Integrins in Cancer Invasion

描述（由申请人提供）：该项目的长期目标是确定由微环境线索触发并由整合素驱动的癌症侵袭机制。1和6?4。这些整合素协调细胞与层粘连蛋白-5 （Ln-5）的相互作用，层粘连蛋白-5是上皮基底膜的主要成分。两者表达的改变？4和Ln-5与癌症进展有关。然而，可能的因果机制的定义一直具有挑战性，因为失去和获得？据报道，4/Ln-5的功能促进肿瘤发生。在本提案中，我们计划评估一个综合观点的有效性，以调和这些对比数据。在Aim 1中，我们将验证入侵癌细胞用自分泌的细胞外基质（特别是Ln-5）“铺平道路”的假设。这是对癌细胞迁移的传统观点的挑战，这一假设是基于在重塑或愈合上皮中发生的从静态粘附到迁移的生理转换，并得到了我们的初步实验的支持，在实验中，癌细胞的散射被Ln-5或3 - 2抑制。1，但不是吗？6抗体。为了验证这个假设，我们将决定是否分泌

DESCRIPTION (provided by applicant): The long-term goal of this project is to define mechanisms of cancer invasion triggered by microenvironment cues and driven by integrins ?3?1 and ?6?4. These integrins negotiate interactions of cells with laminin-5 (Ln-5), a major component of epithelial basement membranes. Altered expression of both ?6?4 and Ln-5 is associated with cancer progression. Definition of possible causal mechanisms, though, has been challenging because both loss and acquisition of ?6?4/Ln-5 functions were reported to promote tumorigenesis. In this proposal, we plan to assess the validity of an integrated view reconciling these contrasting data. In Aim 1, we will test the hypothesis that invading cancer cells "pave their way" with autocrine-secreted extracellular matrix, particularly Ln-5. A challenge of conventional views of cancer cell migration, this hypothesis is based on the physiological switch from static adhesion to migration that occurs in remodeling or healing epithelia, and is supported by our preliminary experiments in which cancer cell scattering was inhibited by Ln-5 or ?3?1, but not ?6 antibodies. To test this hypothesis, we will determine whether secreted Ln-5 is essential for cell scattering induced by the motogens LPA and HGF, and whether these motogenic stimuli coordinate upregulation and/or secretion of Ln-5. In Aim 2, we will test the hypothesis that a Ln- 5/?6?4/hemidesmosome axis regulates cell-cell adhesion and tumor progression. Engagement of ?6?4 with Ln-5 antagonizes ?3?1-mediated migration and enhances cell-cell adhesion via ErbB2. This suggests negative regulation of tumor progression by ?6?4, vis-¿-vis cancer poor prognosis associated with ErbB2 gene amplification. Recent in vivo data, from ourselves and others, suggest a tumor suppressive role for secreted Ln-5 heterotrimers. Our hypothesis is based on the premise that these apparently contradictory data reflect the status of cancer cell anchoring to Ln-5 via hemidesmosomes (HD), regulated by ?6?4 in cells switching from migratory to stationary and vice versa. To test this hypothesis, we will investigate the role of the ?6?4/HD axis in cell-cell adhesion and ErbB2 localization in cell lines genetically manipulated to express normal or oncogenic ErbB2, and siRNA knocked-down of HD components. Readout assays include cell-cell adhesion measurements in vitro and xenogeneic tumor models in vivo. In Aim 3, we will test the hypothesis that the ?2DIII domain of Ln-5 promotes tumor progression through EGFR. Expression of monomeric Ln-5 ?2 chain is consistently associated with invasion by many reports and our own preliminary microarray analyses. The ?2DIII proteolytic fragment binds EGFR and our preliminary data indicate it upregulates resistance to apoptosis and tumorigenesis in vivo. We will test the ?2DIII effects on in vitro morphology and survival and in vivo tumor growth and invasion, by siRNA knockdown and rescue with ?2 chain or ?2DIII fragment variants, and will assess its binding to additional ErbB family members. In summary, the 3 aims will test validity and limitations of an integrated view of the opposing effects on tumor progression by secreted Ln-5 heterotrimers (negative) and monomeric ?2 (positive). Understanding these mechanisms of cancer invasion may point to new molecular targets for controlling cancer invasion and metastasis, the major cause of mortality in cancer.