Advances in Brief: Antibody to ras Proteins in Patients with Colon Cancer

Masazumi Takahashi, Wei Chen, David R. Byrd, Mary L. Disis, Eric S. Huseby, Huilian Qin, Larry McCahill, Heidi Nelson, Hiroshi Shimada, Kiyotaka Okuno, Masayuki Yasutomi, David J. Peace, Martin A. Cheever

Research output: Contribution to journalArticlepeer-review

48 Scopus citations


The current study examined sera from 160 colon cancer patients and 60 normal individuals to determine whether antibody to mutated p21 ras protein was present. Studies focused on the aspartic acid substitution at amino acid position 12 (denoted D12), one of the most common mutations in colon adenocarcinoma. IgA antibodies directed against mutated p21 ras-D12 protein were detected in 51 (32%) of 160 colon cancer patients, but only in 1 (2.5%) of 40 normal individuals. The greater incidence of antibody in cancer patients provides presumptive evidence that immunization to the ras proteins occurred as a result of the malignancy. Examination of sera for antibody reactivity to wild-type p21 ras protein (denoted p21 ras-G12) as well as p21 ras proteins bearing the D12, V12, S12, or L61 mutations showed that antibody detected was largely to normal segments of the p21 ras protein. Epitope mapping, using peptide neutralization assays with mutated or normal ras peptides as competitors, demonstrated that in 10 (67%) of 15 sera examined the antibody reactivity to p21 ras-G12 protein was neutralized by peptides near the carboxyl terminus of p21 ras protein, but not by peptides spanning the specific point mutation region. Antibody reactivities correlated with peripheral blood lymphocyte count, but did not correlate with patient age, sex, histology, stage, tumor locus, lymph node metastasis, or serum carcinoembryonic antigen.

Original languageEnglish (US)
Pages (from-to)1071-1077
Number of pages7
JournalClinical Cancer Research
Issue number10
StatePublished - Oct 1 1995

ASJC Scopus subject areas

  • General Medicine


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