Glial cell differentiation and glioma formation

这项研究的总体目标是阐明神经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。本课题组以前的工作证实，自分泌环PDGF信号导致培养中的星形胶质细胞去分化为神经胶质前体细胞，并在小鼠中形成低级别胶质瘤。药物阻断PDGF受体酪氨酸激酶活性可使细胞恢复分化为星形胶质细胞样细胞。因此，我们假设，已知的促进分化的药物将逆转肿瘤的形成表型。我们对原代少突胶质细胞的研究已经确定了关键的信号蛋白，包括Fyn、p190RhoGAP、Rho和CDK抑制剂，它们参与了少突胶质细胞的分化。因此，我们打算直接测试这些信号分子在培养中调节胶质细胞分化的能力，以及在小鼠和人中调节少突胶质细胞瘤的形成的能力，如下：目的1：确定在培养的神经胶质细胞分化中，Src家族激酶、Rho通路、CDK抑制剂和Rb家族成员的作用。将编码wt的RCAS载体和突变型Fyn、p190RhoGAP、Rho、p21和p27分别感染表达GFAP-PDGF和Nestin-PDGF的细胞，观察其对细胞生长和分化的影响。目的：探讨Src家族、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：分析人少突胶质细胞瘤中上述分子和通路的活性，以验证所提出的实验模型。将测定上述蛋白质在人脑胶质瘤肿瘤样本中的活性。

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.