Inhibitory effect of 17beta-estradiol on growth and the polyamine metabolism of a human gastric carcinoma cell line (HGC-27).
BACKGROUND
Estrogens may, by means of their receptors, modulate the growth of several tumors including gastrointestinal neoplasms. This control may occur through interaction with other molecules such as polyamines. An inverse relation between polyamine levels and the estrogen receptorial content has previously been demonstrated in vivo in human gastric carcinoma. The aim of the present study was to evaluate the effects of 17beta-Estradiol administration on the in vitro cell proliferation rates and the polyamine metabolism of an estrogen receptor-positive human gastric cancer cell line (HGC-27).


METHODS
Estrogen receptors were detected with enzyme immunoassay. Cell proliferation was assessed by means of [3H]-thymidine incorporation and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide test. The polyamine content was evaluated with high-performance liquid chromatography and the ornithine decarboxylase activity with a radiometric technique.


RESULTS
Exposure of HGC-27 cells to increasing concentrations of 17beta-Estradiol showed that an antiproliferative action became evident at concentrations of 8 microM or higher. At such concentrations, ornithine decarboxylase (ODC) activity was also significantly reduced, as were all polyamine levels, compared with the untreated control. These findings suggest that one of the mechanisms underlying 17beta-Estradiol inhibition of HGC-27 cell proliferation is a decrease in ODC activity and, hence, in polyamine production.
Laboratory of Biochemistry, IRCCS Saverio de Bellis, Castellana G. (Bari), Italy.
C
C
Messa
M
M
Pricci
M
M
Linsalata
F
F
Russo
A
A
Di Leo
D002455:Cell Division / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000494:pharmacology*; D006801:Humans; D009955:Ornithine Decarboxylase / Q000378:metabolism; D065108:Ornithine Decarboxylase Inhibitors; D011073:Polyamines / Q000378:metabolism*; D011960:Receptors, Estrogen / Q000378:metabolism; D013274:Stomach Neoplasms / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D014407:Tumor Cells, Cultured
D065108:Ornithine Decarboxylase Inhibitors; D011073:Polyamines; D011960:Receptors, Estrogen; D004958:Estradiol; D009955:Ornithine Decarboxylase