Viral-based Chemokine Receptor Antagonists

描述(申请人提供)：恶性胶质瘤对肿瘤学家来说是一个困难和具有挑战性的问题。虽然一些趋化因子在肿瘤生物学中的作用正在迅速显现，但关于特定的趋化因子Fractalkine(FKN)及其受体CX3CR1在颅内肿瘤中的作用还没有发表的信息。我们已经鉴定了FKN和CX3CR1在同基因小鼠GL261胶质瘤模型中的表达。由于小胶质细胞是中枢神经系统中表达CX3CR1的主要细胞，这些细胞毒效应细胞很可能是FKN和CX3CR1在颅内肿瘤生物学中发挥作用的基础。缺乏高度选择性的CX3CR1拮抗剂阻碍了对FKN和CX3CR1在这些疾病和其他疾病中的进一步了解。我们解决这一困境的方法集中在基于人类疱疹病毒8vMIP-11编码的CC趋化因子的修饰的病毒编码的趋化因子受体拮抗剂的开发和鉴定上。我们对vMIP-11序列进行了简单的修改，在前两个保守的半胱氨酸残基之间插入了三个氨基酸(ASN-LLE-Thr)。生成的多肽vMIP-11/NIT对CX3CR1具有更高的亲和力和选择性。我们将利用CX3CR1选择性激动剂FKN和非选择性趋化因子受体拮抗剂vMIP-11之间的异同，通过产生和鉴定位点特异的和嵌合的FKN/vMIP-11突变体。这些结果将有助于深入了解FKN在CX3CR1中介导亲和力、选择性和信号有效性的特性。在此基础上，将开发高亲和力的选择性CX3CR1拮抗剂，并在颅内肿瘤生长和宿主排斥的体内模型中测试其特性。其目的是：评估GL261细胞移植到CX3CR1缺陷小鼠体内后的颅内GL261肿瘤生长、坏死指数和免疫反应。确定对CX3CR1的亲和力、选择性和激动剂活性重要的FKN的结构特征。用GL261脑胶质瘤模型在体内测定vMIP-11/FKN嵌合体和突变体的拮抗特性。

DESCRIPTION (provided by applicant): Malignant gliomas represent a difficult and challenging problem for oncologists. While roles for some chemokines in the biology of tumors are fast emerging, no published information is available on the involvement of the specific chemokine, fractalkine (FKN), and its receptor, CX3CR1, in intracranial tumors. We have identified FKN and CX3CR1 expression in the syngeneic murine GL261 glioma model. Since microglia represent the major CX3CR1-expressing cell in the CNS, these cytotoxic effector cells most likely underlie any role for FKN and CX3CR1 in the biology of intracranial tumors. The lack of highly selective CX3CR1 antagonists has hampered further understanding of FKN and CX3CR1 in these and other diseases. Our approach to this dilemma has centered on the development and characterization of modified virally encoded chemokine receptor antagonists based upon the CC chemokine encoded by human herpes virus 8, vMIP-ll. We have made a simple modification to the vMIP-ll sequence, inserting three amino acids (Asn-lle-Thr) between the first two conserved cysteine residues. The resultant peptide, vMIP-ll/NIT, displays enhanced affinity and selectivity for CX3CR1. We will take advantage of the similarities and differences between the CX3CR1 selective agonist, FKN, and the non-selective chemokine receptor antagonist, vMIP-ll, by generating and characterizing site-specific and chimeric FKN/vMIP-ll mutants. The results will shed insights into the properties of FKN that mediate affinity, selectivity, and signaling efficacy at CX3CR1. From this, high affinity selective CX3CR1 antagonists will be developed and their properties tested in in vivo models of intracranial tumor growth and host rejection. The aims are designed to: Evaluate intracranial GL261 tumor growth, necrotic index, and immune response after implantation of GL261 cells into mice deficient in CX3CR1. Determine structural features of FKN important for affinity, selectivity, and agonist activity at CX3CR1. Determine the antagonist properties of vMIP-ll/FKN chimeras and mutants in vivo using the intracranial GL261 glioma model.