Circadian Clock and Myc-dependent Regulation of Cellular Transformation

项目摘要/摘要 结直肠癌(CRC)是美国诊断人数第三多的癌症。尽管成人结直肠癌病例 尽管(55岁及以上)儿童的发病率有所下降，但15-40岁年轻人中的CRC发病率呈惊人的上升趋势。它是 据估计，到2030年，早发性(EO)癌症的发病率将惊人地增加11%-12%。 成人结直肠癌患者通常在APC中存在驱动突变，APC是一种调节Wnt信号转导的肿瘤抑制基因 除了在Kras，BRAF，P53和Smad4中的第二次命中。APC突变也在早发性结直肠癌(EO- CRC)，但据报道，典型的二次命中司机路径有所减少。因此，当务之急是 需要更好地确定EO-CRC的根本原因。此外，临床证据表明，饮食很可能是 散发性EO-CRC发病率增加的根本原因。有趣的是，饮食挑战和 食物摄取的时间直接影响到生物钟，而生物钟是我们体内的起搏器，负责 睡眠/清醒周期、进食、荷尔蒙和其他周期节律。这表明昼夜节律的扰乱 时钟可能是食道癌的主要风险因素。为了进一步支持这一想法，临床数据表明时钟 在人类大肠肿瘤中，基因普遍下调，这表明时钟的抑制可能是 对肠道上皮细胞的转化很重要。直接处理时钟之间的潜在链接 和CRC，我们开发了一种新的遗传小鼠模型来定义昼夜节律时钟的中断如何驱动 结直肠癌的发病机制。我们的初步数据表明，肠道上皮生物钟的破坏 在统计上显著增加了息肉的形成。利用我们的小鼠模型系统，器官培养 揭示了时钟紊乱加速了肠道上皮细胞的转化。基于这些发现，我们 假设生物钟紊乱会影响肠道转化，并重新连接细胞代谢以维持 对高增殖性细胞的高需求。目标1将定义时钟机制如何调节基因组 肠道的不稳定和转化。目标2将确定生物钟在控制 EO-CRC建立的小鼠和人肠道上皮细胞在类器官系统中的代谢 病人样本。目标3将描述打乱生物钟的饮食模式如何加速肠道 转型。我们发现的更广泛的影响将概述根除EO-CRC的新的预防策略 以及其他可能与生物钟紊乱有关的癌症。此外，我们的长期目标是 实现有针对性的药物方法来调节生物钟，从而最大限度地减少行为 以及可能影响肿瘤发生的生活方式因素。

PROJECT SUMMARY/ ABSTRACT Colorectal cancer (CRC) is the third most diagnosed cancer in the United States. Though CRC cases in adults (55 and older) have decreased, the incidence of CRC in young adults, ages 15-40, is on an alarming rise. It is estimated that by the year 2030, a staggering 11-12% increase in early-onset (EO) cancers will be observed. Adult cases of CRC typically harbor driver mutations in Apc, a tumor suppressor that regulates Wnt signaling, in addition to second hits in Kras, Braf, p53 and Smad4. Apc mutations are also found in early-onset CRC (EO- CRC), but a decrease in the typical second hit driver pathways has been reported. Therefore, there is an urgent need to better define the root cause of EO-CRC. Moreover, clinical evidence suggests that diet is likely a root underlying cause of the increased incidence in sporadic cases of EO-CRC. Interestingly, dietary challenge and timing of food intake directly impinge on the circadian clock, which is our internal pacemaker that governs sleep/wake cycles, feeding, hormonal and other cyclic rhythms. This suggests that disruption of the circadian clock could be a major risk factor for EO cancers. In further support of this idea, clinical data indicates that clock genes are broadly downregulated in human colorectal tumors, suggesting that suppression of the clock could be important for transformation in the intestinal epithelium. To directly address the potential links between the clock and CRC, we have developed a novel genetic mouse model to define how disruption of the circadian clock drives CRC pathogenesis. Our preliminary data demonstrates that disruption of the clock in the intestinal epithelium drives a statistically significant increase in polyp formation. Using our mouse model system, organoid cultures reveal that clock disruption accelerates transformation in the intestinal epithelium. Based on these findings, we hypothesize that clock disruption impinges on intestinal transformation and rewires cellular metabolism to sustain the heightened demand of hyperproliferative cells. Aim 1 will define how the clock machinery regulates genome instability and transformation in the intestine. Aim 2 will determine the role of the circadian clock in governing metabolism of intestinal epithelial cells in both mouse and human organoid systems, established from EO-CRC patient samples. Aim 3 will delineate how dietary paradigms that disrupt the circadian clock accelerate intestinal transformation. The broader impact of our findings will outline new prevention strategies for eradicating EO-CRC and other cancers that potentially relate to disruption of the circadian clock. Additionally, our long-term goal is to achieve targeted pharmacological approaches to regulate the circadian clock and therefore minimize behavioral and lifestyle factors that potentially impinge on tumorigenesis.