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Hybridoma technology was applied in an effort to create highly specific probes for nonhistone proteins associated with human colon cancer nuclear matrix. Three stable monoclonal antibodies producing cloned cells No. 39, 54 and 58 are described here. All these antibodies showed high reactivity with human colon tumor nuclear matrix. Both antibodies No. 39 and 58 showed an extensive cross reactivity at high concentration of normal colon nuclear matrix. The antigens were determined to be a heterogeneous group of proteins with a major antigen of molecular weight of 140,000 for antibody No. 54 subclone 54-c-5-6 and two major antigens of molecular weight for 105,000 and 116,000 for antibody No. 39 subclone 39-d-11-12. Immunohistochemical localization of the antigens by the horseradish peroxidase bridge method demonstrated their presence in the nuclei.

Colon adenocarcinoma-associated chromosomal nonhistone proteins were determined in rat colon adenocarcinoma chromatin and in colon chromatin of Sprague-Dawley rats treated with 1,2-dimethylhydrazine (DMH) by the enzyme-linked immunosorbent assay method. The specific nuclear proteins are tissue-specific oncofetal antigens. They were also detected in fetal rat colon chromatin but not in adult rat colon chromatin. The specific tumor-associated nonhistone proteins were identified by immunoblot. The molecular weight ranges of these proteins were 79,000-89,000 and 40,000-56,000 daltons. Administration of DMH to Sprague-Dawley rats induced colon tumor and colon tumor-associated nonhistone proteins in the chromatin. However, DMH failed to induce colon tumor and tumor-associated nonhistone proteins in Lobund-Wistar rats.