Lung Cancer in Never-smokers: Role of Estrogen and its Metabolites

项目摘要 从不吸烟的人中的肺癌目前是全球十大癌症死亡原因之一， 在过去的30年里，这一比例翻了一番以上。它在女性中的患病率与以下结果一致 流行病学和机制研究表明，雌激素与肺癌的发生有关。雌激素 可以通过雌激素受体(ER)介导的信号刺激细胞生长，或者被代谢为遗传毒性 和诱变的衍生品；这一过程几乎没有受到关注。这个小组是第一个展示 人肺中存在多种雌激素代谢物，包括致癌的4-羟基雌激素(4-羟基雌激素)。 Ohe)。初步数据显示，肺癌组织中4-OHE水平高于邻近正常组织。 非小细胞肺癌(NSCLC)患者。小鼠缺乏细胞色素P1B1，这是导致4-OHE的酶 与野生型对照相比，Kras驱动的肺腺瘤发生得更少。然而，这一机制通过 目前还不清楚哪种4-OHE促进了肺癌的发生。拟议研究的假设是 4-OHE是细胞色素P1B1的产物，可引起肺内ER信号的激活和癌基因的突变； 会增加患肺癌风险的过程。因此，抑制CYP1B1活性可以降低患肺部疾病的风险 不吸烟者中的癌症。在目标1中，将不同水平的正常人支气管上皮细胞永生化 CYP1B1和COMT，限速雌激素结合酶，将被用于评估 17β-雌二醇或4-OHE诱发：导致肺癌的基因突变(EGFR、KRAS、P53、ALK、HER2、 BRAF，PI3KCA)，内质网的基因组和非基因组活性，以及细胞转化(锚定- SCID小鼠的独立生长和肿瘤形成)。雌激素代谢产物(4-OHE)和雌激素受体的能力 在携带CYP1B1/或-/-小鼠的AIM 2中，将评估合作促进肺肿瘤形成的信号 在ER拮抗剂fulvestrant存在和不存在的情况下，多西环素诱导的EGFR突变。变化 在肿瘤负荷量随时间推移将通过CT扫描和肿瘤分期、肺部雌激素的分布情况进行监测 将在尸检时确定EGFR及其下游靶点的代谢物和磷酸化状态。 将首次建立健康供者肺组织的雌激素代谢物图谱，并 与目标3中的非小细胞肺癌患者(正常组织)进行比较，以确定肺4-OHE水平是否在 患者和健康对照组的正常组织与细胞色素P1B1和COMT活性呈正相关。这个 4-OHE水平与CYP1B1和COMT的特定多态变异之间的关系也将是 探索过了。来自拟议研究的数据有望为雌激素的贡献提供新的见解。 代谢对非吸烟者肺肿瘤发生的影响及揭示细胞色素P1B1和/或ER的潜在作用 作为预防非小细胞肺癌的分子靶点。这一充满希望的战略最终可能导致戏剧性的 减少全世界从不吸烟的人患肺癌的风险。

Project Summary Lung cancer among never-smokers is currently one of the top ten causes of cancer mortality worldwide, with rates more than doubling in the past three decades. Its prevalence in women is consistent with results from epidemiologic and mechanistic studies suggesting that estrogen contributes to lung carcinogenesis. Estrogen can either stimulate cell growth via estrogen receptor (ER)-mediated signaling or be metabolized to genotoxic and mutagenic derivatives; a process that has received little attention. This group is the first to demonstrate the presence of multiple estrogen metabolites in the human lung, including carcinogenic 4-hydroxyestrogen (4- OHE). Preliminary data indicate that the level of 4-OHE is higher in lung tumors vs. adjacent normal tissue from patients with non-small cell lung cancer (NSCLC). Mice deficient in Cyp1b1, the enzyme responsible for 4-OHE production, develop fewer Kras-driven lung adenomas than wild-type controls. However, the mechanism by which 4-OHE promotes lung carcinogenesis remains unknown. The hypothesis of the proposed studies is that 4-OHE, a product of CYP1B1, causes activation of ER signaling and mutation of oncogenes within the lung; processes that increase the risk of lung cancer. Thus, inhibition of CYP1B1 activity could reduce the risk of lung cancer among never-smokers. In Aim 1, immortalized normal human bronchial epithelial cells with variable levels of CYP1B1 and COMT, the rate-limiting estrogen conjugation enzyme, will be employed to assess the ability of 17beta-estradiol or 4-OHE to induce: mutations in genes that drive lung cancer (EGFR, KRAS, p53, ALK, HER2, BRAF, PI3KCA), genomic and nongenomic activities of the ERs, and cellular transformation (anchorage- independent growth and tumor formation in SCID mice). The ability of estrogen metabolites (4-OHE) and ER signaling to cooperate to promote lung tumors formation will be evaluated in Aim 2 in Cyp1b1+/+ or -/- mice carrying a doxycycline-inducible EGFR mutation, in the presence and absence of the ER antagonist fulvestrant. Changes in tumor burden over time will be monitored by CT scans and tumor stage, the profile of pulmonary estrogen metabolites and the phosphorylation status of EGFR and its downstream targets will be determined at necropsy. The estrogen metabolite profile of lung tissue from healthy donors will be established for the first time and compared to that of NSCLC patients (normal tissue) in Aim 3 to determine if pulmonary 4-OHE levels differ in normal tissue from patients and healthy controls and correlate with the activity of CYP1B1 and COMT. The relationship between 4-OHE levels and specific polymorphic variants of CYP1B1 and COMT will also be explored. Data from the proposed studies are anticipated to provide novel insight into the contribution of estrogen metabolism to lung tumorigenesis in never-smokers and reveal the potential utility of CYP1B1 and/or the ERs as molecular targets for the prevention of NSCLC. This promising strategy could ultimately lead to a dramatic reduction in the risk of lung cancer faced by never-smokers worldwide.