c-myc oncogene expression in colorectal cancer.

The pattern of c-myc gene organization and expression has been examined in resected colonic tumors and in the adjacent normal colon from 15 patients undergoing radical surgery. DNA hybridization showed no evidence of gene amplification or rearrangement. Transcripts of the c-myc messenger ribonucleic acid (mRNA) were elevated up to 32-fold in 12 of 15 tumors. The gene product, p62c-myc, was detected by both immunoblotting and immunohistology using a monoclonal antibody raised against a synthetic peptide immunogen. There was close correlation between c-myc mRNA copy number and p62c-myc abundance. Three well differentiated tumors contained high levels of transcript and protein, whereas four poorly differentiated tumors had the lowest levels. The assay of oncogene products may provide new biologically relevant tumor markers for determining prognosis and guiding treatment.