Regulation of beta1 integrin glycosylation by ras

描述(由申请人提供)：与癌症相关的大部分死亡是由于原发肿瘤的不受控制的转移造成的。转移是一个知之甚少的过程，几乎没有有效的治疗方法。人们普遍认为，肿瘤细胞与细胞外基质的结合是转移的重要因素，而这种相互作用又受细胞黏附受体如整合素的调节。我们实验室的工作已经确定了一种新的整合素受体β-L亚家族的调节机制。特别是，我们发现β-L整合素的功能是通过获得α2-6唾液酸来调节的，α2-6唾液酸是ST6GalI添加的一种糖结构，唾液酸转移酶长期以来一直与结肠癌的进展/转移有关。我们的工作表明，ST6GalI和相应的整合素α2-6唾液酸化，在具有致癌ras的肿瘤细胞系中上调，在人类结肠癌中也是如此。体外研究进一步表明，整合素唾液酸化对结肠癌细胞的黏附、迁移和侵袭能力有明显的影响。为了更好地了解唾液酸化对整合素结构/功能的影响，以及整合素唾液酸化在肿瘤细胞转移中的潜在作用，我们提出了以下目标：1.特异性糖基化对整合素构象和功能的影响。作为这一目标的一部分，我们将描述整合素的构象和功能，这些整合素的每个单独的N-糖基化位点都被去除了。具体目标2：整合素唾液酸化对Galectin-3调节的细胞行为的影响。我们将研究整合素唾液酸化在调节GAL-3诱导的细胞反应中的作用，包括黏附、迁移、侵袭和凋亡。具体目标3：通过ras导向的差异唾液酸化来调节与转移相关的细胞行为。这些研究旨在确定整合素唾液酸化是否在介导锚定非依赖性生长和侵袭等行为中作为ras的下游效应因子。特异性目标4：整合素唾液酸化在促进裸鼠肿瘤生长和/或转移中的作用。我们将监测整合素唾液酸化水平不同的细胞的肿瘤发生和转移。

DESCRIPTION (provided by applicant): Much of the mortality associated with cancer results from uncontrolled metastasis of the primary tumor. Metastasis is a poorly-understood process, for which there are few effective treatments. It is well-accepted that tumor cell association with the extracellular matrix comprises an important factor in metastasis, and in turn, this interaction is regulated by cell adhesion receptors such as integrins. Work from our laboratory has identified a novel mechanism for regulation of the beta l subfamily of integrin receptors. In particular, we have found that beta l integrin function is modulated by the acquisition of alpha 2-6 sialic acids, a sugar structure added by ST6Gal I, a sialyl transferase which has long been implicated in the progression/metastasis of colon carcinoma. Our work suggests that ST6Gal I, and accordingly, integrin alpha 2-6 sialylation, are upregulated in tumor cell lines that have oncogenic ras, as well as in human colon tumors. In vitro studies further suggest that integrin sialylation has a marked on the adhesion, migration and invasiveness of colon tumor cells. To better understand the contribution of sialylation to integrin structure/function, as well as the potential role of integrin sialylation in tumor cell metastasis, we have proposed the following aims: Specific Aim 1: Influence of site-specific glycosylation on integrin conformation and function. As part of this aim, we will characterize the conformation and function of integrins that have each of the individual N- glycosylation sites ablated. Specific Aim 2: Effects of integrin sialylation on galectin-3-regulated cell behaviors. We will examine the role of integrin sialylation in regulating gal-3 - induced cellular responses including adhesion, migration, invasion and apoptosis. Specific Aim 3: Modulation of metastasis-related cell behaviors by ras-directed differential sialylation. These studies aim to determine whether integrin sialylation serves as a downstream effector of ras in mediating behaviors such as anchorage-independent growth and invasion. Specific Aim 4: Role of integrin sialylation in promoting tumor growth and/or metastasis in nude mice. We will monitor tumorigenesis and metastasis of cells with variant levels of integrin sialylation.