Mechanisms of Neoplastic Transformation by HMG-I/Y

描述（由申请人提供）：HMG-I/Ygene编码HMG-I和-Y蛋白亚型，其功能是参与转录调节的结构染色质结合蛋白。这些蛋白在人类癌症中被上调，尽管它们在恶性肿瘤发病机制中的作用尚不清楚。为了了解HMG-I/Y蛋白如何促进转化，我们正在探索它们的调控和功能。我们发现HMG-I/Y在伯基特淋巴瘤中是一个重要的直接c-Myc靶基因。我们还证明了HMG-I/Y对于转化是必要的，因为在人类癌细胞系中减少这些蛋白质会阻断转化的表型。我们是第一个证明HMG-I/Y蛋白具有几种致癌特性的人。具体来说，在一些实验细胞系中，HMG-I或y的过表达导致了不依赖于锚定的细胞生长。过表达HMG-I或y的成纤维细胞在裸鼠中具有致瘤性。我们培养了在淋巴样细胞中过表达HMG-/的转基因小鼠，这些小鼠在平均8月龄时均出现淋巴样增生和恶性肿瘤。HMG-I过表达也与基因组不稳定性相关，这可能有助于肿瘤的发生或进展。因此，我假设HMG-I/Y是在人类癌症发病机制中重要的致癌基因。本研究计划的重点是使用我实验室开发的独特试剂确定HMG-I/Y转化所涉及的机制。我们的具体目标是：使用微阵列分析识别和表征参与肿瘤转化的直接HMG-I/Y基因靶标。2)。确定HMG-I/Y参与转化、染色体不稳定性和细胞周期调节的功能域。a .)使用软琼脂转化试验鉴定转化所需的HMG-I/Y的功能域。b .)研究HMGI/ Y在基因组不稳定性中的作用，并利用谱核型分析确定相关结构域。c .)研究HMG-I/Y在细胞周期调节中的作用，并使用细胞周期谱分析确定相关结构域。3)。定义使用我们的HMG-I转基因小鼠进行转化的途径。a .)评估HMG-I转基因小鼠转化淋巴细胞中HMG-I靶基因的过度表达和染色体不稳定性通过将HMG-I转基因小鼠与其他转基因小鼠杂交，确定HMG-I转化的途径。4)。确定HMG-I/ y表达是否与淋巴细胞恶性肿瘤和脑肿瘤的预后和临床结果相关。研究HMG-I/Y基因和蛋白在约翰霍普金斯白血病和脑肿瘤库患者样本中的表达。这一建议意义重大，因为结果将增强我们对HMG-I/Y蛋白增加的人类恶性肿瘤的理解，并可能导致新的治疗策略。

DESCRIPTION (provided by applicant): The HMG-I/Ygene encodes the HMG-I and -Y protein isoforms, which function as architectural chromatin binding proteins involved in transcriptional regulation. These proteins are up-regulated in human cancer, although their role in the pathogenesis of malignancy is unclear. To understand how HMG-I/Y proteins may contribute to transformation, we are exploring their regulation and function. We discovered that HMG-I/Y is a direct c-Myc target gene important in Burkitt's lymphoma. We also demonstrated that HMG-I/Y is necessary for transformation because decreasing these proteins in human cancer cell lines blocks the transformed phenotype. We were the first to show that HMG-I/Y proteins have several oncogenic properties. Specifically, overexprossion of HMG-I or-Y leads to anchorage-independent cell growth in several experimental cell lines. Fibroblasts overexpressing HMG-I or-Y are tumorigenic in nude mice. We developed transgenic mice overexpressing HMG-/in lymphoid cells and all of them develop lymphoid hyperplasia and malignancy at a mean age of 8 months. HMG-I overexpression also correlates with genomic instability, which may contribute to tumor initiation or progression. Thus, I hypothesize that HMG-I/Y is an oncogene important in the pathogenesis of human cancer. The focus of this research proposal is to identify the mechanisms involved in transformation by HMG-I/Y using unique reagents developed in my laboratory. Our Specific Aims Are: 1.) Identify and characterize direct HMG-I/Y gene targets involved in neoplastic transformation using microarray analysis. 2.) Define the functional domains of HMG-I/Y involved in transformation, chromosomal instability, and cell cycle regulation. A.) Identify the functional domains of HMG-I/Y required for transformation using the soft agar transformation assay. B.) Investigate the role of HMGI/ Y in genomic instability and identify the relevant domains using spectral karyotyping analysis. C.) Investigate the role of HMG-I/Y in cell cycle regulation and identify the relevant domains using cell cycle profile analysis. 3.) Define the pathways involved in transformation using our HMG-I transgenic mice. A.) Assess transformed lymphoid cells from the HMG-I trangenic mice for overexpression of HMG-I target genes and chromosomal instability B.) Identify pathways involved in transformation by HMG-I by crossing the HMG-I transgenic mice with other genetically altered mice. 4.) Determine if HMG-I/Yexpression correlates with prognosis and clinical outcome in lymphoid malignancies and brain tumors. Study HMG-I/Y gene and protein expression in patient samples from the Johns Hopkins Leukemia and Brain Tumor Banks. This proposal is significant because the results will enhance our understanding of human malignancies with increased HMG-I/Y proteins and may lead to new treatment strategies.