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

描述（由申请人提供）：全世界每年诊断出近50万结直肠癌（CRC）新发病例。我们实验室和其他实验室的研究表明，CRC起始细胞（CCIC）对CRC的形成很重要。与常用的CRC细胞系相反，CCIC连续维持具有它们所来源的原发性CRC的病理和分子标志物的肿瘤。然而，CCIC肿瘤形成的机制，以及它与常用的CRC细胞系形成肿瘤的机制有何不同，尚不清楚。我们最近获得了新的CCIC系，并取得了一些新的发现。这些包括以下数据：（1）CCIC具有比常用CRC细胞系高30倍以上的NOTCH信号传导水平，（2）NOTCH信号传导对于CCIC自我更新和肿瘤形成至关重要，以及（3）CCIC使用NOTCH驱动的机制来不对称地进行有丝分裂（类似于正常结肠干细胞形成结肠隐窝所使用的机制）并产生不同的子细胞。这是CRC细胞不对称有丝分裂的第一个例子。不对称有丝分裂对于白血病CIC肿瘤的形成和自我更新至关重要，并且可能对CCIC发挥类似的作用。由于常用的CRC细胞系不会不对称地有丝分裂，因此这项研究将为CCIC肿瘤形成机制以及它与常用CRC细胞系的不同之处提供独特的见解。该提案的总体目标是了解调节结肠癌起始细胞对称和不对称有丝分裂之间平衡的机制，以及CCIC自我更新和肿瘤形成中各自的作用。基于NOTCH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，我们假设NOTCH、NUMB和HGF/MET对结肠癌起始细胞不对称/对称有丝分裂、肿瘤形成和自我更新起关键性调节作用。我们提出AIM 1确定NOTCH驱动CCIC不对称有丝分裂和肿瘤形成的机制，AIM 2测试NUMB和HGF/MET调节CCIC对称和不对称有丝分裂的假设

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