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，CSCs）保持多谱系分化的能力，并有效地繁殖肿瘤异种移植物，准确地概括了临床胶质母细胞瘤的复杂组织病理学。识别和靶向调节GBM-CSC表型的分子机制对于最终消耗肿瘤中的csc具有很大的希望，目前认为csc在治疗耐药和肿瘤复发中起主要作用。kruppel样因子9 （KLF9）是一种鲜为人知的转录因子，以前与癌症或干细胞没有明显的联系。我们最近发现KLF9能有效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KLF9的这些肿瘤抑制作用部分是由于直接抑制Notch1转录。KLF9可能调节广泛的转录网络，因为它识别在转录启动子中常见的GC-GT BTE位点。这一建议是基于一般假设，即KLF9调节一个转录网络，抑制GBM-CSCs的致癌表型和治疗耐药性。本提案的总体目标是确定KLF9的治疗和肿瘤抑制作用，其转录靶点，并开发KLF9的直接细胞穿透形式，用于潜在的临床翻译。Aim #1将使用在GBM- csc及其原位肿瘤异种移植物中富集的人GBM球形细胞来确定KLF9如何调节GBM- csc对放射和替莫唑胺化疗的反应，这是目前GBM治疗的主要细胞毒性方式。Aim #2将利用ChIP-Chip芯片、基因表达阵列和广泛的生物信息学分析，确定KLF9在GBM-CSCs中调控的转录网络。Aim #3将使用体内RCAS/tv-a系统来确定KLF9是否调节多能神经干细胞/祖细胞的体内转化和随后的胶质瘤形成。Aim #4将使用羧基末端多精氨酸修饰的KLF9 （KLF9- 11r）开发直接穿透细胞的靶向GBM-CSCs的KLF9蛋白。我们发现KLF9诱导在人GBM-CSCs中具有分化、肿瘤抑制和辐射致敏作用，这一发现是新颖的，具有广泛的生物学和临床可翻译意义。这些实验的积极结果将显著影响识别和理解肿瘤干细胞的分子调节因子，并最终控制它们的生长、命运和化疗/放疗敏感性，以用于脑癌治疗。

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.