Involvement of FKHR (FOXO1) Transcription Factor in Human Uterus Leiomyoma Growth

Objective: To study the expression of FOXO1 and pSer256-FOXO1 parallel to Akt and pSer473-Akt in leiomyoma compared with adjacent myometrium from human uteri.

Design: Prospective study.

Setting: University departments.

Patient(s): Thirty-eight cyclic and 20 menopausal women who underwent hysterectomy for benign indications.

Intervention(s): None.

Main Outcome Measure(s): Western blot analyses were used for evaluation in leiomyoma and adjacent myometrium of Akt and pSer473-Akt, 14-3-3 gamma proteins and expression and subcellular distribution of FOXO1 and pSer256-FOXO1 during the menstrual cycle and at menopause.

Result(s): The present study demonstrates the expression of FOXO1 and pSer256-FOXO1 at the tissue level in the human uterus leiomyoma and adjacent myometrium. The level of phosphorylated FOXO1 in leiomyoma was higher than in matched myometrium. The pSer256-FOXO1 in leiomyoma during menstrual phases was located mostly in the nuclear fraction comparison to that of the myometrium. The reason for this difference is presumably the simultaneously detected lower level of 14-3-3 protein.

Conclusion(s): Abundant level of the phosphorylated FOXO1, its impaired nucleocytoplasmic shuttling, and the lowered expression of 14-3-3 protein in leiomyoma induces a shift in the cellular machinery toward a prosurvival execution program and thus presents a potential therapeutic target for treatment of leiomyoma.