PO.TB10.19 · 肿瘤生物学
利用PWK × NeuT小鼠研究HER2驱动的MHC I类免疫逃逸动态
Dynamics of HER2-driven MHC I immune evasion utilizing PWK x NeuT mice
作者与单位 Authors & Affiliations
摘要 Abstract
中文摘要
主要组织相容性复合体I类（MHC I）的丢失是乳腺癌中一种关键的免疫逃逸机制，常与侵袭性疾病和免疫治疗应答降低相关。鉴于已知HER2/neu表达与MHC I水平之间存在负相关，我们试图建立一个模型来研究这一免疫编辑过程的动力学。我们将自发表达HER2/neu的BALB NeuT模型杂交至多样性远交（DO）背景，发现PWK背景品系可显著加速肿瘤发生。PWKxNeuT小鼠在平均11.5周龄时发生肿瘤，远早于亲本BALB NeuT（17周，p = 0.0001）。矛盾的是，单细胞RNA测序（scRNA-Seq）显示，与BALB NeuT（2% CD3+ T细胞）相比，PWKxNeuT肿瘤含有更多的免疫浸润（8% CD3+ T细胞）。我们与iDEA蛋白质组学核心平台（阿肯色州小石城）合作，采用无标记DIA方法对NeuT和PWKxNeuT的FFPE肿瘤组织进行蛋白质组学分析。肿瘤组织显示对抗原加工和呈递至关重要的蛋白（包括tapasin、TAP1和TAP2）显著下调（p = 0.0003），提示功能性MHC I类和II类水平的系统性降低，从而解释了这一矛盾。此外，我们证实PWKxNeuT小鼠中增加的免疫浸润是有功能的。PWKxNeuT和BALB NeuT小鼠自8周龄起接受编码HER2/neu的DNA与pGM-CSF联合疫苗接种（肌内注射、电穿孔），共三次。采集血清评估抗体产生，采集外周血通过ELISPOT测定T细胞应答。接受对照DNA的小鼠在平均11周龄时发生肿瘤，而接种疫苗的小鼠平均为17周龄，部分小鼠受保护至23.5周龄（p = 0.007）。在PWK背景小鼠中鉴定出neu特异性T细胞，且与BALB NeuT小鼠相比，neu抗体显著增加。因此，PWKxNeuT模型同时表现出加速的HER2驱动的肿瘤发生和MHC呈递通路的严重缺陷，使其成为一个理想的、遗传背景明确的系统，可用于从动力学角度剖析HER2信号如何在乳腺癌进展过程中驱动MHC I类的丢失。目前的工作正在鉴定BALB NeuT和PWKxNeuT小鼠中MHC水平和浸润随时间的变化。
查看英文原文 English abstract
Loss of Major Histocompatibility Complex I (MHC I) is a critical immune evasion mechanism in breast cancer, often associated with aggressive disease and reduced response to immunotherapy. Given the known inverse correlation between HER2/neu expression and MHC I levels, we sought to develop a model to study the kinetics of this immune-editing process. We crossed the spontaneous HER2/neu-expressing BALB NeuT model onto a Diversity Outbred (DO) background and identified that the PWK background strain significantly accelerates tumor onset. PWKxNeuT mice developed tumors at an average of 11.5 weeks of age, substantially earlier than the parental BALB NeuT (17 weeks, p = 0.0001). Paradoxically, single cell RNA sequencing (scRNA-Seq) revealed that PWKxNeuT tumors harbored an increased immune infiltrate (8% CD3+ T cells) compared to BALB NeuT (2% CD3+ T cells). FFPE tumor tissue from NeuT and PWKxNeuT was analyzed using proteomics in collaboration with the iDEA Proteomics Core (Little Rock, Arkansas) using the label-free DIA approach. tumor tissue showed significant down-regulation of proteins essential for antigen processing and presentation, including tapasin, TAP1, and TAP2 ( p = 0.0003), indicative of a systemic reduction in functional MHC I and II levels and resolving the paradox. Furthermore, we confirmed that the increased immune infiltrate in PWKxNeuT mice was functional. PWKxNeuT and BALB NeuT mice were vaccinated with DNA encoding HER2/neu together with pGM-CSF (im, ep) three times beginning at 8 weeks of age. Sera was collected to assess antibody production and peripheral blood was collected to determine T cell response by ELISPOT. Mice receiving control DNA developed tumors at an average of 11 weeks of age, compared with an average of 17 weeks for vaccinated mice, with some mice protected to 23.5 weeks of age ( p = 0.007). Neu-specific T cells were identified in PWK background mice as were significantly increased neu antibodies compared with BALB NeuT mice. Thus, the PWKxNeuT model simultaneously displays accelerated HER2-driven tumorigenesis and a profound defect in the MHC presentation pathway, making it an ideal, genetically defined system to kinetically dissect how HER2 signaling drives the loss of MHC I during breast cancer progression. Current work is identifying changes in MHC levels and infiltrates over time in BALB NeuT and PWKxNeuT mice.
利益披露 Disclosure
R. Ray, None..
H. Chou, None..
W. Wei, None..
J. Jacob, None.