The role of UTX in Epidermal Homeostasis, Carcinogenesis, and Sex Mediated Risk of Cutaneous Squamous Cell Carcinoma

摘要 组蛋白修饰物是所有癌症中突变最多的基因之一，与组蛋白一起 其中最常见的是去甲基酶UTX(KDM6A)。UTX在几种上皮性癌中发生突变 包括皮肤鳞状细胞癌(CSCC)，这是人类第二常见的类型 恶性肿瘤。UTX位于X染色体上，是一种主要的增强子调节因子。它建立了活动的 通过它的组蛋白去甲基酶活性以及它与其他 激活组蛋白修饰物。众所周知，UTX还可以逃脱X灭活，在以下两种情况下产生剂量差异 男性和女性可能解释了观察到的风险和性别差异的一些特定性别差异 某些类型癌症的严重性，包括CSCC。为了支持这一点，当所有的宪法都被淘汰时 在组织中，UTX丢失会导致所有女性胚胎死亡，而大约25%的男性存活到成年。 有趣的是，UTY，UTX的Y连锁同源基因，保留了最小的去甲基酶功能，但可能 通过其他机制补偿UTX的损失。除了它参与了性别特定的 不同的是，UTX被认为是几种上皮性癌症的肿瘤抑制因子。最近，UTX也 被证明能感觉到细胞的氧气。越来越多的数据表明，UTX对于正常的蜂窝网络至关重要 动态平衡，在发育和致癌过程中起着重要作用。然而，尽管有这些证据， 而在宫颈鳞癌中UTX突变的高发率，几乎还没有人了解这种酶是如何 在表皮动态平衡和致癌过程中的作用。为了研究这一点，我们用小鼠 只有雌性UTX基因敲除小鼠表现出明显的异常。 具体地说，纯合子基因敲除雌性小鼠的体型变小，皮肤出现红斑和鳞片 与产仔对照相比。从这些小鼠采集的皮肤进行H&E染色显示出癌前病变 表皮增生症等变化。当在原代人角质形成细胞中被击倒时，UTX丢失导致 到戏剧性的转录变化。低氧反应基因和涉及氧化磷酸化的基因有 在表达差异最大的人群中。这些数据引发了这样一种假设，即UTX对正确的 动态平衡的基因表达，当丢失时会导致新陈代谢改变和更高的癌症风险。为了测试这一点 假设，我将实现以下目标：在Aim1中，我将确定UTX丢失如何影响表皮 体内动态平衡，并研究其在表皮缺氧和新陈代谢中的作用。在AIM2中，我将使用UV- 在我们的UTX基因敲除小鼠模型中辐射诱导肿瘤形成以确定UTX是否作为肿瘤 表皮中的抑制物。我还将评估UTX丢失对肿瘤风险和严重程度的影响 男性和女性收集关于UTX拷贝基因剂量驱动的性别特异性差异的见解。 此外，鉴于表观遗传变化的内在可逆性，这些研究有望提供新的 洞察表观遗传疗法治疗这些令人难以置信的常见癌症的可能性。

ABSTRACT Histone modifiers are amongst the most highly mutated genes in all forms of cancer, with the histone demethylase UTX (KDM6A) being one of the most frequent. UTX is mutated in several epithelial cancers including cutaneous squamous cell carcinoma (cSCC), the second most common type of all human malignancies. UTX is found on the X chromosome and is a major enhancer regulator. It establishes the active enhancer landscape through its histone demethylase activity as well as its ability to complex with other activating histone modifiers. UTX is also known to escape X inactivation creating a dosage disparity between males and females that may account for some of the sex specific differences observed for both the risk and severity of certain types of cancer, including cSCC. In support of this, when constitutively knocked out in all tissues, UTX loss results in embryonic lethality in all females, while ~25% of males survive to adulthood. Interestingly, UTY, the Y-linked paralog of UTX, retains minimal demethylase function but potentially compensates for loss of UTX through other mechanisms. In addition to its involvement in sex specific differences, UTX is implicated as a tumor suppressor in several epithelial cancers. Recently, UTX has also been shown to sense cellular oxygen. Accumulating data suggests that UTX is critical for proper cellular homeostasis and plays fundamental roles in development and carcinogenesis. However, despite this evidence and the high incidence of UTX mutations in cSCC, there is virtually no understanding of how this enzyme functions during epidermal homeostasis and carcinogenesis. To investigate this, we have generated mice with epidermal specific deletions of Utx where only female Utx knockout mice display any obvious abnormalities. Specifically, homozygous knockout female mice present with reduced size as well as erythematous, scaly skin compared to littermate controls. H&E staining of the skin harvested from these mice reveals premalignant changes such as epidermal hyperplasia. When knocked down in primary human keratinocytes UTX loss leads to dramatic transcriptional changes. Hypoxic response genes and those involved oxidative phosphorylation are among the most differentially expressed. These data provoke the hypothesis that UTX is critical for the proper homeostatic gene expression, and when lost lead to altered metabolism and higher cancer risk. To test this hypothesis, I will carry out the following aims: In Aim1 I will determine how Utx loss affects epidermal homeostasis in vivo and investigate its role in hypoxia and metabolism in the epidermis. In Aim2 I will use UV- radiation to induce tumorigenesis in our Utx knockout mouse model to determine if Utx acts as a tumor suppressor in the epidermis. I will also assess how tumor risk and severity is affected by Utx loss between males and females to glean insights about sex specific differences driven by UTX copy gene dosage. Furthermore, given the inherent reversibility of epigenetic changes, these studies hold promise to provide new insight into the potential for epigenetic therapies for these incredibly common cancers.