C-MYC TARGETS IN THE PATHOGENESIS OF HUMAN CANCERS

c-myc癌基因的作用似乎是一个关键的发生， 人类癌症的数量。 c-Myc蛋白对细胞增殖有积极作用， 增殖;然而，活动的分子机制 c-Myc在人类癌症中的作用仍然是未知的。 虽然显著 进展，包括c-Myc的各种功能结构域的鉴定 以及Myc伴侣蛋白Max的发现， 了解Myc的功能，许多关键问题仍然没有答案。 我们的长期目标是了解c-Myc可能 有助于人类癌症的发病机制， 可能会产生癌症治疗的方法。 为了达到我们的目标， 我们提出了具体的目标，以解决以下问题：1）什么是 影响c-Myc激活或抑制的能力的蛋白质 转录？ c-Myc的氨基末端结构域对于其表达是必需的。 功能包括肿瘤转化。 利用我们的c-myc突变体， 大量的嵌合c-myc基因能够产生 嵌合蛋白，我们发现c-Myc的这一区域含有一个 转录激活结构域。 c-Myc扩增物的激活结构域 在模型系统中通过不同于 VP 16酸性激活结构域所利用的那些。 我们提出策略 以鉴定与转录因子相互作用并调节转录因子的蛋白质， c-Myc的激活潜力。 2)马克斯在肿瘤中的作用是什么？ 转化？ 我们已经构建了各种表达载体， 在有义或反义方向上表达麦克斯 实验 提出描绘的作用，外源性和内源性最大的， 由Myc和激活的Ras引起的肿瘤细胞转化。 第三章 在细胞增殖中起关键作用的基因是什么， 是由Myc管理的吗 我们已经证明，在细胞内的c-Myc碱性区， DNA结合结构域可以在功能上替代DNA结合结构域的同源区域。 酵母蛋白CBF 1在酵母中的新遗传系统。 Myc和Max 将在酵母中表达，以进一步表征其转录 在体内的调节功能。 利用这个遗传系统， 在体外DNA结合试验中，我们提出了一种识别DNA位点的策略， 与Myc-Max介导的肿瘤相关的人类基因组 转型 4)是否有其他分子可能与 Myc或Max寡聚化结构域？ 研究蛋白质间的相互作用 在体内，我们开发了一种能够识别cDNA的选择系统 编码与已知靶标寡聚化的蛋白质结构域。 该系统 将用于鉴定编码其他蛋白质的cDNA， 和迈克或者麦克斯 拟议研究的结果应提供 重要的见解的分子机制，潜在的正常 c-Myc的功能及其在人类癌症发病机制中的作用。 在 此外，希望对这些机制的理解将 为潜在的癌症治疗提供了合理的分子途径。

The role of the c-myc oncogene appears to be pivotal in the genesis of a number of human cancers. The c-Myc protein contribute positively to cell proliferation; however, the molecular mechanisms underlying the activities of c-Myc in human cancers remain largely unknown. Although significant advances, including identification of various functional domains of c-Myc and the discovery of a Myc partner protein Max, have been achieved in understanding Myc function, numerous critical questions remain unanswered. Our long term objective is to understand the mechanisms by which c-Myc may contribute to the pathogenesis of human cancers so that potential rational approaches to cancer therapy might be generated. To reach our objective, we propose specific aims to address the following questions: 1) What are the proteins that influence the ability of c-Myc to activate or suppress transcription? The amino-terminal domain of c-Myc is necessary for its function including neoplastic transformation. Using our c-myc mutants and an extensive collection of chimeric c-myc genes capable of producing chimeric proteins, we found that this region of c-Myc contains a transcriptional activation domain. The activation domain of c-Myc augments transcription in a model system through factors which are distinct from those utilized by the VP16 acidic activation domain. We propose strategies to identify proteins that interact with and modulate the transcriptional activation potential of c-Myc. 2) What is the role of Max in neoplastic transformation? We have constructed various expression vectors capable of expressing Max in either sense or anti-sense directions. Experiments are proposed to delineate the role of exogenous and endogenous Max in neoplastic cellular transformation caused by Myc and an activated Ras. 3) What are the genes, which play critical roles in cell proliferation, that are regulated by Myc? We have shown that the c-Myc basic region within the DNA binding domain can functionally substitute for the homologous region of the yeast protein CBF1 in a novel genetic system in yeast. Myc and Max will be expressed in yeast to further characterize their transcriptional regulatory function in vivo. Using this genetic system in conjunction with in vitro DNA binding assays, we propose a strategy to identify DNA sites in the human genome that are relevant to Myc-Max mediated neoplastic transformation. 4) Are there other molecules that might interact with the Myc or Max oligomerization domains? To study protein-protein interactions in vivo, we have developed a selection system capable of identifying cDNAs encoding protein domains that oligomerize with a known target. This system will be used to identify cDNAs that encode other proteins which interact with Myc or Max. The findings from the proposed studies should provide significant insights into the molecular mechanisms underlying the normal function of c-Myc and its role in the pathogenesis of human cancers. In addition, it is hoped that the understanding of these mechanisms will provide a rational molecular approach to potential cancer therapeutics.