TCR-T靶向CCL18诱导的肿瘤干细胞抑制乳腺癌转移的研究

Our previous study shows that CCL18, produced by tumor associated macrophages in breast cancer microenviroment, promotes breast cancer metastasis. On the basis of these studies, our preliminary experiments demonstrate that CCL18 promotes the formation of breast cancer stem cells (BCSCs) during the process of CCL18-induced EMT. BCSCs is the root cause of recurrence and metastasis in breast cancer. How to start immune attack targeting BCSCs induced by CCL18 and inhibit breast cancer metastasis has not been reported. Accordingly, we propose a hypothesis: it should launch immune attack and inhibit breast cancer metastasis to construct TCR-T, targeting CCL18 induced high expression of BCSCs specific antigen. In this study, we demonstrated that CCL18 promotes the formation of migratory BCSCs from cancer tissues, cells and animals. BCSCs should express cancer testis antigen(CTA) of high immunogenicity. We should screen CTA peptides which could induce the strongest immune response, and obtain the T cell receptor(TCR) sequence targeting the MHC-I restrictive CTA peptides. Further, screen for the peptides combining with CTA peptides from the peptide library, transform complementarity determining region 3 (CDR3) of TCR, and construct TCR-T to skill the BCSCs induced by CCL18, and inhibit breast cancer metastasis, to provide new ideas for the treatment of breast cancer.

在我们系列研究证明肿瘤相关巨噬细胞来源的CCL18促进乳腺癌迁移的基础上，我们预实验证明在CCL18促进乳腺癌EMT过程中促进迁移性乳腺癌干细胞（BCSCs）的生成。BCSCs是乳癌复发转移的根源，如何靶向CCL18诱导的BCSCs发动免疫攻击，抑制乳腺癌转移未见报道。据此我们提出假说：靶向CCL18诱导BCSCs高表达的特异抗原，构建TCR-T，发动免疫攻击，抑制乳腺癌转移。本课题将从癌组织、细胞及动物水平证明CCL18促进迁移性BCSCs的生成，BCSCs表达免疫原性强的癌-睾丸抗原（CTA），筛查CTA中引起最强免疫反应的肽段，获得靶向MHC-I限制性CTA肽段的TCR序列，据多肽库中筛查获得的与CTA肽段相结合的肽段，对TCR中与抗原特异结合的可变区CDR3段进行改造，构建TCR-T，实现TCR-T对CCL18诱导的BCSCs的杀伤功能，抑制乳腺癌转移，为乳腺癌的治疗提供新的思路。

在乳腺癌的微环境中，适合环境的肿瘤细胞会生存下来并能够“教育”周围的间质细胞，使这些间质细胞发生适应肿瘤细胞生存发展的特性变化。在乳腺癌细胞的教育下巨噬细胞成为肿瘤相关巨噬细胞（TAMs），TAMs分泌CCL18促进乳腺癌浸润迁移。在乳腺癌细胞迁移过程中，要抵抗失巢性凋亡，具有肿瘤干细胞特性的细胞才可以抵抗失巢性凋亡。我们的研究证明TAMs来源的CCL18促进乳腺癌细胞迁移过程中促进乳腺癌干细胞的生成。癌干细胞是乳腺癌复发转移的根源。提高免疫系统对癌干细胞的清除能力可以改善乳腺癌患者的预后。寻找免疫攻击癌干细胞的靶点是本课题关键。我们的研究表明癌睾抗原PRAME可以作为免疫攻击清除癌干细胞的靶点，我们设计与广东人群中比例高的HLA1101亲和力和稳定性强的五个PRAME肽段作为免疫攻击的精确靶点，我们证明来自PRAME的五个抗原肽段可以被树突状细胞递呈给T淋巴结细胞，使这些T淋巴细胞具备识别抗原肽的能力，并克隆增殖，增强了清除表达PRAME的乳腺癌干细胞的能力。