Xenograft Study on Growth-Control of Human Uterine Leiomyomata

描述(申请人提供)：这项研究的最终目标是阐明子宫肌瘤(UL)形成和生长的分子机制，并确定这种疾病的新的治疗和预防治疗的潜在靶点。UL是一种子宫肌层良性肿瘤，影响数百万育龄妇女。手术切除整个子宫(子宫切除术)是主要的治疗选择，UL的管理给医疗系统带来了巨大的负担。因此，寻找一种替代手术的新的治疗方法是人们非常感兴趣的。由于缺乏一个能反映原发肿瘤特征的研究模型体系，UL的生物学本质和发病机制尚不清楚。尽管UL对卵巢类固醇(172-雌二醇和孕酮)的生长依赖性已得到证实，但172-雌二醇和孕酮的相对重要性和作用尚不清楚。尽管越来越多的证据表明孕酮在UL生长中起着重要的作用，但还没有研究模型明确地证明孕酮对UL的生长促进作用。为了阐明卵巢类固醇在UL中的作用，我们建立了一种新的异种移植模型，在该模型中，将人肌瘤组织片段移植到免疫缺陷小鼠的肾被膜下。通过细胞增殖和细胞外基质的积聚，172-雌二醇和孕酮使肌瘤异种移植瘤的体积增大。相反，抗孕激素RU486可阻断172-雌二醇和孕酮诱导的异种移植瘤生长，提示孕酮和孕激素受体(PR)在子宫肌瘤生长中起重要作用。此前，172-雌二醇一直被认为是UL增长的主要刺激因素。令人惊讶的是，172-雌二醇本身既没有增加也没有维持肿瘤的大小。同样，在这个模型中，单独的黄体酮并不影响UL的生长。虽然不能促有丝分裂，但172-雌二醇是PR表达所必需的，也是孕酮作用于UL异种移植物所必需的。我们的研究清楚地证明了孕酮在UL的生长和维持中的关键作用。我们异种移植模型的结果与临床观察一致，但通过强调孕酮而不是172-雌二醇的重要性，从根本上改变了类固醇激素调节人类UL生长的范式。利用新的异种移植模型，我们将阐明172-雌二醇和孕酮控制人UL肿瘤生长的细胞和分子机制。 公共卫生相关性：更好地了解子宫肌瘤是如何生长的，对于开发这种肿瘤的新疗法是至关重要的。虽然子宫肌瘤对卵巢类固醇的依赖性已得到证实，但172-雌二醇和孕酮的相对重要性和作用尚不清楚。最近，我们发展了一种在免疫缺陷小鼠体内生长人子宫肌瘤的方法。人子宫肌瘤异种移植瘤的生长完全依赖于孕酮和172-雌二醇，保持了原始人子宫肌瘤的表型和激素反应。利用这一新的异种移植模型结合病毒基因转导，我们将阐明人类子宫肌瘤生长的细胞和分子机制。

DESCRIPTION (provided by applicant): The ultimate goal of this study is to elucidate the molecular mechanisms of uterine leiomyoma (UL) formation and growth, and identify potential targets for novel therapeutic and preventive treatments of this disease. UL is a benign tumor of the myometrium that affects millions of reproductive-age women. Surgical removal of the entire uterus (hysterectomy) is the primary treatment option, and management of UL puts an enormous burden on the healthcare system. Therefore, finding a new therapeutic treatment replacing surgery is of great interest to the public. Due to the absence of a proper research model system reflecting characteristics of the original tumors, the biological nature and the causes of UL are poorly understood. Although growth dependency of UL on ovarian steroids (172-estradiol and progesterone) is well established, the relative importance and function of 172-estradiol and progesterone are yet to be clarified. In spite of accumulating evidence for the essential role of progesterone in UL growth, no research model has clearly demonstrated a growth-promoting effect of progesterone on UL. To elucidate the function of ovarian steroids in UL, we have established a novel xenograft model in which tissue fragments of human leiomyoma were grafted beneath the renal capsule of immunodeficient mice. The size of the leiomyoma xenografts increased in response to 172- estradiol and progesterone as demonstrated by cell proliferation and accumulation of extra-cellular matrix. In contrast, xenograft growth induced by 172-estradiol and progesterone was blocked by the anti-progestin RU486, indicating the essential role of progesterone and progesterone receptor (PR) in leiomyoma tumor growth. Previously, 172-estradiol has been thought to be the primary stimulus for UL growth. Surprisingly, 172-estradiol by itself neither increased nor maintained tumor size. Likewise, progesterone alone did not affect UL growth in this model. Although not mitogenic, 172-estradiol was required for expression of PR, and was essential for progesterone to act on UL xenografts. Our study clearly demonstrates the pivotal role of progesterone in growth and maintenance of UL. The results of our xenograft model agree with clinical observations, yet radically change the paradigm of steroid hormone-regulated human UL growth by emphasizing the importance of progesterone instead of 172- estradiol. Using the novel xenograft model, we will elucidate the cellular and molecular mechanisms of human UL tumor growth controlled by 172-estradiol and progesterone. PUBLIC HEALTH RELEVANCE: A better understanding of how uterine leiomyomata grow is essential to developing novel therapies for this tumor. While the dependency of uterine leiomyoma on ovarian steroids is well established, the relative importance and function of 172-estradiol versus progesterone are yet to be clarified. Recently, we developed a method of growing human uterine leiomyoma tumors in immunodeficient mice. The xenografts of human uterine leiomyoma faithfully preserved the phenotype and hormone responsiveness of original human tumors in situ, and their growth was totally dependent on progesterone and 172-estradiol. Using this novel xenograft model in combination with viral gene transduction, we will elucidate the cellular and molecular mechanisms of human uterine leiomyoma growth.