Toxicological evaluation of (processed) red meat ingredients and importance of heme oxygenase 1 in the context of colorectal carcinogenesis

（加工）红肉成分的毒理学评估以及血红素加氧酶 1 在结直肠癌发生过程中的重要性

• 批准号: 530306713
• 负责人: Dr. Tina Kostka
• 金额: --
• 依托单位: UMR 1331 TOXALIM
• 依托单位国家: 德国
• 项目类别: Independent Junior Research Groups
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/530306713?language=en
• 关键词: Toxicological; evaluation; processed; red; meat

Colorectal cancer (CRC) formation is associated with processed and red meat consumption. Upon meat intake, heme is released from protein in the gastrointestinal tract, which results in oxidative stress, DNA strand breaks and mutations in intestinal epithelial cells. If red meat is additionally cured using nitrite, heme will be nitrosylated resulting to the formation of pink-colored NO-heme. It is generally assumed that nitrite increase the toxicity of meat compounds and therefore coloring alternatives like ZnPP are currently tested. Unfortunately, the toxic potential of ZnPP in meat was not yet analyzed. Contrary to the expectation, we were able to show that nitrosylated heme possess an equal or even lower toxicity in in vitro assays than heme. Moreover, as higher the nitrite content in food, as lower was the heme-induced urinary content of lipid peroxidation products. The beneficial effects of nitrite may relate to heme oxygenase 1 (HO-1), an detoxification enzyme responsible for the degradation of heme. The interaction of NO-heme with HO-1 was never tested before, whereby we established the only reliable synthesis method for NO-heme. Even if it was hypothesized that factors like heme, nitrite and HO-1 are involved in processed and red meat-related tumor formation, most aspects are still unknown. Therefore the aim of the project is to analyze such underlying molecular mechanisms as well as possibly occurring synergistic effects due to the complex food matrix including several factors. The following main questions will be answered: 1) Does the addition of nitrite influence the toxic effects of heme from red meat? 2) What is the role of HO-1 in (processed) red meat-associated CRC formation? 3) Is the HO-1 inhibitor ZnPP suitable as non-toxic nitrite alternative in processed red meat? By using an in vitro digestion model, endogenous modifications like nitrosylation reactions will be revealed, while the toxicity of digested meat samples and selected factors like heme compounds, nitrite and ZnPP will be evaluated in a broad range of in vitro toxicity assays. One of the main aspects is the interaction of the different heme compounds and ZnPP with HO-1 using established colon cell lines as well as a cell-free model. The HO-1 activity seems also be involved in tumor progression. Therefore, the toxic effects of meat compounds in presence and absence of HO-1 will be analyzed regarding cell migration, epithelial-mesenchymal transition and anchorage-independent growth.

结直肠癌（CRC）的形成与加工和红肉消费有关。在摄入肉类后，血红素在胃肠道中从蛋白质中释放出来，导致氧化应激，DNA链断裂和肠上皮细胞突变。如果红肉是另外使用亚硝酸盐腌制，血红素将被亚硝基化，导致粉红色的NO-血红素的形成。通常认为亚硝酸盐会增加肉类化合物的毒性，因此目前正在测试ZnPP等着色替代品。遗憾的是，尚未分析ZnPP在肉类中的潜在毒性。与预期相反，我们能够表明亚硝基化血红素在体外试验中具有与血红素相同或甚至更低的毒性。此外，食物中亚硝酸盐含量越高，血红素诱导的脂质过氧化产物的尿含量越低。亚硝酸盐的有益作用可能与血红素加氧酶1（HO-1）有关，HO-1是一种负责血红素降解的解毒酶。NO-血红素与HO-1的相互作用以前从未进行过测试，因此我们建立了NO-血红素的唯一可靠的合成方法。即使假设血红素，亚硝酸盐和HO-1等因素参与了加工和红肉相关的肿瘤形成，但大多数方面仍然是未知的。因此，该项目的目的是分析这种潜在的分子机制，以及由于包括几个因素的复杂食物基质而可能发生的协同效应。将回答以下主要问题：1）添加亚硝酸盐是否会影响红肉中血红素的毒性作用？2)HO-1在（加工）红肉相关CRC形成中的作用是什么？3)HO-1抑制剂ZnPP是否适合作为加工红肉中无毒亚硝酸盐的替代品？通过使用体外消化模型，将揭示内源性修饰，如亚硝基化反应，而消化的肉类样品的毒性和选定的因素，如血红素化合物，亚硝酸盐和ZnPP将在广泛的体外毒性试验中进行评估。其中一个主要方面是不同的血红素化合物和ZnPP与HO-1使用建立的结肠细胞系以及无细胞模型的相互作用。HO-1活性似乎也参与肿瘤的进展。因此，在存在和不存在HO-1的情况下，肉类化合物的毒性作用将在细胞迁移、上皮-间充质转化和锚定非依赖性生长方面进行分析。