MECHANISM OF GROWTH REGULATION BY EGR-1

EGR-1的生长调节机制

• 批准号: 2837762
• 负责人: DAN MERCOLA
• 金额: $ 30.05万
• 依托单位: SIDNEY KIMMEL CANCER CENTER
• 依托单位国家: 美国
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-12-10 至 2002-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2837762
• 关键词: 3T3 cells; biological signal transduction; carcinoma; cell growth regulation; cell line; epidermal growth factor; gene expression; gene induction /repression; genetic regulation; molecular cloning; neoplastic cell; neoplastic transformation; tissue /cell culture; transforming growth factors; tumor promoters

EGR-1 was cloned in several laboratories nearly simultaneously (1-6) as the result of efforts to define new factors responsible for growth regulation. However, direct evidence for growth promoting role by EGR-1 remained elusive. Our studies with PDGF-B transformed NIH-3T3 and human HT1080 fibrosarcoma cells (7-8) and studies of others with v-raf transformed NIH-3T3 cells (9) have revealed that EGR-1 actually exerts a strong growth and transformation suppressor activity including decreased tumorigenicity (7-8). Conversely, expression of antisense EGR-1 RNA in NIH-3T3 cells (7) and human prostate carcinoma PC3 cells (8) leads to reduced endogenous EGR-1 and a much more transformed phenotype indicating that endogenous EGR-1 is growth suppressive. Numerous studies show that EGR-1 is within a small region of 5q31.1 that is consistently deleted in AML and other solid tumor malignancies (11-12, 41-43). Moreover, we find that EGR-1 is not expressed and/or uninducible in a variety of established and primary human tumor lines. Studies summarized here provide a mechanistic basis for the inhibition of transformation by EGR-1 by showing that EGR-1 activates a minimal human TGF-beta 1 promoter and causes secretion of active TGF- beta 1. It is hypothesized that suppression of transformation by EGR-1 is dependent on direct stimulation of the TGF- beta 1 gene leading to secretion of TGF- beta 1 which is growth suppressive for certain tumor cell lines. We will test whether the EGR-1/TGF-beta 1 is a general growth regulatory mechanism (AIM 1), whether EGR-1 is a physiologically relevant activator of TGF- beta 1 (AIM 2), whether induction of TGF-beta 1 by EGR-1 is due to direct TGF- beta 1 promoter binding by EGR-1 (AIM 3), whether restoration of TGF- beta 1 sensitivity in human colon and breast carcinomas also restores suppression by EGR-1 and whether TGF- beta 1 is essential for suppression of growth by EGR-1 (AIM 4), and whether loss of heterozygosity, other deletion or aberrant trans- regulation occur in the tumor lines which exhibit aberrant expression and regulation (AIM 5). These studies will elaborate a new mechanism of action for the transcription factor EGR-1 and will evaluate a new regulatory pathway controlling the expression of TGF- beta 1. Inactivation of the signal transduction pathway of TGF- beta 1 has been implicated as common in several major human malignancies and restoration TGF- beta 1 sensitivity suppresses transformation. Loss or defects in EGR-1 is a potential means of disrupting growth control by TGF- beta 1 and this is the tested here (AIM 2).

EGR-1 几乎同时在多个实验室被克隆 (1-6) 努力定义新的增长因素的结果 规定。 然而，EGR-1 促进生长作用的直接证据 仍然难以捉摸。 我们对 PDGF-B 转化的 NIH-3T3 和人类的研究 HT1080 纤维肉瘤细胞 (7-8) 和其他 v-raf 的研究 转化的 NIH-3T3 细胞 (9) 揭示了 EGR-1 实际上发挥作用 强大的生长和转化抑制活性，包括 降低致瘤性 (7-8)。 相反，反义表达 NIH-3T3 细胞 (7) 和人前列腺癌 PC3 细胞中的 EGR-1 RNA (8) 导致内源性 EGR-1 减少，并且转化程度更高 表型表明内源性 EGR-1 具有生长抑制作用。 大量研究表明 EGR-1 位于 5q31.1 的一个小区域内， 在 AML 和其他实体瘤恶性肿瘤中始终被删除 （11-12、41-43）。 此外，我们发现 EGR-1 不表达和/或 在多种已建立的和原发性人类肿瘤系中不可诱导。 这里总结的研究为抑制提供了机制基础 通过显示 EGR-1 激活最小的 EGR-1 转化 人 TGF-β 1 启动子并导致活性 TGF-β 1 的分泌。 假设 EGR-1 对转化的抑制是 依赖于 TGF-β1 基因的直接刺激 分泌TGF-β1，抑制某些肿瘤的生长 细胞系。 我们将测试EGR-1/TGF-beta 1是否是通用的 生长调节机制（AIM 1），EGR-1是否是一种生理学 TGF-β 1 (AIM 2) 的相关激活剂，是否诱导 TGF-β EGR-1 导致的 1 是由于 EGR-1 直接结合 TGF-β1 启动子（AIM 3)、是否恢复人结肠中的TGF-β1敏感性 乳腺癌还可以恢复 EGR-1 的抑制以及 TGF-β beta 1 对于 EGR-1 (AIM 4) 抑制生长至关重要，并且 无论是杂合性丧失、其他缺失还是异常反式 调节发生在表现出异常表达的肿瘤系中 和监管（AIM 5）。 这些研究将阐述一种新机制 转录因子 EGR-1 的作用并将评估新的 控制TGF-β1表达的调控途径。 TGF-β1 信号转导途径失活 与几种主要的人类恶性肿瘤和恢复有关的常见现象 TGF-β1 敏感性抑制转化。 损失或缺陷 EGR-1 是破坏 TGF-β1 生长控制的潜在手段 这是在这里测试的（AIM 2）。