ; the TrkB expression are stronger in metastasis tissue of anoikis resistant cell compared with the primary tumor and the expression of TrkB the tumor generated from the transformant is the lowest .