ANALYSIS OF ORNITHINE DECARBOXYLASE MESSENGER-RIBONUCLEIC-ACID EXPRESSION IN COLORECTAL-CARCINOMA

PURPOSE: Ornithine decarboxylase (ODC) is a rate-limiting enzyme for p olyamine synthesis. An elevated protein level of ODC was observed in t he tumors. There has been, however, little information reported so far on the expression of ODC messenger ribonucleic acid (mRNA) in clinica l colorectal carcinomas. In vitro studies disclosed that the transcrip tions of the ODC gene is regulated by the c-myc gene. METHODS: The exp ression of ODC and c-myc mRNA in biopsy specimens obtained from both t umor tissue and the corresponding normal tissue was examined by the re verse transcriptase polymerase chain reaction method in 40 cases of co lorectal carcinoma. RESULTS: The expression of ODC mRNA was observed i n both tumor tissue and normal tissue. The tumor to normal ratio of OD C mRNA was higher in cases with deeply invasive tumors than in cases w ith 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 tumo r to normal ratio of c-myc mRNA and that of ODC mRNA in each case. CON CLUSIONS: 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 correlatio n between expression of ODC and c-myc mRNA in the clinical samples, wh ich was similar to the findings of a previous in vitro study.