乳腺癌脑转移中的 DNA 双链断裂修复基因与氧化损伤。
DNA double-strand break repair genes and oxidative damage in brain metastasis of breast cancer.
机构信息
Affiliations of authors: Women's Malignancies Branch (SW, LE, TR, DP, BG, NMF, PSS), DNA Replication Group, Laboratory of Molecular Pharmacology (MIA, HF), and Tumor Biology Section, Radiation Biology Branch (JBM), Center for Cancer Research, National Cancer Institute, Bethesda, MD; Department of Oncology, Military Institute of Medicine, Warsaw, Poland (RD); Laboratory Animal Sciences Program, Frederick National Laboratory, Frederick MD (YQ); Departments of Pathology and Laboratory Medicine (SB), and Departments of Medicine (GS, YG-P), Indiana University School of Medicine, Indianapolis, IN; Department of Pathology (WB), and Department of Oncology and Radiotherapy (ES-Z, JJ), Medical University of Gdańsk, Gdańsk, Poland; Department of Neurosurgery, Maria Skłodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland (TM); Department of Neurosurgery and Children's Neurosurgery Clinic, Medical University of Lublin, Lublin, Poland (TT); Department of Neurosurgery, Interior Affairs Hospital, Olsztyn, Poland (WO); Department of Clinical Oncology, Białystok Oncology Center, Białystok, Poland (BC-A); Present addresses: Teach for America, Baltimore, MD (LE); National Heart, Lung, and Blood Institute, Bethesda, MD (DP); Cancer Biology Program (NMF), and Department of Oncology (GS), Stanford University, Stanford, CA.
出版信息
J Natl Cancer Inst. 2014 Jun 19;106(7). doi: 10.1093/jnci/dju145. Print 2014 Jul.
BACKGROUND
Breast cancer frequently metastasizes to the brain, colonizing a neuro-inflammatory microenvironment. The molecular pathways facilitating this colonization remain poorly understood.
METHODS
Expression profiling of 23 matched sets of human resected brain metastases and primary breast tumors by two-sided paired t test was performed to identify brain metastasis-specific genes. The implicated DNA repair genes BARD1 and RAD51 were modulated in human (MDA-MB-231-BR) and murine (4T1-BR) brain-tropic breast cancer cell lines by lentiviral transduction of cDNA or short hairpin RNA (shRNA) coding sequences. Their functional contribution to brain metastasis development was evaluated in mouse xenograft models (n = 10 mice per group).
RESULTS
Human brain metastases overexpressed BARD1 and RAD51 compared with either matched primary tumors (1.74-fold, P < .001; 1.46-fold, P < .001, respectively) or unlinked systemic metastases (1.49-fold, P = .01; 1.44-fold, P = .008, respectively). Overexpression of either gene in MDA-MB-231-BR cells increased brain metastases by threefold to fourfold after intracardiac injections, but not lung metastases upon tail-vein injections. In 4T1-BR cells, shRNA-mediated RAD51 knockdown reduced brain metastases by 2.5-fold without affecting lung metastasis development. In vitro, BARD1- and RAD51-overexpressing cells showed reduced genomic instability but only exhibited growth and colonization phenotypes upon DNA damage induction. Reactive oxygen species were present in tumor cells and elevated in the metastatic neuro-inflammatory microenvironment and could provide an endogenous source of genotoxic stress. Tempol, a brain-permeable oxygen radical scavenger suppressed brain metastasis promotion induced by BARD1 and RAD51 overexpression.
CONCLUSIONS
BARD1 and RAD51 are frequently overexpressed in brain metastases from breast cancer and may constitute a mechanism to overcome reactive oxygen species-mediated genotoxic stress in the metastatic brain.
背景
乳腺癌常转移到大脑，定植于神经炎症微环境中。促进这种定植的分子途径仍知之甚少。
方法
通过双侧配对 t 检验对 23 对匹配的人切除脑转移和原发性乳腺癌肿瘤的表达谱进行分析，以鉴定脑转移特异性基因。通过慢病毒转导 cDNA 或短发夹 RNA (shRNA) 编码序列，调节涉及的 DNA 修复基因 BARD1 和 RAD51 在人 (MDA-MB-231-BR) 和鼠 (4T1-BR) 脑趋向性乳腺癌细胞系中的表达。在小鼠异种移植模型中评估它们对脑转移发展的功能贡献（每组 10 只小鼠）。
结果
与匹配的原发性肿瘤（分别为 1.74 倍，P<0.001；1.46 倍，P<0.001）或不相关的全身转移相比，人脑转移过度表达 BARD1 和 RAD51。在 MDA-MB-231-BR 细胞中过表达这两种基因，通过心内注射后增加脑转移三倍至四倍，但通过尾静脉注射后不增加肺转移。在 4T1-BR 细胞中，shRNA 介导的 RAD51 敲低减少脑转移 2.5 倍，而不影响肺转移的发展。在体外，BARD1 和 RAD51 过表达的细胞显示基因组不稳定性降低，但只有在 DNA 损伤诱导时才表现出生长和定植表型。肿瘤细胞中存在活性氧，在转移性神经炎症微环境中升高，并可提供内源性遗传毒性应激源。Tempol 是一种可穿透大脑的氧自由基清除剂，可抑制 BARD1 和 RAD51 过表达诱导的脑转移促进作用。
结论
BARD1 和 RAD51 在乳腺癌脑转移中经常过度表达，可能构成克服转移性大脑中活性氧介导的遗传毒性应激的机制。
Zotero 插件