Functional Genetic variants as modifiers of prostate cancer progression in Native Americans

前列腺癌（PCA）的发病率和死亡率在美国的种族之间差异很大。在所有男性中，PCA是最常见的癌症诊断形式，但美洲原住民男性在诊断后的PCA死亡率比白人高出近两倍。这种差异的程度并没有反映在其他常见的癌症类型中，这表明美国土著男性中PCA相关死亡率的独特负担。在纳瓦霍人中，PCA更常在癌症已经扩展到前列腺边缘以外的阶段被诊断出来（在新墨西哥州的纳瓦霍人中PCA诊断为17.9%，在非西班牙裔白人中为3.3%）。这些数据强调了了解所有男性，特别是美洲土著人临床侵袭性前列腺癌的分子机制的必要性。在所有种族中，PCA是高度异质性的，可以从不需要积极治疗的潜伏性局部疾病到与高死亡风险相关的侵袭性疾病。我们的目标是更好地了解侵略性PCA的遗传和分子相关性。我们的实验方法将使我们能够描述对美洲原住民群体特别重要的遗传风险因素。 以前的研究已经确定了许多增加侵袭性PCA风险的体细胞和生殖系遗传变异。特别重要的是影响肿瘤抑制基因PTEN剂量的突变。一个PTEN等位基因的缺失发生在20-40%的局部PCA癌症和~60%的转移瘤中。最近的证据还表明，在缺失突变的情况下，45%的原发性肿瘤中发生PTEN蛋白丢失，这表明PTEN沉默受到影响的替代机制。我们提出的研究将集中在微小RNA介导的（miRNA）调节PTEN的作用，这是一个关键的调节机制，这种肿瘤抑制基因。具体来说，我们将鉴定和分析PTEN及其表达的假基因PTENP 1的miRNA应答元件的变体。这两个基因参与通过竞争miRNA介导的调控串扰，使得PTENP 1中的等位基因变异可以间接影响PTEN的表达。这项研究扩展了我们的试点项目的发现，该项目发现PTEN受到miRNA相互作用网络中等位基因变异的影响，并确定了美洲原住民特有的PTEN miRNA反应元件中的特定遗传变异。我们提出了一个通用的模型，其中生殖系基因突变的miRNA响应元件的PTEN/PTENP 1 3 'UTR扰乱竞争的内源性RNA网络和功能的PCA的侵略性功能的修饰符。为了检验这一假设，并确定对美洲原住民有潜在影响的变体，我们提出了以下具体目标： 具体目标1。鉴定靶向PTEN和PTENPI miRNA应答元件中功能性单核苷酸多态性的miRNA，并确定miRNA在前列腺癌中的表达。我们假设影响PTEN/PTENP 1基因/假基因对的miRNA靶向的变异等位基因与复发性前列腺癌相关 具体目的2.研究靶向miRNA的候选等位基因变体在前列腺癌进展相关信号通路中的作用。我们假设PTENP 1的多态性改变了miRNA：mRNA相互作用的PTEN网络。因此，关键通路中候选miRNA的改变将与作为侵袭性PCA基础的癌分化机制相关。 具体目的3.发现影响肿瘤抑制基因功能的独特的美洲原住民单核苷酸多态性，并检测这些单核苷酸多态性与前列腺癌的关联。我们假设在美洲原住民和美洲原住民混合人群（即西班牙裔）中存在丰富的遗传变异，这些变异与其他世界人群不相同，并且这种变异可能与前列腺癌风险相关。我们在此研究了3 'UTR变异，这些变异可能影响基因/假基因配对之间的调控串扰，并在癌症易感性和进展中发挥作用。

Prostate cancer (PCA) incidence and mortality rates vary widely among races in the United States. Among all men, PCA is the most commonly diagnosed form of cancer, but Native American men suffer a nearly two-fold higher rate of PCA mortality than whites following diagnosis. The extent of this disparity is not mirrored by other common cancer types, suggesting a unique burden of PCA-associated mortality in Native American men. Among the Navajo, PCA is more often diagnosed at a stage when the cancer has extended beyond the margins of the prostate (17.9% of PCA diagnoses among the Navajo, 3.3% among non-Hispanic Whites in New Mexico).These data underscore the need to understand the molecular mechanisms underlying clinically aggressive prostate cancer in all men, and Native Americans in particular. Among all races, PCA is highly heterogeneous and can vary from latent localized disease that does not require active treatment to aggressive disease associated with a high risk of mortality. Our goal is to better understand the genetic and molecular correlates of aggressive PCA. Our experimental approach will allow us to characterize genetic risk factors of particular importance to Native American populations. Previous studies have identified numerous somatic and germline genetic variants that increase risk for aggressive PCA. Of particular importance are mutations that affect the dosage of the tumor suppressor gene PTEN. Deletion of one PTEN allele occurs in 20-40% of localized PCA cancers and ~60% of metastases. Recent evidence also shows that PTEN protein loss occurs in 45% of primary tumors in the absence of deletion mutations, suggesting alternative mechanisms by which PTEN silencing is affected. Our proposed study will focus on the role of microRNA-mediated (miRNA) regulation of PTEN, which is a critical regulatory mechanism for this tumor suppressor gene. Specifically, we will identify and analyze variants in miRNA response elements of PTEN and its expressed pseudogene, PTENP1. These two genes engage in regulatory crosstalk mediated by competition for miRNAs, such that allelic variations in PTENP1 can affect indirectly the expression of PTEN. This research extends the findings of our Pilot Project which found PTEN to be affected by allelic variation in miRNA interaction networks, and identified specific genetic variants in the miRNA response elements of PTEN that are unique to Native Americans. We propose a general model whereby germline genetic variants in the miRNA response elements of PTEN/PTENP1 3'UTR perturb competing endogenous RNA networks and function as modifiers of aggressive features of PCA. To test this hypothesis, and to identify variants with potential for effects in Native Americans, we propose the following specific aims: Specific Aim 1. To identify miRNAs that target functional single nucleotide polymorphisms in PTEN and PTENPI miRNA response elements and determine miRNA expression in prostate cancer. We hypothesize that a variant alleles affecting miRNA-targeting of the PTEN/PTENP1 gene/pseudogene pair will be associated with recurrent prostate cancer Specific Aim 2.To evaluate the function of candidate allelic variant targeting miRNAs in relevant signaling pathways in prostate cancer progression. We hypothesize that there are polymorphisms in PTENP1 that will alter the PTEN network of miRNA: mRNA Interactions. Thus, alteration of candidate miRNAs in key pathways will be correlated with mechanisms of carcinoma differentiation that underlie aggressive PCA. Specific Aim 3.To discover uniquely Native American single nucleotide polymorphisms affecting tumor suppressor gene function and to test for an association of these SNPs with prostate cancer. We hypothesize that there Is abundant genetic variation in Native American and Native American-admixed populations (i.e. Hispanics) that is not shared with other world populations, and that variation may be associated with prostate cancer risk. We examine here 3'UTR variants that may affect regulatory crosstalk between gene/pseudogene pairings and play a role in cancer susceptibility and progression.