MicroRNA control of tumor-promoting inflammation in colon cancer

项目摘要/摘要 炎症细胞因子，白介素17，已经成为炎症相关的主要参与者， 自发性和转移性结直肠癌(CRC)模型，以及人类结直肠癌。事实上，升高的IL-17 与结直肠癌患者的生存呈负相关，甚至与对这两种化疗的耐药性有关 和靶向治疗。然而，掌握控制结直肠癌中IL-17-IL-17R信号的调节机制 在很大程度上仍然不为人知。主要发现：我们最近发现了microRNA，miR-146a，在 预防结肠炎和相关的肿瘤发生。缺乏miR-146a(-/-)的小鼠高度 易患结肠炎相关性和自发性结直肠癌，这似乎是由增强的 肿瘤致癌的IL-17-IL17R信号。从机制上讲，我们的数据表明miR-146a可以抑制肠道炎症和 1)髓系细胞内的miR-146a抑制IL-17诱导的细胞因子， 抑制IL-17的产生；和2)肠上皮细胞(IECS)内的miR-146a抑制致瘤的IL-17R 信号，这限制了IL-17的反应。在髓系细胞中，miR-146a与RIPK2结合，RIPK2是NOD2信号 中间，限制髓系细胞来源的IL-17诱导的细胞因子，如IL-23，并限制结肠IL-17 级别。因此，髓系细胞特异性miR-146a缺失导致CRC易感性。除了抑制 IL-17，miR-146a通过结合TRAF6直接限制IECS内的致瘤IL-17R信号。相应地， IEC特异性的miR-146a缺失也增加了CRC的易感性。重要的是，临床前应用miR- 146A模拟可以改善CRC。最后，我们证明miR-146a似乎类似地靶向RIPK2和 TRAF6在人类，包括在CRC患者中，表明miR-146a也可能限制IL-17-IL-17R信号转导 人类来控制CRC。假设/目标：我们将测试我们的假设，即miR-146a通过 调节小鼠和人类的结肠炎和肿瘤发生。在目标1中，我们将利用特定于IEC的 MIR-146a-/-小鼠，IEC祖细胞特异性miR-146a-/-小鼠，ApcMin/+miR-146a-/-小鼠，ApcMin/+miR-146a-/-KrasLSL- G12D小鼠、miR-146a沉默/过表达的人IECs和CRC患者样本以测试miR-146a在 IECS靶向TRAF6并抑制IL-17R介导的小鼠和人类肿瘤形成。在目标2中，我们将利用 髓系细胞特异性miR-146a-/-小鼠、ApcMin/+miR-146a-/-小鼠和ApcMin/+miR-146a-/-KrasLSL-G12D小鼠，miR- 146a-沉默/过表达的人原代髓系细胞和CRC患者样本，以测试miR-146a是否在 髓系细胞以RIPK2为靶点，在那里它抑制NOD2信号和IL-17诱导的细胞因子，最终限制 在小鼠和人类体内产生IL-17和结直肠癌。在目标3中，我们将利用炎症相关的CRC， 自发性结直肠癌和结直肠癌转移模型测试miR-146a是否具有治疗抑制作用 单独或与化疗联合应用促进肿瘤/化疗耐药的IL-17途径。在……里面 综上所述，miR-146a具有独特意义，因为它构成了调节多个 途径集中在致瘤的IL-17信号，并可能提供新的治疗点的干预。

Project Summary/Abstract The inflammatory cytokine, interleukin (IL)-17, has emerged as a major player in inflammation-associated, spontaneous, and metastatic colorectal cancer (CRC) models, as well as human CRC. In fact, elevated IL-17 has been negatively correlated with CRC patient survival, and even linked to resistance to both chemotherapy and targeted therapeutics. However, master regulatory mechanisms that control IL-17-IL-17R signaling in CRC remain largely unknown. Key Findings: We recently uncovered a critical role for the microRNA, miR-146a, in preventing colonic inflammation and associated tumorigenesis. Mice deficient in miR-146a (-/-) are highly susceptible to both colitis-associated and spontaneous CRC, which appears to be mediated by enhanced tumorigenic IL-17-IL17R signaling. Mechanistically, our data suggest miR-146a limits intestinal inflammation and CRC by two interlinked mechanisms: 1) miR-146a within myeloid cells inhibits IL-17-inducing cytokines, which restricts IL-17 production; and 2) miR-146a within intestinal epithelial cells (IECs) inhibits tumorigenic IL-17R signaling, which restricts IL-17 responsiveness. Within myeloid cells, miR-146a binds RIPK2, an NOD2 signaling intermediate, to limit myeloid cell-derived IL-17-inducing cytokines, such as IL-23, and restrict colonic IL-17 levels. Accordingly, myeloid cell-specific deletion of miR-146a leads to CRC susceptibility. In addition to inhibiting IL-17, miR-146a directly limits tumorigenic IL-17R signaling within IECs by binding TRAF6. Correspondingly, IEC-specific deletion of miR-146a also confers CRC susceptibility. Importantly, preclinical administration of miR- 146a mimic can ameliorate CRC. Finally, we show that miR-146a appears to analogously target RIPK2 and TRAF6 in humans, including in CRC patients, suggesting miR-146a may also limit IL-17-IL-17R signaling in humans to control CRC. Hypothesis/Goal: We will test our hypothesis that miR-146a protects against CRC by regulating colonic inflammation and tumorigenesis in mice and humans. In Aim 1, we will leverage IEC-specific miR-146a-/- mice, IEC progenitor-specific miR-146a-/- mice, ApcMin/+miR-146a-/- mice, ApcMin/+miR-146a-/-KrasLSL- G12D mice, miR-146a-silenced/overexpressing human IECs, and CRC patient samples to test if miR-146a within IECs targets TRAF6 and inhibits IL-17R-mediated tumorigenesis in mice and humans. In Aim 2, we will leverage myeloid cell-specific miR-146a-/- mice, ApcMin/+miR-146a-/- mice and ApcMin/+miR-146a-/-KrasLSL-G12D mice, miR- 146a-silenced/overexpressing human primary myeloid cells, and CRC patient samples to test if miR-146a within myeloid cells targets RIPK2, where it inhibits NOD2 signaling and IL-17-inducing cytokines, ultimately restricting IL-17 production and CRC in mice and humans. In Aim 3, we will leverage inflammation-associated CRC, spontaneous CRC, and CRC metastasis models to test if miR-146a mimic therapeutically inhibits tumor/chemoresistance-promoting IL-17 pathways, either alone or in combination with chemotherapy. In summary, miR-146a is of unique significance because it constitutes a single target that modulates multiple pathways converging on tumorigenic IL-17 signaling and may offer novel therapeutic points of intervention.