FOXA2 loss results in an increase of endometriosis development and LIF reveals a therapeutic effect for endometriosis

Endometriosis, characterized by the growth of uterine-like tissue outside the uterus, causes chronic pain and infertility. Current diagnostic and therapeutic strategies have notable limitations, including delayed diagnosis and adverse effects. The transcription factor forkhead box A2 (FOXA2), which is exclusively expressed in the uterine glandular epithelium, regulates key genes involved in endometrial proliferation, differentiation, fertility, and hormone response. While FOXA2 expression is reduced in the endometrial tissue of women with endometriosis, its pathophysiological role in the disease is not well understood. In this study, we report that endometriosis significantly reduced FOXA2 expression in the eutopic endometrium of mice with endometriosis compared to sham controls, accompanied by decreased expression of its downstream gene, CXCL15. To evaluate the effect of FOXA2 loss in endometriosis, we surgically induced endometriosis by transplanting control Rosa26mTmG/+ or Pgrcre/+Foxa2f/fRosa26mTmG/+ (Foxa2d/dRosa26mTmG/+) endometrial tissue into the peritoneal cavity of mice. The number and weight of ectopic lesions were significantly increased in the mice with Foxa2d/dRosa26mTmG/+ ectopic lesions compared to controls. Furthermore, progesterone receptor expression was significantly reduced in the endometrial epithelium from mice with Foxa2d/dRosa26mTmG/+ ectopic lesions compared to mice with control ectopic lesions. Importantly, treatment with leukemia inhibitory factor (LIF), a cytokine regulated by FOXA2, significantly reduced ectopic lesion formation in Foxa2d/dRosa26mTmG/+ endometriosis mice compared to vehicle-treated mice. This study demonstrates that FOXA2 loss results in an increase in endometriosis incidence and that treatment with LIF offers a novel promising therapeutic approach for endometriosis.

Decreased expression of FOXA2 promotes eutopic endometrial cell proliferation and migration in patients with endometriosis

Endometriosis is characterized by eutopic endometrial cell 'metastasis' to ectopic foci. FOXA2 is a member of the forkhead transcription factor family, which may participate in transcriptional regulation in endometrial cells and contribute to the aetiology of endometriosis. This study investigated the roles played by FOXA2 in eutopic endometrium using endometriosis samples. Western blotting showed that the relative expression of FOXA2 was significantly reduced in eutopic endometrium from patients with endometriosis (n = 14) compared with endometriosis-free controls (n = 16) (0.69 ± 0.07 versus 1.24 ± 0.06, P < 0.05). To mimic eutopic endometrium of endometriosis, primary eutopic endometrial stromal cells (ESC) of controls were harvested and transfected with FOXA2 siRNA. MTT assay showed that cell viability of ESC with transfected FOXA2 siRNA increased significantly, whereas the apoptosis rate decreased as indicated by flow cytometry experiments (both P < 0.05). Wound healing assays revealed that transfection of FOXA2 siRNA promoted ESC migration. Moreover, real-time PCR analysis showed progesterone-induced FOXA2 expression in ESC under physiological conditions. In conclusion, these findings indicate that FOXA2 might be a progesterone-induced gene, which may participate in the 'metastatic' process of eutopic endometrium to ectopic loci in patients with endometriosis.

The FOXA2 transcription factor is frequently somatically mutated in uterine carcinosarcomas and carcinomas

BACKGROUND

Uterine carcinosarcomas (UCSs) are a rare but clinically aggressive form of cancer. They are biphasic tumors consisting of both epithelial and sarcomatous components. The majority of uterine carcinosarcomas are clonal, with the carcinomatous cells undergoing metaplasia to give rise to the sarcomatous component. The objective of the current study was to identify novel somatically mutated genes in UCSs.

METHODS

We whole exome sequenced paired tumor and nontumor DNAs from 14 UCSs and orthogonally validated 464 somatic variants using Sanger sequencing. Fifteen genes that were somatically mutated in at least 2 tumor exomes were Sanger sequenced in another 39 primary UCSs.

RESULTS

Overall, among 53 UCSs in the current study, the most frequently mutated of these 15 genes were tumor protein p53 (TP53) (75.5%), phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) (34.0%), protein phosphatase 2, regulatory subunit A, alpha (PPP2R1A) (18.9%), F-box and WD repeat domain containing 7 (FBXW7) (18.9%), chromodomain helicase DNA binding protein 4 (CHD4) (17.0%), and forkhead box A2 (FOXA2) (15.1%). FOXA2 has not previously been implicated in UCSs and was predominated by frameshift and nonsense mutations. One UCS with a FOXA2 frameshift mutation expressed truncated FOXA2 protein by immunoblotting. Sequencing of FOXA2 in 160 primary endometrial carcinomas revealed somatic mutations in 5.7% of serous, 22.7% of clear cell, 9% of endometrioid, and 11.1% of mixed endometrial carcinomas, the majority of which were frameshift mutations.

CONCLUSIONS

Collectively, the findings of the current study provide compelling genetic evidence that FOXA2 is a pathogenic driver gene in the etiology of primary uterine cancers, including UCSs. Cancer 2018;124:65-73. © 2017 American Cancer Society.

Expression and regulation of Foxa2 in the rat uterus during early pregnancy

The forkhead box a (Foxa) protein family has been found to play important roles in mammals. Recently, the expression of Foxa2 was reported in the mouse uterus, and it was reported to be involved in regulation of implantation. However, the regulation of Foxa2 expression in the uterus is still poorly understood. Therefore, the present study was conducted to investigate the expressional profiles of Foxa2 in the rat uterus during the estrus cycle and pregnancy. Furthermore, the effect of steroid hormones and Hedgehog protein on the expression of Foxa2 was analyzed in vivo and in vitro. In this study, the level of expression of Foxa2 was low in the rat uterus during the different stages of the estrus cycle. However, the expression increased transiently during early pregnancy at 3.5 days post coitus (dpc) and decreased at 5.5 dpc. In ovariectomized rats, P4 treatment had no effect on the expression of Foxa2 compared with the expression in control animals. Moreover, the expression of Foxa2 in cultured epithelial cells was not increased by P4 treatment in vitro. However, Foxa2 expression was significantly decreased in the rat uterus after 24 h of E2 treatment. Treatment of cells with a recombinant Hedgehog protein significantly increased the expression of Foxa2. These results suggest that the expression of Foxa2 may transiently increase just before the implantation and it may be regulated by E2 and Hedgehog protein.

Uncovering molecular events associated with the chemosuppressive effects of flaxseed: a microarray analysis of the laying hen model of ovarian cancer

Background

The laying hen model of spontaneous epithelial ovarian cancer (EOC) is unique in that it is the only model that enables observations of early events in disease progression and is therefore also uniquely suited for chemoprevention trials. Previous studies on the effect of dietary flaxseed in laying hens have revealed the potential for both amelioration and prevention of ovarian cancer. The objective of this study was to assess the effect of flaxseed on genes and pathways that are dysregulated in tumors. We have used a bioinformatics approach to identify these genes, followed by qPCR validation, immunohistochemical localization, and in situ hybridization to visualize expression in normal ovaries and tumors from animals fed a control diet or a diet containing 10% flaxseed.

Results

Bioinformatic analysis of ovarian tumors in hens led to the identification of a group of highly up-regulated genes that are involved in the embryonic process of branching morphogenesis. Expression of these genes coincides with expression of E-cadherin in the tumor epithelium. Levels of expression of these genes in tumors from flax-fed animals are reduced 40-60%. E-cadherin and miR200 are both up-regulated in tumors from control-fed hens, whereas their expression is decreased 60-75% in tumors from flax-fed hens. This does not appear to be due to an increase in ZEB1 as mRNA levels are increased five-fold in tumors, with no significant difference between control-fed and flax-fed hens.

Conclusions

We suggest that nutritional intervention with flaxseed targets the pathways regulating branching morphogenesis and thereby alters the progression of ovarian cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-709) contains supplementary material, which is available to authorized users.

Uterine epithelial cell proliferation and endometrial hyperplasia: evidence from a mouse model

In the uterus, epithelial cell proliferation changes during the estrous cycle and pregnancy. Uncontrolled epithelial cell proliferation results in implantation failure and/or cancer development. Transforming growth factor-β (TGF-β) signaling is a fundamental regulator of diverse biological processes and is indispensable for multiple reproductive functions. However, the in vivo role of TGF-β signaling in uterine epithelial cells remains poorly defined. We have shown that in the uterus, conditional deletion of the Type 1 receptor for TGF-β (Tgfbr1) using anti-Müllerian hormone receptor type 2 (Amhr2) Cre leads to myometrial defects. Here, we describe enhanced epithelial cell proliferation by immunostaining of Ki67 in the uteri of these mice. The aberration culminated in endometrial hyperplasia in aged females. To exclude the potential influence of ovarian steroid hormones, the proliferative status of uterine epithelial cells was assessed following ovariectomy. Increased uterine epithelial cell proliferation was also revealed in ovariectomized Tgfbr1 Amhr2-Cre conditional knockout mice. We further demonstrated that transcript levels for fibroblast growth factor 10 (Fgf10) were markedly up-regulated in Tgfbr1 Amhr2-Cre conditional knockout uteri. Consistently, treatment of primary uterine stromal cells with TGF-β1 significantly reduced Fgf10 mRNA expression. Thus, our findings suggest a potential involvement of TGFBR1-mediated signaling in the regulation of uterine epithelial cell proliferation, and provide genetic evidence supporting the role of uterine epithelial cell proliferation in the pathogenesis of endometrial hyperplasia.

Physiological and molecular determinants of embryo implantation

Embryo implantation involves the intimate interaction between an implantation-competent blastocyst and a receptive uterus, which occurs in a limited time period known as the window of implantation. Emerging evidence shows that defects originating during embryo implantation induce ripple effects with adverse consequences on later gestation events, highlighting the significance of this event for pregnancy success. Although a multitude of cellular events and molecular pathways involved in embryo-uterine crosstalk during implantation have been identified through gene expression studies and genetically engineered mouse models, a comprehensive understanding of the nature of embryo implantation is still missing. This review focuses on recent progress with particular attention to physiological and molecular determinants of blastocyst activation, uterine receptivity, blastocyst attachment and uterine decidualization. A better understanding of underlying mechanisms governing embryo implantation should generate new strategies to rectify implantation failure and improve pregnancy rates in women.