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Development of diagnositic and therapeutic methods using frameshift mutated peptides for colorectal cancers with microsatellite instability

使用移码突变肽开发微卫星不稳定性结直肠癌的诊断和治疗方法

基本信息

批准号：
12557109
负责人：
KAWAKAMI Yutaka
金额：
$ 8.45万
依托单位：
Keio University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

项目摘要

Microsatellite instability positive colorectal cancers (MSI+CRC) caused by malfunction of DNA mismatch repair has unique characteristics including good prognosis with T-cell infiltrates, suggesting immune responses against tumor specific peptides generated by frameshift mutations. In this study, we have attempted to identify tumor antigens involved in MSI+CRC. We first applied SEREX to identify tumor antigens that induced IgG in MSI+CRC patients, then, immunogenicity of the antigens was evaluated by detecting IgG among sera from various cancer patients and healthy individuals. 150 antigens including 75 antigens for that IgG were detected only in MSI+CRC patients, were identified. The frameshift mutation in the repetitive sequence in the isolated CDX2 antigen was found in the tumor tissue of the patient with antrCDX2 antibody. Using recombinant frameshift CDX2 proteins, the antibody was found to recognize the C-terminal unique peptide caused by the frameshift mutation. This antibody was disappeared 7 years after the curative resection, suggesting that the immune responses may be useful as tumor markers. Although in vitro induction of T-cells specific for the mutated CDX2 was attempted, specific T cells were not induced possibly because of the use of lymphocytes from the 7 year disease free patient. We have also evaluated whether IgG were detected against possible frameshift peptides from the known MSI target genes. However, no IgG was detected against any recombinant peptides tested. In summary, we demonstrated for the first time that tumor specific immune response against the frameshift peptides caused by MSI could be induced in MSI+CRC patients. These tumor specific mutated peptides may be useful for the development of diagnostic and therapeutic methods for patients with MSI+ CRC. SEREX using autologous tumors and analysis of immune responses against the frameshift peptides using patient's T-cells should be performed in the further study.

DNA错配修复异常所致的微卫星不稳定性阳性结直肠癌(MSI+CRC)具有预后好、T细胞浸润等特点，提示对移码突变产生的肿瘤特异性多肽有免疫应答。在这项研究中，我们试图确定与MSI+CRC有关的肿瘤抗原。我们首先应用SEREX对MSI+CRC患者进行了诱导免疫球蛋白的肿瘤抗原的鉴定，然后通过检测不同癌症患者和健康人血清中的免疫球蛋白来评价这些抗原的免疫原性。共鉴定出150个抗原，其中75个抗原仅在MSI+CRC患者中检测到。在抗CDX2抗体阳性患者的肿瘤组织中发现CDX2抗原重复序列的移码突变。利用重组移码CDX2蛋白，发现该抗体识别移码突变引起的C末端独特的多肽。这种抗体在根治性切除后7年消失，表明免疫反应可能是有用的肿瘤标记物。虽然在体外尝试了对突变的CDX2特异性T细胞的诱导，但没有诱导出特异性T细胞，这可能是因为使用了7年无病患者的淋巴细胞。我们还评估了是否检测到针对已知MSI靶基因的可能移码多肽的免疫球蛋白。然而，没有检测到任何重组多肽的免疫球蛋白。综上所述，我们首次证明了在MSI+CRC患者中可以诱导针对MSI引起的移码多肽的肿瘤特异性免疫反应。这些肿瘤特异性突变多肽可能有助于MSI+CRC患者的诊断和治疗方法的发展。使用自体肿瘤的SEREX和使用患者T细胞对移码多肽的免疫反应的分析应该在进一步的研究中进行。