| First Author | Giulianelli S | Year | 2012 |
| Journal | Cancer Res | Volume | 72 |
| Issue | 9 | Pages | 2416-27 |
| PubMed ID | 22396492 | Mgi Jnum | J:238452 |
| Mgi Id | MGI:5819341 | Doi | 10.1158/0008-5472.CAN-11-3290 |
| Citation | Giulianelli S, et al. (2012) Estrogen receptor alpha mediates progestin-induced mammary tumor growth by interacting with progesterone receptors at the cyclin D1/MYC promoters. Cancer Res 72(9):2416-27 |
| abstractText | Synthetic progesterone used in contraception drugs (progestins) can promote breast cancer growth, but the mechanisms involved are unknown. Moreover, it remains unclear whether cytoplasmic interactions between the progesterone receptor (PR) and estrogen receptor alpha (ERalpha) are required for PR activation. In this study, we used a murine progestin-dependent tumor to investigate the role of ERalpha in progestin-induced tumor cell proliferation. We found that treatment with the progestin medroxyprogesterone acetate (MPA) induced the expression and activation of ERalpha, as well as rapid nuclear colocalization of activated ERalpha with PR. Treatment with the pure antiestrogen fulvestrant to block ERalpha disrupted the interaction of ERalpha and PR in vitro and induced the regression of MPA-dependent tumor growth in vivo. ERalpha blockade also prevented an MPA-induced increase in CYCLIN D1 (CCND1) and MYC expression. Chromatin immunoprecipitation studies showed that MPA triggered binding of ERalpha and PR to the CCND1 and MYC promoters. Interestingly, blockade or RNAi-mediated silencing of ERalpha inhibited ERalpha, but not PR binding to both regulatory sequences, indicating that an interaction between ERalpha and PR at these sites is necessary for MPA-induced gene expression and cell proliferation. We confirmed that nuclear colocalization of both receptors also occurred in human breast cancer samples. Together, our findings argued that ERalpha-PR association on target gene promoters is essential for progestin-induced cell proliferation. |
