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

摘要 浆液性上皮性卵巢癌（OvCa）通常表现为癌细胞在卵巢内广泛播散。 腹腔和显著的肿瘤负荷。OvCa转移瘤具有高比例的间质， 主要由癌症相关的成纤维细胞（CAF）组成，CAF是一种已知促进肿瘤生长的间充质细胞类型。 肿瘤细胞的侵袭和转移。然而，目前还不清楚正常的成纤维细胞是如何被重编程为 CAFs以及CAFs如何促进肿瘤生长。为了直接解决这些悬而未决的问题，我们进行了 对OvCa患者样本中的原发性和转移性基质进行蛋白质组学分析， 差异表达。我们检测到，特别是在转移瘤中，一个保守的基质标记， 转移，包括高基质表达的烟酰胺N-甲基转移酶（NNMT）。NNMT 催化甲基从S-腺苷甲硫氨酸（SAM）转移到烟酰胺。这消耗了 细胞SAM储存并导致组蛋白的整体低甲基化和肿瘤促进基因的表达。 在初步的实验中，我们发现NNMT可以将正常的成纤维细胞重编程为CAFs，并且NNMT CAF中的抑制阻断OvCa癌细胞粘附、增殖和体内肿瘤生长。在我们的系统中， NNMT表达特异性调节H3 K4和H3 K27的三甲基化。分析NNMT表达在 OvCa患者显示，强间质NNMT表达与不良预后显著相关。 基于这些数据，本申请的主要假设是NNMT在正常人中的表达， 成纤维细胞通过代谢介导的表观遗传改变将它们转化为CAF。拟议 实验将系统地描述NNMT驱动的表观遗传和代谢的贡献， 正常成纤维细胞向CAFs转化的变化。在目标I中，我们建议研究NNMT驱动的 CAF表型的获得和维持中的表观遗传重塑。我们将系统地 分析NNMT如何调节转录组，以及表观遗传学的改变如何在功能上驱动转录组。 正常成纤维细胞转化为CAF。由于NNMT影响多种代谢途径，在Aim II中，我们 将系统地评估NNMT驱动的代谢状态及其对CAF分化的贡献， 促进肿瘤进展。最后，在Aim III中，我们的团队将与NIH中心合作， 转化科学（NCATS）化学基因组学中心（NCGC）发现化合物，抑制 NNMT生物化学活性，使用最先进的高通量筛选和优化的NNMT 超过30万种潜在抑制剂的生化筛选。先导化合物将在高- 在加州大学的肿瘤微环境的3D模型。成功抑制NNMT活性， 肿瘤间质可能导致一种新的和临床相关的方法来治疗转移性卵巢癌， 癌

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.