Molecular regulation of breast cancer growth

描述（由申请人提供）：我们的实验室长期以来一直对鉴定分子和理解调节肿瘤生长的机制感兴趣。 我们最近发现在乳腺癌妇女的尿液中存在NGAL（神经胶质酶相关脂质运载蛋白），既有单独的NGAL，也有与明胶酶MMP-9复合的NGAL。 NGAL是脂质运载蛋白家族的成员，脂质运载蛋白家族是一组小的分泌蛋白，其可以运输和呈递配体，结合细胞表面受体，并形成大分子复合物。 NGAL的存在与乳腺癌的发生和进展相关，并且其作为人类乳腺癌的生物标志物的潜力已被提出。 我们最近已经证明，NGAL在人乳腺癌细胞中的过表达诱导了EMT（上皮细胞向间充质细胞转化），这是癌症进展的标志。 我们已经发现NGAL诱导上皮标志物如E-钙粘蛋白的下调，沿着间充质标志物波形蛋白和纤连蛋白的上调，以及诱导与E-钙粘蛋白介导的细胞-细胞粘附的丧失一致的发展或分散表型。 我们还确定了已知诱导EMT的转录因子Slug的表达水平在表达NGAL的细胞中增加。 此外，NGAL过度表达显著下调了雌激素受体α（ER α）的表达。 最后，我们已经证明NGAL过表达导致人乳腺癌细胞运动性和侵袭性显著增加。 总之，这些数据表明NGAL可以诱导EMT，并可能调节乳腺癌的侵袭性。 在我们提案的具体目标的背景下，我们将确定NGAL诱导乳腺癌细胞EMT的机制。 这些机制的研究将通过一系列的体内研究来补充，在这些研究中，我们将使用三种互补的体内模型来确定NGAL对人乳腺癌进展的影响。 这些研究还将评估NGAL作为乳腺癌治疗靶点的潜在作用。 在本研究的第三个目的中，我们将确定NGAL单独或与其他癌症生物标志物组合是否可以作为乳腺癌的诊断和/或预后生物标志物。 这些研究是在以下具体目标的背景下提出的：1。确定NGAL诱导乳腺癌细胞中上皮向间充质转化的机制; 2.确定NGAL是否可以促进人乳腺癌的体内进展; 3.确定NGAL的存在，单独或与其他泌尿系癌症生物标志物复合，是否预测乳腺癌动物模型和乳腺癌患者中肿瘤的存在和治疗效果。 通过系统地鉴定可能在侵袭性乳腺癌的发展中发挥作用的新分子，并通过剖析这些分子可能发挥其作用的机制，我们将有机会开发新的和改进的治疗，诊断和预后策略，从而显着提高乳腺癌患者的生存率。

DESCRIPTION (provided by applicant): Our laboratory has had a long standing interest in identifying the molecules and understanding the mechanisms that regulate tumor growth. We have recently identified the presence of NGAL (Neutrophil Gelatinase- Associated Lipocalin) both alone, and complexed to the gelatinase MMP-9, in the urine of women with breast cancer. NGAL is a member of the lipocalin family of proteins, a group of small, secreted proteins that can transport and present ligands, bind to cell-surface receptors, and form macromolecular complexes. The presence of NGAL has been correlated with breast cancer development and progression and its potential as a biomarker of human breast cancer has been suggested. We have recently demonstrated that the overexpression of NGAL in human breast cancer cells induces an EMT (Epithelial to Mesenchymal Transformation), a hallmark of cancer progression. We have found that NGAL induces the down-regulation of epithelial markers such as E-cadherin, along with a concomitant upregulation of the mesenchymal markers vimentin and fibronectin as well as inducing the development or a scattering phenotype consistent with the loss of E-cadherin- mediated cell-cell adhesion. We have also determined that the expression level of the transcription factor Slug, known to induce EMT, is increased in NGAL-expressing cells. In addition, the expression of the estrogen receptor alpha (ERalpha) was significantly downregulated by NGAL over-expression. Finally, we have demonstrated that NGAL overexpression leads to significantly increased human breast cancer cell motility and invasivity. Taken together, these data demonstrate that NGAL can induce EMT and may regulate breast cancer aggressiveness. Within the context of the Specific Aims of our proposal, we will determine the mechanism(s) by which NGAL induces EMT in breast cancer cells. These mechanistic studies will be complemented by a series of in vivo ones in which we will determine the effects of NGAL on human breast cancer progression in vivo using three complementary in vivo models. These studies will also evaluate the potential role of NGAL as a therapeutic target in the treatment of breast cancer. In the third aim of this study, we will determine whether NGAL, alone or in combination with other cancer biomarkers, may be a diagnostic and/or prognostic biomarker for breast cancer. These studies are proposed within the context of the following Specific Aims: 1. To determine the mechanism(s) by which NGAL induces an epithelial to mesenchymal transition in breast cancer cells; 2. To determine whether NGAL can promote human breast cancer progression in vivo; 3. To determine whether the presence of NGAL, alone or multiplexed with other urinary cancer biomarkers, predicts tumor presence and therapeutic efficacy in animal models of breast cancer and in human patients with breast cancer. By systematically identifying novel molecules that may be playing a role in the development of aggressive breast cancer, and by dissecting the mechanisms by which such molecules may be exerting their effects, we will have the opportunity to develop new and improved therapeutic, diagnostic and prognostic strategies that could result in significantly improved breast cancer patient survival.