Viral-based Chemokine Receptor Antagonists

描述（由申请人提供）：恶性胶质瘤对于肿瘤学家来说是一个困难且具有挑战性的问题。虽然一些趋化因子在肿瘤生物学中的作用正在迅速显现，但没有关于特定趋化因子Fractalkine（FKN）及其受体CX 3CR 1参与颅内肿瘤的已发表信息。我们已经确定FKN和CX 3CR 1在同基因小鼠GL 261胶质瘤模型中的表达。由于小胶质细胞是CNS中主要的CX 3CR 1表达细胞，这些细胞毒性效应细胞很可能是FKN和CX 3CR 1在颅内肿瘤生物学中发挥作用的基础。缺乏高选择性的CX 3CR 1拮抗剂阻碍了进一步了解FKN和CX 3CR 1在这些和其他疾病。我们解决这一难题的方法集中在基于人疱疹病毒8编码的CC趋化因子vMIP-11的修饰的病毒编码的趋化因子受体拮抗剂的开发和表征上。我们已经对vMIP-11序列进行了简单的修饰，在前两个保守的半胱氨酸残基之间插入三个氨基酸（Asn-Ile-Thr）。所得肽vMIP-11/NIT显示出对CX 3CR 1增强的亲和力和选择性。我们将利用CX 3CR 1选择性激动剂FKN和非选择性趋化因子受体拮抗剂vMIP-11之间的相似性和差异，通过产生和表征位点特异性和嵌合FKN/vMIP-11突变体。结果将揭示FKN介导CX 3CR 1亲和力，选择性和信号传导功效的特性。由此，将开发高亲和力选择性CX 3CR 1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：评价将GL 261细胞植入CX 3CR 1缺陷小鼠后的颅内GL 261肿瘤生长、坏死指数和免疫应答。确定FKN对CX 3CR 1的亲和力、选择性和激动剂活性的重要结构特征。使用颅内GL 261神经胶质瘤模型确定vMIP-11/FKN嵌合体和突变体的体内拮抗剂性质。

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.