C-, N-, AND L-MYC EFFECTS ON HEMATOPOIETIC CELLS

C-、N- 和 L-MYC 对造血细胞的影响

• 批准号: 6497484
• 负责人: Edward Victor Prochownik
• 金额: $ 21.57万
• 依托单位: CHILDREN'S HOSP PITTSBURGH/UPMC HLTH SYS
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-04-01 至 2004-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6497484
• 关键词: DNA damage; antineoplastics; apoptosis; cell cycle proteins; cell growth regulation; cell line; cell proliferation; cell transformation; chimeric proteins; chromosome aberrations; cysteine endopeptidases; drug resistance; fibroblasts; flow cytometry; gene expression; hematopoietic stem cells; interleukin 3; molecular oncology; neoplasm /cancer genetics; oncogenes; oncoproteins; p53 gene /protein; phosphoprotein phosphatase; protein structure function; western blottings

Myc oncoproteins are involved in proliferation, differentiation, cell cycle progression, and apoptosis. The three major myc proteins, c-myc, N-myc, and L-myc, are also implicated in the pathogenesis of malignancies such as Burkitt's and AIDS-related lymphomas, breast cancer, neuroblastoma, and lung cancer. Little is known regarding the functional similarities of these proteins. We have shown that c-, N-, and L-myc differ in their ability to modulate c-myc-responsive promoters. Overexpression of c-myc is associated with increased sensitivity of hematopoietic cells to chemotherapeutic drugs whereas N-myc and L-myc produce resistance. In cells lacking p53, c-myc overexpression also produces genomic instability. In Specific Aim I, we will compare the abilities of c-, N-, and L-myc to restore normal levels of proliferation and transformation by c-myc-dependent oncogenes in c-myc-/- fibroblasts. In Specific Aim II, chimeric and mutant myc proteins will be used to map the domains responsible for imparting pharmacologic sensitivity or resistance to hematopoietic cells. In Specific Aim III, we will determine the role of cysteine proteases ("Caspases") in apoptosis mediated by c-, N-, and L-myc. Finally, in Specific Aim IV, we will again use mutant myc proteins to map the regions responsible for imparting genomic instability to hematopoietic cells lacking p53. We will ask if the overexpression of individual c-myc-regulated genes, is sufficient to produce genomic instability. Abnormalities of cyclins and their kinases will be examined. We will also ask if genes other than c-myc, which can induce unscheduled S-phase can substitute for c-myc in the induction of tetraploidy. Two different models for the induction of tetraploidy will also be tested. The above studies should provide new insights into how myc oncoproteins differ from one another with respect to the phenotypes they impart to hematopoietic cells.

Myc癌蛋白参与增殖、分化、细胞周期进程和凋亡。三种主要的myc蛋白，c-myc、N-myc和L-myc，也与恶性肿瘤的发病机制有关，如伯基特淋巴瘤和艾滋病相关淋巴瘤、乳腺癌、神经母细胞瘤和肺癌。人们对这些蛋白质的功能相似性知之甚少。我们已经证明c-， N-和L-myc在调节c-myc应答启动子的能力上是不同的。c-myc的过表达与造血细胞对化疗药物的敏感性增加有关，而N-myc和L-myc则产生耐药性。在缺乏p53的细胞中，c-myc过表达也会产生基因组不稳定。在Specific Aim I中，我们将比较c-、N-和L-myc在c-myc-/-成纤维细胞中通过c-myc依赖性癌基因恢复正常增殖和转化水平的能力。在Specific Aim II中，嵌合和突变myc蛋白将用于绘制负责赋予造血细胞药理学敏感性或抗性的结构域。在Specific Aim III中，我们将确定半胱氨酸蛋白酶（“Caspases”）在c-、N-和L-myc介导的细胞凋亡中的作用。最后，在Specific Aim IV中，我们将再次使用突变myc蛋白来绘制负责将基因组不稳定性传递给缺乏p53的造血细胞的区域。我们将询问是否过度表达个体c-myc调节基因，足以产生基因组的不稳定性。将检查细胞周期蛋白及其激酶的异常情况。我们还将询问除c-myc以外的基因是否可以诱导非预定的s期，以替代c-myc诱导四倍体。还将测试诱导四倍体的两种不同模型。上述研究应该为myc癌蛋白如何在其赋予造血细胞的表型方面彼此不同提供新的见解。