HepG2细胞外泌体冲击树突状细胞介导的抗肿瘤作用

目的：分析来源于肝癌HepG2细胞外泌体的免疫原性物质，为基于树突状细胞（DCs）的肝癌免疫治疗寻找合适的肿瘤抗原提供思路。方法：用透射电镜和Western blot方法鉴定肝癌HepG2细胞外泌体的形态和蛋白表达；用终浓度为8 μg/mL的外泌体冲击DCs，流式细胞术检测DCs表面分子的变化；将外泌体冲击的DCs与T淋巴细胞共培养5 d，采用羧基荧光素二乙酸盐琥珀酰亚胺酯（CFSE）荧光染色法检测淋巴细胞增殖，Annexin-V/PI双染法检测淋巴细胞对肿瘤的杀伤效应。结果：肝癌HepG2细胞的外泌体表达CD63、CD81标志性蛋白，同时携带大量的肿瘤抗原甲胎蛋白（AFP）和热休克蛋白HSP70、HSP90，不表达细胞蛋白calnexin。与未成熟DCs组比较，外泌体冲击DCs后上调其表面分子如CD83、CD80、CD86的表达（P < 0.01）；且可促进T淋巴细胞增殖（P < 0.01），增加T细胞介导的肿瘤特异性和非特异性杀伤效应（P < 0.01）。结论：肝癌HepG2细胞外泌体可能携带大量肿瘤抗原，刺激DCs成熟，可能是基于DCs的肝癌或其他肿瘤免疫治疗潜在的抗原谱。

Stimulation of dendritic cell-mediated antitumor tumor effect from HepG2 cell exosomes

OBJECTIVE:To investigate the liver cancer cell HepG2-dervied immunogenic substances as tumor antigens for dendritic cell-(DC) based immunotherapy of liver cancer. METHODS:Changes in morphology and protein expression of HepG2 cells were determined by transmission electron microscopy and western blot,respectively; and in surface molecules of DCs by flow cytometry using exosomes with a final concentration of 8 μg/mL. In addition,exosome-pulsed DCs were co-cultured with T lymphocytes for 5 days. Proliferation of lymphocytes was detected by CSFE staining,and their killing of tumors was detected by Annexin-V/PI double staining. RESULTS:The hepatoma cell HepG2 exosomes expressed the marker proteins CD63 and CD81,carried a large number of tumor antigens AFP and heat shock proteins HSP70 and HSP90,but did not express the cellular protein calnexin. Compared with the DC-MOCK group,exosome-pulsed DCs up-regulated the expression of surface molecules such as CD83,CD80,and CD86; promoted T lymphocyte proliferation (P < 0.01),and increased T cell-mediated tumor-specific and non-specific killing effects (P < 0.01). CONCLUSION:Hepatoma cell HepG2 exosomes carried a large number of tumor antigens and stimulated the maturation of DCs,which may serve as a potential antigenic spectrum of DCs-based immunotherapy for liver and other cancers.