Arsenic Repression of GADD153 and Breast Cancer

砷对 GADD153 的抑制与乳腺癌

基本信息

批准号：
8723827
负责人：
KESHAV K SINGH
金额：
$ 18.19万
依托单位：
UNIVERSITY OF ALABAMA AT BIRMINGHAM
依托单位国家：
美国
项目类别：
财政年份：
2013
资助国家：
美国
起止时间：
2013-08-20 至 2016-08-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8723827
关键词：
Address Anchorage-Independent Growth Applications Grants Arsenic Binding Breast Breast Cancer Cell Breast Carcinogenesis Breast Epithelial Cells Carcinogens Cell Death Cell Line Cell Proliferation Cell model Cell physiology Cells Complex Cutaneous Fibrous Histiocytoma Development Dominant-Negative Mutation Dose Endocrine Disruptors Estradiol Estrogens Exposure to Gene Expression Goals Growth Health Hormones Human In Vitro Laboratory Animals Ligands Link Long-Term Effects MCF10A cells Malignant Neoplasms Mammary Gland Parenchyma Measures Mitochondria Mus Oxidative Phosphorylation Pathway interactions Play Population Study Preventive Process Production Reporting Repression Research Risk Role Stress Therapeutic Agents Woman Wound Healing Xenograft Model Xenograft procedure biological adaptation to stress breast tumorigenesis carcinogenesis cell growth cell transformation complex IV exposed human population human population study in vivo insight interest malignant breast neoplasm matrigel model development public health relevance small hairpin RNA transcription factor tumor tumorigenesis tumorigenic

项目摘要

DESCRIPTION (provided by applicant): Arsenic is a well-known human carcinogen. Previous studies including human population studies provide an extensive and important link between the arsenic exposure and development of breast cancer. These studies suggest that arsenic accumulates in breast tissues and acts as an endocrine disruptor to promote development of breast cancer. Arsenic is one of the few human carcinogens that do not induce tumors in laboratory animals. Therefore, development of models for arsenic-induced breast cancer is critical for understanding the mechanism(s) underlying the tumorigenic process. We have developed a mammary epithelial cell model for arsenic-induced cancer. To replicate normal field exposure conditions, we exposed mammary epithelial cells to a low dose of arsenic for several months. We discovered that a five month continuous exposure of mammary epithelial cells results in increased cell proliferation, increased wound healing, increased anchorage independent growth, as well as increased matrigel invasion. These studies suggest a tumorigenic transformation of mammary epithelial cells by exposure to arsenic. Mitochondria control cell growth and cell death. Mitochondria also perform other cellular functions including ATP production via mitochondrial oxidative phosphorylation (mtOXPHOS). Consistent with this finding arsenic-transformed cells show 1) altered mtOXPHOS Complex I and IV activities; 2) an altered expression of subunit NDUFB8 comprising mtOXPHOS Complex I; and 3) altered expression of COXII subunit comprising mtOXPHOS complex IV. Interestingly, our study suggests that arsenic-treatment did not induce changes in mtOXPHOS Complex II and III activities. These preliminary studies revealed that arsenic targets mitochondria and induces mitochondrial stress. Recent studies suggest that human cells contain mitochondria specific stress response pathway in which transcription factor GADD153 (also known as CHOP or DDIT3) plays a key role. We measured the expression of GADD153 and found that arsenic represses GADD153 expression. GADD153 is described to play a critical role in cell death and suppression of GADD153 expression is known to protect cells from cell death. However, GADD153's role in arsenic induced carcinogenesis is unknown. We hypothesize that arsenic represses expression of GADD153/CHOP/DDIT3 to protect cells from arsenic induced cell death which contributes to tumorigenic transformation of mammary epithelial cells induced by arsenic. To address this hypothesis we will: Aim 1: Determine a role for GADD153 in protection against cell death and mitochondrial stress induced by arsenic. Aim 2: Determine whether arsenic repression of GADD153 expression contributes to tumorigenic transformation of breast epithelial cells in vitro and in vivo in mouse xenograft model. The proposed studies should provide insight in to the mechanism involved in arsenic induced breast tumorigenesis.

描述（由申请人提供）：砷是一种众所周知的人类致癌物。包括人群研究在内的先前研究提供了砷暴露与乳腺癌发生之间广泛而重要的联系。这些研究表明，砷在乳腺组织中积聚，并作为内分泌干扰物促进乳腺癌的发展。砷是少数不会诱发实验动物肿瘤的人类致癌物之一。因此，砷诱导乳腺癌模型的开发对于理解致瘤过程的机制至关重要。我们开发了砷诱发癌症的乳腺上皮细胞模型。为了复制正常的现场暴露条件，我们将乳腺上皮细胞暴露在低剂量的砷中几个月。我们发现乳腺上皮细胞连续暴露五个月会导致细胞增殖增加、伤口愈合增加、贴壁独立生长增加以及基质胶侵袭增加。这些研究表明，暴露于砷会导致乳腺上皮细胞发生致瘤性转化。线粒体控制细胞生长和细胞死亡。线粒体还执行其他细胞功能，包括通过线粒体氧化磷酸化 (mtOXPHOS) 产生 ATP。与这一发现一致，砷转化细胞显示：1) mtOXPHOS 复合物 I 和 IV 活性改变； 2)包含mtOXPHOS复合物I的亚基NDUFB8的表达改变； 3)改变包含mtOXPHOS复合体IV的COXII亚基的表达。有趣的是，我们的研究表明砷处理不会引起 mtOXPHOS Complex II 和 III 活性的变化。这些初步研究表明，砷以线粒体为目标并诱导线粒体应激。最近的研究表明，人类细胞含有线粒体特异性应激反应途径，其中转录因子 GADD153（也称为 CHOP 或 DDIT3）发挥关键作用。我们测量了 GADD153 的表达，发现砷抑制 GADD153 的表达。据描述，GADD153 在细胞死亡中发挥关键作用，并且已知抑制 GADD153 表达可以保护细胞免遭细胞死亡。然而，GADD153 在砷诱发的致癌作用中的作用尚不清楚。我们假设砷抑制 GADD153/CHOP/DDIT3 的表达，以保护细胞免受砷诱导的细胞死亡，这有助于砷诱导的乳腺上皮细胞的致瘤性转化。为了解决这一假设，我们将：目标 1：确定 GADD153 在防止砷诱导的细胞死亡和线粒体应激中的作用。目标 2：确定砷对 GADD153 表达的抑制是否有助于小鼠异种移植模型中体外和体内乳腺上皮细胞的致瘤转化。拟议的研究应有助于深入了解砷诱导乳腺肿瘤发生的机制。