A novel mutation in the T8 microsatellite of 3-UTR CDK2-AP1 gene in MSI CRC

描述(由申请人提供)：本应用的目的是确定最近发现的在微卫星不稳定(MSI)结直肠癌(CRC)中细胞周期蛋白依赖性激酶-2相关蛋白-1(CDK2-AP1)基因3‘-UTRPolyT(T)8处的del T突变的频率和作用。目前的文献认识到导致侵袭性结直肠癌的两条途径。微卫星稳定(MSS)途径是最常见的途径，约80%的结直肠癌病例中可见，其中没有观察到微卫星序列改变。另一条途径是MSI途径，在其余20%的结直肠癌病例中可以解释，其特征是微卫星DNA的移码突变和碱基对替换。CDK2-AP1在RC的病因学中是一个已知的生长抑制因子。我们先前报道了CDK2-AP1在人MS RC细胞系中的表达显著降低(袁等人，2003)，并且它的诱导导致细胞增殖减少和凋亡增加(Kent等人，2004)。最近，我们在25%的MSI CRC细胞系(3/12)中发现了一个频繁的、新的单一突变，即CDK2-AP1基因3‘-UTRPoly(T)8中的del T，与DK2-AP1表达降低有关(袁等人，2005年)。在Ruggiero的一项同时研究中，描述了在人类MSI CRC中CEACAM1基因的3‘-UTR区域中类似的聚T(8)改变，加强了我们的项目。根据我们之前发表的发现，我们假设：1)。CDK2-AP1基因3‘-UTR8处的del T是MSI CRC中常见的改变，2)del T是一种躯体改变，与CDK2-AP1的表达降低有关。在这项拟议的项目中，我们将通过完成以下特定目标来验证我们的假设：特定目标1：我们将确定人类MSI CRC中CDK2-AP1基因3‘-UTR的聚(T)8中del T的频率；b)为了进一步确定这种改变是体细胞突变还是生殖系突变，我们将鉴定出的阳性CRC样本与正常组织对进行比较。特定目的2：我们将研究这种del T改变在人类MSI CRC中CDK2-AP1表达降低中的作用。我们提出的特定目标的完成将促进我们对MMR缺陷性结直肠癌中CDK2-AP1表达降低的机制的了解。在这项拟议的初步研究完成后，将进一步确定大量结直肠癌患者的del T改变，以确定高危人群。

DESCRIPTION (provided by applicant): . The objective of this application is to define the frequency and role of a recently discovered del T alternation in poly(T)8 in the 3'-UTR of the Cyclin Dependent Kinase-2- Associated Protein-1 (CDK2-AP1) gene in Microsatellite unstable (MSI) colorectal cancer (CRC). Current literature recognizes two pathways lead to invasive CRC. Microsatellite stable (MSS) pathway is the most common pathway, seen in approximately 80% of CRC cases, in which no microsatellite sequence alterations were observed. The other pathway is MSI pathway, explained in the remaining 20% of CRC cases, characterized by frame shift mutations and base-pair substitutions of the microsatellite DNA. CDK2-AP1 is a known growth suppressor in the etiology of RC. We previously reported that the CDK2-AP1 expression has been significantly decreased in human MS RC cell lines (Yuan et al., 2003) and its induction resulted in decreased cell proliferation and increased apoptosis (Kent et al., 2004). Recently, we detected a frequent, novel single alteration, del T in poly (T)8 of the 3'-UTR of the CDK2-AP1 gene in 25% of MSI CRC cell lines (3 of 12), is associated with decreased DK2-AP1 expression (Yuan et al., 2005). In a concurrent study by Ruggiero, described a similar poly T(8) alteration in 3'-UTR region of the CEACAM1 gene in human MSI CRC, strengthens our project. Based on our previously published findings, we hypothesize: 1). del T in a poly (T)8 of the 3'-UTR of the CDK2-AP1 gene is a frequent alteration in MSI CRC, 2) observed del T is a somatic alteration, associated with decreased expression of CDK2-AP1. In this proposed project, we will test our hypothesis by completion of he following Specific Aims: Specific Aim 1: a) We will determine the frequency of the del T in a poly (T)8 of he 3'-UTR of the CDK2-AP1 gene in human MSI CRC; b) To further determine this alteration is a somatic or a germline mutation, we will compare the identified positive CRC sample with normal tissue pairs. Specific Aim 2: We will characterize the role of this del T alteration in decreased expression of CDK2-AP1 in human MSI CRC. Completion of our proposed Specific Aims will advance our knowledge about the mechanism of decreased CDK2-AP1 expression in MMR deficient CRC. At the completion of this proposed pilot study, will urther determine del T alteration in a large number of CRC patients to identify high risk population.