Targeting the Cancer Glycocalyx

项目总结 细胞表面多聚糖介导与其他细胞、细胞外基质或细胞外基质上的受体相互作用 同样的细胞膜。长期以来，糖基化改变一直被认为是癌症的标志。两次频繁 观察到的与癌症相关的表型是唾液酸化和粘蛋白过度表达。这些癌症 糖签名与疾病侵袭性和不良患者预后密切相关，但它们的功能 对癌症进展的贡献一直不清楚。该计划的广泛目标是使 解决肿瘤学中这一重要问题的化学工具，着眼于开发新的模式 干预的结果。这些研究的一个使能工具是我们用来设计的合成糖共聚物 活细胞上的离散糖基化模式，或以多价结合特定的糖结合蛋白 举止。 在之前的授权期内，我们在癌症的作用方面取得了三项重大发现 疾病中的糖信号：(1)高唾液酸血症是一种通过 Siglec家族的唾液酸结合免疫细胞受体。因此，免疫细胞对癌细胞的杀伤可以 通过使用抗体-唾液酸酶结合物有针对性地切割它们的细胞表面唾液酸苷而得到加强。(2) 粘蛋白的过度表达增加了糖萼的厚度和硬度，从而促进了整合素 聚集性和灶性黏附信号。这反过来又提高了细胞在体外的存活率，并促进了肿瘤的转移 小鼠肿瘤模型。最后，(3)多聚糖切换机制调节Galectin-1，a 显著的乳腺癌标记物，位于细胞的糖基化和细胞核之间。Galectin-1的核定位 促进乳腺癌的侵袭，而这是被细胞外隔离Galectin-1的糖共聚物抑制的。 这些发现构成了本次续展申请中提出的目标的基础。目标1是一个 这是我们发现癌症粘蛋白驱动肿瘤形成的必然结果。我们将开发抗体-酶结合物 含有粘蛋白特异的蛋白水解酶(又名“粘蛋白酶”)，以破坏癌细胞的森林。我们将生成工具 使用已知的细菌粘蛋白酶的分子，并识别人粘蛋白酶以整合到 治疗候选人。在目标2中，我们将用天然多肽构建下一代糖共聚物 脊椎骨。这些将被用于癌症糖生物学的基础研究和翻译 在目标3中的应用。最后，在目标3中，我们介绍了一种新的靶向胞外蛋白的策略 利用劫持甘露糖-6-磷酸受体(M6PR)溶酶体转运的糖共聚物进行降解 路径。我们将构建结合致癌细胞表面分子的抗体-M6P糖共聚物结合物 例如生长因子受体和与癌症相关的粘蛋白MUC1，并将它们作为溶酶体的靶点 通过M6PR的参与而降解。这种新的治疗方式是对流行的PROTAC的补充 针对蛋白酶体降解的细胞内蛋白的靶向方法。

PROJECT SUMMARY Cell surface glycans mediate interactions with receptors on other cells, in the extracellular matrix, or on the same cell membrane. Altered glycosylation has long been known as a hallmark of cancer. Two frequently observed cancer-associated phenotypes are hypersialylation and mucin overexpression. These cancer glycosignatures strongly correlate with disease aggressiveness and poor patient outcomes, but their functional contribution to cancer progression has been unclear. The broad objective of this program is to bring chemical tools to bear on this important problem in oncology, with an eye for developing new modes of intervention. An enabling tool for these studies are synthetic glycopolymers that we used to engineer discrete glycosylation patterns on live cells, or to engage specific glycan-binding proteins in a multivalent manner. In the previous granting period we made three major discoveries regarding the roles of cancer glycosignatures in disease: (1) Hypersialylation is a mechanism of immune evasion mediated through the Siglec family of sialic acid-binding immune cell receptors. Accordingly, immune cell killing of cancer cells can be potentiated by targeted cleavage of their cell-surface sialosides using antibody-sialidase conjugates. (2) Mucin overexpression enhances the thickness and stiffness of the glycocalyx, which promotes integrin clustering and focal adhesion signaling. This, in turn, enhances cell survival in vitro and promotes metastasis in mouse tumor models. And finally, (3) a glycan switching mechanism modulates partitioning of galectin-1, a prominent breast cancer marker, between a cell's glycocalyx and nucleus. Nuclear localization of galectin-1 drives breast cancer invasion, and this is inhibited by glycopolymers that sequester galectin-1 extracellularly. These discoveries form the foundation of the aims proposed in this renewal application. Aim 1 is a corollary to our discovery that cancer mucins drive oncogenesis. We will develop antibody-enzyme conjugates comprising mucin-specific proteases (aka “mucinases”) to deforest cancer cells. We will generate tool molecules using known bacterial mucinases, and also identify human mucinases for incorporation into therapeutic candidates. In Aim 2, we will construct next-generation glycopolymers with native polypeptide backbones. These will be employed for fundamental studies of cancer glycobiology and for translational applications in Aim 3. Finally, in Aim 3 we introduce a new strategy for targeting extracellular proteins for degradation using glycopolymers that hijack the mannose-6-phosphate receptor (M6PR) lysosomal trafficking pathway. We will construct antibody-M6P glycopolymer conjugates that bind oncogenic cell-surface molecules such as growth factor receptors and the cancer-associated mucin MUC1 and target them for lysosomal degradation via engagement of M6PR. This new therapeutic modality complements the popular PROTAC approach for targeting intracellular proteins for proteasomal degradation.