Role of Eaf family proteins in prostate carcinogenesis

描述（由申请方提供）：前列腺癌的发生涉及肿瘤抑制因子的失活和/或癌基因的激活，并且也受到雄激素的深刻影响。雄激素影响前列腺癌的机制仍然知之甚少。初步研究表明，雄激素反应基因Eaf 2，也称为U19（上调基因19），在前列腺中作为一个潜在的肿瘤抑制因子。在>80%的人类晚期前列腺癌标本中检测到Eaf 2下调和等位基因丢失。Eaf 2基因敲除小鼠发生淋巴瘤、肝细胞癌和低分化肺腺癌，表明Eaf 2是体内肿瘤抑制因子。尽管Eaf 2 KO前列腺没有发展成前列腺癌，但它表现出上皮增生和发育不良（mPIN），表明Eaf 2有助于抑制前列腺肿瘤。Eaf 2与Eaf 1沿着被独立鉴定，并基于其与急性髓性白血病中MLL的融合伴侣ELL的相关性而被称为ELL相关因子（Eaf）. Eaf 2和Eaf 1蛋白是Eaf家族中仅有的两个成员，同源性分别为58%和74%。Eaf 1和Eaf 2都在前列腺上皮细胞中表达，Eaf 1是组成型的，Eaf 2是雄激素诱导型的。Eaf 1或Eaf 2的过表达诱导前列腺癌细胞凋亡，表明它们的功能相似。这些发现导致我们的假设，肿瘤抑制需要适当的Eaf基因剂量，Eaf家族基因的丢失可能导致前列腺癌。四个特定的目的将明确Eaf家族基因在前列腺癌发生中的作用。1.确定前列腺中的Eaf 1条件性KO是否会导致与小鼠模型中Eaf 2 KO前列腺中观察到的表型相似的表型。2.在小鼠模型中测试Eaf基因的缺失是否会导致前列腺癌。我们将Eaf 2 KO和前列腺特异性Eaf 1 KO小鼠杂交，以产生Eaf 1-Eaf 2双KO小鼠。3.确定Eaf基因剂量对Eaf下游途径的影响。我们将使用cDNA微阵列比较野生型、Eaf 1 KO、Eaf 2 KO和双KO前列腺中的基因表达谱。4.确定人前列腺癌标本中Eafl和/或Eaf 2的下调是否具有预后价值。我们将通过人前列腺癌组织微阵列的半定量免疫染色来确定Eafl和/或Eaf 2表达，并将其与临床结果（如无病生存）相关联。该项目的成功将Eaf蛋白定义为前列腺中的肿瘤抑制因子，提供雄激素和肿瘤抑制因子之间的联系，并为进一步探索Eaf途径诊断，预后，预防和/或治疗前列腺癌奠定坚实的基础。

DESCRIPTION (provided by applicant): Prostate carcinogenesis involves inactivation of tumor suppressors and/or activation of oncogenes and is also profoundly influenced by androgens. The mechanism by which androgens affect prostate cancer remains poorly understood. Preliminary studies show that the androgen-response gene Eaf2, also termed U19 (up-regulated gene 19), acts as a potential tumor suppressor in the prostate. Eaf2 down-regulation and allelic loss were detected in >80% of human advanced prostate cancer specimens. Eaf2 knockout (KO) mice developed lymphoma, hepatocellular carcinoma, and poorly differentiated lung adenocarcinoma, demonstrating that Eaf2 is a tumor suppressor in vivo. Although the Eaf2 KO prostate did not develop prostate cancer, it exhibited epithelial hyperplasia and dysplasia (mPIN), suggesting that Eaf2 contributes to the suppression of prostate tumors. Eaf2, along with Eafl, was independently identified and termed ELL- associated factors (Eaf), based on its association with ELL, a fusion partner of MLL in acute myeloid leukemia. Eaf2 and Eaf1 proteins, with 58% identity and 74% similarity, are the only members in the Eaf family. Both Eaf1 and Eaf2 are expressed in prostate epithelial cells, with Eaf1 being constitutive and Eaf2 androgen-inducible. Overexpression of either Eaf1 or Eaf2 induces apoptosis of prostate cancer cells, indicating their functional similarities. These findings led to our hypothesis that tumor suppression requires proper Eaf gene dosage and that the loss of both Eaf family genes can lead to prostate cancer. Four Specific Aims will define the roles of Eaf family genes in prostate carcinogenesis. 1. Determine if an Eaf1 conditional KO in the prostate will cause a similar phenotype to that observed in the Eaf2 KO prostate in the mouse model. 2. Test whether the loss of both Eaf genes causes prostate cancer in the mouse model. We will crossbreed the Eaf2 KO and prostate-specific Eaf1 KO mice to generate Eaf1-Eaf2 double KO mice. 3. Determine the effect of Eaf gene dosage on Eaf-downstream pathways. We will compare the gene expression profiles in the wild-type, Eaf1 KO, Eaf2 KO, and double KO prostate using cDNA microarray. 4. Determine if down-regulation of Eafl and/or Eaf2 in human prostate cancer specimens has prognostic value. We will determine Eafl and/or Eaf2 expression by a semiquantitative immunostaining of human prostate cancer tissue microarray and correlate this with clinical outcomes, such as disease-free survival. The success of this project will define Eaf proteins as tumor suppressors in the prostate, providing a link between androgens and tumor suppressors and a strong foundation for further exploring Eaf pathways for diagnosis, prognosis, prevention, and/or treatment of prostate cancer.