Targeting FOXP3 mRNA splicing for breast cancer immunotherapy

项目摘要 癌症免疫治疗的发展，包括免疫检查点抑制剂和过继细胞转移 （ACT）为基础的疗法彻底改变了癌症治疗。然而，成功仅限于相对较小的 患者和癌症类型的子集。调节性T细胞（Regulatory T cells，Tcells）在维持免疫系统中起着重要作用 稳态和负调节免疫介导炎症，例如自身免疫性疾病、哮喘 和过敏。然而，肿瘤浸润性T细胞也抑制有效的抗肿瘤免疫。FOXP 3是一个大师 调节Treg发育和功能。人FOXP 3基因通过mRNA编码两种主要亚型 选择性剪接-长的全长同种型（FOXP 3L）和缺少外显子2区的较短同种型（FOXP 3S）。 为了研究FOXP 3S在Tumor中的功能，我们产生了仅表达Foxp 3S的Foxp 3S小鼠系 同种型我们对原位小鼠乳腺肿瘤模型的初步研究表明，Foxp 3S小鼠 完全抵抗肿瘤发展，而表达Foxp 3L的同窝野生型小鼠表现出 显著的肿瘤生长。将Foxp 3S促进吗啉代药物（MO）瘤内注射到乳腺中 野生型小鼠中的肿瘤显著增加肿瘤中的IFN-γ+ CD 4和CD 8 T细胞，从而抑制了IFN-γ+ CD 4和CD 8 T细胞的表达。 肿瘤生长有趣的是，来自癌症基因组图谱的转录组数据的生物信息学分析 TCGA结果显示FOXP 3S mRNA在乳腺癌中的表达与临床分期呈正相关， 结果。鉴于超过60%的肿瘤浸润性CD 4 T细胞是TCRs，并且肿瘤浸润性CD 4 T细胞中最主要的TCR是TCRs。 肿瘤内TCLs是肿瘤反应性，并识别特异性肿瘤新抗原，我们假设， 促进FOXP 3S同种型表达将重编程肿瘤反应性T细胞，并将这些免疫反应性T细胞转化为细胞因子。 抑制性T细胞对肿瘤特异性T辅助细胞的作用，从而促进抗肿瘤免疫。我们建议使用独特的 小鼠系、促进FOXP 3S的吗啉代和患者来源的类器官来验证我们的假设。我们将 确定FOXP 3S介导的抗肿瘤免疫的机制，并进一步确定FOXP 3S的疗效。 促进吗啉代在乳腺癌治疗中的应用。成功完成这项研究将确定一个新的 乳腺癌免疫治疗的治疗策略。

Project Abstract The development of cancer immunotherapy including immune checkpoint inhibitors and adoptive cell transfer (ACT)-based therapies revolutionized cancer treatment. The success, however, is limited to a relatively small subset of patients and cancer types. Regulatory T cells (Tregs) play a central role in maintaining immune system homeostasis and negatively regulate immune-mediated inflammation such as autoimmune diseases, asthma and allergy. However, tumor infiltrating Tregs also suppress effective anti-tumor immunity. FOXP3 is a master regulator of Treg development and function. Human FOXP3 gene encodes two major isoforms through mRNA alternative splicing – a long full-length isoform (FOXP3L) and a shorter isoform lacking exon 2 region (FOXP3S). To study the function of FOXP3S in Tregs, we generated a Foxp3S mouse line expressing only the Foxp3S isoform. Our preliminary studies with orthotopic mouse breast tumor models demonstrate that the Foxp3S mice are completely resistant to tumor development, while the littermate wildtype mice expressing Foxp3L exhibit significant tumor growth. Intratumoral injection of Foxp3S-promoting morpholino drug (MO) into the breast tumors in wildtype mice markedly increases IFN-γ+ CD4 and CD8 T cells in the tumors and thus suppresses tumor growth. Interestingly, bioinformatics analysis of transcriptomic data from The Cancer Genome Atlas (TCGA) reveals that FOXP3S mRNA expression in human breast cancer is positively correlated with clinical outcomes. Given that over 60% of tumor-infiltrating CD4 T cells are Tregs and the most dominant TCRs from intratumoral Tregs were tumor-reactive and recognize specific tumor neoantigens, we hypothesize that promoting FOXP3S isoform expression will reprogram tumor-reactive Tregs and convert these immune suppressive Tregs to tumor-specific T helpers thus promoting antitumor immunity. We propose to use unique mouse lines, FOXP3S-promoting morpholinos and patient-derived organoids to test our hypothesis. We will determine the mechanisms for FOXP3S-mediated antitumor immunity and further define the efficacy of FOXP3S- promoting morpholinos in breast cancer treatment. Successful completion of this study will identify a novel therapeutic strategy for breast cancer immunotherapy.