Roles of SIRT1 in normal hematopoietic and leukemic stem cells

描述(由申请人提供)：在了解长寿和癌症之间的分子相互关系方面存在着根本的差距。长期目标是了解应激反应基因SIRT1如何参与调节哺乳动物的寿命和癌症，并通过调节该基因来开发治疗和预防癌症的新策略。这项应用的目的是确定SIRT1在衰老和恶性转化过程中如何调节造血干细胞的功能。核心假设是SIRT1对于正常造血干细胞在衰老和应激状态下的细胞寿命是必不可少的，并促进慢性粒细胞白血病(CML)干细胞对化疗耐药的存活。这项拟议研究的基本原理是，更好地了解SIRT1正常干细胞和白血病干细胞的作用将有助于设计一种有效的策略，通过调节SIRT1来根除白血病干细胞，从而治疗CML和潜在的其他血液恶性肿瘤。因此，拟议的研究与美国国立卫生研究院发展基础知识的使命相关，这可能有助于减轻人类残疾的负担。在STOST初步数据的指导下，这一假设将通过追求三个具体目标来检验：1)确定SIRT1对正常造血干细胞功能的作用；2)确定SIRT1对CML干细胞存活和化疗耐药性的作用；以及3)确定SIRT1如何调节正常和白血病干细胞的突变。在目标1下，将通过骨髓移植实验来确定SIRT1缺失对造血干细胞频率、衰老过程中的静止和重建能力以及对DNA损伤的反应的后果。SIRT1介导的干细胞功能的关键分子通路将被破译。在目标2下，将确定通过基因敲除或小分子抑制剂抑制SIRT1后CML干细胞的存活率。在目标3中，将研究SIRT1缺失或抑制对正常造血干细胞和CML干细胞中发育的基因突变的影响，并将确定SIRT1调节的干细胞中DNA损伤修复的关键途径。这项拟议的研究意义重大，因为它有望深入了解SIRT1如何在干细胞老化和肿瘤发生中发挥作用，并开发一种通过调节SIRT1功能来根除耐药CML干细胞的新策略。

DESCRIPTION (provided by applicant): There is a fundamental gap in understanding molecular interrelationship between longevity and cancer. The long term goal is to understand how a stress-response gene SIRT1 is involved in regulating mammalian longevity and cancer, and to develop novel strategies for cancer treatment and prevention through modulating the gene. The objective of this application is to determine how SIRT1 regulates hematopoietic stem cell functions during aging and upon malignant transformation. The central hypothesis is that SIRT1 is essential for cellular longevity of normal hematopoietic stem cells during aging and under stress, and promotes survival of chronic myelogenous leukemia (CML) stem cells for chemoresistance. The rationale for the proposed research is that better understanding roles of SIRT1 normal and leukemic stem cells will help design an effective strategy to treat CML, and potentially other blood maligancies, by eradicating leukemic stem cells through modulating SIRT1. Thus, the proposed studies is relevant to the NIH's mission to develop fundamental knowledge that will potentially help to reduce the burdens of human disability. Guided by stong preliminary data, this hypothesis will be tested by pursuing three specific aims: 1) Determine the role of SIRT1 for normal hematopoietic stem cell functions; 2) Determine the role of SIRT1 for CML stem cell survival and chemoresistance; and 3) Determine how SIRT1 regulates mutagenesis in normal and leukemic stem cells. Under aim 1, the consequence of SIRT1 loss on hematopoietic stem cell frequency, quiescence and reconstitution capacity during aging and in response to DNA damage will be determined using bone marrow transplantation assay. Key SIRT1-mediated molecular pathways for stem cell functions will be deciphered. Under aim 2, CML stem cell survival upon inhibition of SIRT1, by gene knockout or small molecule inhibitor, will be determined. Under aim 3, the impact of SIRT1 loss or inhibition on developing genetic mutations in normal hematopoietic stem cells and CML stem cells will be investigated, and key SIRT1-regulated DNA damage repair pathways in stem cells will be identified. The proposed research is significant, because it is expected to shed insight on how SIRT1 plays a role in stem cell aging and tumorigenesis, and to develop a new strategy to eradicate resistant CML stem cells through modulating SIRT1 functions.