Down-regulated FOXA1 in early-onset pre-eclampsia induces apoptosis, and inhibits migration and invasion of trophoblast cells.

BACKGROUND: Pre-eclampsia (PE) is a major cause of maternal and neonatal mortality and morbidity. Abnormal invasion of trophoblast cells is a major pathogenesis observed in PE. In the present study, we aimed to explore the association between forkhead box A1 (FOXA1) and early-onset pre-eclampsia (EOPE) and to determine the effects of FOXA1 on trophoblast cell apoptosis, migration and invasion. METHODS: Clinical data and placentas of patients with EOPE and normal pregnant women were collected in the First Affiliated Hospital of Hainan Medical College. The protein expression levels of FOXA1 in the clinical samples were evaluated by western blotting and immunohistochemistry. The effects of FOXA1 knockdown on HTR-8/SVneo cell apoptosis, migration and invasion were evaluated by flow cytometry, wound healing and transwell invasion assays, respectively. RESULTS: The western blot and immunohistochemical analysis showed that FOXA1 protein expression in placenta of EOPE group was significantly lower than that of normal group. The expression of FOXA1 in the placentas of EOPE and normal pregnant women was negatively correlated with systolic pressure and diastolic pressure. The expression of FOXA1 in EOPE and normal pregnant women was positively correlated with gestation weeks at delivery and neonatal birthweight. In vitro functional studies showed that silencing FOXA1 increased apoptosis, and inhibited the migration and invasion of HTR-8/SVneo cells. CONCLUSIONS: Down-regulation of FOXA1 in the placentas may indicate poor prognosis of EOPE. Silencing of FOXA1 induced apoptosis in trophoblast cells, and impaired the migratory and invasive capacity of trophoblast cells. FOXA1 may represent a potential therapeutic target for EOPE.

CSN6 inhibition suppresses pancreatic adenocarcinoma metastasis via destabilizing the c-Fos protein.

Deubiquitinase (DUB) can reverse the ubiquitin signal, and participate in virtually all aspects of cancer progression. Thus, DUB represents an attractive target for development of anticancer drugs. However, little is known about DUB which can be used as drug targets. Here, we found that the constitutive photomorphogenic 9 (COP9) signalosome complex subunit 6 (COPS6/CSN6), a DUB belongs to JAMM/MPN domain-associated metallopeptidases(JAMMs) class, was highly expressed in pancreatic adenocarcinoma(PAAD) tissues. High expression of CSN6 was associated with tumor TNM stage and metastasis in PAAD patients. Moreover, we demonstrated that CSN6 promoted invasion and metastasis through regulating forkhead box protein A1 (FOXA1) in PAAD cells. Re-expression of FOXA1 rescued the decreased invasion and metastasis caused by CSN6 knockdown, whereas inhibition of FOXA1 alleviated the pro-metastasis effect induced by CSN6 overexpression. Further, CSN6 regulated the expression of FOXA1 via c-Fos in PAAD cells. Mechanistically, CSN6 stabilized c-Fos protein by binding to it and decreasing its ubiquitination. Our work identified CSN6 as a targeting-permissible deubiquitinase, and CSN6 inhibition maybe a potential treatment strategy for PAAD.

Shaping Chromatin States in Prostate Cancer by Pioneer Transcription Factors.

The androgen receptor (AR) is a critical therapeutic target in prostate cancer that responds to antagonists in primary disease, but inevitably becomes reactivated, signaling onset of the lethal castration-resistant prostate cancer (CRPC) stage. Epigenomic investigation of the chromatin environment and interacting partners required for AR transcriptional activity has uncovered three pioneer factors that open up chromatin and facilitate AR-driven transcriptional programs. FOXA1, HOXB13, and GATA2 are required for normal AR transcription in prostate epithelial development and for oncogenic AR transcription during prostate carcinogenesis. AR signaling is dependent upon these three pioneer factors both before and after the clinical transition from treatable androgen-dependent disease to untreatable CRPC. Agents targeting their respective DNA binding or downstream chromatin-remodeling events have shown promise in preclinical studies of CRPC. AR-independent functions of FOXA1, HOXB13, and GATA2 are emerging as well. While all three pioneer factors exert effects that promote carcinogenesis, some of their functions may inhibit certain stages of prostate cancer progression. In all, these pioneer factors represent some of the most promising potential therapeutic targets to emerge thus far from the study of the prostate cancer epigenome.

MicroRNA-760 inhibits the biological progression of colorectal carcinoma by directly targeting FOXA1 and regulating epithelial-to-mesenchymal transition and PI3K/AKT signaling pathway.

OBJECTIVE: Colorectal carcinoma (CRC) is one of the most common factors for tumor-associated mortalities globally. In recent years, microRNAs (miRNAs) have been identified as novel therapeutic biomarkers for cancer treatment. The purpose of the current study was to unravel the clinical significance and underlying molecular mechanisms of miR-760 in CRC progression. PATIENTS AND METHODS: Fifty-four pairs of CRC tissue samples and adjacent para-carcinoma tissue samples were collected from CRC patients who underwent surgical resection. We measured miR-760 expressions in CRC using quantitative Real-time polymerase chain reaction (qRT-PCR) analysis. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assays and transwell assays were performed to determine the functions of miR-760 in CRC cell proliferation, invasion and migration. Dual-luciferase reporter assays and Western blots were used to investigate the underlying molecular mechanisms. Moreover, the association between miR-760 expressions and clinicopathological features was analyzed. RESULTS: In this study, the results showed that the down-regulated miR-760 expressions were related to the poor prognosis and malignant clinicopathologic features of CRC patients. Furthermore, functional assays revealed that miR-760 restoration obviously suppressed CRC cell proliferation, migration and invasion through modulating phosphatidylinositol 3-kinase/ protein kinase B (PI3K/AKT) pathway and epithelial-mesenchymal transition (EMT). FOXA1 was also considered as a functional target of miR-760 in CRC cells. Furthermore, miR-760 up-regulation also significantly repressed tumorigenesis in vivo. CONCLUSIONS: These results suggested that miR-760 exerted cancer-suppressive functions in CRC, providing a therapeutic strategy for CRC treatment.

Selective targeting of PARP-2 inhibits androgen receptor signaling and prostate cancer growth through disruption of FOXA1 function.

Androgen receptor (AR) is a ligand-activated transcription factor and a key driver of prostate cancer (PCa) growth and progression. Understanding the factors influencing AR-mediated gene expression provides new opportunities for therapeutic intervention. Poly(ADP-ribose) Polymerase (PARP) is a family of enzymes, which posttranslationally modify a range of proteins and regulate many different cellular processes. PARP-1 and PARP-2 are two well-characterized PARP members, whose catalytic activity is induced by DNA-strand breaks and responsible for multiple DNA damage repair pathways. PARP inhibitors are promising therapeutic agents that show synthetic lethality against many types of cancer (including PCa) with homologous recombination (HR) DNA-repair deficiency. Here, we show that, beyond DNA damage repair function, PARP-2, but not PARP-1, is a critical component in AR transcriptional machinery through interacting with the pioneer factor FOXA1 and facilitating AR recruitment to genome-wide prostate-specific enhancer regions. Analyses of PARP-2 expression at both mRNA and protein levels show significantly higher expression of PARP-2 in primary PCa tumors than in benign prostate tissues, and even more so in castration-resistant prostate cancer (CRPC) tumors. Selective targeting of PARP-2 by genetic or pharmacological means blocks interaction between PARP-2 and FOXA1, which in turn attenuates AR-mediated gene expression and inhibits AR-positive PCa growth. Next-generation antiandrogens act through inhibiting androgen synthesis (abiraterone) or blocking ligand binding (enzalutamide). Selective targeting of PARP-2, however, may provide an alternative therapeutic approach for AR inhibition by disruption of FOXA1 function, which may be beneficial to patients, irrespective of their DNA-repair deficiency status.

Targeting FOXA1-mediated repression of TGF-ß signaling suppresses castration-resistant prostate cancer progression.

Prostate cancer (PC) progressed to castration resistance (CRPC) is a fatal disease. CRPC tumors develop resistance to new-generation antiandrogen enzalutamide through lineage plasticity, characterized by epithelial-mesenchymal transition (EMT) and a basal-like phenotype. FOXA1 is a transcription factor essential for epithelial lineage differentiation. Here, we demonstrate that FOXA1 loss leads to remarkable upregulation of transforming growth factor beta 3 (TGFB3), which encodes a ligand of the TGF-ß pathway. Mechanistically, this is due to genomic occupancy of FOXA1 on an upstream enhancer of the TGFB3 gene to directly inhibit its transcription. Functionally, FOXA1 downregulation induces TGF-ß signaling, EMT, and cell motility, which is effectively blocked by the TGF-ß receptor I inhibitor galunisertib (LY2157299). Tissue microarray analysis confirmed reduced levels of FOXA1 protein and a concordant increase in TGF-ß signaling, indicated by SMAD2 phosphorylation, in CRPC as compared with primary tumors. Importantly, combinatorial LY2157299 treatment sensitized PC cells to enzalutamide, leading to synergistic effects in inhibiting cell invasion in vitro and xenograft CRPC tumor growth and metastasis in vivo. Therefore, our study establishes FOXA1 as an important regulator of lineage plasticity mediated in part by TGF-ß signaling, and supports a novel therapeutic strategy to control lineage switching and potentially extend clinical response to antiandrogen therapies.

Silencing FOXA1 gene regulates liver cancer cell apoptosis and cell proliferation.

OBJECTIVE: Liver cancer emerged as a major health problem, and it accounts for leading cancer-related death worldwide. Due to recurrence and metastatic behavior, it is challenging to be controlled and managed. Understanding the regulative role of different proteins, which regulates liver cancer in various pathological stages, is essential to be investigated. In this study, we analyzed the correlation between Foxa1 suppression along with apoptosis and cancer stem cell proliferation. MATERIALS AND METHODS: CD133+ cells were used to induce the initial and advanced stage of liver cancer. Histology was used to study and confirm the tissue complications associated with initial, advanced and Foxa1 silenced liver cancer tissues. Immunohistochemistry and Western blotting were used to quantify Foxa1, CD133 expression. TUNEL assay was performed to study apoptosis. RESULTS: Initially using CD133+ cells, we successfully developed a mouse model with the initial and advanced stage of liver cancer upon 4 and 8 weeks incubation. Histologically, as the tumor progress, it shows more proliferative cells with disorganized tissue structure. Foxa1 silencing aids in recovering from initial liver cancer, but it has only limited effects with advanced liver cancer. The apoptosis process is enhanced in initial liver cancer, and Foxa1 silenced tissue when compared with the advanced stage of liver cancer. Foxa1 silencing also suppresses the cancer stem cell proliferation. CONCLUSIONS: Overall, our results reveal the critical role of Foxa1 in regulating apoptosis and liver cancer stem cells.

MicroRNA-132 suppresses cell proliferation in human breast cancer by directly targeting FOXA1.

Dysregulation of microRNAs (miRNAs) has been implicated in cancer. Recently, miR-132 has been reported to be downregulated in the tissues of patients with breast cancer. In this study, we investigated the functional role of miR-132 and its direct target FOXA1 in breast cancer cells. In 30 human breast cancer tissues, FOXA1 was significantly overexpressed and negatively correlated with miR-132 expression. A bioinformatics analysis suggested that FOXA1 was a potential target of miR-132. Furthermore, dual luciferase reporter assays revealed that miR-132 dose-dependently inhibited the luciferase activity of the wt 3'UTR of FOXA1 rather than the mut 3'UTR of FOXA1 in human MDA-MB-468 and SK-BR3 breast cancer cells. Moreover, ectopic miR-132 expression significantly inhibited FOXA1 protein expression, whereas miR-132 knockdown promoted FOXA1 expression in the breast cancer cells. Ectopic miR-132 expression also suppressed proliferation of the breast cancer cells, whereas miR-132 knockdown promoted proliferation of the breast cancer cells, which was reversed by knockdown of FOXA1 expression. We conclude that MiR-132 suppresses proliferation of breast cancer cells at least partially though inhibition of FOXA1. These results suggest that miR-132 and FOXA1 may be potential biomarkers or therapeutic targets in breast cancer.

miR-204 regulates the biological behavior of breast cancer MCF-7 cells by directly targeting FOXA1.

MicroRNAs (miRNAs) are short, non-protein-coding RNAs and transcripts that are 18-24 nt in length. miR-204 was first identified as an anti-oncogene and is reported to be downregulated in non-small cell lung cancer, glioma, gastric and thyroid cancer. Recent studies have proposed that a low level of miR-204 expression is associated with tumor progression and disease outcome in breast cancer. Forkhead box A1 (FOXA1), a transcription factor, plays a crucial role in breast cancer and has been predicted as a target of miR-204. In the present study, we integrated the results of microarray analyses of breast cancer tissues obtained from an online database with our own determination of the expression of miR-204 in breast cancer MCF-7 cells using real-time qPCR (RT-qPCR). The proliferative capacity of the cells was assessed using MTT assays, and cell mobility and invasiveness were evaluated using cell migration and invasion assays, respectively. Flow cytometry was used to analyze apoptosis. FOXA1 levels were detected using RT-qPCR and western blot analysis. Luciferase assays were performed to confirm that FOXA1 is directly targeted by miR-204. The results showed that miR-204 was downregulated in breast cancer cells, and we found that miR-204 was expressed at a lower level in MCF-7 cells than that observed in normal breast epithelial HBL-100 cells. Overexpression of miR-204 inhibited cell proliferation, migration and invasion and promoted apoptosis. Western blot analysis revealed that the expression of FOXA1 at the protein level was significantly reduced after cells were transfected with miR-204-expressing viruses. Luciferase assays demonstrated that FOXA1 is a direct target of miR-204, which binds to FOXA1 in a complementary region. In conclusion, miR-204 regulates the biological behavior of breast cancer cells, including cell proliferation, invasion, metastasis and apoptosis, by directly targeting FOXA1. Thus, miR-204 may act as a tumor-suppressor, and the results of the present study provide a reference for future research into the potential mechanisms underlying breast cancer progression.

The transcription factor FOXA1 induces epithelial ovarian cancer tumorigenesis and progression.

FOXA1 (forkhead box A1), a member of the FOXA transcription factor superfamily, plays an important role in tumor occurrence and development. However, the relationship between FOXA1 and ovarian cancer has not been reported. We examined normal ovarian tissue and ovarian cancer tissue and found increased FOXA1 expression in the cancer tissue. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and flow cytometry assays demonstrated that transfection with small interfering RNA to silence FOXA1 (si-FOXA1) in ovarian cancer cell lines decreased cell proliferation and induced apoptosis and S-phase arrest. In addition, si-FOXA1 transfection inhibited cell migration and invasion. Western blotting showed that si-FOXA1 transfection decreased the levels of YY1-associated protein 1, cyclin-dependent kinase 1, cyclin D1, phosphatidylinositol-3 kinase, E2F transcription factor 1, B-cell lymphoma 2, and vascular endothelial growth factor A protein. Based on these results, we suggest that FOXA1 plays a catalytic role in ovarian cancer pathogenesis and development by affecting the expression of the above-mentioned proteins.

Heterarchy of transcription factors driving basal and luminal cell phenotypes in human urothelium.

Cell differentiation is affected by complex networks of transcription factors that co-ordinate re-organisation of the chromatin landscape. The hierarchies of these relationships can be difficult to dissect. During in vitro differentiation of normal human uro-epithelial cells, formaldehyde-assisted isolation of regulatory elements (FAIRE-seq) and RNA-seq was used to identify alterations in chromatin accessibility and gene expression changes following activation of the nuclear receptor peroxisome proliferator-activated receptor gamma (PPARγ) as a differentiation-initiating event. Regions of chromatin identified by FAIRE-seq, as having altered accessibility during differentiation, were found to be enriched with sequence-specific binding motifs for transcription factors predicted to be involved in driving basal and differentiated urothelial cell phenotypes, including forkhead box A1 (FOXA1), P63, GRHL2, CTCF and GATA-binding protein 3 (GATA3). In addition, co-occurrence of GATA3 motifs was observed within subsets of differentiation-specific peaks containing P63 or FOXA1. Changes in abundance of GRHL2, GATA3 and P63 were observed in immunoblots of chromatin-enriched extracts. Transient siRNA knockdown of P63 revealed that P63 favoured a basal-like phenotype by inhibiting differentiation and promoting expression of basal marker genes. GATA3 siRNA prevented differentiation-associated downregulation of P63 protein and transcript, and demonstrated positive feedback of GATA3 on PPARG transcript, but showed no effect on FOXA1 transcript or protein expression. This approach indicates that as a transcriptionally regulated programme, urothelial differentiation operates as a heterarchy, wherein GATA3 is able to co-operate with FOXA1 to drive expression of luminal marker genes, but that P63 has potential to transrepress expression of the same genes.

MicroRNA-93 Promotes Epithelial-Mesenchymal Transition of Endometrial Carcinoma Cells.

MicroRNA-93, derived from a paralog (miR-106b-25) of the miR-17-92 cluster, is involved in the tumorigenesis and progression of many cancers such as breast, colorectal, hepatocellular, lung, ovarian, and pancreatic cancer. However, the role of miR-93 in endometrial carcinoma and the potential molecular mechanisms involved remain unknown. Our results showed that miR-93 was overexpressed in endometrial carcinoma tissues than normal endometrial tissues. The endometrial carcinoma cell lines HEC-1B and Ishikawa were transfected with miR-93-5P, after which cell migration and invasion ability and the expression of relevant molecules were detected. MiR-93 overexpression promoted cell migration and invasion, and downregulated E-cadherin expression while increasing N-cadherin expression. Dual-luciferase reporter assay showed that miR-93 may directly bind to the 3' untranslated region of forkhead box A1 (FOXA1); furthermore, miR-93 overexpression downregulated FOXA1 expression while miR-93 inhibitor transfection upregulated FOXA1 expression at both mRNA and protein level. In addition, transfection with the most effective FOXA1 small interfering RNA promoted both endometrial cancer cell migration and invasion, and downregulated E-cadherin expression while upregulating N-cadherin expression. Therefore, we suggest that miR-93 may promote the process of epithelial-mesenchymal transition in endometrial carcinoma cells by targeting FOXA1.

FoxA and LIPG endothelial lipase control the uptake of extracellular lipids for breast cancer growth.

The mechanisms that allow breast cancer (BCa) cells to metabolically sustain rapid growth are poorly understood. Here we report that BCa cells are dependent on a mechanism to supply precursors for intracellular lipid production derived from extracellular sources and that the endothelial lipase (LIPG) fulfils this function. LIPG expression allows the import of lipid precursors, thereby contributing to BCa proliferation. LIPG stands out as an essential component of the lipid metabolic adaptations that BCa cells, and not normal tissue, must undergo to support high proliferation rates. LIPG is ubiquitously and highly expressed under the control of FoxA1 or FoxA2 in all BCa subtypes. The downregulation of either LIPG or FoxA in transformed cells results in decreased proliferation and impaired synthesis of intracellular lipids.

Bisphenol A stimulates the epithelial mesenchymal transition of estrogen negative breast cancer cells via FOXA1 signals.

Estrogen receptor negative (ER-) breast cancer are associated with increased risks for metastasis and high rates of recurrence. Our present study revealed that nanomolar bisphenol A (BPA), a typical endocrine disrupting chemical, promoted the in vitro migration and induced mesenchymal transition (EMT) of ER-breast cancer cells. PCR array revealed that BPA can down regulate 12 and up regulate 2 genes involved in regulation of signal transduction and biological pathways of breast cancer. The down regulated genes included FOXA1, which is a key determinant of endocrine response and down regulated by BPA via a time dependent manner. Silencing of FOXA1 by siRNA triggered the EMT of SkBr3 cells. While over expression of FOXA1 abolished BPA induced EMT. Further, 10(-8) M BPA significantly increased the phosphorylation of ERK1/2, p38-MAPK, and Akt in SkBr3 cells, while only PI3K/Akt inhibitor LY294002 attenuated the BPA induced down regulation of FOXA1 and E-Cadherin (E-Cad). Over expression of Akt also suppressed FOXA1 expression in SkBr3 cells. It suggested that PI3K/Akt mediated, at least partially, BPA induced EMT of ER-breast cancer cells. In summary, our data provided the first evidence that BPA can promote the EMT of ER-breast cancer cells through down regulation of FOXA1.

Epidaurus: aggregation and integration analysis of prostate cancer epigenome.

Integrative analyses of epigenetic data promise a deeper understanding of the epigenome. Epidaurus is a bioinformatics tool used to effectively reveal inter-dataset relevance and differences through data aggregation, integration and visualization. In this study, we demonstrated the utility of Epidaurus in validating hypotheses and generating novel biological insights. In particular, we described the use of Epidaurus to (i) integrate epigenetic data from prostate cancer cell lines to validate the activation function of EZH2 in castration-resistant prostate cancer and to (ii) study the mechanism of androgen receptor (AR) binding deregulation induced by the knockdown of FOXA1. We found that EZH2's noncanonical activation function was reaffirmed by its association with active histone markers and the lack of association with repressive markers. More importantly, we revealed that the binding of AR was selectively reprogramed to promoter regions, leading to the up-regulation of hundreds of cancer-associated genes including EGFR. The prebuilt epigenetic dataset from commonly used cell lines (LNCaP, VCaP, LNCaP-Abl, MCF7, GM12878, K562, HeLa-S3, A549, HePG2) makes Epidaurus a useful online resource for epigenetic research. As standalone software, Epidaurus is specifically designed to process user customized datasets with both efficiency and convenience.

Tumor suppressor long non-coding RNA, MT1DP is negatively regulated by YAP and Runx2 to inhibit FoxA1 in liver cancer cells.

Recent studies are indicative for strong carcinogenetic roles of Runt related transcription factor 2 (Runx2) and Yes associated protein (YAP) in several cancer types. However, whether and how the interaction between Runx2 and YAP plays a role in liver tumorigenesis still remain illusive. Here, we identified a close relationship between Runx2 and YAP in liver cancer cells. Runx2 had a positive role on YAP expression and vice versa. We also found that Rux2 and YAP were capable of inhibiting long non-coding RNA (lncRNA), Metallothionein 1D, Pseudogene (MT1DP) expression through direct promoter binding. Overexpression of MT1DP resulted in reduced cell proliferation and colony formation in soft agar, but increased apoptosis in liver cancer cells, whereas knockdown of this lncRNA had the opposite effect, indicating that MT1DP acts as a tumor suppressor. Furthermore, MT1DP was revealed as a negative regulator of Alfa-fetoprotein (AFP), a classic liver cancer tumor marker, through inhibiting protein synthesis of Forkhead box A1 (FoxA1), an important transcription factor in liver development and cancer progression. Furthermore, we found that FoxA1 plays a positive role on YAP and Runx2 expression. Specially, opening the compacted chromatin by FoxA1 around CREB binding site within the YAP promoter facilitates CREB-mediated YAP transcription. Finally, MT1DP-inhibited in vivo liver cancer cell growth could be rescued by a combination of overexpression of FoxA1, Runx2 and YAP. Taken together, the close relationship between Rnux2 and YAP plays a pro-carcinogenetic role in liver cancer cells through inhibiting tumor suppressor lncRNA, MT1DP in a FoxA1 dependent manner.

Foxa1 and Foxa2 regulate α-cell differentiation, glucagon biosynthesis, and secretion.

The Forkhead box A transcription factors are major regulators of glucose homeostasis. They show both distinct and redundant roles during pancreas development and in adult mouse ß-cells. In vivo ablation studies have revealed critical implications of Foxa1 on glucagon biosynthesis and requirement of Foxa2 in α-cell terminal differentiation. In order to examine the respective role of these factors in mature α-cells, we used small interfering RNA (siRNA) directed against Foxa1 and Foxa2 in rat primary pancreatic α-cells and rodent α-cell lines leading to marked decreases in Foxa1 and Foxa2 mRNA levels and proteins. Both Foxa1 and Foxa2 control glucagon gene expression specifically through the G2 element. Although we found that Foxa2 controls the expression of the glucagon, MafB, Pou3f4, Pcsk2, Nkx2.2, Kir6.2, and Sur1 genes, Foxa1 only regulates glucagon gene expression. Interestingly, the Isl1 and Gipr genes were not controlled by either Foxa1 or Foxa2 alone but by their combination. Foxa1 and Foxa2 directly activate and bind the promoter region the Nkx2.2, Kir6.2 and Sur1, Gipr, Isl1, and Pou3f4 genes. We also demonstrated that glucagon secretion is affected by the combined effects of Foxa1 and Foxa2 but not by either one alone. Our results indicate that Foxa1 and Foxa2 control glucagon biosynthesis and secretion as well as α-cell differentiation with both common and unique target genes.

Foxa1 contributes to the repression of Nanog expression by recruiting Grg3 during the differentiation of pluripotent P19 embryonal carcinoma cells.

Transcription factor Foxa1 plays a critical role during neural differentiation and is induced immediately after retinoic acid (RA)-initiated differentiation of pluripotent P19 embryonal carcinoma cells, correlated with the downregulated expression of pluripotency-related genes such as Nanog. To study whether Foxa1 participates in the repression of pluripotency factors, we expressed Foxa1 ectopically in P19 cells and identified that Nanog was repressed directly by Foxa1. We confirmed that Foxa1 was able to interact with Grg3, which is a transcriptional corepressor that expresses in P19 cells as well as during RA-induced P19 cell differentiation. Knockdown of Foxa1 or Grg3 delayed the downregulation of Nanog expression during RA-induced P19 cell differentiation. Furthermore, we found that Foxa1 recruited Grg3 to the Nanog promoter -2kb upstream region and switched the promoter to an inactive chromatin status represented by typical modifications in histone H3. Together, our results suggested a critical involvement of Foxa1 in the negative regulation of Nanog expression during the differentiation of pluripotent stem cells.