Environmental Pollutants and AHR pathway in Uterine Leiomyoma

子宫肌瘤(LM，肌瘤)扰乱子宫功能，导致反复妊娠丢失，子宫过度 15%-30%的育龄妇女有出血和贫血。没有长期的治疗方法可用。 了解肌萎缩侧索硬化症是如何发展起来的，对于确定新的非手术治疗是至关重要的。MED12突变 (MUT-MED12)发生在所有LM中的70%，并以类固醇激素依赖的方式推动LM的生长。前置和 围绝经期妇女广泛接触内分泌干扰物(EDCs)，例如邻苯二甲酸酯， 在许多消费品中发现，并与许多生殖疾病有关。怎么一个哑巴- MED12影响LM的生长，这一过程是否因暴露于EDCs而增强尚不清楚。我们 最近发现，色氨酸(Trp)2，3-双加氧酶(TDO2)基因表达显著上调。 但不是野生型(Wt)-MED12 Lm。TDO2催化Trp分解为犬尿氨酸(Kyn)的关键步骤 芳香烃受体(AHR)的内源性配体，其激活刺激PRO-2的表达 促进细胞在各种组织中存活和增殖的生长基因。肌萎缩侧索硬化症患者的KYN水平明显较高 VS子宫肌层，尤其是在MUT-MED12 LM。色氨酸和KYN处理的LM细胞激活AHR并增加 细胞存活：siRNA阻断Trp-Kyn-AHR通路或取消TDO2或AHR的抑制剂 这些效应，突变的LM细胞对这些处理表现出更高的敏感性。流行病学研究表明 Lm与邻苯二甲酸二(2-乙基己基)酯(DEHP)暴露呈正相关。在体外，Mono(2- 邻苯二甲酸乙酯(5-羟基己基)邻苯二甲酸乙酯(MEHHP)刺激色氨酸的表达 转运蛋白(LAT1和LAT2)，增加Trp摄取和Kyn的产生，激活AHR，促进LM细胞 生死存亡。此外，孕激素受体对AHR及其核转位蛋白的表达起着至关重要的作用。 阿恩特。因此，Trp-Kyn-AHR途径似乎是MUT-MED12、类固醇激素作用和 EDC效应融合，实现LM增长。我们的总体假设是色氨酸摄取和新陈代谢增加， 由于MUT-MED12或高暴露在环境中，KYN的产生和AHR途径的激活 污染物DEHP，促进细胞存活和增殖，并导致LM生长。使用异种移植小鼠模型 和全基因组研究，我们将在以下目标检验我们的假设：(1)定义 Trp-Kyn-AHR通路在乳头状瘤发生中的作用假说：MUT-2中TDO2酶的表达升高 MED12 LM导致Kyn过度生产，激活AHR，促进Smooth增殖和存活 肌肉细胞和肿瘤生长。(2)确定DEHP是否通过激活Trp-2来刺激LM生长。 Kyn-AHR途径。假设：暴露于DEHP及其代谢物MEHHP可上调色氨酸的表达 转运体增加其摄取，导致Kyn产量增加和AHR激活，从而导致LM细胞 生存和肿瘤生长。这项研究将首次将氨基酸代谢异常与LM生长联系起来， 为翻译研究和新疗法的开发开辟了一条新的途径。

Uterine leiomyomas (LM, fibroids) disrupt uterine function and cause recurrent pregnancy loss, excessive uterine bleeding, and anemia in 15-30% of reproductive-age women. No long-term medical treatment is available. Understanding how a LM develops is essential for identifying new non-surgical treatments. MED12 mutations (mut-MED12) occur in 70% of all LM and drive LM growth in a steroid hormone-dependent manner. Pre- and peri-menopausal women are widely exposed to endocrine disrupting chemicals (EDCs), e.g., phthalates, which are found in many consumer products and associated with a number of reproductive diseases. How a mut- MED12 influences LM growth and whether this process is enhanced by exposure to EDCs remain unknown. We recently found that tryptophan (Trp) 2,3-dioxygenase (TDO2) gene expression is strikingly upregulated in mut- but not wild-type (wt)-MED12 LM. TDO2 catalyzes a critical step in Trp breakdown to kynurenine (Kyn), an endogenous ligand for the aryl hydrocarbon receptor (AHR) whose activation stimulates the expression of pro- growth genes to promote cell survival and proliferation in various tissues. Kyn levels are markedly higher in LM vs myometrium, particularly in mut-MED12 LM. Trp and Kyn treatments of LM cells activated AHR and increased cell survival; blocking the Trp-Kyn-AHR pathway by siRNA knockdown or inhibitors of TDO2 or AHR abolished these effects, with mutant LM cells showing higher sensitivity to the treatments. Epidemiological studies have shown positive associations between LM and exposure to di(2-ethylhexyl) phthalate (DEHP). In vitro, mono(2- ethyl-5-hydroxyhexyl) phthalate (MEHHP), a major metabolite of DEHP, stimulated the expression of Trp transporters (LAT1 and LAT2), increased Trp uptake and Kyn production, activated AHR, and promoted LM cell survival. In addition, progesterone receptor is crucial for the expression of AHR and its nuclear translocator ARNT. Thus, the Trp-Kyn-AHR pathway appears to be a hub at which mut-MED12, steroid hormone action, and EDC effects converge enabling LM growth. Our overall hypothesis is that increased Trp uptake and metabolism, Kyn production, and AHR pathway activation, as a result of mut-MED12 or high exposure to the environmental pollutant DEHP, promote cell survival and proliferation and lead to LM growth. Using a xenograft mouse model and genome-wide studies, we will test our hypothesis in the following Aims: (1) Define the functional role of the Trp-Kyn-AHR pathway in LM tumorigenesis. Hypothesis: elevated expression of the TDO2 enzyme in mut- MED12 LM causes Kyn overproduction that activates AHR and promotes proliferation and survival of smooth muscle cells and tumor growth. (2) Determine whether DEHP stimulates LM growth via activation of the Trp- Kyn-AHR pathway. Hypothesis: exposure to DEHP and its metabolite MEHHP upregulates the expression of Trp transporters to increase its uptake, resulting in increased Kyn production and AHR activation leading to LM cell survival and tumor growth. The study will link, for the first time, abnormal amino acid metabolism and LM growth, opening a new avenue for translational research and the development of novel therapeutics for LM.