Xenograft Study on Growth-Control of Human Uterine Leiomyomata

描述（由申请人提供）：本研究的最终目的是阐明子宫平滑肌瘤（UL）形成和生长的分子机制，并确定该疾病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的管理给医疗保健系统带来了巨大的负担。因此，寻找一种新的治疗方法来取代手术是公众的极大兴趣。由于缺乏反映原发肿瘤特征的适当研究模型系统，UL的生物学性质和原因知之甚少。虽然UL对卵巢类固醇激素（172-雌二醇和孕酮）的生长依赖性已得到很好的证实，但172-雌二醇和孕酮的相对重要性和功能尚待阐明。尽管越来越多的证据表明孕酮在UL生长中的重要作用，但没有研究模型清楚地表明孕酮对UL的生长促进作用。为了阐明卵巢类固醇激素在UL中的作用，我们建立了一种新的异种移植模型，将人平滑肌瘤组织碎片移植到免疫缺陷小鼠的肾包膜下。平滑肌瘤异种移植物的大小增加，172-雌二醇和孕酮的反应所证明的细胞增殖和细胞外基质的积累。相反，172-雌二醇和孕酮诱导的异种移植物生长被抗孕酮RU 486阻断，表明孕酮和孕酮受体（PR）在平滑肌瘤肿瘤生长中的重要作用。以前，172-雌二醇被认为是UL生长的主要刺激因素。令人惊讶的是，172-雌二醇本身既不增加也不维持肿瘤大小。同样地，在该模型中，单独的孕酮不影响UL生长。虽然不促有丝分裂，172-雌二醇是PR表达所必需的，并且是孕酮作用于UL异种移植物所必需的。我们的研究清楚地表明了孕激素在UL的生长和维持中的关键作用。我们的异种移植模型的结果与临床观察一致，但从根本上改变了类固醇激素调节的人类UL增长的范例，强调孕酮的重要性，而不是172-雌二醇。使用新的异种移植模型，我们将阐明172-雌二醇和孕酮控制的人UL肿瘤生长的细胞和分子机制。 公共卫生相关性：更好地了解子宫平滑肌瘤如何生长对于开发这种肿瘤的新疗法至关重要。虽然子宫平滑肌瘤对卵巢类固醇激素的依赖性已得到证实，但172-雌二醇与孕酮的相对重要性和功能尚待阐明。最近，我们开发了一种在免疫缺陷小鼠中生长人子宫平滑肌瘤肿瘤的方法。人子宫平滑肌瘤异种移植物忠实地保留了原位原始人肿瘤的表型和激素反应性，并且它们的生长完全依赖于孕酮和172-雌二醇。利用这种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.