Regulation of beta1 integrin glycosylation by ras

描述（由申请人提供）：大部分与癌症相关的死亡是由原发肿瘤不受控制的转移引起的。转移是一个鲜为人知的过程，目前还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粘附受体（如整合素）的调节。我们实验室的工作已经确定了整合素受体β 1亚家族调节的新机制。特别是，我们发现β 1整合素的功能是通过α 2-6唾液酸的获取来调节的，这是一种由ST6Gal I添加的糖结构，ST6Gal I是一种唾液转移酶，长期以来一直与结肠癌的进展/转移有关。我们的研究表明，ST6Gal I和相应的整合素α 2-6唾液化在具有致癌ras的肿瘤细胞系以及人类结肠肿瘤中上调。体外研究进一步表明，整合素唾液化对结肠肿瘤细胞的粘附、迁移和侵袭有显著影响。为了更好地了解唾液基化对整合素结构/功能的贡献，以及整合素唾液基化在肿瘤细胞转移中的潜在作用，我们提出了以下目标：特异性目标1：位点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，我们将表征具有每个单个N-糖基化位点消融的整合素的构象和功能。特异性目标2：整合素唾液化对半乳糖凝集素-3调节的细胞行为的影响。我们将研究整合素唾液化在调节gal-3诱导的细胞反应中的作用，包括粘附、迁移、侵袭和凋亡。特异性目的3：通过ras定向的差异唾液化调节转移相关的细胞行为。这些研究的目的是确定整合素唾液化是否作为ras的下游效应因子介导诸如锚定不依赖生长和侵袭等行为。特异性目的4：整合素唾液化在促进裸鼠肿瘤生长和/或转移中的作用。我们将监测具有不同水平整合素唾液化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.