Targeting MUC5AC mucin in breast cancer brain metastasis

摘要 乳腺癌（BC）脑/中枢神经系统（CNS）转移与美国患者的生存率低相关。 女性，其中30-40%的病例报告为三重受体阴性（TN）和表皮生长因子 受体阳性（ErbB 2+）BC亚型。尽管在诊断和治疗管理方面取得了进展， 尽管如此，脑转移（BM）病例仍有显著增加，这些BCBM中的生存率 病人非常沮丧。因此，迫切需要鉴定BCBM的主要分子驱动因子， 用于早期检测BM的新的预测性生物标志物。在这方面，我们的全球转录组学分析 结果显示，分泌性凝胶形成粘蛋白MUC 5AC的水平在向脑（BT）细胞中显著更高 比亲本BC细胞更大。此外，计算机模拟分析显示，在小鼠中MUC 5AC的水平显著更高。 存档的BCBM组织与原发性肿瘤相比。最重要的是，MUC 5AC的增强水平 与非BM BC患者相比，在BCBM患者的血清中检测到。这些研究有力地表明 MUC 5AC可能是早期检测BCBM的潜在预测生物标志物。此外，MUC 5AC 敲低（KD）导致BT中运动性、细胞粘附和血脑屏障（BBB）迁移减少 细胞系相对于对照。重要的是，MUC 5AC KD细胞在心内心肌细胞中表现出BM电位降低。 小鼠模型我们对MUC 5AC介导的BM的初步机制研究表明， BT细胞中的CD 44和cMET途径。MUC 5AC与cMET的共受体CD 44 v6相互作用，并与cMET共受体CD 44 v6相互作用。 用活化形式的cMET定位以建立BCBM。CD 44 v6和cMET已被证明 通过使用透明质酸和肝细胞生长因子的前馈回路优先增强BM 途径。我们还观察到在小胶质细胞/星形胶质细胞存在下，BT细胞中MUC 5AC的稳健表达。 条件培养基用PLB-1001靶向MUC 5AC降低BT细胞中的MUC 5AC表达。我们 假设“MUC 5AC通过CD 44 v6/cMET-轴增强BCBM”，因此可能是一种有用标记物， 预测BCBM。在目标1中，我们将建立MUC 5AC作为高风险BC中BM的新型预测生物标志物 患者，并检查原发性肿瘤中的高MUC 5AC表达是否预测BM，以及与 对治疗的反应、总生存期和复发。目的2研究将确定MUC 5AC介导的 使用临床前小鼠模型，通过cMET/CD 44 v6/NF-κ B轴观察BM。在目标3中，我们将使用BBB 可穿透的I期试验cMET抑制剂单独或与顺铂或来那替尼联合作为新型治疗药物 TN和ErbB 2+脑转移性BC策略。总而言之，拟议的研究将确立MUC 5AC作为 一种新的预测高风险BM的生物标志物，将有助于制定BCBM的预防策略， 目前还没有治愈方法。

Abstract Breast cancer (BC) brain/central nervous system (CNS) metastasis is associated with poor survival among U.S. women, with 30-40% of these cases reported as triple receptor-negative (TN) and epidermal growth factor receptor-positive (ErbB2+) BC subtypes. Despite the progress in the diagnostic and therapeutic management of BC, there is still a significant increase in brain metastasis (BM) cases, and the survival rate among these BCBM patients is very bleak. Therefore, there is an urgent need to identify primary molecular drivers of BCBM and novel predictive biomarker(s) for the early detection of BM. In this regard, our global transcriptomic analysis showed that levels of a secretory gel-forming mucin, MUC5AC, is significantly higher in the brain tropic (BT) cells than the parental BC cells. Additionally, an in silico analysis revealed significantly higher levels of MUC5AC in the archived BCBM tissues compared to the primary tumors. Most importantly, the augmented levels of MUC5AC were detected in the serum of BCBM patients compared to non-BM BC patients. These studies strongly suggest that MUC5AC could be a potential predictive biomarker for the early detection of BCBM. Furthermore, MUC5AC knockdown (KD) resulted in reduced motility, cell adhesion, and blood-brain barrier (BBB) transmigration in BT cell lines relative to controls. Importantly, MUC5AC KD cells showed diminished BM potential in an intracardiac mouse model. Our initial mechanistic studies on the MUC5AC-mediated BM showed an important role of the CD44 and cMET pathways in BT cells. MUC5AC interacted with CD44v6, a co-receptor for cMET, and co- localized with the activated form of cMET to establish BCBM. CD44v6 and cMET have been shown to preferentially enhance BM through a feed-forward loop using hyaluronic acid and hepatocyte growth factor pathways. We also observed robust expression of MUC5AC in BT cells in the presence of microglia/astrocyte conditioned media. Targeting MUC5AC with PLB-1001 reduces MUC5AC expression in BT cells. We hypothesize that “MUC5AC enhances BCBM through CD44v6/cMET-axis” and could thus be a useful marker to predict BCBM. In Aim 1, we will establish MUC5AC as a novel predictive biomarker for BM in high-risk BC patients, and examine whether high MUC5AC expression in primary tumors predicts BM, and correlates with response to therapy, overall survival, and relapse. Aim 2 studies will define the regulation of MUC5AC-mediated BM through the cMET/CD44v6/NF-κB-axis using preclinical mouse models. In Aim 3, we will use a BBB penetrable phase 1 tested cMET inhibitor alone or in combination with cisplatin or neratinib as novel therapeutic strategy for TN and ErbB2+ brain metastatic BC. Altogether, the proposed studies will establish MUC5AC as a novel predictive biomarker for high-risk BM and will help in developing preventive strategies for BCBM, which currently has no cure.