Molekulare Mechanismen der Toxizität und Kanzerogenität des Mykotoxins Ochratoxin A

霉菌毒素赭曲霉毒素A毒性和致癌性的分子机制

• 批准号: 15478177
• 负责人: Professorin Dr. Angela Mally
• 金额: --
• 依托单位: Lehrstuhl für Toxikologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2005
• 资助国家: 德国
• 起止时间: 2004-12-31 至 2008-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/15478177?language=en
• 关键词: Molekulare; Mechanismen; der; Toxizit; und

The mycotoxin and food contaminant ochratoxin A (OTA) is one of the most potent renal carcinogens studied to date. The molecular events leading to renal tumor formation by OTA are still poorly understood, but increasing evidence suggests that OTA is not a mutagenic, DNA-reactive carcinogen. Recent work in our laboratory provide important new evidence in support of a mechanism of OTA carciogenicity involving disruption of mitosis through interference with key regulators of chromosome separation and progression through mitosis, resulting in blocked or asymmetric cell division, accompanied by an increased risk of aneuploidy acquisition and subsequent tumor formation. In OTA treated cell cultures, condensed and abnormally separated metaphase chromosomes were frequently observed, suggesting that premature separation of sister chromatids in the presence of OTA may provide the initial trigger for aberrant cell division and cell death at mitosis. It is now known that cohesion between sister chromatids is controlled by several mitotic kinases, e.g. Cdk1, Aurora, or Polo-like-kinases (Plk), and aberrant expression of these key regulators of mitosis has been associated with malignant transformation. Gene expression analyses in kidneys of OTA treated rats support a role of Cdk1, Aurora B and Plk1 in OTA mediated Molecular Mechanism of Ochratoxin A Toxicity and Carcinogenicity 3 carcinogenicity, and preliminary results in vitro also suggest that OTA may indeed alter the activity of mitotic kinases known to be involved in chromosome condensation and segregation. However, for a comprehensive understanding of the mechanism of OTA toxicity, the temporal sequence of events and primary cellular targets of OTA remain to be elucidated. Within this project, we aim to determine the time- and concentration-dependent effects of OTA on the acitivty of Cdk1/Cyclin B1, Plk1 and aurora B through determination of the phosphorylation status of their cellular targets (e.g. histon H1, histon H3 and cohesin) both in renal epithelial cells in vitro and in kidneys of OTA treated rats in vivo using a combination of modern cell & molecular biology techniques, such as immunoblotting, immunofluorescence/confocal microscopy and FACS analysis. It is expected that results from this study will not only help to elucidate the mechanism of OTA carcinogenicity as a basis for improved risk assessment, but will also further our understanding of the carcinogenic action of non-mutagenic, non-DNA reactive chemicals.

霉菌毒素和食品污染物赭曲霉毒素 A (OTA) 是迄今为止研究的最有效的肾脏致癌物之一。 OTA 导致肾肿瘤形成的分子事件仍知之甚少，但越来越多的证据表明 OTA 不是一种致突变、DNA 反应性致癌物。我们实验室最近的工作提供了重要的新证据，支持 OTA 致癌性机制，该机制涉及通过干扰染色体分离和有丝分裂进展的关键调节因子来破坏有丝分裂，导致细胞分裂受阻或不对称，并伴有非整倍体获得风险增加以及随后的肿瘤形成。在 OTA 处理的细胞培养物中，经常观察到浓缩和异常分离的中期染色体，这表明 OTA 存在下姐妹染色单体的过早分离可能是有丝分裂时异常细胞分裂和细胞死亡的最初触发因素。现在已知姐妹染色单体之间的凝聚力是由几种有丝分裂激酶控制的，例如Cdk1、Aurora 或 Polo 样激酶 (Plk) 以及这些有丝分裂关键调节因子的异常表达与恶性转化相关。 OTA 治疗大鼠肾脏的基因表达分析支持 Cdk1、Aurora B 和 Plk1 在 OTA 介导的赭曲霉毒素 A 毒性和致癌性 3 致癌性分子机制中的作用，体外初步结果也表明 OTA 确实可能改变有丝分裂激酶的活性已知参与染色体浓缩和分离。然而，为了全面了解 OTA 毒性机制，OTA 事件的时间顺序和主要细胞靶标仍有待阐明。在这个项目中，我们的目标是通过确定细胞靶标（例如组蛋白 H1、组蛋白 H3 和粘连蛋白）的磷酸化状态来确定 OTA 对 Cdk1/Cyclin B1、Plk1 和 aurora B 活性的时间和浓度依赖性影响。 ）结合现代细胞和分子生物学技术（例如免疫印迹），在体外肾上皮细胞和体内 OTA 治疗大鼠的肾脏中进行研究，免疫荧光/共焦显微镜和 FACS 分析。预计这项研究的结果不仅有助于阐明 OTA 致癌机制，作为改进风险评估的基础，而且还将进一步加深我们对非诱变、非 DNA 反应性化学物质致癌作用的理解。