Glycosynapses in cancer cell adhesion and signaling

描述(由申请人提供)：我们的研究由R01 CA80054资助，揭示了控制碳水化合物依赖或碳水化合物调节的细胞黏附与信号转导相结合的膜微域的存在，被称为“糖突触”(Glysyn)。Glysyn的结构和功能与细胞生长控制和某些肿瘤细胞的侵袭/转移特性密切相关：(1)Glysyn 1由GM3、生长因子受体、CD9或CD81、Src家族激酶及其生理抑制因子CSK组成。它在转化细胞中的功能与失去生长控制(接触抑制)有关，(Ii)Glysyn 3由N-糖基化整合素和与神经节苷脂(GM3)(尤其是GM3)络合的TSP组成，并抑制整合素依赖的运动，最初在IDID细胞模型中发现，后来在各种人类癌细胞系中发现。通过增加Glysyn-3，这些细胞的恶性程度或致癌表型的“逆转”可能发生。这一建议有两个主要的特定目的：1.阐明人类正常上皮细胞与癌细胞系的生长控制机制，类似于先前研究的人肺成纤维细胞WI38和致癌转化的VA13细胞。研究的重点是：(A)Glysyn 1的组成与生长控制有关，特别是CSK依赖的对Src激酶的抑制；(B)Glysyn 1中的TSP CD9-CD81在促进VA13细胞中WI38的接触抑制和其丢失方面的作用；(C)GM3与FGFR的相互作用在同一Glysyn内(顺式相互作用)或界面Glysyn之间的作用(反式相互作用)。2.阐明Glysyn-3控制肿瘤细胞侵袭的机制。研究的重点是：(A)TSP、GG、N-糖基化整合素的组成成分的特征；(B)它们之间的相互作用；(C)这种相互作用与细胞运动的相关性；(D)Glysyn 3组分对整合素信号的影响；(E)通过修饰Glysyn 3组分逆转恶性表型到非恶性表型。

DESCRIPTION (provided by applicant): Our studies supported by grant R01 CA80054 have revealed the presence of membrane microdomains that control carbohydrate-dependent or carbohydrate-modulated cell adhesion coupled with signal transduction, termed "glycosynapses" (Glysyn). Structure and function of Glysyn are correlated closely with cell growth control and invasive/ metastatic properties of certain tumor cells: (i) Glysyn 1 consists of GM3, growth factor receptor, CD9 or CD81, Src family kinase, and its physiological inhibitor Csk. Its function in transformed cells is associated with loss of growth control (contact inhibition), (ii) Glysyn 3 consists of N-glycosylated integrin and tetraspanin (TSP) complexed with ganglioside (Gg) (particularly GM3), and inhibits integrin-dependent motility, as found originally in IdID cell model and later in various human cancer cell lines. Loss of malignancy, or "reversion" of oncogenic phenotype, may occur in these cells through increased Glysyn 3. This proposal has two major Specific Aims: 1. Elucidate the growth control mechanism in human normal epithelial cells vs. cancer cell lines, in analogy to previously-studied human lung fibroblast WI38 and oncogenically transformed VA13 cells. Studies are focused on: (a) Glysyn 1 composition as related to growth control, particularly Csk-dependent inhibition of Src kinase; (b) role of TSP CD9-CD81 in Glysyn 1 in facilitating contact inhibition of WI38 vs. its loss in VA13 cells; (c) role of GM3-to-FGFR interaction within the same Glysyn (cis interaction) or between interfacing Glysyn (trans interaction). 2. Elucidate the mechanisms by which Glysyn 3 controls tumor cell invasiveness. Studies are focused on: (a) characterization of components: TSPs, Gg, N-glycosylated integrins; (b) interactions among them; (c) correlation of such interaction with cell motility; (d) effects of Glysyn 3 components on integrin signaling; (e) reversion from malignant to non-malignant phenotype by modification of Glysyn 3 components.