PURPOSE: Ornithine decarboxylase (ODC) is a rate-limiting enzyme for polyamine synthesis. An elevated protein level of ODC was observed in the tumors. There has been, however, little information reported so far on the expression of ODC messenger ribonucleic acid (mRNA) in clinical colorectal carcinomas. In vitro studies disclosed that the transcriptions of the ODC gene is regulated by the c-myc gene. METHODS: The expression of ODC and c- myc mRNA in biopsy specimens obtained from both tumor tissue and the corresponding normal tissue was examined by the reverse transcriptase polymerase chain reaction method in 40 cases of colorectal carcinoma. RESULTS: The expression of ODC mRNA was observed in both tumor tissue and normal tissue. The tumor to normal ratio of ODC mRNA was higher in cases with deeply invasive tumors than in cases with shallow tumors, and it was also higher in Dukes B or C cases than in Dukes A cases. There was a significant correlation between the tumor to normal ratio of c-myc mRNA and that of ODC mRNA in each case. CONCLUSIONS: These findings suggested that 1) the study of the expression of ODC mRNA may be useful for preoperatively predicting more advanced disease of colon carcinoma, and 2) there was a significant correlation between expression of ODC and c-myc mRNA in the clinical samples, which was similar to the findings of a previous in vitro study.
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