Suppression of Glioblastoma Stem Cells by Kruppel-Like Factor 9

描述（由申请人提供）：胶质母细胞瘤干细胞样细胞（或癌症干细胞，CSC）保持多谱系分化的能力，并有效地繁殖肿瘤异种移植物，准确地再现了临床胶质母细胞瘤的复杂组织病理学。鉴定和靶向调节GBM-CSC表型的分子机制对于最终耗尽肿瘤的CSC具有很大的希望，目前认为这些CSC在治疗抗性和肿瘤复发中起主要作用。Kruppel样因子9（KLF 9）是一种知之甚少的转录因子，与癌症或干细胞没有显著的联系。我们最近发现KLF 9有效地诱导胶质母细胞瘤癌症干细胞（GBM-CSC）分化，抑制GBM-CSC自我更新，并抑制GBM-CSC衍生的肿瘤异种移植物的生长。发现KLF 9的这些肿瘤抑制作用部分来自Notch 1转录的直接抑制。KLF 9可能调节广泛的转录网络，因为它识别转录启动子中常见的GC-GT BTE位点。该提议基于KLF 9调节抑制GBM-CSC的致癌表型和治疗抗性的转录网络的一般假设。该提案的总体目标是确定KLF 9的治疗和肿瘤抑制作用，其转录靶点，并开发KLF 9的直接细胞穿透形式用于潜在的临床翻译。目标#1将使用富含GBM-CSC的人GBM球体形成细胞及其原位肿瘤异种移植物来确定KLF 9如何调节GBM-CSC对辐射和替莫唑胺化疗的反应，这些细胞毒性方式是目前GBM治疗的主要方式。目的#2将使用ChIP芯片、基因表达阵列和广泛的生物信息学分析来鉴定KLF 9在GBM-CSC中调控的转录网络。目的#3将使用体内RCAS/tv-a系统来确定KLF 9是否调节多能神经干/祖细胞的体内转化和随后的胶质瘤发生。目的#4将使用用羧基末端聚精氨酸修饰的KLF 9（KLF 9 - 11 R）来开发用于靶向GBM-CSC的直接细胞穿透KLF 9蛋白。 我们发现KLF 9诱导在人GBM-CSC中分化、肿瘤抑制和辐射增敏是新颖的，具有广泛的生物学和临床可转化的意义。这些实验的阳性结果将显著影响识别和理解肿瘤干细胞的分子调节剂的目标，并最终控制其生长，命运和脑癌治疗的化疗/放射敏感性。

DESCRIPTION (provided by applicant): Glioblastoma stem-like cells (or cancer stem cells, CSCs) maintain a capacity for multi-lineage differentiation and efficiently propagate tumor xenografts that accurately recapitulate the complex histopathology of clinical glioblastoma. Identifying and targeting the molecular mechanisms that regulate the GBM-CSC phenotype holds great promise for ultimately depleting tumors of their CSCs that are currently believed to have a major role in therapeutic resistance and tumor recurrence. Kruppel-like factor 9 (KLF9) is a poorly understood transcription factor with no significant previous link to cancer or stem cells. We recently found that KLF9 potently induces glioblastoma cancer stem cell (GBM-CSC) differentiation, inhibits GBM-CSC self-renewal, and suppresses the growth of GBM-CSC derived tumor xenografts. These tumor suppressing effects of KLF9 were found to result in part from the direct repression of Notch1 transcription. KLF9 is likely to modulate an extensive transcriptional network since it recognizes GC-GT BTE sites that are common in transcriptional promoters. This proposal is based on the general hypothesis that KLF9 regulates a transcriptional network that suppresses the oncogenic phenotype and therapeutic resistance of GBM-CSCs. The general goals of this proposal are to determine KLF9's therapeutic and tumor suppressing effects, its transcriptional targets, and to develop a direct cell-penetrating form of KLF9 for potential clinical translation. Aim #1 will use human GBM sphere-forming cells enriched in GBM-CSCs and their orthotopic tumor xenografts to determine how KLF9 modulates GBM-CSC responses to radiation and temozolomide chemotherapy, cytotoxic modalities that are currently the mainstay of GBM therapy. Aim #2 will identify the transcriptional networks regulated by KLF9 in GBM-CSCs using ChIP-Chip, gene expression array, and extensive bioinformatics analyses. Aim #3 will use the in vivo RCAS/tv-a system to determine if KLF9 modulates in vivo transformation of multipotent neural stem/progenitor cells and subsequent gliomagenesis. Aim #4 will use KLF9 modified with carboxy-terminal poly-arginines (KLF9-11R) to develop direct cell- penetrating KLF9 protein for targeting GBM-CSCs. Our discovery that KLF9 induction is differentiating, tumor suppressing, and radiation sensitizing in human GBM-CSCs is novel with broad biological and clinical translatable implications. Positive results from these experiments will significantly impact the goals to identify and understand molecular regulators of neoplastic stem cells and to ultimately control their growth, fate, and chemo/radiation sensitivity for brain cancer therapy.