Role of Long Intergenic Noncoding RNA in UVB-induced Apoptosis and Skin Cancer

 描述（由申请人提供）：人类基因组中只有约3%编码蛋白质，其余97%称为非编码DNA。最初，许多基因间非编码序列被称为“垃圾DNA”，因为它被认为没有功能。然而，许多基因间序列可以转录成RNA。事实上，约85%的人类基因组被转录成RNA。缺乏蛋白质编码功能的RNA被称为非编码RNA，其中长的非编码RNA（lncRNA>200 nt）占大多数。LncRNA是最大且最多样化的细胞转录物类别之一，拥有超过10，000种转录物。迄今为止，只有少数lncRNA被研究，但新的证据表明lncRNA在调节基因表达中起关键作用，并与人类疾病如癌症，阿尔茨海默病和心脏病有关。确定lncRNA与特定疾病的关联是否在功能上是重要的，以及开发小鼠遗传模型来定义和表征lncRNA在体内疾病中的功能是至关重要的。这些研究可能会导致预后标志物和治疗的分子靶点的发展。鉴于大多数慢性人类疾病的病因学涉及与环境的相互作用，确定环境因素是否会影响lncRNA的表达、活性和功能以促成疾病也很重要。非黑色素瘤皮肤癌（NMSC）是美国最常见的癌症。大多数NMSC是由来自阳光的UVB辐射引起的。p53通过诱导细胞周期阻滞和凋亡在皮肤角质形成细胞对UVB诱导的DNA损伤的反应中起关键作用。在NMSC中，UVB诱导的p53突变允许角质形成细胞在连续UVB暴露后逃避凋亡和细胞周期停滞。这些缺陷在NMSC发展中具有关键作用。LincRNA-p21是一种lncRNA，是p53的直接转录靶点，据报道在培养的小鼠成纤维细胞中诱导凋亡。我们推断lincRNA-p21在UVB诱导的角质形成细胞凋亡中可能具有关键作用，并且其在逃避凋亡和皮肤癌发病机制中的损失。我们的初步数据显示lincRNA-p21是UVB高度诱导的，并且在UVB诱导的角质形成细胞凋亡中具有关键作用。我们计划确定lincRNA-p21在角质形成细胞中的调节和功能，并开发小鼠遗传模型来确定lincRNA-p21在响应UVB辐射控制角质形成细胞基因表达、细胞凋亡和皮肤癌中的分子功能。核心假设是：i）lincRNA-p21在角质形成细胞中由UVB通过p53依赖性途径诱导以触发凋亡性细胞死亡，和ii）lincRNA-p21在NMSC中充当肿瘤抑制因子，由此lincRNA-p21表达的丧失允许突变型p53和非突变型p53角质形成细胞两者逃避UVB诱导的凋亡，导致皮肤癌。如果正确的话，这些研究将首次揭示：i）lncRNA在小鼠模型中作为体内肿瘤抑制因子发挥作用，ii）环境因素可以控制lncRNA的表达、活性和功能，iii）lncRNA在环境诱导的疾病中具有关键作用。

 DESCRIPTION (provided by applicant): Only ~3% of the human genome encodes protein and the remaining 97% is referred to as noncoding DNA. Initially, much of the intergenic noncoding sequence was referred to as "junk DNA" as it was considered to have no function. However, many intergenic sequences can be transcribed into RNA. In fact, ~85% of the human genome is transcribed into RNA. RNAs that lack protein coding function are referred to as noncoding RNAs and of these the long noncoding RNAs (lncRNAs >200 nt) represent the majority. LncRNAs are one of the largest and most diverse classes of cellular transcripts with over 10,000 transcripts. Only a few lncRNAs have been studied to date but emerging evidence indicates lncRNAs have key roles in regulating gene expression and are associated with human diseases such as cancer, Alzheimer's and heart disease. It is critical to determine whether associations of lncRNAs with specific diseases are functionally significant and to develop mouse genetic models to define and characterize the function of lncRNAs in disease in vivo. Such studies could lead to development of prognostic markers and molecular targets for therapy. Given that the etiology of most chronic human diseases involves interactions with the environment, it is also important to determine if environmental factors can impact the expression, activity and function of lncRNAs to contribute to disease. Nonmelanoma skin cancer (NMSC) is the most common cancer in the US. The majority of NMSC is caused by UVB radiation from sunlight. p53 plays a key role in the response of skin keratinocytes to UVB- induced DNA damage by inducing cell cycle arrest and apoptosis. In NMSC, UVB-induced mutation of p53 allows keratinocytes upon successive UVB exposures to evade apoptosis and cell cycle arrest. These defects have a critical role in NMSC development. LincRNA-p21 is an lncRNA and a direct transcriptional target of p53 and is reported to induce apoptosis in mouse fibroblasts in culture. We reasoned that lincRNA-p21 could have a critical role in UVB-induced apoptosis in keratinocytes and its loss in the evasion of apoptosis and the pathogenesis of skin cancer. Our preliminary data show lincRNA-p21 is highly inducible by UVB and has a key role in UVB-induced apoptosis in keratinocytes. We plan to define the regulation and function of lincRNA-p21 in keratinocytes and to develop mouse genetic models to define the molecular function of lincRNA-p21 in controlling keratinocyte gene expression, apoptosis and skin cancer in response to UVB radiation. The central hypotheses are; i) lincRNA-p21 is induced by UVB in keratinocytes through a p53-dependent pathway to trigger apoptotic cell death and ii) lincRNA-p21 functions as a tumor suppressor in NMSC whereby the loss of lincRNA-p21 expression allows both mutant p53 and non-mutant p53 keratinocytes to evade UVB-induced apoptosis leading to skin cancer. If correct, these studies will reveal for the first time that; i) a lncRNA an function as a tumor suppressor in vivo in a mouse model, ii) an environmental factor can control the expression, activity and function of a lncRNA and iii) a lncRNA has a key role in an environmentally-induced disease.