Tumor-specific immunological recognition of frameshift-mutated peptides in colon cancer with microsatellite instability.
Tumor-specific immunological recognition of frameshift-mutated peptides in colon cancer with microsatellite instability.
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DOI：
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发表时间：
2003-09
期刊：
影响因子：
11.2
通讯作者：
T. Ishikawa;T. Fujita;Yuriko Suzuki;S. Okabe;Y. Yuasa;T. Iwai;Y. Kawakami
中科院分区：
文献类型：
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作者：
T. Ishikawa;T. Fujita;Yuriko Suzuki;S. Okabe;Y. Yuasa;T. Iwai;Y. Kawakami
DNA错配修复功能障碍引起的结直肠癌微卫星不稳定性（MSI+ crc）具有独特的临床病理特征，肿瘤中有t细胞浸润，预后良好。为了鉴定诱导MSI+ CRC免疫应答的肿瘤抗原，应用SEREX（重组cDNA表达克隆的血清学分析）。通过对3株MSI+ CRC细胞系构建的lambda噬菌体cDNA文库与肿瘤中大量t细胞浸润的MSI+ CRC患者血清进行筛选，分离出64种抗原。通过筛选不同癌症患者和健康人的血清来评估每种抗原的免疫原性，仅在MSI+ CRC患者中检测到49种抗原的特异性IgG抗体（Abs）。在抗CDX2血清Ab患者的肿瘤组织中，发现CDX2编码区的重复G序列（微卫星）发生移码突变。当使用多种细菌重组CDX2蛋白（包括正常肽和改变肽）进行Western blot分析时，发现Ab既能识别移码突变产生的cooh末端肿瘤特异性肽，也能识别CDX2的NH(2)末端正常肽。这表明通过MSI产生的肿瘤特异性肽可以引起免疫反应。抗CDX2抗体仅在肿瘤中发生CDX2移码突变的患者中检测到，并在治愈性切除7年后消失，这表明这种免疫反应也可能作为肿瘤标志物有用。突变的CDX2的亚细胞定位和转录能力没有改变，尽管免疫组织化学分析表明表达降低。因此，MSI产生的肿瘤特异性肽可能参与抗肿瘤免疫反应，可能有助于MSI+ CRC患者诊断和治疗方法的发展。
Colorectal cancers with microsatellite instability (MSI+ CRCs) caused by dysfunction of DNA mismatch repair have unique clinicopathological characteristics including good prognosis with T-cell infiltration in tumor. To identify tumor antigens that induce immune response against MSI+ CRC, SEREX (serological analysis of recombinant cDNA expression cloning) was applied. By screening a lambda phage cDNA library constructed from three MSI+ CRC cell lines with serum from a patient with MSI+ CRC with abundant T-cell infiltrates in tumor, 64 antigens were isolated. Immunogenicity of each antigen was evaluated by screening sera from patients with various cancers and from healthy individuals, and specific IgG antibodies (Abs) for 49 antigens were detected only in MSI+ CRC patients. A frameshift mutation in the repetitive G sequences (microsatellite) in the coding region of CDX2, one of the identified antigens, was found in the tumor tissue of the patient who had anti-CDX2 serum Ab. The Ab recognized both the COOH-terminal tumor-specific peptides created by the frameshift mutation and the NH(2)-terminal normal peptides of CDX2 when Western blot analysis was performed using various bacterial recombinant CDX2 proteins including the normal and altered peptides, which indicated that immune response could be raised against tumor-specific peptides generated through MSI. The anti-CDX2 Ab was detected only in the patient with the CDX2 frameshift mutation in tumor and disappeared 7 years after the curative resection, suggesting that this immune response may also be useful as a tumor marker. No altered subcellular localization and transcription ability was demonstrated in the mutated CDX2, although decreased expression was suggested in immunohistochemical analysis. Therefore, tumor-specific peptides generated by MSI may be involved in antitumor immune responses and may be useful for the development of diagnostic and therapeutic methods for patients with MSI+ CRC.