POD-1 binding to the E-box sequence inhibits SF-1 and StAR expression in human adrenocortical tumor cells

Transcription Factor 21: A Transcription Factor That Plays an Important Role in Cardiovascular Disease

BACKGROUND

According to the World Health Organisation's Health Report 2019, approximately 17.18 million people die from cardiovascular disease each year, accounting for more than 30% of all global deaths. Therefore, the occurrence of cardiovascular disease is still a global concern. The transcription factor 21 (TCF21) plays an important role in cardiovascular diseases. This article reviews the regulation mechanism of TCF21 expression and activity and focuses on its important role in atherosclerosis in order to contribute to the development of diagnosis and treatment of cardiovascular diseases.

SUMMARY

TCF21 is involved in the phenotypic regulation of vascular smooth muscle cells (VSMCs), promotes the proliferation and migration of VSMCs, and participates in the activation of inflammatory sequences. Increased proliferation and migration of VSMCs can lead to neointimal hyperplasia after vascular injury. Abnormal hyperplasia of neointima and inflammation are one of the main features of atherosclerosis. Therefore, targeting TCF21 may become a potential treatment for relieving atherosclerosis.

KEY MESSAGES

TCF21 as a member of basic helix-loop-helix transcription factors regulates cell growth and differentiation by modulating gene expression during the development of different organs and plays an important role in cardiovascular development and disease. VSMCs and cells derived from VSMCs constitute the majority of plaques in atherosclerosis. TCF21 plays a key role in regulation of VSMCs' phenotype, thus accelerating atherogenesis in the early stage. However, TCF21 enhances plaque stability in late-stage atherosclerosis. The dual role of TCF21 should be considered in the translational medicine.

Preclinical Models of Adrenocortical Cancer

Adrenocortical cancer is an aggressive endocrine malignancy with an incidence of 0.72 to 1.02 per million people/year, and a very poor prognosis with a five-year survival rate of 22%. As an orphan disease, clinical data are scarce, meaning that drug development and mechanistic research depend especially on preclinical models. While a single human ACC cell line was available for the last three decades, over the last five years, many new in vitro and in vivo preclinical models have been generated. Herein, we review both in vitro (cell lines, spheroids, and organoids) and in vivo (xenograft and genetically engineered mouse) models. Striking leaps have been made in terms of the preclinical models of ACC, and there are now several modern models available publicly and in repositories for research in this area.

Human theca arises from ovarian stroma and is comprised of three discrete subtypes

Theca cells serve multiple essential functions during the growth and maturation of ovarian follicles, providing structural, metabolic, and steroidogenic support. While the function of theca during folliculogenesis is well established, their cellular origins and the differentiation hierarchy that generates distinct theca sub-types, remain unknown. Here, we performed single cell multi-omics analysis of primary cell populations purified from human antral stage follicles (1-3 mm) to define the differentiation trajectory of theca/stroma cells. We then corroborated the temporal emergence and growth kinetics of defined theca/stroma subpopulations using human ovarian tissue samples and xenografts of cryopreserved/thawed ovarian cortex, respectively. We identified three lineage specific derivatives termed structural, androgenic, and perifollicular theca cells, as well as their putative lineage-negative progenitor. These findings provide a framework for understanding the differentiation process that occurs in each primordial follicle and identifies specific cellular/molecular phenotypes that may be relevant to either diagnosis or treatment of ovarian pathologies.

Transgenic Mouse Models to Study the Development and Maintenance of the Adrenal Cortex

The cortex of the adrenal gland is organized into concentric zones that produce distinct steroid hormones essential for body homeostasis in mammals. Mechanisms leading to the development, zonation and maintenance of the adrenal cortex are complex and have been studied since the 1800s. However, the advent of genetic manipulation and transgenic mouse models over the past 30 years has revolutionized our understanding of these mechanisms. This review lists and details the distinct Cre recombinase mouse strains available to study the adrenal cortex, and the remarkable progress total and conditional knockout mouse models have enabled us to make in our understanding of the molecular mechanisms regulating the development and maintenance of the adrenal cortex.

Homodimeric and Heterodimeric Interactions among Vertebrate Basic Helix-Loop-Helix Transcription Factors

The basic helix–loop–helix transcription factor (bHLH TF) family is involved in tissue development, cell differentiation, and disease. These factors have transcriptionally positive, negative, and inactive functions by combining dimeric interactions among family members. The best known bHLH TFs are the E-protein homodimers and heterodimers with the tissue-specific TFs or ID proteins. These cooperative and dynamic interactions result in a complex transcriptional network that helps define the cell’s fate. Here, the reported dimeric interactions of 67 vertebrate bHLH TFs with other family members are summarized in tables, including specifications of the experimental techniques that defined the dimers. The compilation of these extensive data underscores homodimers of tissue-specific bHLH TFs as a central part of the bHLH regulatory network, with relevant positive and negative transcriptional regulatory roles. Furthermore, some sequence-specific TFs can also form transcriptionally inactive heterodimers with each other. The function, classification, and developmental role for all vertebrate bHLH TFs in four major classes are detailed.

Upregulation of TCF21 inhibits migration of adrenocortical carcinoma cells

BACKGROUND

Adrenocortical carcinomas (ACC) are rare and aggressive cancer. Our previous study has revealed that the transcription factor 21, TCF21, is downregulated in ACC and regulates steroidogenic factor 1 (SF-1) binding to the SF-1 E-box promoter. In addition, it could be found that TCF21 is a predictor of overall survival (OS) in adult carcinomas.

METHODS

In this study, it was investigated the correlation between TCF21 expression and the promoter methylation status in adrenocortical tumor cells, carcinomas and adenoma. The biological function and potential molecular mechanism of TCF21 restoration in migration and invasion of ACC cells was examined.

RESULTS

We could be demonstrated a negative correlation between the level of TCF21 expression and methylation of its promoter in adenoma and carcinoma cells indicating the epigenetic control of TCF21 expression. It was also demonstrated that the expression of TCF21 inhibits migration and invasion in the ACC cell line, H295R cells, using plasmid transfection to express TCF21. Furthermore, it could be investigated the TCF21 function as tumor suppressor probably through Kisspeptin 1 (KISS-1) expression and epithelial-mesenchymal transition (EMT) reversion, as well as the modulation of several metalloproteinases in ACC cells.

CONCLUSIONS

Our results suggest that enhancement of TCF21 expression levels may be a potential strategy to revert invasive abilities in adrenocortical carcinomas.

Role of the bHLH transcription factor TCF21 in development and tumorigenesis

Transcription factors control, coordinate, and separate the functions of distinct network modules spatially and temporally. In this review, we focus on the transcription factor 21 (TCF21) network, a highly conserved basic-helix-loop-helix (bHLH) protein that functions to integrate signals and modulate gene expression. We summarize the molecular and biological properties of TCF21 control with an emphasis on molecular and functional TCF21 interactions. We suggest that these interactions serve to modulate the development of different organs at the transcriptional level to maintain growth homeostasis and to influence cell fate. Importantly, TCF21 expression is epigenetically inactivated in different types of human cancers. The epigenetic modification or activation and/or loss of TCF21 expression results in an imbalance in TCF21 signaling, which may lead to tumor initiation and, most likely, to progression and tumor metastasis. This review focuses on research on the roles of TCF21 in development and tumorigenesis systematically considering the physiological and pathological function of TCF21. In addition, we focus on the main molecular bases of its different roles whose importance should be clarified in future research. For this review, PubMed databases and keywords such as TCF21, POD-1, capsulin, tumors, carcinomas, tumorigenesis, development, and mechanism of action were utilized. Articles were selected within a historical context as were a number of citations from journals with relevant impact.

Construction of a risk signature for adrenocortical carcinoma using immune-related genes

Background

Adrenocortical carcinoma (ACC) is considered a rare tumor with a dismal prognosis. Expression of immune-related genes (IRGs) in ACC and correlations between IRGs and ACC prognosis were assessed using The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) databases.

Methods

To preliminarily predict immune cell infiltration, an immune score was calculated using ESTIMATE. Differentially expressed IRGs were screened, and potential biological functions were investigated. We then performed univariate Cox regression to identify IRGs associated with survival, and the regulatory mechanisms of IRGs associated with survival were predicted. We built a risk signature through multivariate Cox regression to evaluate patient overall survival (OS).

Results

A high immune score predicted a good prognosis and an early clinical stage in ACC. We identified 30 IRGs associated with survival and then predicted associated regulatory mechanisms via protein-protein interaction (PPI) and transcription factor (TF) regulatory networks. The risk signature established by multivariate Cox regression correlated significantly with prognosis in ACC.

Conclusions

The vital roles of IRGs in ACC were assessed, and the risk signature obtained based on IRGs associated with survival independently predicted ACC prognosis.

Stathmin 1 is highly expressed and associated with survival outcome in malignant adrenocortical tumours

Adrenocortical carcinoma (ACC) is an aggressive endocrine cancer with few molecular predictors of malignancy and survival, especially in paediatric patients. Stathmin 1 (STMN1) regulates microtubule dynamics and has been involved in the malignant phenotype of cancer cells. Recently, it was reported that STMN1 is highly expressed in ACC patients, and STMN1 silencing reduces the clonogenicity and migration of ACC cell lines. However, the prognostic significance of STMN1 and its therapeutic potential remain undefined in ACC. In the present study, STMN1 mRNA levels were significantly higher (p < 0.05) in ACC patients, especially in an advanced stage, and correlated with BUB1B and PINK1 expression, the prognostic-related genes in ACC. In paediatric tumours, high STMN1 expression was observed in both adrenocortical carcinoma and adrenocortical adenoma patients. Among the adult malignant tumours, STMN1 level was an independent predictor of survival outcomes (overall survival: hazard ratio = 6.08, p = 0.002; disease-free survival: hazard ratio = 4.65, p < 0.0001). Paclitaxel, a microtubule-stabilizing drug, reduces the activation of STMN1 and significantly decreases cell migration and invasion in ACC cell lines and ACC cells from secondary cell culture (all p < 0.0001). In summary, STMN1 expression may be of great value to clinical and pathological findings in therapeutic trials and deserves future studies in ACC.

TCF21 inhibits proliferation and chemoresistance through the AKT pathway in human gastric cancer

In a previous study, we showed that transcription factor 21 (TCF21) is methylated and downregulated in human gastric cancer samples and serves as an independent prognostic factor. However, its biological role and potential mechanism in gastric cancer cells remain unexplored. In the current study, we examined TCF21 expression in 6 gastric cancer cell lines. The BGC-823 and SGC-7901 cell lines were selected for small interfering RNA and plasmid transfection, respectively. The results of the Cell Counting Kit-8 assay demonstrated that TCF21 inhibited gastric cancer cell proliferation. Cell cycle analysis suggested that TCF21 inhibited cell cycle progression in gastric cancer cells. The Matrigel invasion assay demonstrated that TCF21 negatively regulated invasion. The cell adhesion assay showed that TCF21 increased cell adhesion. Gastric cancer cells were treated with cisplatin to explore the role of TCF21 in chemoresistance. Cell Counting Kit-8 assay and AnnexinV/propidium iodide analyses showed that TCF21 overexpression sensitized SGC-7901 cells to cisplatin, whereas its depletion reduced sensitivity in BGC-823 cells. JC-1 staining was performed to measure the effect of TCF21 on mitochondrial potential. TCF21 downregulated mitochondrial membrane potential after treatment with cisplatin. Western blot analysis showed that TCF21 overexpression negatively regulated Bcl-xL, phosphorylated extracellular signal regulated kinase, and phosphorylated AKT expression and induced caspase 3 cleavage. LY294002, an AKT inhibitor, blocked the effect of TCF21 on Bcl-xL, caspase 3 and CDDP-induced apoptosis. Nude mice experiments demonstrated that TCF21 inhibited gastric cancer growth in vivo. In conclusion, our results suggest that TCF21 inhibits gastric cancer growth and chemoresistance possibly through the AKT signaling pathway.

The human adrenal cortex: growth control and disorders

This review summarizes key knowledge regarding the development, growth, and growth disorders of the adrenal cortex from a molecular perspective. The adrenal gland consists of two distinct regions: the cortex and the medulla. During embryological development and transition to the adult adrenal gland, the adrenal cortex acquires three different structural and functional zones. Significant progress has been made in understanding the signaling and molecules involved during adrenal cortex zonation. Equally significant is the knowledge obtained regarding the action of peptide factors involved in the maintenance of zonation of the adrenal cortex, such as peptides derived from proopiomelanocortin processing, adrenocorticotropin and N-terminal proopiomelanocortin. Findings regarding the development, maintenance and growth of the adrenal cortex and the molecular factors involved has improved the scientific understanding of disorders that affect adrenal cortex growth. Hypoplasia, hyperplasia and adrenocortical tumors, including adult and pediatric adrenocortical adenomas and carcinomas, are described together with findings regarding molecular and pathway alterations. Comprehensive genomic analyses of adrenocortical tumors have shown gene expression profiles associated with malignancy as well as methylation alterations and the involvement of miRNAs. These findings provide a new perspective on the diagnosis, therapeutic possibilities and prognosis of adrenocortical disorders.

The molecular pathways underlying early gonadal development

The body of knowledge surrounding reproductive development spans the fields of genetics, anatomy, physiology and biomedicine, to build a comprehensive understanding of the later stages of reproductive development in humans and animal models. Despite this, there remains much to learn about the bi-potential progenitor structure that the ovary and testis arise from, known as the genital ridge (GR). This tissue forms relatively late in embryonic development and has the potential to form either the ovary or testis, which in turn produce hormones required for development of the rest of the reproductive tract. It is imperative that we understand the genetic networks underpinning GR development if we are to begin to understand abnormalities in the adult. This is particularly relevant in the contexts of disorders of sex development (DSDs) and infertility, two conditions that many individuals struggle with worldwide, with often no answers as to their aetiology. Here, we review what is known about the genetics of GR development. Investigating the genetic networks required for GR formation will not only contribute to our understanding of the genetic regulation of reproductive development, it may in turn open new avenues of investigation into reproductive abnormalities and later fertility issues in the adult.

Transcription factor 21 regulates expression of ERβ and SF-1 via upstream stimulatory factor-2 in endometriotic tissues

Steroidogenic factor-1 (SF-1, encoded by NR5A1) and estrogen receptor beta (ERβ, encoded by ESR2), which are highly expressed in endometriotic stromal cells (ESCs), contribute to the pathogenesis of endometriosis, but the regulation mechanism remains largely unknown. Transcription factor 21 (TCF21) belongs to the helix-loop-helix (bHLH) family characterized by regulating gene expression via binding to E-box element. Here, we attempted to determine the molecular mechanism of TCF21 on SF-1 and ERβ expression in endometriosis. We found that TCF21 expression in ESCs was higher than that in endometrial stromal cells (EMs), and positively correlated with SF-1 and ERβ expression in ESCs. Since the importance of E-box element for NR5A1 promoter activity has been previously reported, we performed site-mutation and luciferase assay, revealing that the E-box sequence in the ESR2 promoter is also a critical element modulating ERβ expression. Upstream stimulatory factor 2 (USF2) is another bHLH factor implicated in transcriptional regulation. Further analyses elucidated that it is not TCF21, but USF2 exhibited higher binding affinities in ESCs to NR5A1 and ESR2 promoters than in EMs. Additionally, TCF21 knockdown significantly decreased the binding activities of USF2 to NR5A1 and ESR2 promoters via disruption of the TCF21-USF2 complex. Meanwhile, manipulating TCF21 expression significantly affected MMP9 and cyclinD1 expression, as wells as proliferation and invasion of ESCs. Moreover, TCF21 depletion in endometriotic xenografts reduced SF-1 and ERβ expression, abrogating ectopic lesion growth in mice. Cumulatively, a critical role of TCF21 in the pathogenesis of endometriosis is demonstrated, suggesting a potential druggable target for future therapy.

Multiple biological functions of transcription factor 21 in the development of various cancers

Transcription factor 21 (TCF21) is a basic helix–loop–helix transcription factor that binds to DNA and regulates cell differentiation and cell fate specification through mesenchymal–epithelial transition during development. The TCF21 gene is epigenetically inactivated in many types of human cancers and exerts a wide variety of functions, including the regulation of epithelial–mesenchymal transition, invasion, metastasis, cell cycle, and autophagy. This review focuses on research progress in relation to the roles of TCF21 in tumor development. We systematically consider multiple pathological functions of TCF21 in various cancers, revealing the molecular bases of its diverse biological roles and providing new directions for future research.

The tyrosine kinase inhibitor nilotinib is more efficient than mitotane in decreasing cell viability in spheroids prepared from adrenocortical carcinoma cells

Background

New drugs for adrenocortical carcinoma (ACC) are needed because most patients undergo rapid disease progression despite surgery and adjuvant therapy with mitotane. In this study, we aimed to investigate the in vitro effects of different chemotherapy drugs, alone or combined with mitotane, on the viability of adrenocortical carcinoma cells.

Methods

Everolimus, sunitinib, zoledronic acid, imatinib and nilotinib cytotoxicity, alone or combined with mitotane were tested on ACC H295R cells in monolayer or spheroid cultures using MTS assays and confocal microscopy. Moreover, the nilotinib effects were investigated in spheroids cultured from patient tumor-derived ACC-T36 cells.

Results

Morphological characterization of H295R cell spheroids using histochemistry was performed and showed that dense, homogenously sized, multicellular spheroids were obtained. We observed that sunitinib and nilotinib alone were equally effective in a monolayer preparation, whereas mitotane was the most effective even at a low dose. A combination of sunitinib and mitotane was the most effective treatment, with only 23.8% of cells in the monolayer remaining viable. Spheroid preparations showed resistance to different drugs, although the poor effect produced by mitotane alone was surprising, with a cell viability of 84.6% in comparison with 13.1% in monolayer cells. The most ineffective drugs in spheroid preparations were everolimus, zoledronic acid and imatinib. In both cell types, nilotinib, either alone or in combination with mitotane induced more significant cell viability inhibition in monolayer and spheroid preparations. In addition, the mechanism of nilotinib activity involves the ERK1/2 pathway.

Conclusion

Taken together, our data identified nilotinib as a cytotoxic drug that combined with ERK inhibitors deserves to be tested as a novel therapy for adrenocortical carcinoma.

Sumoylation of TCF21 downregulates the transcriptional activity of estrogen receptor-alpha

Aberrant estrogen receptor-α (ERα) signaling is recognized as a major contributor to the development of breast cancer. However, the molecular mechanism underlying the regulation of ERα in breast cancer is still inconclusive. In this study, we showed that the transcription factor 21 (TCF21) interacted with ERα, and repressed its transcriptional activity in a HDACs-dependent manner. We also showed that TCF21 could be sumoylated by the small ubiquitin-like modifier SUMO1, and this modification could be reversed by SENP1. Sumoylation of TCF21 occurred at lysine residue 24 (K24). Substitution of K24 with arginine resulted in complete abolishment of sumoylation. Sumoylation stabilized TCF21, but did not affect its subcellular localization. Sumoylation of TCF21 also enhanced its interaction with HDAC1/2 without affecting its interaction with ERα. Moreover, sumoylation of TCF21 promoted its repression of ERα transcriptional activity, and increased the recruitment of HDAC1/2 to the pS2 promoter. Consistent with these observations, sumoylation of TCF21 could inhibit the growth of ERα-positive breast cancer cells and decreased the proportion of S-phase cells in the cell cycle. These findings suggested that TCF21 might act as a negative regulator of ERα, and its sumoylation inhibited the transcriptional activity of ERα through promoting the recruitment of HDAC1/2.

TCF21/POD-1, a Transcritional Regulator of SF-1/NR5A1, as a Potential Prognosis Marker in Adult and Pediatric Adrenocortical Tumors

With recent progress in understanding the pathogenesis of adrenocortical tumors (ACTs), identification of molecular markers to predict their prognosis has become possible. Transcription factor 21 (TCF21)/podocyte-expressed 1 (POD1) is a transcriptional regulatory protein expressed in mesenchymal cells at sites of epithelial-mesenchymal transition during the development of different systems. Adult carcinomas express less TCF21 than adenomas, in addition, the KEGG pathway analysis has shown that BUB1B, among others genes, is negatively correlated with TCF21 expression. The difference between BUB1B and PTEN-induced putative kinase 1 (PINK1) expression has been described previously to be associated with survival in adult but not in pediatric carcinomas. Here, we analyzed the gene expression of TCF21, BUB1B, PINK1, and NR5A1 in adult and pediatric ACTs. We found a negative correlation between the relative expression levels of TCF21 and BUB1B in adult ACTs, but the relative expression levels of TCF21, BUB1B, PINK1, and NR5A1 were similar in childhood ACTs. In addition, we propose using the subtracted expression levels of the TCF21/POD-1 genes as a predictor of overall survival (OS) in adult carcinomas and TCF21-NR5A1 as a predictor of malignancy for pediatric tumors in patients aged <5 years. These results require further validation in different cohorts of both adult and pediatric samples. Finally, we observed that the OS for patients aged <5 years was markedly favorable compared with that for patients >5 years as well as adult patients with carcinoma. In summary, we propose TCF21/POD-1 as a new prognostic marker in adult and pediatric ACTs.

New evidences on the regulation of SF-1 expression by POD1/TCF21 in adrenocortical tumor cells

OBJECTIVES:

Transcription Factor 21 represses steroidogenic factor 1, a nuclear receptor required for gonadal development, sex determination and the regulation of adrenogonadal steroidogenesis. The aim of this study was to investigate whether silencing or overexpression of the gene Transcription Factor 21 could modulate the gene and protein expression of steroidogenic factor 1 in adrenocortical tumors.

METHODS:

We analyzed the gene expression of steroidogenic factor 1 using qPCR after silencing endogenous Transcription Factor 21 in pediatric adrenal adenoma-T7 cells through small interfering RNA. In addition, using overexpression of Transcription Factor 21 in human adrenocortical carcinoma cells, we analyzed the protein expression of steroidogenic factor 1 using Western blotting.

RESULTS:

Transcription Factor 21 knockdown increased the mRNA expression of steroidogenic factor 1 by 5.97-fold in pediatric adrenal adenoma-T7 cells. Additionally, Transcription Factor 21 overexpression inhibited the protein expression of steroidogenic factor 1 by 0.41-fold and 0.64-fold in two different adult adrenocortical carcinoma cell cultures, H295R and T36, respectively.

CONCLUSIONS:

Transcription Factor 21 is downregulated in adrenocortical carcinoma cells. Taken together, these findings support the hypothesis that Transcription Factor 21 is a regulator of steroidogenic factor 1 and is a tumor suppressor gene in pediatric and adult adrenocortical tumors.

Unraveling the expression of the oncogene YAP1, a Wnt/beta-catenin target, in adrenocortical tumors and its association with poor outcome in pediatric patients

BACKGROUND

Overexpression of the oncogene yes-associated-protein-1 (YAP1) is associated with increased cell proliferation in human cancers. YAP1 is a potential target of the Wnt/beta-catenin pathway, which plays an important role in adrenocortical tumors (ACT). The role of YAP1 in adrenocortical tumorigenesis has not been assessed.

AIMS

To evaluate YAP1 expression in normal adrenals and pediatric ACT and its association with disease outcome. To investigate the interaction between YAP1 and the Wnt/beta-catenin pathway in adrenocortical cells.

RESULTS

Strong YAP1 staining was present in fetal adrenals and pediatric ACT but weak in postnatal adrenals. In pediatric ACT, YAP1 mRNA overexpression was associated with death, recurrent/metastatic disease and lower overall survival. The inhibition of the Wnt/beta-catenin pathway increased YAP1 mRNA expression. siYAP1 increased CTNNB1/beta-catenin expression and nuclear staining regardless of DLV2, moreover, it decreased cell growth and impaired cell migration.

MATERIALS AND METHODS

We assessed in 42 pediatric ACT samples the YAP1 protein expression by immunohistochemistry and mRNA expression by RT-qPCR and analyzed their association with outcome. As controls, we resort 32 fetal and postnatal normal adrenals for IHC and 10 normal adrenal cortices for RT-qPCR. The interaction between YAP1 and the Wnt/beta-catenin pathway was assessed in NCI-H295 adrenocortical cells by inhibiting the TCF/beta-catenin complex and by knocking down YAP1.

CONCLUSION

YAP1 overexpression is a marker of poor prognosis for pediatric patients with ACT. In adrenocortical cells, there is a close crosstalk between YAP1 and Wnt/beta-catenin. These data open the possibility of future molecular therapies targeting Hippo/YAP1 signaling to treat advanced ACT.

Inhibition of the Tcf/beta-catenin complex increases apoptosis and impairs adrenocortical tumor cell proliferation and adrenal steroidogenesis

Background

To date, there is no effective therapy for patients with advanced/metastatic adrenocortical cancer (ACC). The activation of the Wnt/beta-catenin signaling is frequent in ACC and this pathway is a promising therapeutic target.

Aim

To investigate the effects of the inhibition of the Wnt/beta-catenin in ACC cells.

Methods

Adrenal (NCI-H295 and Y1) and non-adrenal (HeLa) cell lines were treated with PNU-74654 (5–200 μM) for 24–96 h to assess cell viability (MTS-based assay), apoptosis (Annexin V), expression/localization of beta-catenin (qPCR, immunofluorescence, immunocytochemistry and western blot), expression of beta-catenin target genes (qPCR and western blot), and adrenal steroidogenesis (radioimmunoassay, qPCR and western blot).

Results

In NCI-H295 cells, PNU-74654 significantly decreased cell proliferation 96 h after treatment, increased early and late apoptosis, decreased nuclear beta-catenin accumulation, impaired CTNNB1/beta-catenin expression and increased beta-catenin target genes 48 h after treatment. No effects were observed on HeLa cells. In NCI-H295 cells, PNU-74654 decreased cortisol, testosterone and androstenedione secretion 24 and 48 h after treatment. Additionally, in NCI-H295 cells, PNU-74654 decreased SF1 and CYP21A2 mRNA expression as well as the protein levels of STAR and aldosterone synthase 48 h after treatment. In Y1 cells, PNU-74654 impaired corticosterone secretion 24 h after treatment but did not decrease cell viability.

Conclusions

Blocking the Tcf/beta-catenin complex inhibits the Wnt/beta-catenin signaling in adrenocortical tumor cells triggering increased apoptosis, decreased cell viability and impairment of adrenal steroidogenesis. These promising findings pave the way for further experiments inhibiting the Wnt/beta-catenin pathway in pre-clinical models of ACC. The inhibition of this pathway may become a promising adjuvant therapy for patients with ACC.

POD-1/Tcf21 overexpression reduces endogenous SF-1 and StAR expression in rat adrenal cells

During gonad and adrenal development, the POD-1/capsulin/TCF21transcription factor negatively regulates SF-1/NR5A1expression, with higher SF-1 levels being associated with increased adrenal cell proliferation and tumorigenesis. In adrenocortical tumor cells, POD-1 binds to the SF-1 E-box promoter region, decreasing SF-1 expression. However, the modulation of SF-1 expression by POD-1 has not previously been described in normal adrenal cells. Here, we analyzed the basal expression of Pod-1 and Sf-1 in primary cultures of glomerulosa (G) and fasciculata/reticularis (F/R) cells isolated from male Sprague-Dawley rats, and investigated whether POD-1 overexpression modulates the expression of endogenous Sf-1 and its target genes in these cells. POD-1 overexpression, following the transfection of pCMVMycPod-1, significantly decreased the endogenous levels of Sf-1 mRNA and protein in F/R cells, but not in G cells, and also decreased the expression of the SF-1 target StAR in F/R cells. In G cells overexpressing POD-1, no modulation of the expression of SF-1 targets, StAR and CYP11B2, was observed. Our data showing that G and F/R cells respond differently to ectopic POD-1 expression emphasize the functional differences between the outer and inner zones of the adrenal cortex, and support the hypothesis that SF-1 is regulated by POD-1/Tcf21 in normal adrenocortical cells lacking the alterations in cellular physiology found in tumor cells.

POD-1/TCF21 Reduces SHP Expression, Affecting LRH-1 Regulation and Cell Cycle Balance in Adrenocortical and Hepatocarcinoma Tumor Cells

POD-1/TCF21 may play a crucial role in adrenal and gonadal homeostasis and represses Sf-1/SF-1 expression in adrenocortical tumor cells. SF-1 and LRH-1 are members of the Fzt-F1 subfamily of nuclear receptors. LRH-1 is involved in several biological processes, and both LRH-1 and its repressor SHP are involved in many types of cancer. In order to assess whether POD-1 can regulate LRH-1 via the same mechanism that regulates SF-1, we analyzed the endogenous mRNA levels of POD-1, SHP, and LRH-1 in hepatocarcinoma and adrenocortical tumor cells using qRT-PCR. Hereafter, these tumor cells were transiently transfected with pCMVMycPod-1, and the effect of POD-1 overexpression on E-box elements in the LRH-1 and SHP promoter region were analyzed by ChIP assay. Also, Cyclin E1 protein expression was analyzed to detect cell cycle progression. We found that POD-1 overexpression significantly decreased SHP/SHP mRNA and protein levels through POD-1 binding to the E-box sequence in the SHP promoter. Decreased SHP expression affected LRH-1 regulation and increased Cyclin E1. These findings show that POD-1/TCF21 regulates SF-1 and LRH-1 by distinct mechanisms, contributing to the understanding of POD-1 involvement and its mechanisms of action in adrenal and liver tumorigenesis, which could lead to the discovery of relevant biomarkers.

Steroidogenic organ development and homeostasis: A WT1-centric view

Adrenal and gonads are the main steroidogenic organs and are central to regulate body homeostasis in the vertebrate organism. Although adrenals and gonads are physically separated in the adult organism, both organs share a common developmental origin, the adrenogonadal primordium. One of the key genes involved in the development of both organs is the Wilms' tumor suppressor WT1, which encodes a zinc finger protein that has fascinated the scientific community for more than two decades. This review will provide an overview of the processes leading to the development of these unique organs with a particular focus on the multiple functions WT1 serves during adrenogonadal development. In addition, we will highlight some recent findings and open questions on how maintenance of steroidogenic organs is achieved in the adult organism.

WT1 maintains adrenal-gonadal primordium identity and marks a population of AGP-like progenitors within the adrenal gland

Adrenal glands and gonads share a common primordium (AGP), but the molecular events driving differentiation are poorly understood. Here we demonstrate that the Wilms tumor suppressor WT1 is a key factor defining AGP identity by inhibiting the steroidogenic differentiation process. Indeed, ectopic expression of WT1 precludes differentiation into adrenocortical steroidogenic cells by locking them into a progenitor state. Chromatin immunoprecipitation experiments identify Tcf21 and Gli1 as direct targets of WT1. Moreover, cell lineage tracing analyses identify a long-living progenitor population within the adrenal gland, characterized by the expression of WT1, GATA4, GLI1, and TCF21, that can generate steroidogenic cells in vivo. Strikingly, gonadectomy dramatically activates these WT1(+) cells and leads to their differentiation into gonadal steroidogenic tissue. Thus, our data describe a mechanism of response to organ loss by recreating hormone-producing cells at a heterotopic site.

Fetal adrenal capsular cells serve as progenitor cells for steroidogenic and stromal adrenocortical cell lineages in M. musculus

The lineage relationships of fetal adrenal cells and adrenal capsular cells to the differentiated adrenal cortex are not fully understood. Existing data support a role for each cell type as a progenitor for cells of the adult cortex. This report reveals that subsets of capsular cells are descendants of fetal adrenocortical cells that once expressed Nr5a1. These fetal adrenocortical cell descendants within the adrenal capsule express Gli1, a known marker of progenitors of steroidogenic adrenal cells. The capsule is also populated by cells that express Tcf21, a known inhibitor of Nr5a1 gene expression. We demonstrate that Tcf21-expressing cells give rise to Nr5a1-expressing cells but only before capsular formation. After the capsule has formed, capsular Tcf21-expressing cells give rise only to non-steroidogenic stromal adrenocortical cells, which also express collagen 1a1, desmin and platelet-derived growth factor (alpha polypeptide) but not Nr5a1. These observations integrate prior observations that define two separate origins of adult adrenocortical steroidogenic cells (fetal adrenal cortex and/or the adrenal capsule). Thus, these observations predict a unique temporal and/or spatial role of adult cortical cells that arise directly from either fetal cortical cells or from fetal cortex-derived capsular cells. Last, the data uncover the mechanism by which two populations of fetal cells (fetal cortex derived Gli1-expressing cells and mesenchymal Tcf21-expressing mesenchymal cells) participate in the establishment of the homeostatic capsular progenitor cell niche of the adult cortex.