Phosphoinsitide signaling in Breast Epithelial Morphogenesis and Metastasis

描述(申请人提供)：根据美国癌症协会的报告，自1990年以来，美国的乳腺癌死亡率每年下降~2%。这一令人印象深刻的连胜在很大程度上是由于早期发现和治疗方面的进步。大约90%的癌症死亡是由转移形成的。了解转移的潜在机制将为发现生物标记物提供线索，这对于明确诊断和个体化治疗非常重要。极化上皮形态的建立和维持对于正常乳腺结构的发育和肿瘤转移的抑制是至关重要的。细胞之间的相互作用通常抑制细胞迁移和肿瘤转移，而细胞-基质粘附处的整合素信号是迁移和转移所必需的。我们的长期目标是了解控制上皮细胞形态发生的分子和机制，包括两个方面：上皮极性和细胞运动性。为此，我们一直专注于一种关键的脂蛋白激酶，称为PIPKI3，它通过调节E-钙粘蛋白介导的细胞间黏附组装或促进细胞-基质黏附转换来调节上皮细胞的极性和细胞的迁移。PIPKI3产生磷脂酰肌醇-4，5-二磷酸(PI4，5P2)，通过调节肌动蛋白重组、细胞黏附组装和囊泡运输来调节细胞形态发生的关键脂质第二信使。然而，它是如何受到监管的尚不清楚。我们观察到，在创伤愈合过程中，PIPKI3从细胞-细胞黏附向细胞-基质黏附重新分布，提示该激酶在同一形态转化过程中可能具有重要作用。在这项研究中，我们将通过调节PI4，5P2的区域水平来研究PIPKI3参与上皮形态发生和细胞迁移/转移的分子机制。使用一系列互补的方法，我们将确定PIPKI3如何调控E-钙粘附素到基底膜的运输，细胞-细胞黏附的成熟，以及当重新分布到细胞-基质黏附时，如何促进细胞迁移。对PIPKI3不同细胞功能的研究将有助于揭示参与乳腺上皮形态发生的复杂信号网络，并有助于理解乳腺上皮向移行性形态转化和肿瘤发生的机制。最终，我们希望将这些知识转化为新的策略，在细胞有机会发展为侵袭性转移肿瘤之前，检测PI4，5P2信号没有得到适当调控的细胞。此外，这些研究将为新的生物标记物和抗癌药物靶点提供有力的候选。该项目的成果显然将使基础研究和临床病人护理都受益。 公共卫生相关性：上皮极化的丧失和迁移表型的获得对于癌症转移的发展至关重要，而转移是乳腺癌真正致命的方面。这一建议旨在了解驱动这一过程的启动和进展的分子机制。通过探索磷脂信号在肿瘤转移过程中的作用，我们应该获得有价值的信息，以了解转移的信号网络，并为旨在阻止或逆转转移的癌症治疗定义更有效的靶点。

DESCRIPTION (provided by applicant): Since 1990, the breast cancer death rate in the United States has decreased by ~2% per year, as reported by the American Cancer Society. This impressive winning streak was made possible in large part by advances in early detection and treatment. Approximately 90% of all cancer deaths arise from metastasis formation. Understanding the underlying mechanisms of metastasis will provide clues for biomarker discovery, which could be extremely important for definitive diagnosis and personalized treatment. Establishment and maintenance of the polarized epithelial morphology is essential for the development of normal breast structure and suppression of tumor metastasis. Cell-cell interactions generally inhibit cell migration and cancer metastasis, whereas integrin signals at cell-matrix adhesions are required for migration and metastasis. Our long-term goal is to understand the molecules and mechanisms that control the morphogenesis of epithelial cells including two aspects: epithelial polarity and cell motility. Towards this aim, we have been focusing on a critical lipid kinase, named PIPKI3, that regulates both epithelial polarity and cell migration via modulating E- cadherin mediated intercellular adhesion assembly or facilitating cell-matrix adhesion turnover. PIPKI3 generates phosphatidylinositol-4,5-bisphosphate (PI4,5P2), a critical lipid second messenger for cell morphogenesis by regulating actin reorganization, cell adhesion assembly, and vesicular trafficking. However, how it is regulated is not known. We observed that PIPKI3 was re-distributed from cell-cell adhesion to cell- matrix adhesion during the epithelial-to-migratory transition when wound healing occurs, indicating this kinase may have an important role in the same morphogenic transformation during the development of metastasis. In this proposal, we will investigate the molecular mechanisms by which PIPKI3 participates in epithelial morphogenesis and cell migration/metastasis via regulating the regional levels of PI4,5P2. Using a series of complementary approaches, we will define how PIPKI3 modulates the transport of E-cadherin to the basolateral membrane, maturation of cell-cell adhesion, and facilitates cell migration when re-distributed to the cell-matrix adhesions. Investigation of the diverse cellular roles of PIPKI3 will shed light on the complicated signaling networks that contribute to breast epithelial morphogenesis and will aid in the understanding of the mechanisms of the epithelial-to-migratory morphogenic transformation and tumorigenesis. Ultimately, we hope to translate this knowledge into new strategies for detecting cells where PI4,5P2 signaling is not appropriately regulated, before they have the opportunity to develop into aggressive metastatic tumors. Furthermore, these studies will provide potent candidates for new biomarkers and cancer drug targets. The outcomes of this project will clearly benefit both basic research and clinical patient care. PUBLIC HEALTH RELEVANCE: The loss of epithelial polarization and acquisition of migratory phenotype is essential for the development of cancer metastasis, the real lethal aspect of breast cancers. This proposal is designed to understand the molecular mechanism driving the initiation and the progression of this process. By exploring the role of phospholipid signaling in the progression of cancer metastasis, we should get valuable information toward understanding the signaling networks underlying metastasis, as well as define more potent targets for cancer therapies that aim to stop or reverse metastasis.