Identify And Isolation Of Tumor Stem Cell Of ACC-2

Objectives: The mechanisms involved in the arising and development of malignancies are still remain unresolved, enhancing the difficulties on the treatment of this kind of diseases, which represent the majority threaten on health of humankind. Recently, the conception of "cancer stem cell" provides a new approach to explore the puzzle about the origin of tumors. The present study is designed to analyze the biologic characteristics of different subclones of adenoid cystic carcinoma cell line (ACC-2) by seeking the evidences of tumor stem cell and revealing its impact on the tumorigenesis of ACC-2 cell line.Methods: in vitro individual cell culture was employed to observe the proliferating character of ACC-2 cells. The expression of CD44 and CD24 of ACC-2 cells were investigated by immunohistochemical study. Immunomagnetic isolation of different phenotype of ACC-2 cells, followed by cell culture, was used to study the proliferating abilities ofdifferent clusters of the cell line. The hetero-transplanted tumor mold was established using BALB/C nude mice by subcutaneous injection of tumor cells. The tumorigenic and differentiating properties of the different cluster were investigated. The genomic differences of different clusters were checked using genechip.Results: The result of in vitro individual cell culture revealed that only 4.41% of cultured ACC-2 cell underwent division, proliferation and establish of cell clone, which indicating preservation of the prolonged live ability. CD44+/CD24~ cluster consist in about 8.1% of total ACC-2 cells, among which, 25.71% cells could divide and proliferate. All of CD44" and CD44+/CD24+ cells were failure to be eternal alive in the condition of in vitro individual cell culture. According to the results of in vivo tumorgenic study, the minimal cell quantity to develop a subcutaneous transplanted tumor by CD44+CD24~ cells was 1 X 103, where as the needed cell amount are 1 X105 and 1X 104 as to non-isolated ACC-2 cells and CD44+ cells, respectively. The CD44~ and CD44+/CD24+ were failure to develope transplanted tumors. Immunohistochemistry study proved CD44+CD24~ ACC-2 cell could differentiate into cells of other phenotypes. The genechip experiment find 502 different genes between CD44+CD24~ ACC-2 cell and non-isolated ACC-2 cell.Conclusion: It was suggested that the heterogeneity exists in ACC-2 cell lines. There are some of ACC-2 cells display the following properties: l.They consisted in a very small portion of all ACC-2 cells (about 4%). 2.They were possessed of remarkable proliferating ability, and represent the sole cluster that can establish cell clone and alive eternally. 3.They borne special phenotypes, and CD44+/CD24~ were necessary. 4. During the proliferation and differentiation, the expressing fashion of CD44 and CD24 might be changed. 5. The tumorogenic ability of CD44+/CD24~ cells were stronger than CD44+ and non-isolated ACC-2 cells. Eliminating of this cluster from ACC-2 would actually deprive the tumorogenic ability of the cell line. Taken into account, above features meet the biologic characters of STEM CELL. These cells could be assumed as ACC-2 stem cells. The further purification and isolation are needed for next research.