Mechanisms of NOTCH, NUMB and MET signaling in Colon Cancer Initiating Cell Asymm

描述(申请人提供)：全世界每年诊断出近50万新的结直肠癌(CRC)病例。我们实验室和其他实验室的研究表明，CRC起始细胞(CCIC)对CRC的形成非常重要。与常用的CRC细胞系不同，CCIC使用原代CRC的病理和分子标记物连续维持肿瘤。然而，CCIC肿瘤的形成机制，以及它与通常使用的CRC细胞系形成肿瘤的不同之处，尚不清楚。我们最近得到了新的CCIC线，并有了几个新的发现。这些数据包括：(1)CCIC的Noch信号水平比常用的CRC细胞株高30倍以上，(2)Noch信号对CCIC的自我更新和肿瘤形成至关重要，(3)CCIC使用缺口驱动机制进行不对称有丝分裂(类似于正常结肠干细胞形成结肠隐窝的机制)并生成不同的子细胞。这是第一例结直肠癌细胞不对称有丝分裂。不对称有丝分裂对白血病CIC肿瘤的形成和自我更新至关重要，并可能在CCIC中发挥类似的作用。由于常用的结直肠癌细胞系不会有丝分裂不对称，这项研究将为CCIC肿瘤的形成机制以及它与常用的结直肠癌细胞系的不同提供独特的见解。这项建议的总体目标是了解结肠癌启动细胞对称和不对称有丝分裂之间的平衡机制，以及各自在CCIC自我更新和肿瘤形成中的作用。根据Noch在正常结肠干细胞不对称有丝分裂中的作用和我们的初步数据，我们推测Noch、Numb和HGF/MET对结肠癌启动细胞不对称/对称有丝分裂、肿瘤形成和自我更新具有重要调控作用。我们提出目标1确定缺口驱动CCIC不对称有丝分裂和肿瘤形成的机制，以及目标2检验假设NAME和HGF/MET调节CCIC对称和不对称有丝分裂 公共卫生相关性：在美国，结直肠癌是导致癌症死亡的第二大原因。当结直肠癌扩散到其他器官时，5年存活率为10-15%。由于结肠癌起始细胞(CCIC)与肿瘤的发生和转移有关，但特性较差，了解CCIC的自我更新、不对称有丝分裂和转移的机制是发现更好的结直肠癌化学预防和化疗靶点的重要创新途径。

DESCRIPTION (provided by applicant): Almost half a million new cases of colorectal cancer (CRC) worldwide are diagnosed each year. Studies from our lab and others have shown that CRC initiating cells (CCIC) are important for CRC formation. In contrast to commonly used CRC cell lines, CCIC serially maintain tumors with the pathological and molecular markers of the primary CRCs from which they were derived. However, the mechanism of CCIC tumor formation, and how it differs from that used by commonly used CRC cell lines to form tumors, is poorly characterized. We recently derived new CCIC lines and made several novel findings. These include data that (1) CCIC have 30X+ higher NOTCH signaling levels than commonly used CRC cell lines, (2) NOTCH signaling is critical for CCIC self-renewal and tumor formation and (3) CCIC use a NOTCH driven mechanism to mitose asymmetrically (similar to the mechanism used by normal colon stem cells to form colon crypts) and generate distinct daughter cells. This is the first example of CRC cell asymmetric mitosis. Asymmetric mitosis is critical for leukemia CIC tumor formation and self-renewal and is likely to play a similar role for CCIC. Since commonly used CRC cell lines do not mitose asymmetrically this study will provide unique insights into the mechanism of CCIC tumor formation and how it differs from that used by commonly used CRC cell lines. The overall goal of this proposal is to understand the mechanism that regulates the balance between colon cancer initiating cell symmetric and asymmetric mitosis and the role of each in CCIC self-renewal and tumor formation. Based on the role of NOTCH in normal colon stem cell asymmetric mitosis and our preliminary data we hypothesize that NOTCH, NUMB and HGF/MET critically regulate colon cancer initiating cell asymmetric/symmetric mitosis, tumor formation and self-renewal. We propose AIM 1 Identify the mechanism of NOTCH driven CCIC asymmetric mitosis and tumor formation and AIM 2 Test hypotheses that NUMB and HGF/MET regulate CCIC symmetric and asymmetric mitosis PUBLIC HEALTH RELEVANCE: CRC is the 2nd leading cause of cancer death in the United States. When CRC has spread to other organs, 5- year survival is 10-15%. Because colon cancer initiating cells (CCIC) are linked to tumorigenesis and metastasis but are poorly characterized, understanding the mechanisms of CCIC self-renewal, asymmetric mitosis and metastasis are important innovative approaches to discover better CRC chemoprevention and chemotherapy targets.