Breast Cancer Biomarkers in the KLF4 Signaling pathway

KLF 4是一种锌指转录因子，属于癌基因和肿瘤抑制基因家族 基因.项目3表明，KLF 4在大多数乳腺癌中上调，并显示出以下特性： 这与最近的研究表明其在多能干细胞表型中的作用一致。我们 证明KLF 4作为癌基因通过调节Notchl的转录和功能发挥作用， （Ntc 1）途径蛋白。此外，KLF 4诱导类维生素A受体的表达，其功能类似于 乳腺癌中的肿瘤抑制基因。我们的遗传学和药理学研究表明， KLF 4调节途径是KLF 4功能的关键决定因素。无论是使用γ- 分泌酶抑制剂或给予RXR选择性类维生素A有效地阻断了转化活性 KLF 4在体外或体内的表达。这些效应是KFL 4特异性的，并且在对照癌基因中未观察到。 我们已经证明KLF 4和Ntc 1是预后因子，它们在人类乳腺癌中一致表达。 乳腺肿瘤我们使用这两种蛋白的抗体作为乳腺癌的联合预后因素。 这些研究表明，KLF 4-Ntc 1通路活性增加的肿瘤具有临床侵袭性， KLF 4和Ntc 1抗体可用于评估乳腺癌预后（Aim 1）。 而Ntc 1通过经典途径诱导转化（即，CSL和MAML 1）、KLF 4 抑制CSL并将Ntc 1分流至备用途径。当在人乳腺MCF 10A中表达时 细胞，KLF 4或Ntc 1在3D培养中诱导腺泡成熟的阻滞。KLF 4阻断上皮化 这通常在MCF 10A细胞接种到基质胶层上后第6天发生。改进 小分子的临床前测试，我们将使用MCF 10A细胞来开发一种模型， 通过Ntc 1替代途径转化（Aim 2）。 抑制Ntc 1或促进类维生素A受体信号传导的小分子阻断了KLF 4的转化。 使用体外乳腺上皮模型、人乳腺癌异种移植物和ErbB 2诱导的快速模型， 我们开发的乳腺癌，这些小分子将被单独测试，并作为抑制剂组合使用。 KLF 4在乳腺癌中的作用（目的3）。在临床试验中，我们将探索维甲酸受体的作用， KLF 4-Ntc 1通路的信号传导，并评估γ-分泌酶抑制剂在 转移性乳腺癌（Aim 4）。在疗效试验中，KLF 4-Ntc 1通路组分将与 与肿瘤反应或耐药性，以确定哪些患者最有可能受益。 与公共卫生的相关性：我们的研究将测试是否可以使用两种KLF 4特异性抑制剂 单独或联合用于治疗乳腺癌，以及KLF 4-Ntc 1通路分析是否可以预测 哪些患者可能复发，哪些患者可能对KLF 4-Ntc 1抑制剂有反应。

KLF4 is a zinc finger transcription factor and part of a family that includes oncogenes and tumor suppressor genes. Project 3 has shown that KLF4 is upregulated in a majority of breast cancers and shows properties of an oncogene, consistent with recent studies showing its role in the pluripotent stem cell phenotype. We demonstrate that KLF4 functions as an oncogene by regulating the transcription and function of Notchl (Ntc1) pathway proteins. In addition, KLF4 induces expression of retinoid receptors that function similarly to tumor suppressor genes in breast cancer. Our genetic and pharmacologic studies show that these two KLF4-regulated pathways are critical determinants of KLF4 function. Either inhibition of Ntc1 using y- secretase inhibitors or administration of an RXR-selective retinoid efficiently blocked the transforming activity of KLF4 in vitro or in vivo. These effects were KFL4-specific and were not observed for control oncogenes. We have shown that KLF4 and Ntc1 are prognostic factors that are concordantly expressed in human breast tumors. We used antibodies to these two proteins as combination prognostic factors in breast cancer. These studies suggest that tumors with increased KLF4-Ntc1 pathway activity are clinically aggressive, and that KLF4 and Ntc1 antibodies can be use to assess prognosis in breast cancer (Aim 1). Whereas Ntc1 induces transformation through the Classical Pathway (i.e., CSL and MAML1), KLF4 suppresses CSL and shunts Ntc1 to an Alternate Pathway. When expressed in human mammary MCF10A cells, KLF4 or Ntc1 induced a block to acinar maturation in 3D cultures. KLF4 blocked the epithelialization that normally occurs by day 6 following inoculation of MCF10A cells onto a Matrigel layer. For improved preclinical testing of small molecules we will use MCF10A cells to develop a model in which cells are transformed by the Ntc1 Alternate Pathway (Aim 2). Small molecules that inhibit Ntc1 or promote retinoid receptor signaling blocked transformation by KLF4. Using in vitro breast epithelial models, human breast cancer xenografts, and a rapid model of ErbB2-induced breast cancer that we developed, these small molecules will be tested alone and in combination as inhibitors of KLF4 effects in breast cancer (Aim 3). In clinical trials, we will explore the effects of retinoid receptor signaling on the KLF4-Ntc1 pathway and estimate the anti-tumor efficacy of y-secretase inhibitors in metastatic breast cancer (Aim 4). In the efficacy trial, KLF4-Ntc1 pathway components will be correlated with tumor response or resistance to identify which patients are most likely to benefit. Relevance to public health: Our studies will test whether two specific inhibitors of KLF4 can be used alone or in combination for treatment of breast cancer, and whether KLF4-Ntc1 pathway analysis can predict which patients are likely to have recurrence/relapseand which patients may respond to KLF4-Ntc1 inhibitors.