Small molecule targeting of MIF as a novel melanoma therapeutic

描述(申请人提供)：肿瘤相关巨噬细胞(TAMs)和髓系来源的抑制细胞(MDSCs)是实体瘤免疫抑制、新生血管形成和转移扩散的关键决定因素。尽管为确定/多药耐药细胞的调控效应而进行了密集的努力，但很少发现能够协调这一过程并有效靶向的药物。巨噬细胞移动抑制因子(MIF)是被描述的最古老的细胞因子活性之一，是单核/巨噬细胞免疫反应的中枢重要介质。来自携带MIF缺陷小鼠的黑色素瘤的TAM和MDSCs表现出独特的极化逆转，导致从免疫抑制的血管生成表型(MIF//MDSC)转变为免疫刺激的非血管生成表型(MIF-/-/MDSC)，从而显著降低了原发和转移性黑色素瘤疾病的进展。有趣的是，我们之前发现的MIF小分子拮抗剂4-碘-6-苯基嘧啶(4-IPP)在体外和体内都能完全概括MIF缺乏，并有助于减弱和MDSC的替代激活、免疫抑制、新血管生成和黑色素瘤疾病进展[1601]。我们最近发现，4-IPP通过以蛋白酶体依赖的方式显著降低细胞内MIF蛋白水平而在功能上抑制MIF。然而，相对较高的4-IPP IC50值以及缺乏关于其作用机制、生物利用度和慢性毒性的信息，这意味着在将小分子MIF靶向用于临床之前，需要进行更多的研究来充分识别、优化和表征MIF降解诱导化合物。为了实现本申请所述的目标，以下目标是 提出：目的1：阐明4-ipp和MIF依赖的/骨髓间充质干细胞极化的作用机制；目的2：表征/骨髓间充质干细胞的调控、体内生物利用度、毒性和抗肿瘤活性； 铅MIF小分子拮抗剂作为单独和联合治疗已建立的黑色素瘤的治疗潜力。

DESCRIPTION (provided by applicant): Tumor-associated macrophages (TAMs) and myeloid-derived suppressor cells (MDSCs) are critically important determinants of solid tumor immunosuppression, neovascularization and metastatic dissemination. Despite intensive efforts aimed at identifying TAM/MDSC regulatory effectors, very few have been identified that can orchestrate this process and be effectively targeted. Macrophage migration inhibitory factor (MIF) is one the oldest cytokine activities described and is a centrally important mediator of monocyte/macrophage immune responses. TAMs and MDSCs from melanoma bearing MIF-deficient mice exhibit a unique reversion in their "polarization" state resulting in a switch from n immunosuppressive, angiogenic phenotype (MIF+/+ TAM/MDSC) into an immunostimulatory, non-angiogenic phenotype (MIF-/- TAM/MDSC) which results in significant reductions in primary and metastatic melanoma disease progression. Intriguingly, our previously discovered MIF small molecule antagonist - 4-iodo-6- phenylpyrimidine (4-IPP) - fully recapitulates MIF-deficiency, both in vitro and in vivo, and serves to attenuate TAM and MDSC alternative activation, immunosuppression, neoangiogenesis and melanoma disease progression [1601]. We very recently discovered that 4-IPP functionally inhibits MIF by dramatically reducing intracellular MIF protein levels in a proteasome-dependent manner. However, relatively high 4-IPP IC50 values and a lack of information on its mechanism of action, bioavailability and chronic toxicity dictate that much more study is needed to fully identify, optimize and characterize lead MIF-degradation inducing compounds before moving forward with small molecule MIF targeting in a clinical setting. To fulfill the stated objectives of this application, the following aims are proposed: Aim 1: Delineate the mechanisms of action of 4-IPP and MIF-dependent TAM/MDSC polarization, Aim 2: Characterize TAM/MDSC modulatory, in vivo bioavailability, toxicity and anti-tumor activities of existing and newly identified MIF inhibitor scaffolds, and Aim 3: Evaluate the therapeutic potential of lead MIF small molecule antagonists as individual and combinatorial modalities against established melanoma.