PO.IM01.12 · 免疫学
通过靶向EGFL6重编程卵巢癌的肿瘤免疫原性
Reprogramming tumor immunogenicity by targeting EGFL6 in ovarian cancer
作者与单位 Authors & Affiliations
摘要 Abstract
中文摘要
卵巢癌仍是最致命的妇科恶性肿瘤，目前手术和化疗以外的治疗选择仅提供有限的获益。尽管免疫检查点抑制剂（ICIs）已改变了多种癌症类型的治疗，但其在卵巢癌中的疗效有限，部分原因是主要组织相容性复合体I类分子（MHC-I）的下调损害了抗原提呈和CD8⁺T细胞介导的肿瘤控制。新出现的证据提示，由癌症相关成纤维细胞和恶性上皮细胞产生的表皮生长因子样蛋白6（EGFL6）促进肿瘤进展和免疫逃逸；然而，其在肿瘤免疫原性中的作用仍不明确。为填补这一空白，我们在使用慢病毒shRNA敲低EGFL6后通过流式细胞术定量表面MHC-I，并通过Western blot验证敲低效率。通过SDS-PAGE和免疫印迹评估蛋白丰度和信号变化。在与活化的OT-I CD8⁺T细胞的共培养实验中评估功能后果，以测量细胞毒性和细胞因子产生。我们发现EGFL6表达与人卵巢肿瘤中的免疫浸润呈负相关，EGFL6高表达肿瘤的CD8⁺T细胞密度降低30-50%。使用单克隆抗体对EGFL6进行治疗性阻断，在C57BL/6小鼠的ID8和KPCA卵巢癌模型中显著增强了抗肿瘤免疫，使瘤内CD8⁺T细胞浸润增加约1.5倍，并提高了granzyme B⁺和IFN-γ⁺ CD8⁺T细胞的频率。从机制上讲，EGFL6促进了表面MHC-I的内化和溶酶体降解，使小鼠和人卵巢癌细胞中的H-2Kᵇ/H-2Dᵇ或HLA-A/B/C表达降低40-60%。EGFL6敲低或抗体阻断恢复了MHC-I的稳定性，使表面MHC-I增加约2倍，并改善了CD8⁺T细胞介导的肿瘤识别。这些发现将EGFL6确定为一种此前未被认识的肿瘤免疫原性调节因子，并为在卵巢癌中将EGFL6抑制与免疫治疗策略相联合提供了强有力的临床前依据。
查看英文原文 English abstract
Ovarian cancer remains the most lethal gynecologic malignancy, and current therapeutic options beyond surgery and chemotherapy provide only modest benefit. Although immune checkpoint inhibitors (ICIs) have transformed treatment for several cancer types, their efficacy in ovarian cancer is limited, partly due to downregulation of Major Histocompatibility Complex class I (MHC-I) that impairs antigen presentation and CD8⁺ T cell-mediated tumor control. Emerging evidence suggests that epidermal growth factor-like protein 6 (EGFL6), produced by cancer-associated fibroblasts and malignant epithelial cells, promotes tumor progression and immune evasion; however, its role in tumor immunogenicity remains unclear. To address this gap, we quantified surface MHC-I by flow cytometry following EGFL6 knockdown using lentiviral shRNA, with efficiency validated by western blotting. Protein abundance and signaling changes were assessed by SDS-PAGE and immunoblotting. Functional consequences were evaluated in co-culture assays with activated OT-I CD8⁺ T cells to measure cytotoxicity and cytokine production. We found that EGFL6 expression inversely correlates with immune infiltration in human ovarian tumors, with EGFL6-high tumors exhibiting a 30-50% reduction in CD8⁺ T-cell density. Therapeutic blockade of EGFL6 using a monoclonal antibody significantly enhanced antitumor immunity in ID8 and KPCA ovarian cancer models in C57BL/6 mice, increasing intratumoral CD8⁺ T-cell infiltration by ~1.5-fold and elevating granzyme B⁺ and IFN-gamma⁺ CD8⁺ T-cell frequencies. Mechanistically, EGFL6 promoted internalization and lysosomal degradation of surface MHC-I, reducing H-2Kᵇ/H-2Dᵇ or HLA-A/B/C expression by 40-60% in mouse and human ovarian cancer cells. EGFL6 knockdown or antibody blockade restored MHC-I stability, resulting in a ~2-fold increase in surface MHC-I and improved CD8⁺ T cell-mediated tumor recognition. These findings identify EGFL6 as a previously unrecognized regulator of tumor immunogenicity and provide strong preclinical rationale for combining EGFL6 inhibition with immunotherapeutic strategies in ovarian cancer.
利益披露 Disclosure
W. Wu, None.