Research Center for Gene Therapy, Escola Paulista de Medicina, Universidade Federal de São Paulo Rua Mirassol, 207 CEP 04044-010, São Paulo, SP, Brazil.
Department of Microbiology, Immunology, and Parasitology, Escola Paulista de Medicina, Universidade Federal de São Paulo Rua Botucatu, 862 CEP 04023-062, São Paulo, SP, Brazil.
Gene Ther. 2019 Nov;26(10-11):441-454. doi: 10.1038/s41434-019-0062-y. Epub 2019 Feb 15.
The carcinoembryonic antigen (CEA) is the main tumor-associated antigen of colorectal cancers. Previously, we developed a DNA vaccine using scFv6.C4, a CEA surrogate, against CEA-expressing tumors; 40% of the vaccinated mice were tumor-free after tumor challenge. In order to enhance vaccine efficacy, fragment C of Tetanus Toxin (FrC) was tested as adjuvant. C57BL/6J-CEA2682 mice were electroporated intramuscularly 4 times with uP-PS/scFv6.C4-FrC or uP-PS/scFv6.C4, challenged by s.c. injection of 1 × 10 MC38-CEA cells, and tumor growth was monitored over 100 days. The humoral and cellular immune responses were assessed by ELISA, immunocytochemistry, in-vitro lymphocyte proliferation, and CTL cytotoxicity assays. Immunization with uP-PS/scFv6.C4-FrC or uP-PS/scFv6.C4 induced similar anti-CEA antibody titers. However, immunocytochemistry analysis showed stronger staining with uP-PS/scFv6.C4-FrC-immunized mice sera. When challenged with MC38-CEA cells, 63% of the FrC-vaccinated mice did not develop tumors, half of the rest had a significant tumor growth delay, and the probability of being free of tumors was on average 40% higher than that of scFv6.C4-immunized mice. Addition of the adjuvant led to higher CD4+ and CD8+ proliferative responses and strong CD8+ CTL response against MC38-CEA cells. DNA immunization with scFv6.C4 and FrC increased antitumor effect via induction of high and specific humoral and cellular immune responses to CEA.
癌胚抗原（CEA）是结直肠癌的主要肿瘤相关抗原。此前，我们开发了一种 DNA 疫苗，使用 scFv6.C4（CEA 替代物）针对表达 CEA 的肿瘤；接种疫苗的 40%的小鼠在肿瘤挑战后无肿瘤。为了增强疫苗的疗效，测试了破伤风毒素片段 C（FrC）作为佐剂。C57BL/6J-CEA2682 小鼠肌肉内电穿孔 4 次，给予 uP-PS/scFv6.C4-FrC 或 uP-PS/scFv6.C4，皮下注射 1×10 MC38-CEA 细胞进行攻击，并在 100 天内监测肿瘤生长。通过 ELISA、免疫细胞化学、体外淋巴细胞增殖和 CTL 细胞毒性测定评估体液和细胞免疫反应。用 uP-PS/scFv6.C4-FrC 或 uP-PS/scFv6.C4 免疫诱导相似的抗 CEA 抗体滴度。然而，免疫细胞化学分析显示，用 uP-PS/scFv6.C4-FrC 免疫的小鼠血清的染色更强。用 MC38-CEA 细胞攻击时，63%的 FrC 疫苗接种小鼠未形成肿瘤，其余小鼠的肿瘤生长延迟一半，无肿瘤的概率平均比 scFv6.C4 免疫小鼠高 40%。佐剂的添加导致更高的 CD4+和 CD8+增殖反应和针对 MC38-CEA 细胞的强烈 CD8+CTL 反应。通过诱导针对 CEA 的高特异性体液和细胞免疫反应，scFv6.C4 和 FrC 的 DNA 免疫增加了抗肿瘤作用。
