Zhang Huidan, Xie Wenjing, Duan Wenliang, Yuan Xueli, Yang Yaxin, Chen Qin, Zhu Yiqiang, Chen Yuqing
Jiangsu Province Key Laboratory for Molecular and Medical Biotechnology, Life Sciences College, Nanjing Normal University, Nanjing, China.
Front Nutr. 2025 May 16;12:1556533. doi: 10.3389/fnut.2025.1556533. eCollection 2025.
1,25(OH)D supplementation alone does not provide sufficient benefit to hepatocellular carcinoma (HCC) patients in clinical trials. Tumor-associated macrophages (TAMs)-mediated immunosuppression is regarded as a major hurdle for the effectiveness of several treatments. Previous studies revealed that hCAP18/LL-37 was an important factor which directly suppresses the anticancer activity of 1,25(OH)D on HCC cells. However, whether TAMs contribute to the limited clinical efficacy of 1,25(OH)D through hCAP18/LL-37 remains unclear.
Co-culture systems of HCC cells (PLC/PRF-5, Huh7) with THP-1-derived macrophages and co-xenograft mouse models were established. Anticancer activity was evaluated and mouse models using standard assays. Mechanistic investigations utilized qRT-PCR, Western blot, flow cytometry, ELISA, and immunohistochemistry. Therapeutic efficacy of 1,25(OH)D/suramin combination was assessed in co-xenograft and N-Nitrosodiethylamine (DEN)/Carbon tetrachloride (CCl)-induced HCC models.
1,25(OH)D (200-500 nM) promoted macrophage recruitment, M2 polarization, Akt/mTOR signal and STAT3 signal activation in HCC/macrophage co-culture systems. This effect was mediated by 1,25(OH)D-induced hCAP18/LL-37 overexpression, which facilitated TAM infiltration and M2 reprogramming. Suramin, a potent LL-37 inhibitor, abrogated these immunosuppressive effects by blocking LL-37 internalization, restoring M1 polarization and suppressing Akt/mTOR and STAT3 pathways. Notably, 1,25(OH)D/suramin combination therapy synergistically inhibited HCC proliferation, colony formation, and invasion . In xenograft models and DEN/CCl-induced HCC models, suramin enhanced 1,25(OH)D's efficacy by promoting M1 polarization, increasing intratumoral M1/M2 ratios, reducing tumor growth, and diminishing macroscopic nodules.
The 1,25(OH)D-LL-37-TAM axis drives immunosuppression in HCC by modulating macrophage phenotypes. While suramin potently disrupts this axis, blocking LL-37-mediated TAMs recruitment and M2 polarization, while promoting antitumor M1 phenotype responses. These findings highlight suramin as a promising adjunct to 1,25(OH)D-based immunotherapy for HCC.
在临床试验中，单独补充1,25(OH)D对肝细胞癌（HCC）患者未产生足够的益处。肿瘤相关巨噬细胞（TAM）介导的免疫抑制被认为是几种治疗方法有效性的主要障碍。先前的研究表明，hCAP18/LL-37是直接抑制1,25(OH)D对HCC细胞抗癌活性的重要因素。然而，TAM是否通过hCAP18/LL-37导致1,25(OH)D的临床疗效有限仍不清楚。
建立HCC细胞（PLC/PRF-5、Huh7）与THP-1来源的巨噬细胞的共培养系统以及共异种移植小鼠模型。使用标准检测方法评估抗癌活性和小鼠模型。机制研究采用qRT-PCR、蛋白质免疫印迹法、流式细胞术、酶联免疫吸附测定和免疫组织化学。在共异种移植和N-亚硝基二乙胺（DEN）/四氯化碳（CCl）诱导的HCC模型中评估1,25(OH)D/苏拉明联合治疗的疗效。
在HCC/巨噬细胞共培养系统中，1,25(OH)D（200-500 nM）促进巨噬细胞募集、M2极化、Akt/mTOR信号和STAT3信号激活。这种作用由1,25(OH)D诱导的hCAP18/LL-37过表达介导，其促进TAM浸润和M2重编程。苏拉明是一种有效的LL-37抑制剂，通过阻断LL-37内化、恢复M1极化并抑制Akt/mTOR和STAT3途径消除了这些免疫抑制作用。值得注意的是，1,25(OH)D/苏拉明联合治疗协同抑制HCC增殖、集落形成和侵袭。在异种移植模型和DEN/CCl诱导的HCC模型中，苏拉明通过促进M1极化、增加肿瘤内M1/M2比率、减少肿瘤生长和缩小肉眼可见结节增强了1,25(OH)D的疗效。
1,25(OH)D-LL-37-TAM轴通过调节巨噬细胞表型驱动HCC中的免疫抑制。而苏拉明可有效破坏该轴，阻断LL-37介导的TAM募集和M2极化，同时促进抗肿瘤M1表型反应。这些发现突出了苏拉明作为基于1,25(OH)D的HCC免疫治疗的有前景的辅助药物。
