Progestins activate the AKT pathway in leiomyoma cells and promote survival.
BACKGROUND
Progesterone has been associated with promoting growth of uterine leiomyomas. The mechanisms involved remain unclear.


OBJECTIVE
In this study we investigated the activation of the AKT pathway and its downstream effectors, glycogen synthase kinase-3b and Forkhead box O (FOXO)-1 by progesterone as a mechanism of proliferation and survival of leiomyoma cells. Inhibitors of the AKT pathway were used to demonstrate the role of phosphatidylinositol 3-kinase, AKT, and FOXO1 in contributing to cell proliferation and apoptosis.


RESULTS
Treatment of leiomyoma cells with R5020 over a period of 72 h resulted in higher cell numbers compared with untreated cells. When cells were treated with 100 nm R5020 for 1 and 24 h, the levels of phospho(Ser 473)-AKT increased. This increase was inhibited when cells were cotreated with RU486. Treatment of leiomyoma cells with a phosphatidylinositol 3-kinase inhibitor, LY294 dramatically decreased levels of phospho(Ser 473)-AKT, despite R5020 treatment. In addition to increased phospho(Ser 473)-AKT levels, R5020 treatment resulted in an increase in phospho(Ser 256)-FOXO1 and phosphoglycogen synthase kinase-3b. Inhibition of AKT using API-59 decreased proliferation and cell viability even in the presence of R5020. Higher concentrations of API-59-induced apoptosis of leiomyoma cells, even in the presence of R5020. Psammaplysene A increased nuclear FOXO1 levels and did not affect cell proliferation but induced apoptosis of leiomyoma cells.


CONCLUSIONS
The progestin, R5020, can rapidly activate the AKT pathway. Inhibition of the AKT pathway inhibits cell proliferation and promotes apoptosis of leiomyoma cells.
Hoekstra
Anna V
AV
Division of Gynecologic Oncology, Department of Obstetrics and Gynecology, Northwestern University, Chicago, Illinois 60611, USA.
Sefton
Elizabeth C
EC
Berry
Emily
E
Lu
Zhenxiao
Z
Hardt
Jennifer
J
Marsh
Erica
E
Yin
Ping
P
Clardy
Jon
J
Chakravarti
Debabrata
D
Bulun
Serdar
S
Kim
J Julie
JJ
D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D005260:Female; D005455:Fluorescent Antibody Technique; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors / Q000235:genetics; D006801:Humans; D007889:Leiomyoma / Q000473:pathology*; D015735:Mifepristone / Q000494:pharmacology; D051058:Oncogene Protein v-akt / Q000378:metabolism / Q000502:physiology*; D010766:Phosphorylation; D011372:Progestins / Q000494:pharmacology*; D011397:Promegestone / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects*; D014594:Uterine Neoplasms / Q000473:pathology*
C085126:FOXO1 protein, human; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors; D011372:Progestins; D015735:Mifepristone; D011397:Promegestone; D051058:Oncogene Protein v-akt