PROJECT 4: Targeting Methionine Adenosyltransferases in Liver Metastasis

项目4：靶向肝转移中的甲硫氨酸腺苷转移酶 摘要 该项目的一个关键假设是，正常肝脏具有抑制转移的防御机制。 增长项目4的重点是蛋氨酸腺苷转移酶（MAT）蛋白的作用，MAT 1A MAT 2A和MAT 2B是抵抗肝转移的重要分子，而MAT 2A和MAT 2B则破坏这种防御。MAT催化 形成S-腺苷甲硫氨酸（SAMe），甲基供体。MAT 1A和MAT 2A基因编码MAT α1 和α2催化亚基;第三个基因，MAT 2B，编码β亚基，调节MAT 2A-β亚基。 编码酶。在正常肝脏中表达的MAT 1A在肝脏疾病中下调，而MAT 2A和 在非肝组织中表达的MAT 2B在多种人类癌症中过表达。初步数据显示 Mat 1a基因敲除（KO）小鼠对肝转移高度敏感， 囊泡含有癌蛋白;而MAT 2A/MAT 2B具有相互抑制作用， 转移抑制肿瘤抑制miRNAs miR-34 a和miR-34 b，但具有正前馈环 转移促进癌基因叉头盒M1（FOXM 1）。与此相反，MAT 1A和FOXM 1呈负相关， 互相规范。项目4研究了三种靶向这些相互作用的分子抑制肝脏的作用， 转移：SAMe;其代谢物甲硫腺苷（MTA）;和FOXM 1抑制剂FDI-6。该项目测试 假设癌细胞中的高MAT 2A/2B表达通过降低肝转移而增强肝转移， MAT 1A，并且SAMe、MTA和FDI-6部分地通过靶向MAT蛋白来抑制肝转移。重要的是， 患有转移性癌症的人类肝脏具有较低的MAT 1A表达，并且GEO数据库显示转移性 结肠癌、胰腺癌和前列腺癌具有较高的MAT 2A/2B表达。核心B将提供人类 标本和动物模型，以检查这些MAT蛋白在肝转移，从结肠，胰腺， 前列腺癌在三个具体目标：目标1。检查肝脏MAT 1A表达在肝脏中的作用 转移这一目的将检验以下假设：MAT 1A的缺失改变了细胞外囊泡的含量， 肝脏以促进转移性生长。目标2.确定癌症表达的MAT蛋白是否影响 肝转移这一目标将阐明负责MAT 2A/MAT 2B介导的调控机制 miR-34 a/B和FOXM 1的表达，并检查癌细胞中较高的MAT 2A/2 B表达是否增强肝细胞凋亡。 转移目标3。检查肝脏中SAMe、MTA和FDI-6的机制和治疗潜力 转移本研究旨在评估这三种分子（单独和联合）对癌细胞的作用。 体外迁移和侵袭。最佳疗法将使用小鼠模型和原位移植在体内验证。 使用来自肝转移患者的组织建立的患者来源的异种移植物。项目4协同增效 其中：项目1，因为内皮糖蛋白/BMP信号传导激活FOXM 1，项目2，因为脂肪肝中MAT 1A表达福尔斯下降 和Mat 1a KO肝脏具有更高的透明质酸;和项目3，因为Metavert降低MAT 2A表达。 成功完成将明确定义MAT蛋白在肝转移中的作用。

PROJECT 4: Targeting Methionine Adenosyltransferases in Liver Metastasis ABSTRACT A key central hypothesis for this Program is that the normal liver has defense mechanisms to suppress metastatic growth. Project 4 is focused on the role of methionine adenosyltransferase (MAT) proteins, with MAT1A defending against liver metastasis, while MAT2A and MAT2B break down this defense. MAT catalyzes the formation of S-adenosylmethionine (SAMe), the methyl donor. The MAT1A and MAT2A genes encode MAT α1 and α2 catalytic subunits, respectively; a third gene, MAT2B, encodes the β subunit that regulates the MAT2A- encoded enzyme. MAT1A, expressed in normal liver, is downregulated in liver diseases, whereas MAT2A and MAT2B, expressed in non-hepatic tissues, are overexpressed in multiple human cancers. Preliminary data show that Mat1a knockout (KO) mice are highly sensitized to develop liver metastasis and release extracellular vesicles that contain oncoproteins; whereas MAT2A/MAT2B have a reciprocal inhibition interplay with metastasis-inhibiting tumor suppressor miRNAs miR-34a and miR-34b, but have a positive feed-forward loop with the metastasis-promoting oncogene Forkhead box M1 (FOXM1). In contrast, MAT1A and FOXM1 negatively regulate each other. Project 4 examines the effect of three molecules that target these interplays to inhibit liver metastasis: SAMe; its metabolite methylthioadenosine (MTA); and the FOXM1 inhibitor FDI-6. This project tests the hypothesis that high MAT2A/2B expression in cancer cells enhances liver metastasis by lowering hepatic MAT1A, and that SAMe, MTA, and FDI-6 inhibit liver metastasis in part by targeting MAT proteins. Importantly, human livers with metastatic cancers have lower MAT1A expression and the GEO database shows metastatic colon, pancreatic and prostate cancers have higher MAT2A/2B expression. Core B will provide human specimens and animal models to examine these MAT proteins in liver metastases from colon, pancreas, and prostate cancers over three specific aims: Aim 1. Examine the role of hepatic MAT1A expression in liver metastasis. This aim will test the hypothesis that loss of MAT1A alters extracellular vesicle content released by the liver to enhance metastatic growth. Aim 2. Determine if MAT proteins expressed by the cancer influence liver metastasis. This aim will elucidate the mechanisms responsible for MAT2A/MAT2B-mediated regulation of miR-34a/b and FOXM1, and examine whether higher MAT2A/2B expression in cancer cells enhance liver metastasis. Aim 3. Examine mechanisms and therapeutic potential of SAMe, MTA, and FDI-6 in liver metastasis. This aim will assess the effects of these three molecules (individually and combined) on cancer cell migration and invasion in vitro. The best therapy will be verified in vivo using mouse models and orthotopic patient-derived xenografts established using tissues from patients with liver metastasis. Project 4 synergizes with: Project 1, as endoglin/BMP signaling activates FOXM1, Project 2, as MAT1A expression falls in fatty liver and Mat1a KO livers have higher hyaluronic acid; and Project 3, as Metavert lowers MAT2A expression. Successful completion will define clearly the role of MAT proteins in liver metastasis.