Beta 2-Microglobulin signaling and targeting in bone metastasis

描述（由申请人提供）：在此修订后的申请中，我们采纳了评审员的建议，专门专注于开发抗b2-微球蛋白（b2-M）抗体作为治疗人前列腺癌骨转移的治疗剂。此外，我们还提供了关于推定的b2-M受体的新信息，一种利用b2-M受体介导的细胞信号传导机制的新策略，以及实现抗b2-M单克隆抗体（mAb）与放射之间协同作用的组合方法，作为前列腺癌骨转移的有希望的治疗方案。该提议的假设是抗b2-M mAb干扰HFE（遗传性血色素沉着症相关基因）-TFRC（转铁蛋白受体）-TF（转铁蛋白）复合物和铁转运，从而引起下游氧化还原信号传导变化，其中microRNA（miRNAs）充当一系列细胞应激反应蛋白和DNA修复酶的调节剂，其最终触发癌症而非正常细胞中的细胞死亡。本修订申请中提出了两个具体目标。具体目标1：使用实验性人前列腺癌异种移植物和转基因小鼠模型开发抗b2-M mAb作为前列腺癌骨转移治疗的治疗性抗体，评价小鼠中的抗体毒性，并确定抗b2-M mAb与电离辐射对前列腺癌细胞和肿瘤生长的协同作用。这一目标是基于我们的发现，即b2-M是一种主要的生长因子和多效性信号分子，赋予人前列腺癌细胞的生长，存活和上皮间质转化（EMT）。这一目标的成功实现将允许靶向b2-M作为人前列腺癌骨转移的新治疗方法的加速翻译。具体目标二：评估和验证一个假定的b2-M受体，一个非经典的主要组织相容性复合体（MHC）样分子，遗传性血色病相关基因，HFE。将评估HFE的功能作用及其与TFRC-TF复合物、铁摄取、活性氧（ROS）产生、DNA损伤和细胞死亡的关系。在这个目标中，我们将研究抗b2-M mAb对TFRC-TF复合物的功能，其可以通过内体铁再循环促进铁摄取，产生ROS和高活性羟基自由基，这些自由基可以引起癌症中而不是正常细胞中的DNA损伤。miRNAs是氧化还原信号的潜在下游靶点，对细胞应激反应蛋白和DNA修复酶的调控将特别强调。总之，该修订后的申请仔细遵循了评审员的建议，以开发靶向人前列腺癌中b2-M介导的下游生长和信号传导途径的新方法，该方法具有令人兴奋的临床转化潜力，可用于管理前列腺癌骨转移。公共卫生相关性：前列腺癌骨转移导致前列腺癌患者的死亡率和发病率。我们已经开发了一种新的治疗方法，通过使用一种新的抗b2-微球蛋白抗体加辐射，这已被证明可以完全消除小鼠体内人类肿瘤的生长。该项目的重点是定义这种协同作用的分子机制和适当的临床前研究，以将这些发现从实验室转移到床边。

DESCRIPTION (provided by applicant): In this revised application, we have taken the recommendations from the reviewers by focusing specifically on the development of anti-b2-Microglobulin (b2-M) antibody as a therapeutic agent for the treatment of human prostate cancer bone metastasis. In addition, we also provided new information on a putative b2-M receptor, a novel strategy exploiting b2-M-receptor mediated cell signaling mechanisms and combinatorial approach achieving synergism between anti-b2-M monoclonal antibody (mAb) plus radiation as a promising therapeutic regimen for prostate cancer bone metastases. The hypothesis of this proposal is that anti-b2-M mAb interferes with HFE (a hereditary hemochromatosis associated gene)-TFRC (Transferrin Receptor)-TF (Transferrin) complex and iron transport, thus provokes downstream redox signaling changes with microRNAs (miRNAs) serving as regulators for a series of cell stress response proteins and DNA repair enzymes that ultimately trigger cell death in cancer but not normal cells. Two Specific Aims are proposed in this revised application. Specific Aim 1: to develop anti-b2-M mAb as a therapeutic antibody for prostate cancer bone metastasis therapy using experimental human prostate cancer xenograft and transgenic mouse models, evaluate antibody toxicity in mice, and determine the synergistic interaction between anti-b2-M mAb plus ionizing radiation on the growth of prostate cancer cells and tumors. This Aim is based on our discovery that b2-M is a major growth factor and pleiotropic signaling molecule that confers the growth, survival, and epithelial to mesenchymal transition (EMT) of human prostate cancer cells. Successful accomplishment of this Aim will allow accelerated translation of targeting b2-M as a novel therapeutic approach for human prostate cancer bone metastasis. Specific Aim 2: to evaluate and validate a putative b2-M receptor, a non-classical major histocompatibility complex (MHC)-like molecule, the hereditary hemochromatosis associated gene, HFE. The functional role of HFE and its relationship to TFRC-TF complex, iron uptake, reactive oxygen species (ROS) production, DNA damages, and cell death will be assessed. In this aim, we will investigate the function of anti-b2-M mAb on TFRC-TF complex that could promote iron uptake via endosomal iron recycling, production of ROS and highly reactive hydroxy radicals that could cause DNA damages in cancer but not normal cells. Regulation of miRNAs, potential downstream targets of redox signaling, on cell stress response proteins and DNA repair enzymes will be specially emphasized. In summary, this revised application carefully follows the recommendations of the reviewers to develop novel approaches for targeting b2-M-mediated downstream growth and signaling pathways in human prostate cancer, which has exciting potential for clinical translation to manage prostate cancer bone metastasis. PUBLIC HEALTH RELEVANCE: Prostate cancer bone metastasis contributes to mortality and morbidity of prostate cancer patients. We have developed a new therapeutic approach by using a novel anti-b2-Microglobulin antibody plus radiation, which has been shown to completely abolish the growth of human tumors in mice. This project focuses on defining the molecular mechanism of this synergism and the appropriate preclinical studies to move these discoveries from bench to the bedside.