Glial cell differentiation and glioma formation

该研究的总体目标是阐明胶质细胞分化的分子机制，并利用参与分化的信号成分作为最终治疗低级别胶质瘤的工具。本小组先前的工作证实，自分泌环PDGF信号传导导致培养的星形胶质细胞向胶质祖细胞去分化，并在小鼠体内形成低级别胶质瘤。药物阻断PDGF受体酪氨酸激酶活性导致细胞恢复为分化的星形细胞样细胞。因此，我们假设已知促进分化的药物将逆转致瘤表型。我们对原代少突胶质细胞的研究发现了参与少突胶质细胞分化的关键信号蛋白，包括Fyn、p190RhoGAP、Rho和Cdk抑制剂。因此，我们打算直接测试这些信号分子调节培养胶质细胞分化和小鼠和人类少突胶质细胞瘤形成的能力，具体如下：目的1：确定Src家族激酶、Rho通路、Cdk抑制剂和Rb家族成员在培养胶质细胞分化中的作用。用编码wt和Fyn、p190RhoGAP、Rho、p21和p27突变型的RCAS载体感染表达GFAP-PDGF和巢蛋白- pdgf的细胞，确定对细胞生长和分化的影响。目的2：确定Src家族激酶、Rho通路、Cdk抑制剂和Rb家族成员在体内少突胶质细胞瘤形成中的作用。将利用转基因小鼠来确定上述分子在小鼠肿瘤形成中的作用。目的3：分析人类少突胶质细胞瘤中上述分子和途径的活性，以验证所提出的实验模型。上述蛋白在人类胶质瘤样本中的活性将被确定。

The overall goal of the proposed research is to elucidate the molecular mechanisms responsible for glial cell differentiation and to exploit the signaling components involved in differentiation as tools for the ultimate treatment of low grade gliomas. Previous work by our group established that autocrine loop PDGF signaling causes a dedifferentiation of astrocytes to glial progenitors in culture, and formation of low- grade gliomas in mice. Pharmacologic blockade of PDGF receptor tyrosine kinase activity causes the cells to revert to differentiated astrocyte-like cells. We therefore hypothesize that agents that are known to promote differentiation will reverse the tumorigenic phenotype. Our studies in primary oligodendrocytes have identified key signaling proteins, including Fyn, p190RhoGAP, Rho, and Cdk inhibitors, that are involved in oligodendrocyte differentiation. We therefore intend to directly test the ability of these signaling molecules to regulate glial cell differentiation in culture, and oligodendroglioma formation in mice and humans, as follows: Aim 1: To determine the role of Src family kinases, the Rho pathway, Cdk inhibitors and Rb family members in glial cell differentiation in culture. GFAP-PDGF as well as nestin-PDGF expressing cells will be infected with RCAS vectors encoding wt and mutant forms of Fyn, p190RhoGAP, Rho, p21 and p27 and the effects on growth and differentiation of the cells will be determined. Aim 2: To determine the role of Src family kinases, the Rho pathway, Cdk inhibitors and Rb family members in oligodendroglioma formation in vivo. Transgenic mice will be utilized to determine the role of the above molecules in tumor formation in mice. Aim 3: To analyze human oligodendrogliomas for activity of the above molecules and pathways in order to validate the proposed experimental models. The activity of the above proteins in human glioma tumor samples will be determined.