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

描述（由申请人提供）：全球每年诊断出近50万例结直肠癌（CRC）新病例。我们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细胞系相比，CCIC连续维持肿瘤与原代CRC的病理和分子标记，它们来源于原代CRC。然而，CCIC形成肿瘤的机制，以及它与常用的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系，并有了一些新的发现。这些数据包括：(1)CCIC的NOTCH信号水平比常用的CRC细胞系高30倍以上，(2)NOTCH信号对CCIC自我更新和肿瘤形成至关重要，(3)CCIC使用NOTCH驱动的机制进行不对称的有丝分裂（类似于正常结肠干细胞形成结肠隐窝的机制）并产生不同的子细胞。结直肠癌细胞不对称有丝分裂的第一例。不对称有丝分裂是白血病CIC肿瘤形成和自我更新的关键，可能在CCIC中发挥类似的作用。由于常用的CRC细胞系没有不对称的有丝分裂，本研究将为CCIC肿瘤形成的机制以及它与常用CRC细胞系的不同之处提供独特的见解。本课题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平衡的调节机制，以及它们在CCIC自我更新和肿瘤形成中的作用。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对结肠癌启动细胞不对称/对称有丝分裂、肿瘤形成和自我更新起到关键调控作用。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验证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