Role of putrescine in cell proliferation in a colon carcinoma cell line.
OBJECTIVE
Putrescine, the precursor for higher polyamine biosynthesis, is necessary for cell growth in mammals. Ornithine decarboxylase (ODC) activity and polyamine production are increased in neoplastic cells. Using colon cancer cell line derived from a tumor with high metastatic potential (CT-26), our objective was to study the effect of exogenous putrescine on ODC regulation, polyamine metabolism, and cell proliferation.


METHODS
Cells cultured with fetal calf serum were exposed to 100, 550, and 1000 microM putrescine for 24 h.


RESULTS
Intracellular free putrescine, determined by high-performance liquid chromatography, showed a statistically significant increase in exposed cells compared with controls and a significant correlation with levels of the metabolite present in the medium (r = 0.93; P < 0.001). Bromodeoxyuridine incorporation into newly synthesized DNA, a marker of cell proliferation, showed a statistically significant increase in the three putrescine groups as opposed to the control group. In samples with added aminoguanidine, significant increases in DNA synthesis were observed in the 550- and 1000-microM putrescine groups as opposed to the control group. Spermidine and spermine intracellular contents in all three putrescine-treated groups remained below control levels. No statistical differences in ODC enzymatic activity or ODC mRNA content were observed. Newly incorporated putrescine stimulated colon tumor cell growth.


CONCLUSIONS
Because neither enhanced conversion into the higher polyamines nor aminoguanidine inhibition of proliferation was observed, we suggest that this effect can be attributed to the putrescine molecule itself.
Farriol
M
M
Centro de Investigaciones Bioquímicas y Biología Molecular, Barcelona, Spain. farriol@hg.vhebron.es
Segovia-Silvestre
T
T
Castellanos
J M
JM
Venereo
Y
Y
Orta
X
X
D000230:Adenocarcinoma; D002455:Cell Division / Q000187:drug effects* / Q000502:physiology; D002851:Chromatography, High Pressure Liquid; D003110:Colonic Neoplasms; D004305:Dose-Response Relationship, Drug; D006801:Humans; D009955:Ornithine Decarboxylase / Q000378:metabolism*; D011073:Polyamines / Q000378:metabolism; D011700:Putrescine / Q000494:pharmacology / Q000502:physiology*; D013997:Time Factors; D014407:Tumor Cells, Cultured
D011073:Polyamines; D009955:Ornithine Decarboxylase; D011700:Putrescine