Forkhead-box A1 suppresses the progression of endometrial cancer via crosstalk with estrogen receptor α

Abstract

Mechanisms governing the function of Forkhead-box A1 (FOXA1), a member of the FOX class of transcription factors, have been extensively studied. However, little is known about the activities and expression pattern of FOXA1 in endometrial cancer (EC). In the present study, we investigated the level of FOXA1 in multiple human EC cell lines and clinical samples by immunohistochemistry, qRT-PCR and Western blot analysis. FOXA1 overexpression was observed in estrogen receptor (ER)α-positive EC cell lines (P=0.0048). In endometrial tissues, FOXA1 was significantly upregulated in both normal endometrium and well-differentiated endometrial cancer tissues (P<0.001). Functional analyses of FOXA1 were evaluated by MTT, plate colony formation and Transwell assay. The results revealed that forced expression of FOXA1 inhibited EC cell proliferation, whereas FOXA1 depletion promoted cell viability and was associated with tumorigenesis. The nude mouse tumor xenograft assay also confirmed that ablation of FOXA1 expression promoted cell proliferation. Furthermore, we found that knockdown of FOXA1 decreased the expression of ERα, and FOXA1 interacted with this receptor in the EC cell lines. Collectively, these experiments suggest that FOXA1 is a tumor suppressor in EC and has a possible interaction with ERα.

Forkhead-box A1 induces cell senescence in endometrial cancer by regulating p16INK4a

“…Primary fresh tissues were obtained from patients immediately after surgical removal and were snap-frozen in liquid nitrogen for storage prior to further use. The IHC protocol was performed as previously described (4).…”

“…In our previous study, we found that FOXA1 was significantly downregulated in EC tissues compared to that noted in normal endometrium (4). To further assess the role of FOXA1 in EC, we compared FOXA1 expression with prognostic factors in normal endometrium and EC tissues using initial reverse transcription-quantitative PCR (RT-qPCR) and IHC analyses.…”

“…The cells were counted at 24 h intervals using a colorimetric assay with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT; Sigma) performed as previously described (4). For the plate colony formation assay, 1,000 cells/well were seeded in 6-well plates.…”

“…The cells were cultured in Dulbecco's modified Eagle's medium/nutrient mixture F-12 (DMEM/F12) supplemented with 10% fetal bovine serum (FBS) and 1% penicillin/streptomycin (Gibco, Auckland, New Zealand) at 37˚C in a humidified atmosphere containing 5% CO 2 . HEC-1B and RL95-2 cells stably expressing ectopic FOXA1 or FOXA1-specific short hairpin RNA (shRNA) were generated as previously described (4). Where relevant, the AKT pathway agonist LY 294002 (10 µM; Beyotime, Shanghai, China) was added to the cells 30 min prior to co-treatment with the shRNA plasmid.…”

“…We have previously shown that FOXA1 is a tumor-suppressor in EC, although the mechanism by which FOXA1 affects the progression of EC is incompletely understood (4).…”