THE ROLE OF MXIL IN PROSTATE CANCER PROGRESSION

C-myc原癌基因参与正常和非癌基因的调控。 肿瘤细胞生长。自从发现了麦克斯，一种伴侣蛋白质 使c-Myc与DNA结合，使其他与MAX相互作用的基因产物 都被描述过。Mxi1基因的产物是一种蛋白质，它 与c-Myc和Max有显著的同源性，其表达 与造血细胞中的细胞分化有关。Mxi1是 被认为参与了与Max、c-Myc和其他公司的监管网络 Myc蛋白家族的成员。在这个方案中，c-Myc被激活 转录和刺激细胞增殖，推测是Mxi1 负向调节这些行为，促进细胞分化。 因此，mxi1基因的突变或丢失可以阻止 在正常水平下分化和促进增殖 因此，mxi1是一个潜在的肿瘤抑制基因。我们有 将mxi1基因定位于染色体长臂远端 10，被重新排列或大量丢失的区域 前列腺癌和脑瘤。我们有兴趣调查 Mxi1在前列腺细胞生长、分化和肿瘤发生中的作用 设定以下具体目标： 具体目标#1.确定mxi1的完整结构 基因： A.分离启动子序列以了解mxi1的调控 B.准确识别外显子/内含子边界以帮助突变 分析 C.评估特定内含子调控序列的存在 特定目标#2.mxi1表达影响的特征 细胞生长和分化 A.介绍构成和可诱导的mxi1表达载体 B.确定mxi1对细胞生长和分化的影响 这些细胞在体外和体内都有 特定目标#3.确定mxi1在转录中的作用 调制 A.确定Mxi1对c-Myc依赖转录的影响 在细胞和体外转录检测中 B.研究Mxi1对转录的调控能力 独立于c-Myc 具体目标#4.评估肿瘤样本杂合性缺失 (LOH)和mxi1基因座的突变 A.筛查前列腺癌mxi1杂合性缺失 B.检查携带杂合性缺失的肿瘤的mxi1基因突变 C.将含有mxi1突变的表达载体导入细胞 证明mxi1肿瘤抑制活性丧失的品系。

The c-myc proto-oncogene is involved in the regulation of both normal and neoplastic cell growth. Since the discovery of Max, a partner protein enabling c-Myc to bind to DNA, other gene products which interact with Max have been described. The product of the mxi1 gene is a protein which shares significant homology to c-Myc and Max, and whose expression correlates with cellular differentiation in hematopoietic cells. Mxi1 is thought to be involved in a regulatory network with Max, c-Myc and other members of the Myc protein family. In this scheme, c-Myc activates transcription and stimulates cell proliferation, and Mxi1 putatively negatively regulates these actions, promoting cellular differentiation. Mutations in or loss of the mxi1 gene could therefore prevent differentiation and enhance proliferation in the presence of normal levels of c-Myc, and thus mxi1 is a potential tumor suppressor gene. We have mapped the mxi1 gene to the distal portion of the long arm of chromosome 10, a region which is rearranged or missing in significant numbers of prostate and brain tumors. We are interested in investigating the role of mxi1 in cell growth, differentiation and neoplasia of prostate cells by setting the following specific aims: Specific Aim #1. Identification of the complete structure of the mxi1 gene: a. Isolate promoter sequences to understand mxi1 regulation b. Precisely identify exon/intron boundaries to aid in mutation analysis c. Assess for presence of specific intronic regulatory sequences Specific Aim #2. Characterization of the effects of mxi1 expression on cell growth and differentiation a. Introduce constitutive and inducible mxi1 expression vectors b. Determine the effect of mxi1 on growth and differentiation of these cells both in vitro and in vivo Specific Aim #3. Determination of the role of mxi1 in transcriptional modulation a. Determine the effect of Mxi1 on c-Myc-dependent transcription in both cellular and in vitro transcription assays b. Investigate the ability of Mxi1 to modulate transcription independent of c-Myc Specific Aim #4. Evaluation of tumor samples for Loss of Heterozygosity (LOH) and mutation at the mxi1 locus a. Screen prostate adenocarcinomas for mxi1 LOH b. Examine LOH-bearing tumors for mutations in the mxi1 gene c. Introduce expression vectors containing mxi1 mutations into cells lines to demonstrate abrogation of mxi1 tumor suppressor activity.