ODC ACTIVITY AND POLYAMINE LEVELS IN ISOLATED HUMAN COLONOCYTES

Ornithine decarboxylase (ODC) is the first and often rate-limiting enz yme in polyamine biosynthesis. ODC and polyamines (putrescine, spermid ine, spermine, and cadaverine) have an essential role in cell prolifer ation. In this study, we investigated ODC activity and the polyamine l evels of normal human colonocytes isolated from the upper and lower cr ypt regions. We found no significant differences in ODC activity betwe en upper and lower crypt regions (mean +/- SEM: 105 +/- 60 and 103 +/- 52 pmol CO2/mg protein/hr, respectively). This result was further sub stantiated by ODC immunoreactive antibody staining technique. Levels o f polyamines (putrescine, spermidine, spermine, and cadaverine) were s imilar in the upper and lower crypt regions (mean +/- SEM; upper/lower : 79 +/- 29/79 +/- 18; 189 +/- 116/ 137 +/- 38; 174 +/- 58/204 +/- 35; and 52 +/- 10/51 +/- 10 nmol/mg protein, respectively). Acetyl-polyam ines (acetyl-putrescine, acetyl-spermidine, and acetyl-spermine) level s in human colonocytes showed no significant differences between upper and lower crypt regions (mean +/- SEM; U/L: 368 +/- 109/408 +/-89, 63 +/- 22/51 +/- 12, and 39 +/- 12/41 +/- 14 nmol/mg protein, respective ly). Our results suggest that in isolated normal human colonocytes, OD C activity and polyamine levels are similar in the upper and the lower crypt regions.