Influence of estradiol and triiodothyronine on breast cancer cell lines proliferation and expression of estrogen and thyroid hormone receptors.
OBJECTIVE
To better understand the estrogen (E2) agonist action of triiodothyronine (T3) the effects of these hormones on ER negative MDA-MB-231 breast cancer cells were compared with those on S30, a clone of MDA-MB-231 stably transfected with ERalpha cDNA, in terms of proliferation and modulation of hormone receptors.


RESULTS
Growth experiments showed that MDA-MB-231 was not modulated by any hormone or tamoxifen (TAM). Treatment with E2, 10(-8)M or 10(-9)M had little effect on S30 proliferation. T3 at 10(-8)M significantly inhibited proliferation. This effect was not reverted by TAM. Treatments with 10(-8)M concentration of E2 or T3 reduced ERalpha gene expression in S30, an effect partially blocked by association with TAM, with no effect on TR expression. These results suggest that, in S30, 10(-8)M T3 has a similar action to E2 relative to ERalpha gene modulation.


CONCLUSIONS
Such results emphasize the need of determining T3 levels, before the introduction of antiestrogenic forms of treatment in breast cancer patients.
Cestari
Sílvia Helena
SH
Departamento de Clínica Médica, Universidade Estadual Paulista Júlio de Mesquista Filho, Botucatu, SP, Brasil.
Figueiredo
Nancy Bueno
NB
Conde
Sandro José
SJ
Clara
Sueli
S
Katayama
Maria Lucia Hirata
ML
Padovani
Carlos Roberto
CR
Brentani
Maria Mitzi
MM
Nogueira
Célia Regina
CR
D000704:Analysis of Variance; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D002999:Clone Cells; D004958:Estradiol / Q000494:pharmacology*; D004965:Estrogen Antagonists / Q000494:pharmacology; D005260:Female; D006801:Humans; D011960:Receptors, Estrogen / Q000235:genetics / Q000378:metabolism*; D011988:Receptors, Thyroid Hormone / Q000235:genetics / Q000378:metabolism*; D013629:Tamoxifen / Q000494:pharmacology; D014284:Triiodothyronine / Q000494:pharmacology*
D004965:Estrogen Antagonists; D011960:Receptors, Estrogen; D011988:Receptors, Thyroid Hormone; D014284:Triiodothyronine; D013629:Tamoxifen; D004958:Estradiol