Regulation of cancer stem cell quiescence: Implications to tumor recurrence and t

描述(由申请人提供)：细胞毒性药物治疗后的临床复发对大量癌症患者来说是一个威胁生命的问题。据推测，这种形式的治疗抵抗是由一小部分生长受阻的癌症干细胞介导的，这些干细胞在治疗后存活并开始复发。虽然耐人寻味，但这一假说仍未得到检验，因为技术限制，无法直接检测到这些生长受阻的完整肿瘤内的癌细胞。我们已经克服了这个问题，开发了一种双重荧光报告系统，它永久地标记了所有癌细胞的红色荧光蛋白的表达，同时它通过在脉冲追逐实验中保留多西环素可抑制的组蛋白2B绿色荧光融合蛋白(H2BGFP)来区分慢周期癌细胞和快速增殖的癌细胞。使用鳞状细胞癌作为分级组织肿瘤的范例，我们能够检测到具有肿瘤启动潜力的快速周期和生长受阻的癌细胞。此应用程序旨在测试 假设：(1)鳞状细胞癌包含癌症干细胞，它们通过反应适应机制在快循环和慢循环状态之间相互转换；快周期和慢周期的癌症干细胞由控制其增殖行为的特征分子签名来定义；以及(3)慢周期的癌症干细胞对细胞毒性药物不敏感，治疗后能够引发复发。我们的研究结果可望取得积极的进展 影响治疗方法的设计和癌症患者的治疗由于识别静止的癌症干细胞及其行为的机制是朝着识别预测哪些癌症将抵抗细胞毒治疗的预后标志物迈出的第一步，它还将促进新的联合疗法的发展，这种联合疗法专门刺激静止的癌症干细胞的增殖，以增加它们对细胞毒药物的易感性，而不影响正常的成人干细胞的静止。

DESCRIPTION (provided by applicant): Clinical recurrence after therapy with cytotoxic agents presents a life threatening problem for a large number of cancer patients. It has been hypothesized that this form of therapy resistance is mediated by a small population of growth arrested cancer stem cells that survive treatment and initiate recurrence. Although intriguing, this hypothesis remains untested due to technical limitations that preclude direct detection of these growth arrested cancer cells within intact tumors. We have overcome this problem with the development of a dual fluorescent reporter system that permanently marks all cancer cells with the expression of a red fluorescent protein, while it distinguishes slow-cycling from rapidly proliferating cancer cells by their retention of a doxycycline repressible Histone 2B green fluorescent fusion protein (H2BGFP) in pulse-chase experiments. Using squamous cell carcinoma as a paradigm for hierarchically organized tumors, we are able to detect fast cycling and growth arrested cancer cells with tumor initiating potential. This application aims to test the hypothesis that: (1.) squamous cell carcinomas contain cancer stem cells that interconvert between fast and slow cycling states by responsive adaptation mechanisms; (2.) fast and slow cycling cancer stem cells are defined by characteristic molecular signatures that govern their proliferative behavior; and (3.) slow cycling cancer stem cells are inert to cytotoxic drugs and able to initiate recurrence after treatment. The results of our research are expected to positively impact the design of therapies and treatment of cancer patients as the identification of quiescent cancer stem cells and the mechanisms that govern their behavior presents a first step towards the identification of prognostic markers that predict which cancers will resist cytotoxic therapies It will also promote the development of novel combination therapies that specifically stimulate proliferation of quiescent cancer stem cells to increase their vulnerability to cytotoxic drugs, without affecting quiescence of normal, adult stem cells.