Understanding the epigenetic basis of human familial paraganglioma

描述(申请人提供)：了解人类家族性副神经节瘤的表观遗传学基础。我们的实验室感兴趣的是了解代谢缺陷如何促进肿瘤的发生。具体地说，我们研究了家族性副神经节瘤(PGL)，这是一种神经内分泌癌，作为代谢紊乱的典型模型。家族性PGL表现常染色体显性遗传，是由于琥珀酸脱氢酶(SDH)亚单位编码基因的两个拷贝丢失所致。SDH是一种三羧酸循环酶。SDH功能的丧失特别有趣，因为它体现了有氧糖酵解的华宝效应，这是许多癌症的神秘特征。到目前为止，SDH功能的丧失如何导致神经内分泌细胞肿瘤的形成还没有明确的解释。此外，目前还没有研究这种癌症的临床前模型。这项建议的长期目标是了解SDH功能丧失如何诱导神经内分泌细胞中的PGL。这一认识将为PGL的防治提供新的途径。我们的中心假设是，琥珀酸积累对双加氧酶的抑制会导致致癌表观遗传效应，包括低氧诱导因子(HIF)的激活，组蛋白甲基化的积聚，以及5-羟甲基脱氧胞嘧啶(5hmdC)的耗尽。我们的策略是开发三个模型来研究琥珀酸积累。这些包括(1)人类家族性PGL肿瘤组织学标本，(2)SDHB慢病毒击倒式人类组织培养细胞，(3)小鼠SDHC-/-细胞系。目的1研究SDH缺失对PGL肿瘤标本的影响。目的2将确定SDH基因敲除对组织培养细胞的影响，以及SDH基因替换或增加2-酮戊二酸水平是否可以克服这些影响。最后，目标3将描述SDH丢失对小鼠SDHC-/-细胞系的影响。

DESCRIPTION (provided by applicant): Understanding the epigenetic basis of human familial paraganglioma. Our laboratory is interested in understanding how defects in metabolism can promote tumorigenesis. Specifically, we study familial paraganglioma (PGL), a neuroendocrine cancer, as a model that exemplifies metabolic derangement. Familial PGL displays autosomal dominant inheritance and is due to loss of both copies of genes encoding subunits of succinate dehydrogenase (SDH), a tricarboxylic acid (TCA) cycle enzyme. Loss of SDH function is particularly interesting because it exemplifies the Warburg effect of aerobic glycolysis, a mysterious feature of many cancers. To date, there is no clear explanation for how loss of SDH function leads to tumor formation in neuroendocrine cells. Furthermore, there is no preclinical model to study this cancer. The long-term goal of this proposal is to understand how loss of function of SDH induces PGL in neuroendocrine cells. This knowledge will provide new approaches to PGL prevention and treatment. Our central hypothesis is that dioxygenase inhibition by succinate accumulation causes oncogenic epigenetic effects including activation of Hypoxia Inducible Factor (HIF), accumulation of histone methylation, and depletion of 5-hydroxymethyl-deoxycytosine (5hmdC). Our strategy is to develop three models to study succinate accumulation. These include (1) human familial PGL tumor histology specimens, (2) SDHB lentiviral knockdown human tissue culture cells, and (3) a mouse SDHC-/- cell line. Aim 1 will examine the effects of SDH loss in PGL tumor specimens. Aim 2 will determine effects of SDH knockdown in tissue culture cells and if these effects can be overcome by SDH gene replacement or increasing 2-ketoglutarate levels. Finally, Aim 3 will characterize the effects of SDH loss in a mouse SDHC-/- cell line.