Expression of progesterone receptor isoforms A and B is differentially regulated by estrogen in different breast cancer cell lines.
Progesterone action in target tissues is mediated through two progesterone receptor (PR) isoforms, PR-A and PR-B, which display different regulatory functions in target cells. Relative expression ratio of these isoforms varies depending on cell and tissue types. Here, we studied the regulation of PR isoform expression by estradiol (E(2)), insulin, IGF-1 and cAMP in different breast cancer cell lines. Although, E(2) induced PR expression in all cell lines studied, the expression ratio of PR-A/PR-B induced by E(2) was dependent on the cell line. The differential regulation of the isoforms was also seen at the mRNA level suggesting that the PR-A and PR-B promoters are differentially regulated by E(2) in different breast cancer cells. Insulin, IGF-1 or cAMP previously reported to induce PR expression however failed to alter the PR expression in our study. This is the first report describing that in different breast cancer cell lines the expression of PR-A and PR-B is regulated by E(2) in a distinct way.
Vienonen
Annika
A
Tampere Graduate School of Biomedicine, Medical School, FIN 33014, University of Tampere, Finland. annika.vienonen@uta.fi
Syvälä
Heimo
H
Miettinen
Susanna
S
Tuohimaa
Pentti
P
Ylikomi
Timo
T
D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D000242:Cyclic AMP / Q000502:physiology; D004958:Estradiol / Q000502:physiology*; D005786:Gene Expression Regulation / Q000502:physiology*; D006801:Humans; D007328:Insulin / Q000502:physiology; D007334:Insulin-Like Growth Factor I / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011980:Receptors, Progesterone / Q000235:genetics / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D007328:Insulin; D012333:RNA, Messenger; D011980:Receptors, Progesterone; C101118:progesterone receptor A; C097314:progesterone receptor B; D004958:Estradiol; D007334:Insulin-Like Growth Factor I; D000242:Cyclic AMP