The role of mixed lineage leukemia (MLL/KMT2) core complex in directing FOXQ1 activity for triple negative breast cancer progression

项目摘要 三阴性乳腺癌（TNBC）占所有乳腺癌病例的20%， 由于缺乏靶向治疗选择和快速治疗， 肿瘤复发、化疗耐药和转移的发生。一种表型变化， 被称为上皮向间质转化（EMT）的癌细胞已经被观察到， 促进细胞对药物治疗的存活并促进转移进展。FOXQ 1已经 被鉴定为诱导TNBC中EMT表型的有效致癌转录因子。 初步数据揭示了FOXQ 1调节的潜在机制 转录活性蛋白质相互作用筛选鉴定了FOXQ 1与 MLL核心复合物，一个突出的表观遗传调控复合物。进一步调查发现 FOXQ 1和MLL核心复合物共定位在转录调控的染色质区域内， 具有诱导EMT的已知功能的基因的调控元件。这表明，MLL 核心复合物作为FOXQ 1的转录辅激活因子发挥作用，以驱动EMT 转录程序和由此产生的肿瘤进展。目标1将全面询问 通过绘制FOXQ 1-MLL核心的结构， 复合结合口袋关键相互作用域的识别将通过以下方式完成： 用重组纯化蛋白质进行GST-下拉。映射将由连续的 蛋白质截短和点突变的产生，以及计算机结构建模。目的 2将阐述FOXQ 1-MLL复合物相互作用的功能含义。的 从Aim 1获得的生物化学见解将用于生成FOXQ 1构建体， 诱导合成突变，降低FOXQ 1相互作用和招募MLL核心的能力 复杂.所得FOXQ 1突变体将在乳腺癌细胞系模型中异位表达。 急救员该模型系统将用于评估破坏FOXQ 1结合到 MLL核心复合物减弱了驱动EMT、细胞侵袭和远处转移特征的能力， 体内转移进展。本研究的结果将用于评价 靶向FOXQ 1-MLL核心复合物蛋白相互作用作为潜在的药理学策略 以防止三阴性乳腺癌的肿瘤进展。

Project Summary Triple negative breast cancer (TNBC) accounts for up to 20% of all breast cancer cases and presents with the worst clinical outcomes due to lack of targeted therapeutic options and rapid onset of tumor recurrence, chemotherapy resistance and metastasis. A phenotypic change within the cancer cells, known as the epithelial to mesenchymal transition (EMT), has been observed to promote cell survival against drug treatment and foster metastatic progression. FOXQ1 has been identified as a potent oncogenic transcription factor that induces the EMT phenotype in TNBC. Preliminary data have uncovered a potential mechanism for the regulation of FOXQ1 transcriptional activity. Protein interaction screening identified binding between FOXQ1 and the MLL core complex, a prominent epigenetic regulatory complex. Further investigation identified that FOXQ1 and the MLL core complex co-localize within the chromatin regions of transcriptional regulatory elements of genes with known functions in inducing EMT. This suggests that the MLL core complex is functioning as a transcriptional coactivator for FOXQ1 to drive the EMT transcription program and resultant tumor progression. Aim 1 will fully interrogate the biochemical nature of this protein interaction by mapping the structure of the FOXQ1-MLL core complex binding pocket. Identification of the critical interacting domains will be accomplished by GST-pull down with recombinant purified proteins. Mapping will be accomplished by successive generation of protein truncations and point mutations, as well as, in silico structural modeling. Aim 2 will elaborate on the functional implication of the FOXQ1-MLL complex interaction. The biochemical insights gained from Aim 1 will but utilized to generate a FOXQ1 construct with induced synthetic mutations that diminish the ability of FOXQ1 to interact and recruit the MLL core complex. The resultant FOXQ1 mutant will be ectopically expressed in a cell line model of breast EMT. The model system will be used to assess the extent to which disrupting FOXQ1 binding to the MLL core complex attenuates the ability to drive features of EMT, cell invasion and distant metastatic progression in vivo. The results of this study will be used to evaluate the efficacy of targeting the FOXQ1-MLL core complex protein interaction as a potential pharmacologic strategy to prevent tumor progression in triple negative breast cancer.