Nicotinamide N-Methyltransferase (NNMT) as a master regulator of cancer stroma

摘要 浆液性上皮性卵巢癌(OvCa)通常表现为癌细胞广泛播散于 腹膜腔内肿瘤负担明显。卵巢转移瘤有很高比例的间质，这 主要由癌症相关成纤维细胞(CAF)组成，这是一种已知的间质细胞类型，可促进 肿瘤细胞的侵袭和转移。然而，尚不清楚正常的成纤维细胞是如何被重新编程为 CAF以及CAF如何促进肿瘤生长。为了直接回答这些公开的问题，我们执行了 对卵巢癌患者原发和转移间质进行蛋白质组学分析，以确定 差异表达。我们发现，特别是在转移瘤中，一种保守的间质信号与 转移包括烟酰胺N甲基转移酶(NNMT)的高间质表达。NNMT 催化甲基从S-腺苷蛋氨酸转移到烟酰胺。这耗尽了 细胞SAM存储并导致组蛋白的整体低甲基化和肿瘤促进基因的表达。 在初步实验中，我们发现NNMT可以将正常的成纤维细胞重新编程为CAF，并且NNMT 在CAF中的抑制可阻止OvCa癌细胞的黏附、增殖和体内肿瘤生长。在我们的系统中， NNMT的表达特异性地调节H3K4和H3K27的三甲基化。NNMT在人卵巢癌组织中的表达分析 OvCa患者显示，间质NNMT的强表达与预后不良显著相关。 根据这些数据，支持这一应用的主要假设是NNMT在正常情况下的表达 成纤维细胞通过代谢介导的表观遗传学改变将它们转化为CAF。建议数 实验将系统地表征NNMT驱动的表观遗传和代谢的贡献 正常成纤维细胞向CAF转化的变化。在Aim I中，我们建议调查NNMT驱动的 表观遗传重塑在CAF表型的获得和维持中的作用。我们将系统地 分析NNMT如何调节转录组以及表观遗传功能的改变如何驱动 将正常成纤维细胞转化为CAF。由于NNMT涉及多个代谢途径，在AIM II中，我们 将系统地评估NNMT驱动的代谢状态及其对CAF分化和 促进肿瘤进展。最后，在AIM III中，我们的团队将与NIH中心合作推进 翻译科学(NCATS)化学基因组学中心(NCGC)发现抑制 NNMT生化活性，使用最先进的高通量筛选和优化的NNMT 对30多万种潜在的抑制剂进行生化筛选。先导化合物将在功能上进行筛选。 北卡罗来纳大学肿瘤微环境的吞吐量3D模型成功地抑制了NNMT活性 肿瘤间质可能为卵巢转移性肿瘤的治疗提供一种新的和临床相关的方法。 癌症。

ABSTRACT Serous epithelial ovarian cancer (OvCa) typically presents with wide dissemination of cancer cells within the abdominal cavity and significant tumor burden. OvCa metastases have a high proportion of stroma, which consists primarily of cancer associated fibroblasts (CAFs), a mesenchymal cell type known to promote the invasion and metastasis of tumor cells. However, it is unclear how normal fibroblasts are reprogrammed into CAFs and how CAFs promote tumor growth. To directly address these open questions, we performed proteomic analyses of the primary and metastatic stroma in OvCa patient samples to identify proteins that were differentially expressed. We detected, specifically in the metastases, a conserved stromal signature associated with metastasis that included high stromal expression of Nicotinamide N-Methyltransferase (NNMT). NNMT catalyzes the transfer of a methyl group from S-adenosyl methionine (SAM) to nicotinamide. This depletes cellular SAM stores and leads to global hypomethylation of histones and expression of tumor-promoting genes. In preliminary experiments, we found that NNMT can reprogram normal fibroblasts into CAFs and that NNMT inhibition in CAFs blocks OvCa cancer cell adhesion, proliferation, and in vivo tumor growth. In our system, NNMT expression specifically regulates trimethylation of H3K4 and H3K27. Analysis of NNMT expression in OvCa patients revealed that strong stromal NNMT expression is significantly associated with a poor prognosis. Based on these data, the primary hypothesis underlying this application is that expression of NNMT in normal fibroblasts transforms them to CAFs through metabolically-mediated epigenetic alterations. The proposed experiments will systematically characterize the contribution of NNMT-driven epigenetic and metabolic changes to the transformation of normal fibroblasts to CAFs. In Aim I, we propose to investigate NNMT-driven epigenetic remodeling in the acquisition and maintenance of the CAF phenotype. We will systematically analyze how NNMT regulates the transcriptome and how alteration of epigenetics functionally drives the conversion of normal fibroblasts to CAFs. Since NNMT impinges on multiple metabolic pathways, in Aim II we will systematically assess the NNMT-driven metabolic state and its contribution to CAF differentiation and the promotion of tumor progression. Finally, in Aim III, our group will work with the NIH Center for Advancing Translational Sciences (NCATS) Chemical Genomics Center (NCGC) to discover compounds that inhibit NNMT biochemical activity, using state of the art high-throughput screening with an optimized NNMT biochemical screen of over 300,000 potential inhibitors. Lead compounds will be functionally screened in high- throughput 3D models of the tumor microenvironment at U of C. Successful inhibition of NNMT activity in the tumor stroma could result in a novel and clinically relevant approach to the treatment of metastatic ovarian cancer.