Putrescine does not support the migration and growth of IEC-6 cells

The migration of IEC-B cells is inhibited when the cells are depleted of po lyamines by inhibiting ornithine decarboxylase with alpha-difluoromethylorn ithine (DFMO). Exogenous putrescine, spermidine, and spermine completely re store cell migration inhibited by DFMO. Because polyamines are interconvert ed during their synthesis and catabolism, the specific role of individual p olyamines in intestinal cell migration, as well as growth, remains unclear. In this study, we used an inhibitor of S-adenosylmethionine decarboxylase, diethylglyoxal bis-(guanylhydrazone)(DEGBG), to block the synthesis of spe rmidine and spermine from putrescine. We found that exogenous putrescine do es not restore migration and growth of IEC-6 cells treated with DFMO plus D EGBG, whereas exogenous spermine does. In addition, the normal distribution of actin filaments required for migration, which is disrupted in polyamine -deficient cells, could be achieved by adding spermine but not putrescine a long with DFMO and DEGBG. These results indicate that putrescine, by itself , is not essential for migration and growth, but that it is effective becau se it is converted into spermidine and/or spermine.