Arsenic Repression of GADD153 and Breast Cancer

砷对 GADD153 的抑制与乳腺癌

• 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
• 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

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。以前的研究，包括人口研究，提供了砷暴露与乳腺癌发展之间广泛而重要的联系。这些研究表明，砷在乳腺组织中积累，并作为内分泌干扰物促进乳腺癌的发展。砷是少数几种在实验动物中不会诱发肿瘤的人类致癌物之一。因此，开发砷诱导乳腺癌的模型对于理解其致瘤过程的机制至关重要。我们建立了一种砷诱导癌症的乳腺上皮细胞模型。为了复制正常的野外暴露条件，我们将乳腺上皮细胞暴露在低剂量的砷中数月。我们发现连续暴露乳腺上皮细胞5个月导致细胞增殖增加，伤口愈合增加，锚定独立生长增加，以及基质侵袭增加。这些研究表明，乳房上皮细胞的致瘤性转化暴露于砷。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)组成mtOXPHOS复合物IV的COXII亚基的表达改变。有趣的是，我们的研究表明砷处理不会引起mtOXPHOS复合物II和III活性的变化。这些初步研究揭示了砷靶向线粒体并诱导线粒体应激。最近的研究表明，人类细胞中含有线粒体特异性应激反应通路，其中转录因子GADD153（也称为CHOP或DDIT3）起着关键作用。我们测量了GADD153的表达，发现砷抑制GADD153的表达。据描述，GADD153在细胞死亡中起关键作用，抑制GADD153的表达可保护细胞免于死亡。然而，GADD153在砷致癌变中的作用尚不清楚。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。目的2：在小鼠异种移植模型中，确定砷抑制GADD153表达是否有助于乳腺上皮细胞在体外和体内的致瘤转化。提出的研究应提供深入了解砷诱导乳腺肿瘤发生的机制。