Colorectal ornithine decarboxylase activity in human mucosa and tumors: elevation of enzymatic activity in distal mucosa

Ornithine decarboxylase activity as a prognostic marker for colorectal cancer

Ornithine decarboxylase (ODC) is a key enzyme in the biosynthesis of polyamines, which are essential for cell proliferation. ODC activity was measured in 47 colorectal cancer patients, 5 patients with adenoma of colorectum and 4 healthy volunteers. Mean ODC activities of cancer tissue, non-cancerous mucosa from cancer-bearing colorectum, adenoma tissue, and normal mucosa from healthy volunteers were 435+/-392, 154+/-173, 295+/-202, 103+/-60 pmol CO2/h/mg protein, respectively. ODC activity of cancer tissue or adenoma tissue was significantly higher than that of the others. Among colorectal cancer patients, ODC activity in cancer tissue was correlated with T factors, lymph node metastasis and stages. Patients with tumors that had high ODC activity (> or =350 pmol CO2/h/mg protein) showed a poor 10-year survival rate. These results suggest that ODC activity may be a useful marker for patients' prognosis after surgery.

Prostanoids, ornithine decarboxylase, and polyamines in primary chemoprevention of familial adenomatous polyposis

BACKGROUND & AIMS

Familial adenomatous polyposis because of germline mutation of the adenomatous polyposis coli gene is characterized by development of colorectal adenomas and, ultimately, colorectal cancer. The usefulness of colorectal mucosal compounds to predict the effect on adenoma development of primary chemoprevention with the nonsteroidal anti-inflammatory drug sulindac was evaluated.

METHODS

A randomized, double-blind, placebo-controlled study of 41 subjects genotypically affected with familial adenomatous polyposis but phenotypically unaffected was conducted. Patients received either sulindac or placebo for 48 months, and development of new adenomas was evaluated. The levels of 5 prostanoids, ornithine decarboxylase, and polyamines were measured serially in normal-appearing rectal mucosa.

RESULTS

There were no statistically significant differences between treatment groups in baseline levels of prostanoids, ornithine decarboxylase, or polyamines. At conclusion of the study, 4 of 5 prostaglandin levels were statistically significantly lower in the sulindac group than in the placebo group. Among the subset of patients taking sulindac, 3 of 5 prostaglandin levels were statistically significantly lower in patients who were polyp free than in those who developed polyps. By contrast, there were no statistically significant differences in ornithine decarboxylase or polyamines between treatment groups or in those on sulindac who were polyp free compared with those who developed polyps.

CONCLUSIONS

Colorectal mucosal prostaglandin levels, but not ornithine decarboxylase or polyamines, may be valuable biomarkers to assess appropriate drug dosage and medication compliance in patients undergoing primary chemoprevention therapy with sulindac. Reduction of mucosal prostaglandin levels may be necessary to achieve chemopreventive benefit from this agent.

Construction of cDNA bank from biopsy specimens for multiple gene analysis of cancer

We constructed a “cDNA bank” of human colorectal cancer and surrounding normal tissues with our unique mRNA assay system. Total nucleic acids extracted from patients’ tissues were applied to 96-well plates, where poly(dT) sequences of oligonucleotides were immobilized. After hybridization, the cDNA was reverse-transcribed on the plate with the captured mRNA as a template, followed by synthesis of double-stranded (ds) cDNA. The resulting sense cDNA was removed from the plate, then used in PCR for analysis of various genes. The sense strand of the cDNA was repeatedly synthesized by using the immobilized antisense cDNA as a template even from plates used once and stored at 4 °C for as long as 6 months. Furthermore, the results of PCR could be easily compared among different specimens if the same amount of total mRNA were applied to the plate for the ds cDNA synthesis. This demonstrated that the cDNA bank constructed from clinical materials provides almost unlimited supplies of cDNA for multiple gene analysis of cancer.