The Differential Expression Of IL-2Rα In Malignant Tumors And Its Construction Of Eukaryotic Expression Vector

The genesis and progress of a malignant tumor is closely related to the disturbance of immune defense function. Immune responses mediated by T cell play an important role in eliminating immunogenic neoplastic cells; Antigen activated T cells kill and dissolved the malignant cells with related antigens on their surface. IL-2 enhances the killing activities of T cell through regulating the interaction cascades among the cytokines. The IL-2 receptor (IL-2R) on the surface of target cells specifically binds IL-2 and transmits its signals into the cells and therefore, plays an important role in host vs tumor immunity. At least, three different subunitsα,β,γconstitute IL-2R. Physiologically, IL-2Rαsubunit was induced to expression only on the lymphocytes activated by antigen or mitogen. Middle-affinity receptor which composed byβandγsubunits was constructive expression on the surface of lymphocytes. Meanwhile, they are also the components of IL-15 receptor and also involved in the compositions of IL-4, IL-7, and IL-9 receptors. Therefore, induced expression of IL-2Ra gene is the basis of lymphocyte clone expansion, and play the key role in directing immune functions.In the previous studies, we cloned and identified IL-2Rαgene as cancer suppression related gene from the COP rat which is resistant to the genesis of breast cancers induced by chemicals. It was also shown that the levels of IL-2R was low or absence in rat and human breast cancer cell line, suggesting that the reduced expression of IL-2Rαis an important factor in the development of breast cancer. Little is known on the roles of IL-2Rαcorrelated with breast cancer. The differential expression of IL-2Rαin breast cancer, relative to its benign control tissues were analyzed in protein and mRNA levels respectively, by immunohistochemistry staining and RT-PCR techniques. The specific aim is to correlate the expression with the index of clinical phenotype of breastcarcinomas. The similar expressions in various kinds of cell lines were estimated as well by using above techniques. The final purpose of the studies is to explore the effects of disturbance of IL-2Rαexpressions on the development of breast cancer. Meanwhile, we also construct IL-2Rαeukaryotic expression vector for the further studies in order to explore the role of IL2Rαin the progress of breast carcinomas. The results show:1. Results from immunohistochemistry staining show that the positive rate of IL-2Rαwas 80% (24/30) in benign breast fibro adenomas and 55.26% (21/38) in malignant breast carcinomas. IL-2Rαexpression in malignant breast carcinoma is significant lower than that in its benign control (P <0.05). The expression of IL-2Rαdoes not change following the varieties in ages, malignancy, and metastasis (P >0.05), but show negatively correlation with the clinical stage of the breast carcinomas (P <0.05). The results suggest IL-2Rαimportant roles in the genesis and progress of the breast carcinomas, and the possibilities for it to be used as an index estimating the prognosis of the tumors.2.RT-PCR results based on RNA purified from different cell lines show that normal breast cells line HBL-100, MCF-7, SMMC - 7721 and SK-MES expressed IL-2Rα,but the other tumor cells did not express the detectable IL-2Rα. The differences in expressions of IL-2Rαin various cell lines may reflect the tissue specific expression of it. The results also show:The expression of IL-2Rαin MCF-7 cells is lower than its expression in HBL-100 cells,and there is no expression in MDA-MB231 cellsThe results show that the expression of IL-2Rαmay be relevant to the invasiveness of breast cancer.3. Furthermore, the human IL-2RαcDNA was amplified by RT-PCR, cloned to pGERM (T-A) vector. After proving by full length sequencing, the coding fragment was inserted into pcDNA3.1 eukaryotic expression vector. The expression vector will be used as a tool in transfection studies. The ectopic expression of IL-2Rαwill provide more solid knowledge on the roles IL-2Rα.Above results show that IL-2Rαmay play an important role in the progress of breast cancer, and could be used as an index to estimate prognosis of the tumors. The IL-2Rαeukaryotic expression vector provides pre-required tools for further studies to explore the roles of IL-2Rαon the genesis and progress of breast carcinomas.