MNSOD ACETYLATION PROMOTES CANCER STEM CELL PHENOTYPES IN BREAST CANCER

项目总结/摘要： 肿瘤干细胞是肿瘤中一种罕见但极其重要的细胞亚群 与治疗失败和转移复发相关。虽然它越来越 很明显，针对这一亚群的治疗可能会带来更好的治愈几率， 目前还不清楚这些细胞是如何起源的，以及促进这些细胞的生物化学过程是什么。 癌症中的“干性”我们的实验室发现线粒体代谢的改变 活性氧促进缺氧诱导因子2α的异常激活 (HIF2α）。HIF 2 α的激活是一种成熟的干性机制， 与乳腺癌妇女的转移复发和治疗失败有关 癌我们发现，一种主要酶的翻译后修饰（即乙酰化） 参与线粒体活性氧代谢的锰超氧化物歧化酶（MnSOD） 破坏具有抗氧化功能的四聚体结构，将酶转化为单体 促进ROS形成并激活HIF 2 α。我们还发现MnSOD-K68 Ac 在表达低雌激素受体水平的乳腺癌中显著积累。因此， 提出MnSOD具有作为肿瘤抑制剂的二分行为 启动（抗氧化功能），但促进癌症干细胞重编程后， 建立肿瘤。这一主张得到了以下发现的支持： 与原发性肿瘤样本相比，转移性病变中存在MnSOD/HIF 2 α特征 来自同一个乳腺癌患者因此，本申请旨在确定：（1）如果 MnSOD-Ac将肿瘤细胞重编程为与化疗耐药性相关的干细胞样表型。 (2)如果MnSOD-Ac或HIF 2 α在已建立的肿瘤中的生物化学和/或遗传靶向作用， 具有MnSOD高/HIF 2 α特征的小鼠（MMTV.PyVT）抑制化学抗性和/或 转移(3)如果在患有乳腺癌的女性亚群之间存在关联， 表现出MnSODhigh或MnSOD-Ac或MnSOD-ROS-HIF 2 α分子轴特征， 出现化疗耐药性或转移复发风险增加。

PROJECT SUMMARY / ABSTRACT: Cancer stem cells are a rare and yet critically important subpopulation of cells in tumors associated with treatment failure and metastatic recurrence. Though it is becoming increasingly clear that targeting this subpopulation could lead to therapies with better odds of a cure it is still unknown how these cells originate and what are the biochemical processes that promote “stemness” in cancer. Our laboratory found that alterations in the metabolism of mitochondrial reactive oxygen species (ROS) promote aberrant activation of hypoxia-induced factor 2α (HIF2α). The activation of HIF2α is a well-established mechanism of stemness that has also been implicated in metastatic recurrence as well as treatment failure in women with breast cancer. We found that a posttranslational modification (i.e. acetylation) of a primary enzyme involved in the metabolism of mitochondrial ROS, manganese superoxide dismutase (MnSOD) breaks the tetrameric structure that has antioxidant function turning the enzyme into a monomer that promotes ROS formation and activates HIF2α. We also found that MnSOD-K68Ac accumulates prominently in breast cancers expressing low estrogen receptor levels. Hence, it is proposed that MnSOD has a dichotomous behavior functioning as a suppressor of tumor initiation (antioxidant function) and yet promotes cancer stem cell reprogramming later on in established tumors. This proposition is supported by the finding of strong associations between a MnSOD/HIF2α signature present in metastatic lesions compared to primary tumor samples from the same breast cancer patients. Hence, this application aims at determining: (1) if MnSOD-Ac reprograms tumor cells to stem-like phenotypes associated with chemoresistance. (2) if the biochemical and/or genetic targeting of MnSOD-Ac or HIF2α in established tumors of mice with the MnSODhigh/HIF2α signature (MMTV.PyVT) suppresses chemoresistance and/or metastasis. (3) if there is an association between subsets of women with breast cancer that exhibit a MnSODhigh or MnSOD-Ac, or MnSOD-ROS-HIF2α molecular axis signature and develop chemoresistance or have increased risk of metastatic recurrence.