CDK6 in T cell development and cancer

CDK6 在 T 细胞发育和癌症中的作用

• 批准号: 8007389
• 负责人: Philip W. Hinds
• 金额: $ 32.41万
• 依托单位: TUFTS MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-01-15 至 2013-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8007389
• 关键词: Accounting; Adult; Alleles; Animal Testing; Animals; Apoptosis; Apoptotic; Biological Assay; Bone Marrow; Bone Marrow Aspiration; Bone Marrow Cells; CD44 gene; CD8B1 gene; CDKN2A gene; Cell Count; Cell Culture Techniques; Cell Cycle; Cell Cycle Regulation; Cell division; Cells; Cellularity; Control Animal; Cyclin D1; Cyclins; Data; Defect; Development; Enzymes; Event; Fetal Liver; Fibroblasts; Financial compensation; Future; Generations; Genetic; Genetic Epistasis; Genetic Techniques; Genetic Transcription; Growth; Harvest; Hyperactive behavior; IL2RA gene; IL7R gene; Immune System Diseases; In Vitro; Intervention; Knock-out; Knockout Mice; Learning; Malignant Neoplasms; Mammary Neoplasms; Masks; Measures; Mediating; Mediator of activation protein; Modeling; Mouse Strains; Mus; Mutant Strains Mice; Mutation; Oncogenes; Other Genetics; Partner in relationship; Pharmacologic Substance; Phosphorylation; Phosphotransferases; Play; Population; Pre-Clinical Model; Predisposition; Process; Production; Proteins; Proto-Oncogene Proteins c-akt; Reporting; Resistance; Role; Seeds; Signal Transduction; Source; Staging; Staining method; Stains; Stem cells; System; T-Cell Development; T-Cell Leukemia; T-Cell Proliferation; T-Lymphocyte; T-Lymphocyte Subsets; Testing; Therapeutic; Thymoma; Thymus Gland; Thymus Neoplasms; Tissues; Transgenes; Transgenic Organisms; Transplantation; Tumor Stem Cells; Tumor Suppressor Proteins; Tumor-Derived; cell transformation; cell type; cohort; design; developmental plasticity; human disease; leukemia/lymphoma; loss of function; mimetics; mutant; neoplastic cell; notch protein; novel; prevent; progenitor; public health relevance; research study; response; stem; thymocyte; tool; tumor; tumorigenesis

DESCRIPTION (provided by applicant): Cdk4 and cdk6 have been widely thought to be essential but redundant for initiation of the cell cycle in response to growth regulatory signals. In contradiction to this concept, recent genetic evidence indicates that cdk4 and cdk6 are not essential for early development, nor for proliferation of primary cells in culture. However, this insensitivity to cdk4/6 loss may be ascribed to compensation, since "free" D-type cyclins in cdk4/6 knockout cells appear able to activate cdk2 to allow proliferation. Further, considerable evidence now exists to support a crucial role of cdk4/6 in transformed and tumor cells. For example, cdk4 knockout fibroblasts resist transformation and mice lacking the ability of cyclin D1 to activate cdk4/6 are resistant to ErbB2-induced mammary tumors. The role of cdk6 in tumorigenesis is poorly understood, however recent studies have revealed a novel function of cdk6 in the differentiation of some cell types. For example, mice lacking cdk6 show defects in T cell proliferation. Importantly, conventional knockout experiments may underestimate the impact of specific subunits on development and cancer, due to promiscuity of D cyclin subunits that activate different cdks when their "proper" partners are lost. To clarify the role of cdk6 in cell cycle control and tumorigenesis using refined genetic tools, we have generated mice with targeted mutations in Cdk6. These knockin alleles generate hyperactive or inactive kinase subunits that may better mimic hyperactivation of cdk6 in tumor cells or model pharmaceutical intervention, respectively. We have found that loss of cdk6 or specific inactivation of cdk6 kinase function greatly reduces thymocyte numbers and significantly reduces proliferation in DN2 cells while concomitantly increasing the DN3 fraction. Conversely, the INK4-insensitive, hyperactive CDK6R31C allele increases thymic cellularity, consistent with increased proliferation of most T cell subsets, most notably the DN2 and CD8+ fractions. However, this increase in proliferation is countered by increased apoptosis, which may limit thymocyte expansion and tumorigenesis. Notably, preliminary analysis of LCK-myrAKT;cdk6-/- mice shows a complete absence of tumors, in contrast to LCK-myrAKT;cdk6WT mice, which quickly succumb to massive T cell tumors. Together, these data demonstrate that cdk6 is an important regulator of T cell proliferation and development, and may be crucial in some forms of T cell leukemia and lymphoma. Cdk6 may thus prove to be a valuable therapeutic candidate for treatment of both T cell tumors and immune disorders. To further characterize the role of cdk6 mutants in T cell development in mice, with particular emphasis on early progenitor function and formation of T cell cancers, we propose to (1) Assess the role of Cdk6 in extra-thymic T cell progenitors and determine the source of alterations in CD25 and CD44 expression in Cdk6-mutant thymocytes; (2) Determine the impact of cdk6 loss or mutation on AKT-induced tumors in the thymus; and (3) Determine if loss of p53 collaborates with cdk6 hyperactivity in R31C thymocytes and study the effects of cdk6 loss of function on tumor formation in p53 mutant mice. PUBLIC HEALTH RELEVANCE: It has become increasingly clear that the enzymes that control the ability of cells to divide play key roles in stem and progenitor cells that act in cellular differentiation, the process whereby cells acquire their specific functions in adult tissue, and also in tumor formation. Here we describe our extensive preliminary studies of cdk6, a cell division control enzyme that we show is key to the formation of normal T cells in the thymus and we find that loss of this enzyme prevents T cell tumor formation. The studies we propose herein are aimed at using unique, genetically altered mice that we have produced to understand the role of cdk6 in T cell development and tumorigensis in an effort to learn how to best target this enzyme with future therapeutics.

描述（由申请人提供）：CDK4和CDK6被普遍认为是必不可少的，但对于响应生长调节信号而开始细胞周期是多余的。与这个概念相矛盾，最近的遗传证据表明，CDK4和CDK6对于早期发育不是必不可少的，也不是培养中原代细胞的增殖。但是，由于CDK4/6基因敲除细胞中的“游离” D型细胞周期蛋白似乎能够激活CDK2以允许增殖，因此对CDK4/6损失的这种不敏感可能归因于补偿。此外，现在存在大量证据来支持CDK4/6在转化和肿瘤细胞中的关键作用。例如，CDK4基因敲除成纤维细胞抵抗转化，而小鼠缺乏Cyclin D1激活CDK4/6的能力，对ERBB2诱导的乳腺肿瘤具有抗性。 CDK6在肿瘤发生中的作用知之甚少，但是最近的研究表明，CDK6在某些细胞类型的分化中的新功能。例如，缺乏CDK6的小鼠在T细胞增殖中显示出缺陷。重要的是，由于d Cyclin亚基的滥交，当其“适当的”伴侣丢失时激活不同的CDK的disclin滥用，传统的敲除实验可能会低估特定亚基对发育和癌症的影响。为了阐明使用精制遗传工具在细胞周期控制和肿瘤发生中的作用，我们在CDK6中产生了具有靶向突变的小鼠。这些敲蛋白等位基因产生过度活跃或无活跃的激酶亚基，这些亚基可以更好地模仿肿瘤细胞中CDK6或模拟药物干预的过度激活。我们发现，CDK6或CDK6激酶功能的特异性失活的丧失会大大降低胸腺细胞数量，并显着降低DN2细胞的增殖，同时同时增加DN3的分数。相反，对Ink4不敏感的，多动的CDK6R31C等位基因会增加胸腺细胞性，这与大多数T细胞亚群增殖的增加一致，最值得注意的是DN2和CD8+级分。但是，凋亡增加可以抵消增殖的增加，这可能限制胸腺细胞的扩张和肿瘤发生。值得注意的是，与lck-myrakt; cdk6wt小鼠相比，lck-myrakt; cdk6 - / - 小鼠的初步分析显示出完全没有肿瘤，这些小鼠迅速屈服于大规模的T细胞肿瘤。总之，这些数据表明CDK6是T细胞增殖和发育的重要调节剂，在某些形式的T细胞白血病和淋巴瘤中可能至关重要。因此，CDK6可能被证明是治疗T细胞肿瘤和免疫疾病的有价值的治疗候选者。为了进一步表征CDK6突变体在小鼠T细胞发育中的作用，特别强调了早期祖细胞功能和T细胞癌的形成，我们建议（1）评估CDK6在外胞外T细胞祖细胞中的作用并确定CDK6突变胸腺细胞中CD25和CD44表达的改变来源； （2）确定CDK6损失或突变对胸腺中Akt诱导的肿瘤的影响； （3）确定p53的丧失是否与R31C胸腺细胞中的CDK6多功能合作，并研究CDK6功能丧失功能对p53突变小鼠肿瘤形成的影响。 公共卫生相关性：越来越清楚的是，控制细胞分裂能力的酶在作用在细胞分化中的茎和祖细胞中起关键作用，该过程使细胞在成人组织中获得特定功能以及在肿瘤中获得特定功能形成。在这里，我们描述了我们对CDK6的广泛初步研究，CDK6是一种细胞分裂控制酶，我们表明的是胸腺中正常T细胞形成的关键，我们发现该酶的丧失阻止了T细胞肿瘤的形成。我们在本文提出的研究旨在使用我们生成的独特的，遗传上改变的小鼠，以了解CDK6在T细胞发育和肿瘤中的作用，以学习如何最好地用未来的治疗剂靶向这种酶。