Remediating Ing4 tumor suppressor deficiency using a zebrafish model

摘要 癌症的多面性导致了一种复杂且难以治疗的疾病。一个共同之处 这种疾病的特点是癌细胞能够重新获得类似干细胞的特征，从而导致异常 基因表达与治疗抵抗力。因为在癌症中经常发生异常的分子网络 也被正常干细胞利用，了解这些途径和机制是如何发挥作用的至关重要 在干细胞中，并被癌细胞利用来促进疾病进展。基因的异常表达 肿瘤通常是癌基因表达或肿瘤抑制基因失活的结果。肿瘤抑制因子是 尤其具有挑战性，因为这些蛋白质通常在肿瘤中缺失或仅以很低的水平存在 细胞。我们的实验室最近发现了肿瘤抑制因子ING4，一种染色质修饰物和一种转录因子 含有PHD指状域的调节子，作为造血干细胞规格的关键调节子。ING4 已经被证明在几种类型的人类癌症中被灭活，包括乳腺癌，前列腺癌，结直肠癌， 卵巢癌、肺癌、星形细胞瘤和肝细胞癌。ING4的表达缺失是 与预后不良有关，但ING4的抑瘤作用机制尚不完全 明白了。ING4抑制肿瘤活性的一个潜在机制是通过负调控 核因子-B途径，参与肿瘤的发生、发展和耐药。我们发现Ing4 斑马鱼耗竭刺激核因子-B活性，抑制核因子-B可挽救由 Ing4的损失。我们提出的具体目标将使用遗传学和药理学方法，这两种方法都是在 开发斑马鱼和在ING4缺陷的人类肿瘤细胞中，以确定潜在的抗击机制 这种蛋白质在癌症中的丢失。目的1研究斑马鱼Ing4失活对基因的影响 并确定是否靶向在Ing4缺失时上调的基因表达途径 将挽救Ing4失活对斑马鱼HSC规格的影响。目标2是确定是否很小 NF-κB和其他上调途径的分子抑制剂将挽救Ing4丢失的影响 在斑马鱼身上发挥作用。目标3是确定基因和途径，抑制这些基因和途径可以修复细胞的影响 ING4在哺乳动物肿瘤细胞中的失活，使用斑马鱼和一种遗传基因的分析结果 在ING4缺陷的人肿瘤细胞中进行筛选。拟议研究的成功将成为 确定可以补救ING4缺乏症表型效应的药物的基础，最终目标是 为ING4失活的癌症制定治疗策略。

ABSTRACT The multifaceted nature of cancer results in a disease that is complicated and difficult to treat. One common characteristic of this disease is the ability of cancer cells to re-acquire stem-cell like traits resulting in aberrant gene expression and resistance to therapy. As the molecular networks that are frequently aberrant in cancer are also utilized by normal stem cells, it is critical to understand how these pathways and mechanisms function in stem cells and are harnessed by cancer cells to promote disease progression. Aberrant gene expression in tumors is often a result of oncogene expression or tumor suppressor inactivation. Tumor suppressors are particularly challenging to target as these proteins are often missing or present only at very low levels in tumor cells. Our lab has recently identified the tumor suppressor, ING4, a chromatin modifier and a transcriptional regulator containing a PHD finger domain, as a critical regulator of hematopoietic stem cell specification. ING4 has been shown to be inactivated in several types of human cancer, including breast, prostate, colorectal, ovarian and lung cancers, astrocytomas, and hepatocellular carcinomas. Loss of ING4 expression is associated with a poor prognosis but the mechanisms of tumor-suppressive functions of ING4 are not yet fully understood. A potential mechanism of tumor suppressor activity of ING4 is through its negative regulation of the NF-B pathway, implicated in carcinogenesis, tumor progression and drug resistance. We found that Ing4 depletion in zebrafish stimulates NF-B activity and NF-B inhibition can rescue HSC deficiency caused by the loss of Ing4. Our proposed Specific Aims will use both genetic and pharmacological approaches, both in developing zebrafish and in ING4-deficient human tumor cells, to identify potential mechanisms for combating the loss of this protein in cancer. Aim 1 is to investigate the effects of Ing4 inactivation in zebrafish on gene expression and to determine if targeting of gene expression pathways that are upregulated upon loss of Ing4 would rescue the effects of Ing4 inactivation on HSC specification in zebrafish. Aim 2 is to determine if small molecule inhibitors of the NF-κB and other upregulated pathways would rescue the effects of Ing4 loss of function in zebrafish. Aim 3 is to identify genes and pathways, inhibition of which remediates cellular effects of ING4 inactivation in mammalian tumor cells, by using the results of the analysis in zebrafish and of a genetic screen conducted in ING4-deficient human tumor cells. The success of the proposed study will serve as the basis for identifying drugs that could remediate phenotypic effects of the ING4 deficiency, with the ultimate goal of developing therapeutic strategies for cancers where ING4 has been inactivated.