Functional analysis of a novelintegrin-dependent metastasis pathway in melanoma

人类恶性黑色素瘤是一种侵袭性癌症，有很高的转移扩散倾向。 尽管最近黑色素瘤治疗取得了进展，但大多数转移性疾病的患者并没有经历 从目前的治疗选择中获得持久的好处。事实上，现有的靶向和癌症免疫疗法 治疗方法不能直接抑制肿瘤转移，而肿瘤转移是大多数癌症相关死亡的原因。因此， 针对黑色素瘤细胞固有的促转移途径的新药物的开发 可以极大地改善治疗结果并减少非靶标毒性。观察到的贩运过程 在转移癌的扩散方面，至少在一定程度上类似于白细胞归巢范式，即一种连续的 涉及微血管内皮细胞系留和滚动的多步骤粘附级联，随后 整合素介导的阻止和跨内皮细胞向次级组织的迁移。白细胞归巢依赖于 关于内皮细胞上的特殊整合素异源二聚体及其同源配体。然而，到目前为止， 这些不同的白细胞归巢整合素亚群在黑色素瘤中的表达尚未被描述。我们的 初步研究首次证明了整合素异源二聚体的异常表达。 被认为仅限于白细胞，由具有高转移能力的黑色素瘤细胞亚群。住院病人 原发黑色素瘤、癌细胞固有整合素阳性与前哨淋巴结转移相关。 黑色素瘤特异性抑制这些整合素异源二聚体抑制内皮细胞黏附和显著 阻断临床前人类黑色素瘤小鼠模型的生长和转移形成。这些范例- 不断变化的发现表明，白细胞归巢整合素是肿瘤细胞扩散的新介质。 虽然包括人源化抗体在内的造血整合素靶向方法已经 他们是为治疗炎症性和自身免疫性白细胞运输障碍患者而开发的 从未在癌症的背景下进行过检查。在这项提案中，我们重新研究了治疗 这些有效且容易获得的整合素抑制剂在阻止肿瘤转移中的作用 临床前黑色素瘤模型。我们的具体目标是：1)剖析黑色素瘤细胞的内在机制 归巢整合素诱导和功能激活，并定义整合素糖基化状态和异源二聚体 不同进展阶段患者肿瘤生物标本的成分，以及2)检查治疗方法 CRISPR/Cas-9介导的白细胞整合素基因敲除或临床级整合素抑制剂的疗效 在临床前黑色素瘤模型中用于治疗免疫运输障碍的配方。我们有 组建了一个黑色素瘤转移、白细胞归巢、基因编辑、皮肤病理学、 和糖生物学领域，以实现这项提议的翻译相关目标。结果来自我们的 研究可以确定黑色素瘤细胞表达的白细胞整合素及其糖结构决定因素如下 选择性抑制转移扩散的新治疗靶点。

Human malignant melanoma is an aggressive cancer with high propensity for metastatic dissemination. Despite recent advances in melanoma therapy, most patients with metastatic disease do not experience durable benefit from current treatment options. Indeed, existing targeted and cancer immunotherapeutic modalities do not directly inhibit tumor metastasis, which accounts for most cancer-related deaths. Accordingly, the development of new agents that specifically target pro-metastatic pathways intrinsic to melanoma cells could greatly improve treatment outcomes and reduce off-target toxicities. The trafficking processes observed in disseminating metastatic cancers resemble, at least in part, the leukocyte homing paradigm, a sequential multistep adhesive cascade involving cell tethering and rolling on microvascular endothelium, followed by integrin-mediated arrest and transendothelial migration into secondary tissues. Leukocyte homing is dependent on specialized integrin heterodimers and their cognate ligands on endothelial cells. To date, however, expression of these distinct leukocytic homing integrin subsets has not been described in melanoma. Our preliminary studies demonstrate, for the first time, aberrant expression of integrin heterodimers, conventionally thought to be restricted to leukocytes, by melanoma cell subsets with high metastatic capacity. In patient primary melanomas, cancer cell-intrinsic integrin positivity correlated with sentinel lymph node metastases. Melanoma-specific inhibition of these integrin heterodimers suppressed endothelial adhesion and significantly blocked growth and metastasis formation in preclinical mouse models of human melanoma. These paradigm- shifting findings identify leukocytic homing integrins as novel mediators of tumor cell dissemination. While hematopoietic integrin targeting approaches, including humanized antibodies, have already been developed for the treatment of patients with inflammatory and autoimmune leukocyte trafficking disorders, they have never been examined in the context of cancer. In this proposal, we newly investigate the therapeutic utility of these validated and readily available integrin inhibitors in blocking metastatic dissemination in preclinical melanoma models. Our specific aims are to 1) dissect mechanisms of melanoma cell-intrinsic homing integrin induction and functional activation, and define integrin glycosylation states and heterodimer composition in patient tumor biospecimens at various stages of progression, and 2) examine the therapeutic efficacy of CRISPR/Cas-9-mediated leukocytic integrin knockout or clinical-grade integrin inhibitors originally formulated for the treatment of immune trafficking disorders, in preclinical melanoma models. We have assembled a team of experts in the melanoma metastasis, leukocyte homing, gene editing, dermatopathology, and glycobiology fields, to bring to fruition the translationally relevant aims of this proposal. Results from our studies could establish melanoma cell-expressed leukocytic integrins and their glycostructural determinants as novel therapeutic targets for selective inhibition of metastatic dissemination.