Microenvironment-Leukemia Communication Through Lectins

描述（由申请人提供）：由于频繁的治疗失败和快速复发，Ph阳性急性淋巴细胞白血病（ALL）的预后仍然很差。ALL细胞在其微环境中通过基质细胞显著保护其免受药物治疗，但介导保护的分子信号并不明确。所有的细胞，特别是免疫系统的细胞，都被一层致密的碳水化合物修饰的蛋白质和糖脂所覆盖，其功能尚未被探索。然而，ALL细胞和基质之间的通讯的第一步是通过细胞表面结构进行的，其中碳水化合物可能起关键作用。我们的初步数据表明，聚LacNAC结合凝集素半乳糖凝集素-3（Gal 3）是基质细胞产生的微环境的一部分，并将细胞外Gal 3鉴定为ALL细胞和基质之间的通讯分子，保护ALL细胞免受药物治疗。我们假设ALL微环境中的Gal 3是一种分子传播者，通过糖基化细胞表面蛋白的细胞外晶格形成和细胞内B与Bcr/Bcr的相互作用促进Ph阳性ALL细胞存活。这一假设的推论是：去除Galectin-3将1）中断这些细胞类型之间的重要信号，2）将产生对药物治疗更敏感的ALL细胞。以下目标（将同时研究独立实验）将测试这些预测：目标1将通过使用不同互补方法鉴定Ph阳性ALL细胞上Gal 3的细胞表面配体/结合配偶体来确定信号的细胞外组分。目的2将通过检查Bcr/Abl和Gal 3之间的分子相互作用及其对ALL细胞存活的影响来研究信号的细胞内成分。目的3将确定细胞外 和细胞内Gal 3对前B ALL细胞的功能，通过比较gal 3-/-和gal 3 +/+前B ALL细胞中的基因表达，在用外源Gal 3刺激并用尼洛替尼处理的这些细胞中，以及通过将gal 3-/-和gal 3 +/+前B ALL细胞移植到gal 3-/-和+/+受体中并比较归巢，增殖和长春新碱和尼洛替尼治疗的效果。这些实验一起将是第一个充分表征Gal 3在任何类型的癌症中的意义，并且具体地将梳理这种碳水化合物结合蛋白在其细胞外位置作为基质和ALL细胞之间的通信信使以及在其细胞内位置作为抗凋亡分子的功能。

DESCRIPTION (provided by applicant): Prognosis of Ph-positive acute lymphoblastic leukemia (ALL) remains poor because of frequent treatment failure and rapid relapse. ALL cells are significantly protected against drug treatment by stromal cells in their microenvironment, but the molecular signals that mediate the protection are not well-defined. All cells, and in particula cells of the immune system, are covered by a dense layer of carbohydrate-modified proteins and glycolipids, of which the function has not been explored. However, the first step in the communication between ALL cells and the stroma takes place through cell surface structures, of which carbohydrates are likely to play key roles. Our preliminary data show that the polyLacNAC-binding lectin Galectin-3 (Gal3) is part of the microenvironment created by stromal cells and identify extracellular Gal3 as a communication molecule between ALL cells and the stroma that protects ALL cells against drug treatment. We hypothesize that Gal3 in the ALL microenvironment is a molecular communicator that promotes Ph-positive ALL cell survival through extracellular lattice formation of glycosylated cell surface proteins and intracellularly b interactions with Bcr/Abl. Corollaries of this hypothesis are: Removal of Galectin-3 will 1) interrupt an important signal between these cell types and 2) will generate ALL cells that are more sensitive to drug treatment. The following Aims, with independent experiments that will be studied concurrently, will test these predictions: Aim 1 will determine the extracellular component of the signal by identification of the cell surface ligands/binding partners of Gal3 on Ph-positive ALL cells using different complementary approaches. Aim 2 will investigate the intracellular component of the signal by examining molecular interactions between Bcr/Abl and Gal3 and their effects on ALL cell survival. Aim 3 will determine the significance of extracellular and intracellular Gal3 to pre-B ALL cell function both in vitro, by comparing gene expression in gal3-/- and gal3+/+ pre-B ALL cells, in these cells stimulated with exogenous Gal3, and treated with nilotinib and in vivo through transplant of gal3-/- and gal3+/+ pre-B ALL cells into gal3 -/- and +/+ recipients and comparing homing, proliferation and the effect of vincristine and nilotinib treatment. These experiments together will be the first to fully characterize the significance of Gal3 in any type of cancer, and specifically will tease apart the function of this carbohydrate-binding protein in its extracellular location as communication messenger between stroma and ALL cells and in its intracellular location as an anti-apoptotic molecule.