DIOXIN/EPITHELIAL CELL INTERACTIONS--MECHANISM AND ASSAY

二恶英/上皮细胞相互作用——机制和测定

• 批准号: 2153345
• 负责人: JOHN F GIERTHY
• 金额: $ 14.86万
• 依托单位: WADSWORTH CENTER
• 依托单位国家: 美国
• 财政年份: 1985
• 资助国家: 美国
• 起止时间: 1985-01-01 至 1998-08-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2153345
• 关键词: RNase protection assay; acetylcholine; bioassay; breast neoplasms; cell cell interaction; dioxins; drug resistance; environmental toxicology; estrogen inhibitor; gas chromatography; gas chromatography mass spectrometry; genetic transcription; growth inhibitors; hormone related neoplasm /cancer; human tissue; hydroxylation; laboratory mouse; molecular oncology; neoplastic cell; neoplastic growth; northern blottings; steroid hormone metabolism; toxicant interaction; tumor promoters; western blottings

The objective of this proposal is to determine the mechanism of regulation by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) of estrogen dependent human breast cancer tumor growth in mice. Ultimately, knowledge of this mechanism will provide: 1) the basis of the observed drug resistance to antiestrogen therapy for estrogen dependent breast cancer, 2) and approach for mechanism-based endocrine related risk assessment associated with chronic low level exposures to dioxin-like xenobiotics, and 3) novel Ah locus-mediated chemotherapeutic strategy for steroid hormone-dependent cancer and understanding of the role of estrogen and estrogen receptors in breast cancer etiology. TCDD inhibits the 17beta-estradiol (E2)-dependent postconfluent proliferation of MCF-7 human breast cancer cells in vitro. This effect is elicited though an Ah locus-mediated process which is coincident with depletion of E2 by increased metabolism. In vivo studies demonstrated a similar, but transient suppression of E2-dependent human breast cancer MCF-7 tumor growth in immunosuppressed male BDF1 mice. There was a two-week period of TCDD sensitivity, in which TCDD suppresses E2 stimulation of MCF-7 tumor growth, followed by a TCDD-resistant phase, during which the tumor growth rate is similar to that in non TCDD-treated controls. The conversion of this estrogenic effect from TCDD sensitive to TCDD resistant offers a unique opportunity to examine changes in a human estrogen-regulated tissue in vivo, for further elucidation of the mechanism of TCDD mediated antiestrogenicity. It was also determined that E2 depletion results in increased levels of MCF-7 estrogen receptor. This suggests the hypothesis that the sensitivity and subsequent resistance to TCDD suppression of E2-dependent MCF-7 human breast tumor growth in vivo is initially due to TCDD-dependent, Ah locus mediated estrogen depletion in the tumor with subsequent enhancement of tumor sensitivity to E2 resulting from a compensatory increase in estrogen receptor levels. The following specific aims are proposed to test this hypothesis: 1) Determine if there is a requirement for Ah locus function in the host or tumor for sensitivity and resistance to TCDD suppression of E2-dependent MCF-7 tumor growth by use of mice and MCF-7 cells of various Ah locus competency. 2) Determine if the TCDD suppression of E2-dependent MCF-7 tumor growth is associated with E2 depletion by induced metabolism by measurement of E2 and E2 metabolism. 3) Determine if the estrogen receptor status of the TCDD resistant tumor is altered compared to non TCDD-treated tumors by measurement of estrogen receptor function, abundance, and synthesis.

该提议的目的是确定调节机制 雌激素依赖人类的2,3,7,8-四氯二苯甲酸-P-二恶英（TCDD） 小鼠乳腺癌肿瘤的生长。 最终，对此有所了解 机制将提供：1）观察到的耐药性的基础 抗雌激素依赖性乳腺癌的抗雌激素治疗，2）和方法 用于基于机制的内分泌相关风险评估 慢性低水平暴露于二恶英样异生元和3）新颖AH 基因座介导的类固醇激素依赖性的化学治疗策略 癌症以及对雌激素和雌激素受体在 乳腺癌病因。 TCDD抑制17beta-雌二醇（E2）依赖性 MCF-7人类乳腺癌细胞体外的冲积后增殖。 尽管AH基因座介导的过程是 与新陈代谢增加的E2耗竭相吻合。体内研究 表现出对E2依赖性人类的相似但短暂的抑制 免疫抑制的雄性BDF1小鼠的乳腺癌MCF-7肿瘤生长。那里 是TCDD敏感性为期两周，其中TCDD抑制E2 刺激MCF-7肿瘤生长，其次是抗TCDD的阶段 在此期间，肿瘤生长速率与未经TCDD处理的肿瘤生长速率相似 控件。这种雌激素效应从TCDD敏感到 TCDD抗性提供了一个独特的机会来检查人类的变化 体内雌激素调节的组​​织，以进一步阐明 TCDD介导的抗雌激素的机制。还确定 E2耗竭会导致MCF-7雌激素受体的水平升高。 这 提出了以下假设 TCDD抑制E2依赖性MCF-7人体乳腺肿瘤在体内的生长 最初是由于TCDD依赖性的，AH基因座介导的雌激素消耗 在肿瘤中，随后肿瘤对E2的敏感性增强 雌激素受体水平的补偿性增加。这 提出了以下特定目的来检验此假设：1）确定 如果需要在宿主或肿瘤中进行AH基因座功能 对TCDD抑制E2依赖性MCF-7肿瘤的敏感性和抗性 通过使用各种AH基因座能力的小鼠和MCF-7细胞的生长。 2） 确定TCDD抑制E2依赖性MCF-7肿瘤生长是否为 通过测量E2与诱导代谢的E2耗竭相关 和E2代谢。 3）确定是否的雌激素受体状态是否 与非TCDD治疗的肿瘤相比，TCDD耐药性肿瘤被改变 测量雌激素受体功能，丰度和合成。