Characterization of putrescine uptake in hamster amelanocytic melanoma AMEL-3 cells.
The uptake of putrescine, spermidine and spermine by Fortner's hamster amelanocytic melanoma AMEL-3 cells was observed in this study to be time-dependent, temperature-sensitive, pH-dependent and saturable. Metabolic poisons nullified polyamine uptake, an indication that this is an energy-requiring mechanism. The presence of Na+ ions was found to be requisite to full activity. Valinomycin, gramicidin, monensin and the calcium ionophore calcimycin were also observed to inhibit the process substantially. The transporter active site would seem to contain sulfhydryl groups. Other diamines and polyamine analogues, as well as cationic diamidines, suppressed putrescine uptake. The presence of the ornithine decarboxylase inhibitor DFMO in the culture medium induced putrescine inflows. Putrescine, in turn, induced the negative expression of the carrier, thus suggesting that this influx mechanism is governed by up/down regulation. The cationic diamidine CGP 40215A and its analogue CGP039937A competitively inhibited putrescine transport, with Ki values of 1.9 and 15 microM, respectively. The role of polyamine uptake in these cultures is discussed.
García-Fernández
Antonio J
AJ
Departamento de Farmacología y Toxicología, Facultad de Veterinaria, Universidad de León, Campus de Vegazana (24071), León, Spain.
Rodríguez
Rosa A
RA
Pérez-Pertejo
Yolanda
Y
Balaña-Fouce
Rafael
R
D000578:Amidines / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002453:Cell Cycle / Q000187:drug effects; D006224:Cricetinae; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects; D005033:Ethylmaleimide / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D018328:Melanoma, Amelanotic; D008647:Mesocricetus; D011700:Putrescine / Q000737:chemistry / Q000378:metabolism*; D012878:Skin Neoplasms / Q000378:metabolism; D013095:Spermidine / Q000378:metabolism; D013096:Spermine / Q000378:metabolism; D013439:Sulfhydryl Reagents / Q000494:pharmacology; D013997:Time Factors; D014407:Tumor Cells, Cultured
D000578:Amidines; D013439:Sulfhydryl Reagents; D013096:Spermine; D005033:Ethylmaleimide; D013095:Spermidine; D011700:Putrescine