ISOPRENIOD SYNTHESIS & TUMOR CELL GROWTH

该项目的长期目标是研究 类异戊二烯生物合成与细胞增殖的关系， 发展新的癌症化疗方法， 抑制类异戊二烯途径中的调节酶， 3羟基3甲基戊二酰辅酶A（HMG-CoA）还原酶。 这种酶催化甲羟戊酸的形成， 甾醇和其它类异戊二烯如泛醌的前体， 多萜醇和新发现的类异戊二烯蛋白。 活动 HMGCoA还原酶在许多类型的肿瘤中升高， 上一个项目期间的数据显示， 这种酶，mevinolin，抑制皮下 小鼠神经母细胞瘤。 持续评价美维诺林， 下一个项目期间将确定该大院是否能够 在大鼠脑肿瘤模型中抑制肿瘤生长， 脑内C-6胶质瘤和脑池内步行者256 carcinoma. 将使用几个标准来评估 mevinolin，包括生存曲线和克隆形成试验， 残留肿瘤 正常大脑的组织学研究，以及 骨髓细胞集落形成试验将确定潜在的 美维诺林的毒副作用 这些研究的结果将 表明mevinolin的I期临床试验是否 有正当理由 培养的神经母细胞瘤和LM细胞将用于 基础研究，以确定为什么阻断甲羟戊酸合成 导致细胞周期停滞。 这些研究将重点 特别是对一类新的蛋白质， 与衍生自以下的类异戊二烯辅基反应： 甲羟戊酸 其中一种蛋白质，位于 细胞核，将通过等电聚焦和SDSgel纯化 电泳，单克隆抗体将通过 标准小鼠杂交瘤技术。 然后，抗体将 用于确定（1）高分子量核 类异戊二烯蛋白与低分子量的 在其他亚细胞中发现的类异戊二烯蛋白 （2）是否抑制甲羟戊酸合成， mevinolin导致多肽合成减少 类异戊二烯蛋白质的一部分，（3）是否合成的 核类异戊二烯蛋白发生在一个特定的阶段， 细胞周期，以及（4）核类异戊二烯蛋白是否表现出 DNA结合蛋白的性质。 这些研究将提供 对甲羟戊酸的作用机制的新认识 细胞生长的需要。

The long-term objectives of the project are the study of isoprenoid biosynthesis in relation to cell proliferation, and the development of new approaches to cancer chemotherapy based on inhibition of the regulatory enzyme in the isoprenoid pathway, 3hydroxy3methylglutaryl coenzyme A (HMG-CoA) reductase. This enzyme catalyzes the formation of mevalonate, an essential precursor of sterols and other isoprenoids such as ubiquinone, dolichol, and newly discovered isoprenoid proteins. The activity of HMGCoA reductase is elevated in many types of tumors, and data from the preceding project period showed that an inhibitor of this enzyme, mevinolin, suppresses the growth of subcutaneous neuroblastoma in mice. Continued evaluation of mevinolin during the next project period will establish whether this compound can suppress tumor growth in rat brain tumor models such as intracerebral C-6 glioma and intracisternal Walker 256 carcinoma. Several criteria will be used to assess the efficacy of mevinolin, including survival curves and clonogenic assays of residual tumors. Histological studies of normal brain, and colonyforming assays of bone marrow cells will identify potential toxic side effects of mevinolin. The results of these studies will indicate whether phaseI clinical trials of mevinolin are warranted. Cultured neuroblastoma and LM cells will be used in basic studies to determine why blocking mevalonate synthesis leads to arrest of cell cycling. These studies will focus specifically on a novel class of proteins which are modified post- translationally with isoprenoid prosthetic groups derived from mevalonate. One of these proteins, which is localized in the nucleus, will be purified by isoelectric focusing and SDSgel electrophoresis, and a monoclonal antibody will be raised by standard mouse hybridoma technology. The antibody will then be used to determine (1) whether the highmolecular weight nuclear isoprenoid protein is related antigenically to the lowermolecular weight isoprenoid proteins found in other subcellular compartments, (2) whether suppression of mevalonate synthesis by mevinolin results in a decreased synthesis of the polypeptide portion of the isoprenoid protein,, (3) whether the synthesis of the nuclear isoprenoid protein occurs during a specific phase of the cell cycle, and (4) whether the nuclear isoprenoid protein exhibits properties of a DNAbinding protein. These studies will provide new insight into the mechanism underlying the mevalonate requirement for cell growth.