Kohlgraf Karl G, Gawron Andrew J, Higashi Michiyo, VanLith Michelle L, Shen XiaoLing, Caffrey Thomas C, Anderson Judy M, Hollingsworth Michael A
Eppley Institute for Research in Cancer and Allied Diseases, Department of Pathology and Microbiology, University of Nebraska Medical Center, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, USA.
Cancer Immunol Immunother. 2004 Dec;53(12):1068-84. doi: 10.1007/s00262-004-0557-1.
CD227 (MUC1), a membrane-associated glycoprotein expressed by many types of ductal epithelia, including pancreas, breast, lung, and gastrointestinal tract, is overexpressed and aberrantly glycosylated by malignant cells. We sought to define epitopes on MUC1 recognized by the different cell-mediated immune responses by an in vivo assay. Epitopes identified by this assay were evaluated for efficacy to protect mice transgenic for human MUC1 (MUC1.Tg) against MUC1-expressing tumor growth.
We investigated contributions of the tandem repeat (TR) and the cytoplasmic tail (CT) of MUC1 to the MUC1-specific immunological rejection of tumor cells. MUC1 cDNA constructs, in which the TR region was deleted or the CT was truncated, were transfected into two different murine tumor cell lines (B16 and Panc02), which were used to challenge mice and evaluate immunological rejection of the tumors. We used tumor rejection in vivo to define epitopes on the TR and CT of MUC1 recognized by T cell-mediated immune responses in a preclinical murine model.
Our findings demonstrated that the TR and a portion of the MUC1 CT contributed to CD4+ T cell rejection of MUC1-expressing B16 tumor cells, but not rejection of MUC1-expressing Panc02 tumor cells. A separate epitope in the CT of MUC1 was necessary for CD8+ T cell rejection of Panc02 tumor cells. Based on these studies, we sought to evaluate the efficacy of immunizing mice transgenic for (and immunologically tolerant to) human MUC1 with peptides derived from the amino acid sequence of the CT of MUC1. Results showed that survival can be significantly prolonged in vaccinated MUC1.Tg mice challenged with MUC1-expressing tumor cells, without induction of autoimmune responses.
These studies demonstrated that MUC1 peptides may be utilized as an effective anticancer immunotherapeutic, and confirmed the importance of immunogenic epitopes outside of the TR.
CD227（MUC1）是一种由多种类型的导管上皮细胞表达的膜相关糖蛋白，这些上皮细胞包括胰腺、乳腺、肺和胃肠道上皮细胞，恶性细胞会使其过度表达并发生异常糖基化。我们试图通过体内试验来确定不同细胞介导的免疫反应所识别的MUC1上的表位。对通过该试验鉴定出的表位进行评估，以确定其保护人MUC1转基因小鼠（MUC1.Tg）免受表达MUC1的肿瘤生长的功效。
我们研究了MUC1的串联重复序列（TR）和细胞质尾（CT）对肿瘤细胞的MUC1特异性免疫排斥反应的作用。将缺失TR区域或截断CT的MUC1 cDNA构建体转染到两种不同的小鼠肿瘤细胞系（B16和Panc02）中，用这些细胞系攻击小鼠并评估肿瘤的免疫排斥反应。我们利用体内肿瘤排斥反应在临床前小鼠模型中确定T细胞介导的免疫反应所识别的MUC1的TR和CT上的表位。
我们的研究结果表明，TR和MUC1 CT的一部分有助于CD4 + T细胞对表达MUC1的B16肿瘤细胞的排斥反应，但对表达MUC1的Panc02肿瘤细胞没有排斥作用。MUC1 CT中的一个单独表位是CD8 + T细胞排斥Panc02肿瘤细胞所必需的。基于这些研究，我们试图评估用源自MUC1 CT氨基酸序列的肽免疫对人MUC1转基因（并对其免疫耐受）的小鼠的功效。结果显示，在用表达MUC1的肿瘤细胞攻击的接种疫苗的MUC1.Tg小鼠中，生存期可显著延长，且不会诱导自身免疫反应。
这些研究表明，MUC1肽可作为一种有效的抗癌免疫疗法，并证实了TR之外的免疫原性表位的重要性。
