Antiestrogen-induced autophagy: a mechanism of cell survival in ER+ breast cancer

抗雌激素诱导的自噬：ER 乳腺癌细胞存活的机制

• 批准号: 7570105
• 负责人: PATRICIA V SCHOENLEIN
• 金额: $ 30.5万
• 依托单位: AUGUSTA UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-03-01 至 2011-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7570105
• 关键词: Ablation; Affect; Antiestrogen Therapy; Apoptosis; Aromatase; Autophagocytosis; Autophagosome; Binding; Breast Cancer Cell; Breast Cancer Model; Cancer Model; Cancer Patient; Caspase; Catabolic Process; Cell Death; Cell Death Induction; Cell Survival; Cell model; Cells; Ceramides; Cessation of life; Chloroquine; Cleaved cell; Combined Modality Therapy; Cytoplasm; Development; E2F transcription factors; Engineering; Estrogen Antagonists; Estrogen Receptor Modulators; Estrogen Receptors; Estrogen receptor positive; Estrogens; Fatty acid glycerol esters; Figs - dietary; Goals; Growth Factor; Human; In Vitro; Knowledge; Laboratories; Lamin Type A; Lymphoma; MAP2K1 gene; MCF7 cell; Mammary gland; Mediating; Mitochondria; Nude Mice; Organelles; Pathway interactions; Pharmaceutical Preparations; Phase; Play; Production; Proteins; Relative (related person); Resistance; Retinoblastoma Protein; Role; Signal Transduction; Small Interfering RNA; Somatic Cell Genetics; System; Tamoxifen; Testing; Tumor Suppressor Proteins; Tumor Volume; Xenograft procedure; abstracting; base; cancer therapy; cytochrome c; cytotoxic; improved; in vivo; inhibitor/antagonist; killings; kinase inhibitor; malignant breast neoplasm; novel; pro-apoptotic protein; resistance mechanism; sphingosine kinase; treatment strategy; tumor growth

DESCRIPTION (provided by applicant): Our long term goal is to identify antiestrogen-resistant mechanisms operative in human breast cancer in order to improve breast cancer therapy. Our studies are novel and show that the catabolic process of autophagy (also referred to as macroautophagy), which is induced by antiestrogen treatment of estrogen receptor positive (ER+) breast cancer cells, facilitates breast cancer cell survival and contributes to the development of antiestrogen resistance. We further demonstrate that the tumor suppressor protein Rb plays a pivotal role in the survival of breast cancer cells undergoing antiestrogen-induced macroautophagy, while high-level ceramide and its downstream effector BNIP3 affects autophagocytic cell death and apoptosis of antiestrogen- treated breast cancer cells. We hypothesize that (1) antiestrogen-induced macroautophagy is a cell survival mechanism dependent on active Rb and low-level ceramide levels; and (2) surviving cells undergoing antiestrogen-induced macroautophagy can be effectively killed by blocking macroautophagsome function or by treating with agents that raise intracellular ceramide levels to a threshold that induces expression of the pro- apoptotic protein BNIP3. Our aims are (1) to determine how Rb regulates antiestrogen-induced macroautophagy and cell survival versus ACD II and apoptosis in ER+ breast cancer cells; (2) to determine if the level of ceramide determines the fate of antiestrogen-treated cells undergoing macroautophagy (ACD II/apoptosis or survival) by regulating the levels of pRb and BNIP3; and (3) to determine if inhibitors of macroautophagosome function increase the cytotoxic effects of antiestrogen therapies in vivo by increasing cellular levels of ceramide and inducing BNIP3. We will utilize a combination of in vitro-based somatic cell genetic approaches, siRNA targeting, and in vivo tumor growth studies to study the survival mode of macroautophagy. Analysis of cell death will include a determination of caspase activation, cleaved PARP, cleaved lamin A, ceramide levels, and BNIP3 levels and subcellular localization. This study will further our understanding of how macroautophagy and macroautophagosme function is regulated in antiestrogen- sensitive and -resistant ER+ breast cancer cells. Such knowledge is critical to devising treatment strategies that suppress autophagy-mediated survival and restore antiestrogen sensitivity in breast cancer patients. Project Narrative: The expression of antiestrogen resistance is the most common impediment to the successful treatment of estrogen receptor-positive breast cancer. This study proposes that breast cancer cell survival and antiestrogen resistance is dependent on activated autophagosomes, organelles within the cytoplasm of breast cancer cells, and that blocking their function will restore sensitivity to antiestrogen treatment and promote breast cancer cell death.

描述（由申请人提供）：我们的长期目标是确定人类乳腺癌中抗雌激素的机制，以改善乳腺癌治疗。我们的研究是新颖的，表明自噬的分解代谢过程（也称为大自源）是由抗雌激素受体阳性（ER+）乳腺癌细胞的抗雌激素治疗引起的，促进了乳腺癌细胞的存活，并有助于抗抑制的发展。我们进一步证明，肿瘤抑制蛋白Rb在经历了抗雌激素诱导的巨噬细胞的乳腺癌细胞的存活中起关键作用，而高级神经酰胺及其下游效应BNIP3影响自噬细胞细胞死亡和抗雌激素治疗的乳腺癌细胞的凋亡。我们假设（1）抗雌激素诱导的大噬细胞是一种细胞存活机制，取决于活性RB和低级神经酰胺水平； （2）经历了抗雌激素诱导的大自噬细胞的幸存细胞可以通过阻断大型自源功能或用将细胞内神经酰胺水平提高到阈值的剂量来有效地杀死，从而诱导凋亡蛋白BNIP3的表达。我们的目的是（1）确定RB如何调节抗雌激素诱导的大型噬菌体和细胞存活与ACD II的生存以及ER+乳腺癌细胞中的凋亡； （2）通过调节PRB和BNIP3的水平，确定神经酰胺的水平是否确定经受大量自源性细胞（ACD II/凋亡或生存）的命运； （3）为了确定大藻毒素功能的抑制剂是否通过增加ceramide的细胞水平和诱导BNIP3的细胞水平来增加体内抗雌激素疗法的细胞毒性作用。我们将利用基于体外的体体细胞遗传方法，siRNA靶向和体内肿瘤生长研究的组合来研究大噬菌的生存模式。细胞死亡的分析将包括确定胱天冬酶激活，裂解的PARP，裂解层固定层A，神经酰胺水平和BNIP3水平以及亚细胞定位。这项研究将进一步理解大藻类和大型自源性的功能，在抗雌激素敏感和耐药性ER+乳腺癌细胞中受到调节。这种知识对于制定抑制自噬介导的生存并恢复乳腺癌患者抗雌激素敏感性的治疗策略至关重要。项目叙述：抗雌激素耐药性的表达是成功治疗雌激素受体阳性乳腺癌的最常见障碍。这项研究提出，乳腺癌细胞的存活和抗雌激素耐药性取决于活化的自噬体，乳腺癌细胞细胞质内的细胞器，而阻止其功能将恢复对抗雌激素治疗的敏感性并促进乳腺癌细胞死亡。