ODC activity and polyamine levels in isolated human colonocytes.

Ornithine decarboxylase (ODC) is the first and often rate-limiting enzyme in polyamine biosynthesis. ODC and polyamines (putrescine, spermidine, spermine, and cadaverine) have an essential role in cell proliferation. In this study, we investigated ODC activity and the polyamine levels of normal human colonocytes isolated from the upper and lower crypt regions. We found no significant differences in ODC activity between upper and lower crypt regions (mean +/- SEM: 105 +/- 60 and 103 +/- 52 pmol CO2/mg protein/hr, respectively). This result was further substantiated by ODC immunoreactive antibody staining technique. Levels of polyamines (putrescine, spermidine, spermine, and cadaverine) were similar 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-polyamines (acetyl-putrescine, acetyl-spermidine, and acetyl-spermine) levels 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, respectively). Our results suggest that in isolated normal human colonocytes, ODC activity and polyamine levels are similar in the upper and the lower crypt regions.