OP-13 - Effects of cytonuclear estrogen receptor alpha on mitochondrial function and cell cycle endometrial carcinoma cells

Abstract

The effects of estrogen on cells are mediated through the estrogen receptor α (ERα) which localizes at the peri-membrane, cytoplasm, and the nucleus of cells. To investigate how cytonuclear ERα plays its roles in different cellular activities, ERα-negative endometrial carcinoma cells (ERα-) were stably transfected with plasmid of human ERα carrying a substituted phenylalanine at position 445 with alanine (ERα-F445A), which was localized at the cytoplasm and nucleus but has no direct DNA-binding activities. Treated with 17β-estrogen (E2) or bazedoxifene (BDF), cell proliferation, cell-size, migration and expression of kinases related to ERα signal transduction pathways were observed. E2 significantly activated proliferation and migration in ERα-F445A cells, but not in ERα- cells. In addition, cell cycle-related changes in cell-size were also found in ERα-F445A cells. Simultaneously there was a significant increase in mitochondrial membrane potential. The expression of mammalian target of Rapamycin (mTOR) phosphorylated at serine 2448 was decreased, which was recovered in presence of E2 in the ERα-F445A cells. On the other hand, the expression of focal adhesion kinase (FAK) phosphorylated at tyrosine at 297 was attenuated in the ERα-F445A cells treated with E2. The present results indicate that the cytonuclear ERα-F445A induces phosphorylation of kinases in downstream pathways, which regulate cell proliferation, migration, and cell-cycle related changes in cell-size.