结直肠癌（CRC）是一种恶性肿瘤，起源于人类内部结肠内衬，可能蔓延到其他器官，如肝脏和肺部。包含ARNT Sim区域的1（PASD1）是一种在多种癌症中表达的肿瘤-睾丸抗原，包括CRC，但在除了睾丸以外的正常组织中不表达。本研究旨在研究PASD1蛋白作为CRC免疫治疗的潜在靶点。通过实时聚合酶链反应和免疫组织化学染色，分别对90例CRC和息肉组织样本进行了PASD1 RNA和蛋白表达的研究。使用PASD1肽处理匹配的患者外周血单个核细胞，并进行免疫原性，细胞毒性和细胞因子测定。同时收集和分析临床数据。我们的结果表明，PASD1_v2 mRNA在CRC（46.0％）和息肉样本（33.3％）中高表达。CRC和息肉样本中，PASD1-1和PASD1-2蛋白均表达于31.7％和29.4％。蛋白表达在组织的细胞质和/或细胞核中呈弱到中度阳性。CD4特异性的PASD1肽的免疫反应在CRC和息肉患者中分别检测到21.7％和23.5％。CRC中最具免疫原性的肽是PASD1（1），而在息肉中是PASD1（3）。在CRC样本中，细胞毒性效应的检测率高达57.20％，同时IL-17A和IL-6细胞因子表达较高。人口统计数据表明，中国女性60岁以上、被诊断为晚期直肠乙状结肠肿瘤的患者可以从PASD1肽免疫治疗方法中受益。这是第一份描述PASD1阳性CRC患者CD4阳性T辅助细胞反应及其细胞毒性的报告。© TÜBİTAK

Colorectal cancer (CRC) is a malignant tumor arising from a human inner colon lining that may spread to other organs such as the liver and lungs. Per ARNT Sim domain containing 1 (PASD1) is a cancer-testis antigen expressed in cancers including CRC but not in normal tissues except for normal testes. This study aims to study PASD1 protein as a potential target for CRC immunotherapy. A total of 90 CRC and polyps tissue samples were investigated for PASD1 RNA and protein expression using a real-time polymerase chain reaction and immunohistochemical staining, respectively. Matched patients' peripheral blood mononuclear cells were pulsed with PASD1 peptides and measured for immunogenicity, cell cytotoxicity, and cytokine assays. The clinical data were collected and analyzed accordingly. Our results show that PASD1_v2 mRNA expression was highly expressed in CRC (46.0%) and polyps samples (33.3%). Both PASD1-1 and PASD1-2 proteins were expressed in 31.7% of CRC and 29.4% of polyps samples. Protein expression was weak to moderate positive in the cytoplasm and/or nucleus of the tissues. Immune responses towards CD4-specific PASD1 peptides were detected in 21.7% of CRC and 23.5% of polyps patients. The most immunogenic peptide was PASD1 (1) in CRC while PASD1 (3) in polyps. Cytotoxicity effects were detected up to 57.20% observed in CRC samples while IL-17A and IL-6 cytokines were highly expressed. The demographic data suggest that Chinese female patients more than 60 years old, diagnosed with late-stage rectosigmoid tumors may benefit from the PASD1 peptide immunotherapy approach. This is the first report describing CD4-positive T-helper response to the PASD1 positive CRC patients and its cytotoxicity.© TÜBİTAK.