Hydrogen sulfide functions as a tumor suppressor in glioblastoma

摘要：胶质母细胞瘤（GBM）是成人中最常见的恶性原发性脑肿瘤。GBM增长 和治疗耐药性是由自我更新的癌症干细胞（CSC）和衰老- 诱导的肿瘤支持微环境。CSC受细胞内在遗传和表观遗传的调控 网络，外部细胞与周围微环境的相互作用，以及 那些内在的和外在的调节程序。当驱动自我更新的多种分子机制 虽然已经确定，但高龄对CSC维持的影响还有待探讨。具体来说就是 尚不清楚高龄如何改变CSC维持和GBM生长。一个最近被认可的 高龄是含硫氨基酸代谢的转变，抑制了酶依赖性硫化氢 (H2S)生成、信号传导和生物利用度。H2S是一种氧化还原活性代谢物，通过蛋白质S- 硫氢化（R-SSnH），并影响代谢，免疫激活和寿命。其酶促生产， 胱硫醚γ-裂解酶（CGL）受甲状腺激素（TH）抑制。H2S具有促肿瘤和抗肿瘤作用， 肿瘤类型依赖的功能。然而，关于细胞内在和肿瘤的信息有限。 H2S在GBM中的微环境作用。最近，我们通过饮食调节硫化氢水平， 药理学干预，并发现H2S在GBM中起肿瘤抑制剂的作用，并减弱CSC 自我更新和肿瘤生长。在人体中，H2S的产生和硫化氢化减少 GBM标本与非肿瘤对照相比。虽然数据支持H2S功能的假设， 作为GBM中的肿瘤抑制因子，衰老诱导的H2S下降对GBM进展和CSC的影响， 如何将其逆转用于临床应用尚未探索。根据我们已发表的研究结果和新的初步数据， 我们假设衰老过程中H2S产生的减少促进了CSC的启动， 抑制，并驱动GBM生长，但最终可以通过基于抗TH的H2S促进来逆转 接近。我们将通过整合我们新开发的H2S和 与操纵H2S的体外和体内GBM模型组合的硫化氢化检测测定 通过对人类样本进行遗传和药理学干预来生产，以提供临床相关性。目的 1检验了衰老诱导的CGL衍生的H2S抑制加速GBM进展的假设。目的 2检验了化学诱导的甲状腺功能减退症刺激CGL增加全身和神经功能的假设。 H2S产生导致GBM进展减少、CSC富集和临床前生存期改善 GBM模型。本项目的长期目标是探究H2S作为GBM肿瘤抑制因子的功能 同时还研究了甲状腺功能减退引起的H2S产生的治疗作用， 信号传导以减少CSC维持和免疫抑制。利用这个轴心代表了一种新的战略 用于GBM的管理，其可与护理标准化疗、放疗和免疫疗法协同作用。

ABSTRACT: Glioblastoma (GBM) is the most common malignant primary brain tumor in adults. GBM growth and therapeutic resistance are driven by a combination of self-renewing cancer stem cells (CSCs) and an aging- induced tumor-supportive microenvironment. CSCs are regulated by cell intrinsic genetic and epigenetic networks, extrinsic cellular interactions with the surrounding microenvironment, and the interaction between those intrinsic and extrinsic regulatory programs. While multiple molecular mechanisms that drive self-renewal have been identified, the effects of advanced age on CSC maintenance has yet to be explored. Specifically, it is unclear how advanced age alters CSC maintenance and GBM growth. A recently recognized hallmark of advanced age is the shift in sulfur amino acid metabolism that suppresses enzyme-dependent hydrogen sulfide (H2S) generation, signaling, and bioavailability. H2S is a redox-active metabolite that signals through protein S- sulfhydration (R-SSnH) and impacts metabolism, immune activation, and longevity. Its enzymatic production by cystathionine γ-lyase (CGL) is repressed by thyroid hormone (TH). H2S has both pro- and anti-tumorigenic functions that are tumor-type dependent. However, there is limited information on cell intrinsic and tumor microenvironment functions of H2S in GBM. Recently, we modulated H2S levels through dietary and pharmacological interventions and found that H2S functions as a tumor suppressor in GBM and attenuates CSC self-renewal and tumor growth in pre-clinical models. H2S generation and sulfhydration were decreased in human GBM specimens as compared to non-tumor controls. While the data support the hypothesis that H2S functions as a tumor suppressor in GBM, the effects of aging-induced H2S declines on GBM progression and CSCs, and how to reverse this for clinical use, are unexplored. Based on our published findings and new preliminary data, we hypothesize that decreased H2S production during aging promotes CSC initiation, immune suppression, and drives GBM growth but can ultimately be reversed by anti-TH based H2S boosting approaches. We will test this hypothesis through the following aims by integrating our newly developed H2S and sulfhydration detection assays in combination with in vitro and in vivo GBM models that manipulate H2S production via genetic and pharmacological interventions with human samples to provide clinical relevance. Aim 1 tests the hypothesis that aging-induced suppression of CGL-derived H2S accelerates GBM progression. Aim 2 tests the hypothesis that chemically-induced hypothyroidism stimulates CGL to increase systemic and neural H2S production resulting in reduced GBM progression, CSC enrichment, and improved survival in preclinical GBM models. The long-term goal of this project is to interrogate the function of H2S as a GBM tumor suppressor that is lost during aging, while also studying the therapeutic effects of hypothyroid-induced H2S production and signaling to reduce CSC maintenance and immune suppression. Leveraging this axis represents a new strategy for the management of GBM that may synergize with standard of care chemo-, radio-, and immunotherapies.