靶向抗衰老联合LMP疫苗改善鼻咽癌放疗抵抗并预防复发的作用及机制研究

Recurrence remains one of the main patterns of failure for patients with nasopharyngeal carcinoma (NPC) after definitive radiation therapy. Recent studies have shown that senescent cells lead to chemo- and radio-resistance through senescence-associated secretory phenotypes (SASP) and induction of stem cell phenotypes. ABT263, a specific inhibitor of the anti-apoptotic proteins BCL-2 family, can selectively clear senescent cells. However, in vivo use has been limited due to its main toxicity, severe thrombocytopenia. Our previous study showed that high expressions of SRB1 proteins could be found in NPC cells. Our current preliminary study show that senescent NPC cells keep the characteristics, and SRB1-α peptide can specifically bind to SRB1. Thus we successfully developed a complex, tumor-derived microparticles (TMPs) functionalized with SRB1-α peptide to package ABT263 (SRB1-TMPs-ABT263). The complex can selectively clear senescent NPC cells by targeting SRB1. Our preliminary applications shew this new targeted treatment could effectively clear senescent cells and enhance radiosensitivity without influencing platelet levels in mice. Interestingly, we also found that the complex could initiate active immune-responses in the tumor microenvironment. However, the long-term anti-tumor immune response was relatively weak. Anti-tumor immunity is closely correlated with the mDC antigen presentation in the drainage lymph nodes. High expressions of SRB1 have also been found in mature dendritic cells (mDC). Therefore, we further developed another complex, SRB1-TMPs to package LMP vaccines, i.e., SRB1-TMPs-LMP, to activate systemic anti-tumor immunity response through SRB1-targeted delivery of LMP peptides to mDC. Therefore, this study aims to: (1) selectively clear senescent cells induced by radiation therapy to enhance radiosensitivity with the SRB1-TMPs-ABT263 complex; (2) targeting delivery of antigens to DCs and activate antitumor immunity with the SRB1-TMPs-LMP complex; (3) investigate the synergistic effect to decrease tumor recurrence by combining SRB1-TMPs-ABT263 with SRB1-TMPs-LMP vaccine in a transgenic mouse model. Taken together, our project innovatively establishes a new method of combining selective clearance of senescence cells with targeted LMP vaccine, thus providing a novel strategy to reduce recurrence of NPC after radiation therapy.

衰老肿瘤细胞通过衰老相关分泌表型及诱导干细胞表型导致肿瘤细胞放疗抵抗和复发。课题组已发现鼻咽癌及其衰老细胞高表达SRB1，因此我们利用肿瘤来源微颗粒（TMPs）包裹抗衰老药物ABT263，并连接SRB1靶向性α肽，构建SRB1-TMPs-ABT263复合物。预实验表明：该复合物可靶向清除衰老肿瘤细胞，增强放疗敏感性，降低ABT263血小板毒性，并改善肿瘤免疫微环境，但长期抗肿瘤免疫效应有限。抗肿瘤免疫与引流淋巴结内的mDC抗原提呈密切相关，我们前期发现mDC高表达SRB1。为此我们拟制备SRB1-TMPs-LMP疫苗，靶向呈递LMP多肽至mDC，激活抗肿瘤免疫。本课题以期明确：①靶向抗衰老的放疗增敏作用及机制；②该疫苗靶向抗原呈递及抗肿瘤免疫刺激作用；③转基因鼠模型验证联合治疗效果及免疫机制。本课题创新性地将靶向抗衰老与靶向疫苗联合，为减少鼻咽癌放疗后复发提供新策略，具有重要转化医学意义。

衰老细胞可通过衰老相关分泌表型及诱导干细胞表型导致肿瘤细胞放疗抵抗。本研究着重阐明了放疗诱导的衰老细胞导致肿瘤细胞放疗抵抗的分子机制，即：衰老细胞可通过衰老相关分泌表型，活化肿瘤细胞JAK/STAT信号通路，导致肿瘤细胞放疗抵抗。项目组还发现FOXO4-DRI多肽能在体内外选择性清除衰老细胞，增强肿瘤放疗敏感性，同时能减轻放疗损伤。为抑制肿瘤放疗后复发，本研究发现放疗诱导肿瘤细胞释放的胞外囊泡（RT-MPs）携载了肿瘤抗原，且具有免疫活化作用。以RT-MPs作为肿瘤疫苗可抑制皮下移植瘤生长。为进一步增强RT-MPs疫苗疗效，项目组通过基因编辑，在囊泡膜表面过表达TGFβRII的胞外段及新冠病毒刺突蛋白，分别利用TGFβRII对TGF-β的清除和S蛋白对天然免疫的活化作用，实现更强的抗肿瘤免疫活化。将改进后的囊泡疫苗与PD-1单抗联合使用，可增强PD-1单抗的抗肿瘤效果，二者具有显著的协同效应。以上研究成果创新性地将靶向抗衰老与靶向疫苗联合，为增强恶性肿瘤放疗敏感性及预防肿瘤复发提供新策略，具有重要转化医学意义。该项目共发表SCI论文12篇，其中研究型论文7篇，获批发明专利1项，培养博士及硕士研究生各3名。