Targeting interplay between KLF4 and PRMT5 in carcinogenesis

靶向KLF 4和PRMT 5在癌发生中的相互作用 本项目的目标是确定KLF 4和PRMT 5之间的相互作用对乳腺癌的影响。 致癌作用和抗乳腺癌治疗。Krüppel样因子4（KLF 4）是细胞增殖的关键调节因子， 细胞分裂，凋亡和DNA损伤的命运，并在肿瘤发生中起着矛盾的作用。 超过70%的人类原发性乳腺癌表现出KLF 4的细胞积累， KLF 4对乳腺癌形成的影响最近已被TCGA（癌症基因组）所证实。 Atlas）。我们和其他人最近的研究表明，KLF 4在癌症中具有致癌作用。 乳腺癌然而，KLF 4是如何被监管的，以及它的放松管制如何有助于 乳腺癌的发生机制尚不清楚。我们最近纯化KLF 4蛋白的结果 复合物显示，两个关键酶，VHL和PRMT 5与KLF 4紧密相互作用并调节KLF 4。 虽然泛素E3连接酶VHL/VBC催化KLF 4的泛素化，然后降解， 观察到KLF 4蛋白通过PRMT 5（一种基于精氨酸的甲基转移酶）的甲基化导致 稳定KLF 4并促进KLF 4介导的转录。KLF 4意外升高 由于KLF 4甲基化增强而导致的水平抵消了KLF 4泛素化，这反过来又引发了肿瘤。 启动并促进肿瘤侵袭。我们进一步观察到KLF 4甲基化的失调， PRMT 5的异常表达会损害DNA损伤检查点功能，这可能会诱导恶性肿瘤的发生。 由于基因组完整性的丧失而导致的转化。因此，我们问PRMT 5是否是一个关键因素， 确定KLF 4在乳腺癌发生中的致癌作用，如果PRMT 5-KLF 4级联反应 可能成为乳腺癌治疗的新靶点。本建议旨在确定 PRMT 5引起的KLF 4甲基化在乳腺肿瘤发生中的病理生理作用，并进一步 确定KLF 4-PRMT 5轴在乳腺癌治疗中的临床相关性。本课题 计划检验PRMT 5对KLF 4的失调促进肿瘤发生和肿瘤生长的假设。 通过追求以下具体目标来研究KLF 4的侵袭：（1）确定PRMT 5 调节KLF 4蛋白的稳定性和功能;（2）确定KLF 4的失调如何通过 PRMT 5影响乳腺癌干细胞的自我更新并促进肿瘤发生;以及（3） 确定PRMT 5对KLF 4的失调在乳腺肿瘤进展/侵袭中的影响， 验证我们新开发的KLF 4甲基化抑制剂在乳腺癌中的治疗干预 使用鼠模型的癌症治疗。

Targeting the interplay between KLF4 and PRMT5 in carcinogenesis The goal of this project is to determine the impact of interplay between KLF4 and PRMT5 in breast carcinogenesis and anti-breast cancer therapy. Krüppel-like factor 4 (KLF4) is a critical regulator of cell fate for cell division, apoptosis, and DNA damage, and plays an ambivalent role in tumorigenesis. Over 70% of human primary mammary cancers exhibit cellular accumulation of KLF4, and the impact of KLF4 on breast cancer formation has been recently indicated by the TCGA (The Cancer Genome Atlas). The most recent studies by us and others have demonstrated an oncogenic role for KLF4 in breast carcinogenesis. Nevertheless, how KLF4 is regulated and how its deregulation contributes to breast carcinogenesis remains unknown. Results from our recent purification of the KLF4 protein complex revealed that two critical enzymes, VHL and PRMT5, tightly interact with and regulate KLF4. While the ubiquitin E3 ligase VHL/VBC catalyzes KLF4 for ubiquitylation followed by degradation, we observed that methylation of KLF4 protein by PRMT5 (an arginine-based methyltransferase) results in the stabilization of KLF4 and promotion of KLF4-mediated transcription. Unexpected elevation of KLF4 levels due to enhanced KLF4 methylation counteracts KLF4 ubiquitylation, which in turn triggers tumor initiation and promotes tumor invasion. We further observed that deregulation of KLF4 methylation by aberrant PRMT5 expression impairs DNA damage checkpoint function, which could induce malignant transformation due to loss of genomic integrity. Thus, we ask if PRMT5 is a critical factor that determines the oncogenic role for KLF4 in breast carcinogenesis, and if the PRMT5-KLF4 cascade could be a novel target for breast cancer therapy. This proposal aims to determine the pathophysiological role of KLF4 methylation by PRMT5 in mammary tumorigenesis, and to further identify the clinical relevance of the KLF4-PRMT5 axis in breast cancer therapy. In this project, we plan to test the hypothesis that deregulation of KLF4 by PRMT5 promotes tumorigenesis and tumor invasion by pursuing the following specific aims: (1) to determine how methylation of KLF4 by PRMT5 regulates KLF4 protein stability and function; (2) to determine how the dysregulation of KLF4 by PRMT5 affects the self-renewal of breast cancer stem cells and promotes tumorigenesis; and (3) to determine the impact of deregulation of KLF4 by PRMT5 in breast tumor progression/invasion and validate the therapeutic intervention of our newly developed KLF4 methylation inhibitor in breast cancer treatment using murine models.