Specific immunotherapy against cancer using adenocarcinoma restricted antigen peptide that is recognized by human monoclonal antibody.

SK1，一种人IgM单克隆抗体识别抗原，被称为AgSK1，它被证明在人腺癌，特别是人类胃肠道恶性肿瘤中优先表达。癌症杂志，78,1313-22,1998)。最近，我们从结肠癌细胞系HT29的mRNA中筛选cDNA表达文库，并分离出部分cDNA克隆，命名为AgSK1-2HT（组织抗原55,157 - 61,2000）。该克隆由54个氨基酸的氨基端开放阅读框组成，该编码区羧基端20个氨基酸包含SK1识别的抗原表位。为了证明我们所鉴定的肽是SK1识别的主要抗原表位，我们试图确定该克隆的全长cDNA序列。利用BLAST程序对非冗余数据库和EST数据库进行检索，发现克隆DJ1129D05含有与AgSK1-2HT编码区高度同源的片段。根据该克隆的序列，我们利用人结肠癌细胞系LoVo的mRNA进行PCR扩增出多个重叠片段，并直接测序。这些序列的组装得到了AgSK1-2HT的完整编码序列，该序列似乎包含387个核苷酸，编码129个氨基酸肽（NCBI genbank登录号AF316855和AAK15476）。我们还发现该克隆由9-mer和10-mer肽组成，分别携带HLA-A2402和HLA-A0201的强等位基因特异性锚位点残基。我们现在正尝试用这些肽在体外诱导CTL。虽然我们需要进一步分析这些肽，但AgSK1-2HT可能被用作一种有用的癌症疫苗。

SK1, a human IgM monoclonal antibody recognizes the antigen, termed AgSK1, which was shown to be preferentially expressed by human adenocarcinomas, particularly human gastrointestinal malignancies (Bt.J.Camcer 78, 1313-22, 1998). Recently, we screened a cDNA expression library constructed using mRNA from a colon carcinoma cell line HT29 and isolated a partial cDNA clone designated AgSK1-2HT ( Tissue Antigens 55, 157-61, 2000). This clone consisted of an amino terminal open reading frame of 54 amino acids and the carboxyl terminal 20 amino acids of this coding region contained the antigenic epitope recognized by SK1. In order to show additional evidence for our claim that the identified peptide was the main antigenic epitope recognized by SK1, we tried to determine a full length cDNA sequence of this clone. Searching the nonredundant and EST database using the BLAST program, we found a clone DJ1129D05 that contained a highly homologous fragment to the coding region of AgSK1-2HT.According to the sequence of this clone, we PCR amplified several overlapping fragments using mRNA from a human colon carcinoma cell line LoVo and directly sequenced them. Assembly of these sequences yielded the entire coding sequence of AgSK1-2HT that seemed have 387 nucleotides encoding 129 amino acid peptide ( NCBI Gen Bank accession number AF316855 and AAK15476). We also found that this clone consisted of 9-mer and 10-mer peptide which carried the strong allele specific anchor residues to HLA-A2402 and HLA-A0201 respectively. We are now trying to induce CTL using these peptides in vitro. Although we should further analyze these peptides, AgSK1-2HT may be utilized as a useful cancer vaccine.