Impact of FOXL2 mutations on signaling in ovarian granulosa cell tumors

Role of ERβ in the ovary and ovary related diseases

Estrogen and estrogen receptors (ERα and ERβ) regulate a multitude of complicated physiological and pathological processes. Jan-Ake Gustafsson's group discovered ERβ in 1996, this crucial finding gives us new insights into the understanding of estrogen signaling. ERβ is highly expressed in the ovary and particularly exists in granulosa cells (GCs). ERβ is a key transcription factor in the maintenance of ovarian granulosa cell growth, differentiation, and homeostasis, and the ovulation function of ovarian follicles and oocytes. Additionally, ERβ can modulate the steroidogenic transcriptional program through phosphorylation and regulate both gonadotropin response and FOXL2 expression within the ovary. In this review, we focus on the role of ERβ in regulating ovarian granulosa cell development and homeostasis, particularly its significance in ovarian cancer (OC), premature ovarian failure (POF), and polycystic ovary syndrome (PCOS). It also highlights the prospects of small molecule compounds targeting ERβ, providing a new strategy for the treatment of ovarian-related diseases.

Sertoli Cell-Specific Activation of Transforming Growth Factor Beta Receptor 1 Leads to Testicular Granulosa Cell Tumor Formation

The transforming growth factor β (TGFβ) superfamily, consisting of protein ligands, receptors, and intracellular SMAD transducers, regulates fundamental biological processes and cancer development. Our previous study has shown that sustained activation of TGFβ receptor 1 (TGFBR1) driven by anti-Mullerian hormone receptor type 2 (Amhr2)-Cre in the mouse testis induces the formation of testicular granulosa cell tumors (TGCTs). As Amhr2-Cre is expressed in both Sertoli cells and Leydig cells, it remains unclear whether the activation of TGFBR1 in Sertoli cells alone is sufficient to induce TGCT formation. Therefore, the objective of this study was to determine whether Sertoli cell-activation of TGFBR1 drives oncogenesis in the testis. Our hypothesis was that overactivation of TGFBR1 in Sertoli cells would promote their transdifferentiation into granulosa-like cells and the formation of TGCTs. To test this hypothesis, we generated mice harboring constitutive activation of TGFBR1 in Sertoli cells using anti-Mullerian hormone (Amh)-Cre. Disorganized seminiferous tubules and tumor nodules were found in TGFBR1CA; Amh-Cre mice. A histological analysis showed that Sertoli cell-specific activation of TGFBR1 led to the development of neoplasms resembling granulosa cell tumors, which derailed spermatogenesis. Moreover, TGCTs expressed granulosa cell markers including FOXL2, FOXO1, and INHA. Using a dual fluorescence reporter line, the membrane-targeted tdTomato (mT)/membrane-targeted EGFP (mG) mouse, we provided evidence that Sertoli cells transdifferentiated toward a granulosa cell fate during tumorigenesis. Thus, our findings indicate that Sertoli cell-specific activation of TGFBR1 leads to the formation of TGCTs, supporting a key contribution of Sertoli cell reprogramming to the development of this testicular malignancy in our model.

Developments in Genetics: Better Management of Ovarian Cancer Patients

The purpose of this article is to highlight the new advancements in molecular and diagnostic genetic testing and to properly classify all ovarian cancers. In this article, we address statistics, histopathological classification, molecular pathways implicated in ovarian cancer, genetic screening panels, details about the genes, and also candidate genes. We hope to bring new information to the medical field so as to better prevent and diagnose ovarian cancer.

Forkhead box L2 is a target of miR-133b and plays an important role in the pathogenesis of non-small cell lung cancer

BACKGROUND

Forkhead box L2 (FOXL2) has been recognized as a transcription factor in the progression of many malignancies, but its role in non-small cell lung cancer (NSCLC) remains unclear. This research clarified on the role of FOXL2 and the specific molecular mechanism in NSCLC.

METHODS

RNA and protein levels were detected by quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting assays. Cell proliferation was examined by cell counting kit-8 (CCK-8) and clonogenic assays. Transwell and wound healing assays were used to detect cell invasion and migration. Cell cycle alterations were assessed by flow cytometry. The relationship between FOXL2 and miR-133b was verified by dual-luciferase reporter assays. In vivo metastasis was monitored in the tail vein-injected mice.

RESULTS

FOXL2 was upregulated in NSCLC cells and tissues. Downregulation of FOXL2 restrained cell proliferation, migration, and invasion and arrested the cell cycle of NSCLC cells. Moreover, FOXL2 promoted the epithelial-mesenchymal transition (EMT) process of NSCLC cells by inducing the transforming growth factor-β (TGF-β)/Smad signaling pathway. miR-133b directly targeted the 3'-UTR of FOXL2 and negatively regulated FOXL2 expression. Knockdown of FOXL2 blocked metastasis in vivo.

CONCLUSIONS

miR-133b downregulates FOXL2 by targeting the 3'-UTR of FOXL2, thereby inhibiting cell proliferation, EMT and metastasis induced by the TGF-β/Smad signaling pathway in NSCLC. FOXL2 may be a potential molecular target for treating NSCLC.

Fertility Sparing Surgery in Young Woman With Granulosa Cell Tumor Followed by a Successful Pregnancy

An uncommon form of cancer known as a granulosa cell tumor (GCT) arises from ovarian sex cord cells that produce estrogen. The goal of conservative surgery in cancer is to retain organ functions while avoiding severe excision wherever possible. In oncologic gynecological surgery, fertility-sparing surgery (FSS) is a technique that tries to preserve the uterus and ovarian tissue. A 26-year-old woman with nulligravida presented with the main complaints of pain in the right iliac fossa for 10 to 15 days and fullness in the abdomen for one month, along with a change in appetite and noticeable weight loss. The Magnetic Resonance Imaging (MRI) revealed a large, well-defined, multiloculated, solid cystic mass with altered signal intensity. On exploratory laparotomy, an intraoperatively left ovarian cystic mass was seen. The ovarian mass was histopathologically diagnosed as a sex cord tumor of the ovary, with characteristics compatible with adult GCT. Disregarding the follow-up advice on discharge four months later, the patient conceived spontaneously and gave birth to a male child via emergency lower segment cesarean section. In GCTs that have not spread beyond the ovary or in people who have had relapses of the disease, FSS created the groundwork for conception and appeared safe. In the lack of any compelling supporting evidence, the line of care of terminal surgery should always be thoroughly discussed with the patient and advised for women after their families are complete.

A case series of triplet anti-hormonal therapy in androgen receptor-positive recurrent adult ovarian granulosa cell tumor

Therapeutic options for recurrent adult granulosa cell tumors (AGCT) are limited. After examining the hormonal pathways involved in FOXL2-mutated granulosa cell tumor development, a novel treatment regimen was utilized for recurrent AGCT: a combination of an androgen receptor antagonist, a gonadotropin-releasing hormone receptor agonist, and an aromatase inhibitor for hormonal blockade. In this case series, seven patients at our institution were treated with bicalutamide 50 mg orally once daily, Leuprolide acetate 7.5 mg intramuscular (IM) injection every 4 weeks, and a daily oral aromatase inhibitor. These patients had recurrent AGCT with androgen receptor positive tumors and had failed prior aromatase inhibitor therapy. All patients had undergone multiple surgical resections and many cycles of chemotherapy. Patients were monitored for toxicities and for response to treatment. Of the seven patients receiving the triple therapy, six saw clinical benefit. Two patients demonstrated a partial response and four patients had stable disease. One patient had progressive disease on the regimen. For the two patients who had a partial response to the triple therapy, there was strong expression of the androgen receptor (AR) noted on tumor immunohistochemistry. This drug combination was well-tolerated except for severe hot flashes in one patient. In conclusion, the triple therapy combination of an androgen receptor antagonist, aromatase inhibitor, and GnRH agonist demonstrated measurable responses in patients with recurrent AGCTs after multiple previous treatments. A prospective clinical trial is planned to further investigate these findings.

Serum FSH as a Useful Marker for the Differential Diagnosis of Ovarian Granulosa Cell Tumors

Background: We evaluated whether the serum hormone levels are useful in the differential diagnosis of granulosa cell tumors (GCTs), regardless of menopausal status. Methods: Serum levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH), testosterone, estradiol, and progesterone were measured preoperatively in all patients (n = 471) who underwent surgery for ovarian tumors at Chiba University Hospital between 2009 and 2021. These were compared in two groups, a GCT group (n = 13) and a group with other histological types (non-GCT) (n = 458). Results: The GCT group had significantly lower serum LH and FSH (p = 0.03 and p < 0.001, respectively) and significantly higher testosterone, estradiol, and progesterone (p < 0.001, p < 0.001, and p = 0.045, respectively) than the non-GCT group. Multivariate analysis revealed that serum FSH and estradiol were significantly associated with GCT (FSH, odds ratio (OR) = 0.0046, 95% confidence interval (CI) = 0.0026−0.22, p = 0.004; estradiol, OR = 0.98, 95% CI = 0.96−0.998, p = 0.046). Receiver-operating characteristic curve analysis for GCTs showed that the area under the curve of serum FSH was 0.99, with a sensitivity of 100% and a specificity of 98%, when the cutoff level was set at 2.0 IU/L. Conclusions: Preoperative serum FSH level is an extremely useful marker for differentiating GCTs from all ovarian tumors.

Targeted Next-Generation Sequencing of Thymic Epithelial Tumours Revealed Pathogenic Variants in KIT, ERBB2, KRAS, and TP53 in 30% of Thymic Carcinomas

Simple Summary

The biology of thymic epithelial tumours (TETs), including thymomas and thymic carcinomas, and particularly the extent of molecular dysregulation, is poorly understood. Through next-generation sequencing of 15 genes implicated in common solid tumours in 53 TETs, we found a larger number of single nucleotide variants (SNVs) in thymic carcinomas than thymomas. About 30% of thymic carcinomas had at least one somatic pathogenic gene variant in TP53, ERBB2, KIT, or KRAS, whereas variants of uncertain clinical significance in KIT, ERBB2, and FOXL2 were found exclusively in thymomas. The presence of somatic pathogenic variants was non-significantly associated with shorter disease-free survival in thymic carcinoma patients. No somatic pathogenic or likely pathogenic SNV was found in thymomas. Importantly, we also evaluated germline SNVs, adding to the number of known genetic alterations in TETs and thereby enhancing our molecular understanding of these neoplasms.

Abstract

A better understanding of the molecular pathogenesis of thymic epithelial tumours (TETs) could revolutionise their treatment. We evaluated thymomas and thymic carcinomas by next-generation sequencing (NGS) of somatic or germline single nucleotide variants (SNVs) in genes commonly mutated in solid tumours. In total, 19 thymomas and 34 thymic carcinomas were analysed for nonsynonymous SNVs in 15 genes by targeted NGS (reference genome: hg19/GRCh37). Ten SNVs in TP53 (G154V, R158P, L194H, R267fs, R273C, R306 *, Q317 *), ERBB2 (V773M), KIT (L576P), and KRAS (Q61L) considered somatic and pathogenic/likely pathogenic were detected in 10 of 34 (29.4%) thymic carcinomas. No somatic SNVs confirmed as pathogenic/likely pathogenic were found in thymomas. Rare SNVs of uncertain or unknown functional and clinical significance, to our knowledge not reported previously in TETs, were found in ERBB2 (S703R), KIT (I690V), and FOXL2 (P157S) in 3 of 19 (16%) thymomas. The most frequent germline SNVs were TP53 P72R (94% TETs), ERBB2 I655V (40% TETs), and KIT M541L (9% TETs). No significant difference in median disease-free survival (DFS) was found between thymic carcinoma patients with and without pathogenic SNVs (p = 0.190); however, a trend toward a longer DFS was observed in the latter (16.0 vs. 30.0 months, respectively). In summary, NGS analysis of TETs revealed several SNVs in genes related to the p53, AKT, MAPK, and K-Ras signalling pathways. Thymic carcinomas showed greater genetic dysregulation than thymomas. The germline and rare SNVs of uncertain clinical significance reported in this study add to the number of known genetic alterations in TETs, thus extending our molecular understanding of these neoplasms. Druggable KIT alterations in thymic carcinomas have potential as therapeutic targets.

FOXL2 regulates the expression of the Col4a1 collagen gene in chicken granulosa cells

Forkhead box L2 (FOXL2), one member in the superfamily of forkhead transcription factors, is a core transcription factor specifically expressed in ovarian granulosa cells and is essential for the development of follicles. FOXL2 has been shown to regulate the transcription of genes encoding enzymes that synthesize steroid hormones and estrogen receptors and regulate the expression of collagen genes in granulosa cells. This study explored the effect of FOXL2 on collagen gene expression in granulosa cells by overexpressing Foxl2 in pregranulosa cells, prehierarchical follicles and preovulation follicle granulosa cells. The results showed that FOXL2 regulated the expression of several genes encoding collagens in chicken granulosa cells and that overexpression of Foxl2 significantly reduced the messenger RNA and protein levels of Col4a1 in different granulosa cells. Moreover, luciferase reporter and chromatin immunoprecipitation assays were performed to study how FOXL2 regulates the expression of collagen genes, and the results showed that FOXL2 directly regulated the expression of Col4a1 by binding to the motif of CAGCAGCACCAGCAG between -640 and -625 bp upstream of the coding region. The results indicated that FOXL2 could regulate the components of the extracellular matrix; however, the biological significance of this regulation needs further clarification.

Effects of Sex Steroid Receptor Agonists and Antagonists on the Expression of the FOXL2 Transcription Factor and its Target Genes AMH and CYP19A1 in the Neonatal Porcine Ovary

Recently, we have demonstrated that neonatal exposure to androgen and estrogen agonists or antagonists influenced the number of ovarian follicles in piglets. Since the FOXL2 transcription factor is required for proper ovarian follicle formation and activation, the objective of the study was to examine effects of exposure of the neonatal porcine ovary to testosterone propionate (TP; an androgen), flutamide (FLU; an antiandrogen), 4-tert-octylphenol (OP; compound with estrogenic activity), ICI 182,780 (ICI; an antiestrogen), and methoxychlor (MXC; compound with estrogenic, antiestrogenic and antiandrogenic properties) on FOXL2 expression and expression of its target genes, AMH and CYP19A1. Piglets were injected subcutaneously with TP, FLU, OP, ICI, MXC, or corn oil (control) between postnatal days 1 and 10 (n = 4/each group). Ovaries were excised from the 11-day-old piglets and the expression of FOXL2, AMH and CYP19A1 was examined using immunohistochemistry and/or real-time PCR and Western blot. FOXL2 was localized in stroma cells surrounding egg nests and in granulosa cells. TP, OP and MXC increased both FOXL2 and AMH mRNAs, while FLU and ICI decreased CYP19A1 mRNA. The increased FOXL2 protein abundance was found in all examined groups. In addition, TP, OP, ICI and MXC increased AMH protein abundance, while TP, FLU and OP decreased CYP19A1 protein abundance. In conclusion, neonatal exposure to sex steroid receptor agonists and antagonists increased FOXL2 expression at mRNA and/or protein levels and affected FOXL2 target genes in the ovaries of 11-day-old piglets. Therefore, it seems that impaired ovarian folliculogenesis induced by altered steroid milieu during the neonatal development period in pigs may, at least in part, involve FOXL2.

Estradiol Signaling at the Heart of Folliculogenesis: Its Potential Deregulation in Human Ovarian Pathologies

Estradiol (E2) is a major hormone controlling women fertility, in particular folliculogenesis. This steroid, which is locally produced by granulosa cells (GC) within ovarian follicles, controls the development and selection of dominant preovulatory follicles. E2 effects rely on a complex set of nuclear and extra-nuclear signal transduction pathways principally triggered by its nuclear receptors, ERα and ERβ. These transcription factors are differentially expressed within follicles, with ERβ being the predominant ER in GC. Several ERβ splice isoforms have been identified and display specific structural features, which greatly complicates the nature of ERβ-mediated E2 signaling. This review aims at providing a concise overview of the main actions of E2 during follicular growth, maturation, and selection in human. It also describes the current understanding of the various roles of ERβ splice isoforms, especially their influence on cell fate. We finally discuss how E2 signaling deregulation could participate in two ovarian pathogeneses characterized by either a follicular arrest, as in polycystic ovary syndrome, or an excess of GC survival and proliferation, leading to granulosa cell tumors. This review emphasizes the need for further research to better understand the molecular basis of E2 signaling throughout folliculogenesis and to improve the efficiency of ovarian-related disease therapies.

FOXL2C134W : much ado about something!†

Recent studies have suggested that the unique FOXL2^C134W mutation, which is pathognomonic for adult granulosa cell tumours of the ovary, is a tumour suppressor gene. In a recent issue of The Journal of Pathology, a detailed study by Pilsworth et al seeks to rebut the proposition that the FOXL2^C134W mutation, which uniquely characterises adult granulosa cell tumours of the ovary, leads to reduced transcript levels with the implication that FOXL2 is a tumour suppressor gene. The study provides compelling evidence that both wild-type and mutant FOXL2 transcripts and protein are expressed at equivalent levels. In the context of other recent studies, one is drawn to the conclusion that FOXL2^C134W is a gain-of-function mutation whose impact is mediated through enhanced interactions with the SMAD transcription factor complex. © 2021 The Pathological Society of Great Britain and Ireland.

A phase 2 study of anastrozole in patients with oestrogen receptor and/progesterone receptor positive recurrent/metastatic granulosa cell tumours/sex-cord stromal tumours of the ovary: The PARAGON/ANZGOG 0903 trial

BACKGROUND

Hormonal therapies are commonly prescribed to patients with metastatic granulosa cell tumours (GCT), based on high response rates in small retrospective studies. Aromatase inhibitors (AIs) are reported to have high response rates and an accepted treatment option. We report the results of a phase 2 trial of an AI in recurrent/metastatic GCTs.

METHODS

41 patients with recurrent ER/PR + ve GCT received anastrozole 1 mg daily until progression or unacceptable toxicity. The primary endpoint was clinical benefit rate (CBR) at 12 weeks, evaluated by RECIST1.1 criteria. Secondary endpoints included progression-free survival (PFS), CBR duration, quality of life and toxicity.

RESULTS

The CBR at 12 weeks in 38 evaluable patients was 78.9%, which included one (2.6%; 95% CI: 0.5-13.5%) partial response and 76.3% stable disease. Two additional patients without measurable disease were stable, based on inhibin. Median PFS was 8.6 m (95% CI 5.5-13.5 m). There were delayed responses observed after 12 weeks with a total of 4 pts. (10.5%; 95% CI 4.2%-24.1%) with a RECIST partial response; 23 (59%) patients were progression-free at 6 months. The adverse effects were predominantly low grade.

CONCLUSIONS

This is the first prospective trial of hormonal therapy in GCTs. Although there was a high CBR, the objective response rate to anastrozole was much lower than the pooled response rates of >70% to AIs reported in most retrospective series and case reports. PARAGON demonstrates the importance of prospective trials in rare cancers and the need to reconsider the role of AIs as single agents in GCTs.

Progress in the management of ovarian granulosa cell tumor: A review

Ovarian granulosa cell tumor (GCT) is a rare, low-grade malignant tumor that accounts for 70% of the sex cord-stromal tumors. It has two histopathologic types with different clinical and biologic features: adult GCT and juvenile GCT. Most women diagnosed with the adult GCT have a favorable prognosis, with a 5-year survival rate of 97%-98%, but adult GCT has a feature of late relapse; the recurrence time could be more than 20 years after diagnosis. Juvenile GCT has a survival rate of 97% in stage I and a 5-year survival rate of 0%-22% in advanced stage with earlier recurrence than adult GCT. Consequently, the scenario emphasizes the need for early diagnosis, standardized treatment protocols, and long-term follow up. However, there is a lack of consensus regarding accurate diagnosis of GCT and adjuvant treatment. Furthermore, GCT tends to occur in young women, which emphasizes the viability of fertility-sparing surgery. The current review performed a systematic literature review of 60 articles to summarize the latest advances in GCT, with an emphasis on the molecular pathogenesis and survival after fertility-sparing surgery. We found that young women with fertility-sparing surgery had a desirable reproductive and survival outcome compared with those undergoing radical surgery.

The Genetic and Clinical Features of FOXL2-Related Blepharophimosis, Ptosis and Epicanthus Inversus Syndrome

Blepharophimosis, ptosis, and epicanthus inversus syndrome (BPES) is a craniofacial disorder caused by heterozygous variants of the forkhead box L2 (FOXL2) gene. It shows autosomal dominant inheritance but can also occur sporadically. Depending on the mutation, two phenotypic subtypes have been described, both involving the same craniofacial features: type I, which is associated with premature ovarian failure (POF), and type II, which has no systemic features. The genotype-phenotype correlation is not fully understood, but it has been hypothesised that type I BPES involves more severe loss of function variants spanning the whole gene. Type II BPES has been linked to frameshift mutations that result in elongation of the protein rather than complete loss of function. A mutational hotspot has been identified within the poly-alanine domain, although the exact function of this region is still unknown. However, the BPES subtype cannot be determined genetically, necessitating informed genetic counselling and careful discussion of family planning advice in view of the associated POF particularly as the patient may still be a child. Following puberty, female patients should be referred for ovarian reserve and response assessment. Oculofacial features can be managed with surgical intervention and regular monitoring to prevent amblyopia.

FOXO1 mitigates the SMAD3/FOXL2C134W transcriptomic effect in a model of human adult granulosa cell tumor

BACKGROUND

Adult granulosa cell tumor (aGCT) is a rare type of stromal cell malignant cancer of the ovary characterized by elevated estrogen levels. aGCTs ubiquitously harbor a somatic mutation in FOXL2 gene, Cys134Trp (c.402C < G); however, the general molecular effect of this mutation and its putative pathogenic role in aGCT tumorigenesis is not completely understood. We previously studied the role of FOXL2C134W, its partner SMAD3 and its antagonist FOXO1 in cellular models of aGCT.

METHODS

In this work, seeking more comprehensive profiling of FOXL2C134W transcriptomic effects, we performed an RNA-seq analysis comparing the effect of FOXL2WT/SMAD3 and FOXL2C134W/SMAD3 overexpression in an established human GC line (HGrC1), which is not luteinized, and bears normal alleles of FOXL2.

RESULTS

Our data shows that FOXL2C134W/SMAD3 overexpression alters the expression of 717 genes. These genes include known and novel FOXL2 targets (TGFB2, SMARCA4, HSPG2, MKI67, NFKBIA) and are enriched for neoplastic pathways (Proteoglycans in Cancer, Chromatin remodeling, Apoptosis, Tissue Morphogenesis, Tyrosine Kinase Receptors). We additionally expressed the FOXL2 antagonistic Forkhead protein, FOXO1. Surprisingly, overexpression of FOXO1 mitigated 40% of the altered genome-wide effects specifically related to FOXL2C134W, suggesting it can be a new target for aGCT treatment.

CONCLUSIONS

Our transcriptomic data provide novel insights into potential genes (FOXO1 regulated) that could be used as biomarkers of efficacy in aGCT patients.

The role of FOXL2, SOX9, and β-catenin expression and DICER1 mutation in differentiating sex cord tumor with annular tubules from other sex cord tumors of the ovary

Sex cord tumor with annular tubules (SCTAT) is a highly rare type of ovarian sex cord-stromal tumor (SCST), the diagnosis of which remains to be challenging. The aim of this study was to scrutinize the utility of three immunohistochemical markers including Forkhead box protein 2 (FOXL2), SOX9, and β-catenin and DICER1 mutation status in distinguishing SCTATs from other ovarian SCSTs. Nine cases of SCTAT, 10 Sertoli-Leydig cell tumor (SCLT), 10 adult-type granulosa cell tumor (AGCT), and 8 juvenile-type granulosa cell tumor (JGCT) were included in the study. SCTATs were characterized by diffuse and strong expression of SOX9, focal and weak expression of FOXL2, and the absence of DICER1 mutation. However, AGCTs and JGCTs displayed strong and diffuse expression of FOXL2, focal/no immunoreaction for SOX9. SLCTs generally showed moderate intensity of FOXL2 and SOX9 expression. Nuclear β-catenin expression was observed in none of SLCT, 1/9 of SCTAT, 6/8 JGCT, and 4/10 AGCT cases, respectively. DICER1 hotspot mutation was detected in only 3 cases of SLCT and 2 cases of JGCT. We conclude that in addition to strong and diffuse SOX9 expression, weak/absent expression of FOXL2 is suggestive for the diagnosis of SCTAT. Hence, we suggest that inclusion of these two markers, SOX-9 and FOXL2, to the immunohistochemical panel helps in differentiation of SCTAT from other SCSTs in addition to morphologic findings. We also conclude that SCTATs of the ovary do not harbor DICER1 hotspot mutation.

New insights into testicular granulosa cell tumors

Testicular granulosa cell tumors (TGCTs) are rare tumors of sex cord-stromal origin. TGCTs are mostly benign and can be classified into the adult type and the juvenile type. Due to the rarity of clinical cases and limited research efforts, the mechanism underpinning the development of TGCTs remains poorly understood. A landmark study has identified a forkhead box L2 mutation (C134W) in nearly all adult ovarian GCTs, but its implications in TGCTs are unclear. The present study focuses on reviewing the major signaling pathways (e.g., the transforming growth factor β signaling pathway) critical for the development of TGCTs, as revealed by genetically modified mouse models, with a goal of providing new insights into the pathogenesis of TGCTs and offering directions for future studies in this area. We posit that a comparative approach between testicular and ovarian GCTs is valuable, as granulosa cells and Sertoli cells arise from the same progenitor cells during gonadal development. Developing pre-clinical mouse models that recapitulate TGCTs will help answer the remaining questions around this type of rare tumor.

Estrogen Signaling and Its Potential as a Target for Therapy in Ovarian Cancer

The estrogen receptor (ER) has functionality in selected ovarian cancer subtypes and represents a potential target for therapy. The majority (>80%) of high grade serous, low grade serous and endometrioid carcinomas and many granulosa cell tumors express ER-alpha (ERα), and these tumor types have demonstrated responses to endocrine therapy (tamoxifen and aromatase inhibitors) in multiple clinical studies. Biomarkers of responses to these drugs are actively being sought to help identify responsive cancers. Evidence for both pro-proliferative and pro-migratory roles for ERα has been obtained in model systems. ER-beta (ERβ) is generally considered to have a tumor suppressor role in ovarian cancer cells, being associated with the repression of cell growth and invasion. The differential expression of the specific ERβ isoforms may determine functionality within ovarian cancer cells. The more recently identified G protein-coupled receptor (GPER1; GPR30) has been shown to mediate both tumor-suppressive and tumor-promoting action in ovarian cancer cells, suggesting a more complex role. This review will summarize recent findings in this field.

Molecular Pathways and Targeted Therapies for Malignant Ovarian Germ Cell Tumors and Sex Cord-Stromal Tumors: A Contemporary Review

Non-epithelial ovarian tumors are heterogeneous and account for approximately 10% of ovarian malignancies. The most common subtypes of non-epithelial ovarian tumors arise from germ cells or sex cord and stromal cells of the gonads. These tumors are usually detected at an early stage, and management includes surgical staging and debulking. When indicated for advanced disease, most respond to chemotherapy; however, options for patients with refractory disease are limited, and regimens can be associated with significant toxicities, including permanent organ dysfunction, secondary malignancies, and death. Targeted therapies that potentially decrease chemotherapy-related adverse effects and improve outcomes for patients with chemotherapy-refractory disease are needed. Here, we review the molecular landscape of non-epithelial ovarian tumors for the purpose of informing rational clinical trial design. Recent genomic discoveries have uncovered recurring somatic alterations and germline mutations in subtypes of non-epithelial ovarian tumors. Though there is a paucity of efficacy data on targeted therapies, such as kinase inhibitors, antibody–drug conjugates, immunotherapy, and hormonal therapy, exceptional responses to some compounds have been reported. The rarity and complexity of non-epithelial ovarian tumors warrant collaboration and efficient clinical trial design, including high-quality molecular characterization, to guide future efforts.

The French national network dedicated to rare gynecological cancers diagnosis and management could improve the quality of surgery in daily practice of granulosa cell tumors. A TMRG and GINECO group Study

OBJECTIVE

The French national rare gynecological tumor network has been established to improve the quality of care through offering expertise in double reading histological diagnosis, reviewing cases and guiding management of these tumors through specialized multidisciplinary tumor boards and online clinical guidelines (www.ovaire-rare.com). The aim of this study is to evaluate the impact of the development and implementation of this network by assessing the conformity of medical practice with the guidelines concerning the granulosa cell tumors (GCTs).

METHODS

This is a French nationwide study, including 463 patients (out of the 639 identified patients) with a definitive diagnosis of GCT between 2011 and 2016. Surgical practices were analyzed for conformity with the current guidelines (www.ovaire-rare.org). Medical records, surgical and pathological reports were systematically analyzed. Total conformity was defined by a conservative (unilateral salpingo-oophorectomy) or radical surgery (hysterectomy and bilateral salpingo-oophorectomy) including surgical staging (omentectomy, peritoneal biopsies and peritoneal cytology) according to the FIGO stage. Partial conformity referred to a conservative or radical surgery without surgical staging and non-conformity was defined as a non-optimal surgery as recommended by the guidelines.

RESULTS

Median age at diagnosis was 49 years old (range 10-89). The median size of tumor was 94 mm (range 5-400). Radical surgery was performed in 240 patients (52%); while a fertility-sparing surgery was performed in 98 cases (21%). A surgical staging was performed in 76 cases (16%) and an evaluation of the endometrium in 289 cases (62%). Surgery was fully compliant with the guidelines in 65 patients (14%), partially compliant in 213 patients (46%), non-compliant in 137 patients (30%) and not assessable in 48 cases (10%). A statistically significant difference for compliance was observed in restaging surgery (p < 0,001), radical surgery (p = 0,017) and the period (before or after) of the implementation of the network (p < 0,001). Survival analyses did not allow us to demonstrate a significant difference in overall survival nor in PFS although there was a trend in favor of optimal surgery compared to incomplete/non optimal surgery.

CONCLUSION

Surgical management's conformity to the guidelines increases over time from 2011 to 2016. According to this study, the implementation of a national network dedicated to rare gynecologic tumors seems to significantly improve the surgical management of the patients with ovarian granulosa cell tumors.

Multimodality imaging and genomics of granulosa cell tumors

OBJECTIVE

The purpose of this article is to review the imaging findings and genomics of granulosa cell tumors (GCTs) in order to aid in diagnosis and management of GCTs. GCTs are the most common type of sex cord-stromal tumors of the ovary. They are usually diagnosed initially with ultrasound and are subsequently further characterized with CT and MRI. PET/CT is often ordered as well to measure the extent of disease and for follow-up, but its usefulness is in question as some GCTs lack FDG avidity. There is significant variability in imaging phenotypes of GCTs, ranging from mostly cystic to almost solid. More resources have recently been dedicated to understanding the genetics and molecular mechanisms of GCT development. Current research shows that the main cause of GCT carcinogenesis is the FOXL2 mutation, but there are several other noteworthy mutations that contribute to the pathogenesis of this disease. Certain mutations, like GATA4, are known to be associated with more aggressive disease and higher rates of recurrence.

CONCLUSION

Using this information, imaging protocols can be altered depending on the genotype of the tumor. Further understanding of the genetic alterations that underpin the development of GCTs is indicated as genotypic knowledge could be used to guide optimal imaging and management strategies.

Biological and physiological characteristics of human cumulus cells in adherent culture condition

Background

Cumulus cells, as oocyte nurse cells, provide a suitable microenvironment with growth factors and cellular interactions required for oocyte maturation. Thus, these cells may serve as a natural niche for in vitro studies of female germ cell development. Cumulus cells may help attain a better understanding of the causes of infertility in women and eventually improve the outcomes of cases that respond poorly to standard infertility treatment.

Objective

The aim of this study was to isolate, culture, and investigate the biological characteristics of human cumulus cells.

Materials and Methods

In this experimental study, cumulus cells were isolated, cultured, and characterized using reverse transcription-polymerase chain reaction analyses of specific genes including FOXL2, CYP19A1, FSHR, AMHR, and LHR. The presence of vimentin, a structural protein, was examined via immunofluorescent staining. Moreover, levels of anti-mullerian hormone (AMH) and progesterone secretion by cumulus cells were measured with ELISA after 2, 4, 12, 24, and 48 hr of culture.

Results

In adherent culture, human cumulus cells expressed specific genes and markers as well as secreted AMH and progesterone into the medium.

Conclusion

Cumulus cells secrete AMH and progesterone in an adherent culture and might be applicable for in vitro maturation (IVM) and in vitro gametogenesis (IVG) studies.

FOXO1 Negates the Cooperative Action of FOXL2C134W and SMAD3 in CYP19 Expression in HGrC1 Cells by Sequestering SMAD3

Adult granulosa cell tumor (aGCT) is a rare type of ovarian cancer characterized by estrogen excess. Interestingly, only the single somatic mutation FOXL2 ^C134W was found across virtually all aGCTs. We previously reported that FOXL2^C134W stimulates CYP19 transcription synergistically with SMAD3, leading to elevated estradiol synthesis in a human granulosa cell line (HGrC1). This finding suggested a key role for FOXL2^C134W in causing the typical estrogen overload in patients with aGCTs. We have now investigated the effect of FOXO1, a tumor suppressor, on CYP19 activation by FOXL2^C134W in the presence of SMAD3. Intriguingly, FOXO1 antagonized the positive, synergistic effect of FOXL2^C134W and SMAD3 on CYP19 transcription. Similar to FOXL2^C134W, FOXO1 binds SMAD3 but not the proximal FOXL2^C134W binding site (-199 bp) of the CYP19 promoter identified in our earlier studies. The results of a competitive binding assay suggested a possible underlying mechanism in which FOXO1 sequesters SMAD3 away from FOXL2^C134W, thereby negating the cooperative action of FOXL2^C134W and SMAD3 in inducing CYP19 expression. To our knowledge, this study is the first to demonstrate the ability of FOXO1 to restore an altered CYP19 expression by FOXL2^C134W and SMAD3 and provides insight as to why FOXO1 deficiency promotes GCT development in mice.

Targeting TGFβ Pathway in Adult Granulosa Cell Tumor: Opening Pandora's Box?

Adult granulosa cell tumor (AGCT) is a rare malignancy characterized by FOXL2 (C134W) mutation, an inherent component of the TGFβ pathway. Activin A, a TGFβ superfamily member, is a driver of this activity and is a potential target in AGCT.See related article by Tao et al., p. 5458.

Investigations on the Relationship between Ovarian, Endocrine, and Renal Findings in Nonclinical Safety Studies of the γ-secretase Inhibitor Avagacestat

Avagacestat, a gamma (γ)-secretase inhibitor that was in development for treatment of Alzheimer's disease, produced ovarian granulosa-thecal cell tumors in rats and dogs and a glomerulopathy with profound proteinuria in female rats. This report describes the results of follow-up investigative studies, including the use of ovariectomized (OVX) rats, to further characterize these findings and determine their mechanism(s). Ovarian proliferative changes in rats likely resulted from: 1) inhibition of Notch signaling pathways regulating ovarian follicular differentiation/development, characterized microscopically as altered ovarian cyclicity and/or ovarian follicular degeneration; 2) subsequent disruption of the hypothalamic-pituitary-ovarian axis due to ovarian atrophy with decreases in serum estrogen and progesterone (as low as 0.45× and 0.21× controls, respectively); and 3) chronic gonadotropin stimulation and pituitary hypertrophy/hyperplasia in response to the absence of negative feedback. Gonadotropin stimulation in rats was confirmed by increases in serum follicle-stimulating hormone (FSH; up to 7.75× controls) and luteinizing hormone (LH; up to 5.84×). A similar non-genotoxic mechanism was likely responsible for the ovarian findings in dogs although changes in serum hormone levels were not detected. The dose- and time-dependent glomerulopathy with progression to chronic progressive nephropathy in female rats appears to be a direct effect of avagacestat and was not ameliorated with co-administration of 17β-estradiol or an antihypertensive (enalapril) and was not present in control OVX rats. In contrast, adrenocortical hypertrophy in female rats was considered secondary to ovarian changes based on the absence of this finding in avagacestat-treated OVX rats and no increase in ACTH staining in the pituitary.

Granulosa cells from human primordial and primary follicles show differential global gene expression profiles

STUDY QUESTION

Can novel genetic candidates involved in follicle dormancy, activation and integrity be identified from transcriptomic profiles of isolated granulosa cells from human primordial and primary follicles?

SUMMARY ANSWER

The granulosa cell compartment of the human primordial and primary follicle was extensively enriched in signal transducer and activator of transcription 3 (STAT3) and cAMP-response element binding protein (CREB) signalling, and several other putative signalling pathways that may also be mediators of follicle growth and development were identified.

WHAT IS KNOWN ALREADY

Mechanistic target of rapamycin kinase (mTOR) signalling and the factors Forkhead Box L2 (FOXL2) and KIT proto-oncogene receptor tyrosine kinase (KITL) may be involved in defining the early steps of mammalian follicular recruitment through complex bidirectional signalling between the oocyte and granulosa cells. cAMP/protein kinase K (PKA)/CREB signalling is a feature of FSH-induced regulation of granulosa cell steroidogenesis that is essential to normal human fertility.

STUDY DESIGN, SIZE, DURATION

A class comparison study was carried out on primordial follicles (n = 539 follicles) and primary follicles (n = 261) follicles) donated by three women having ovarian tissue cryopreserved before chemotherapy.

PARTICIPANTS/MATERIALS, SETTING, METHODS

RNA samples from isolates of laser capture micro-dissected oocytes and follicles from the primordial and primary stage, respectively, were sequenced on the HiSeq Illumina platform. Data mapping, quality control, filtering, FPKM (fragments per kilobase of exon per million) normalization and comparisons were performed. The granulosa cell contribution in whole follicle isolates was extracted in silico. Modelling of complex biological systems was performed using Ingenuity Pathway Analysis (IPA). For validation of transcriptomic findings, we performed quantitative RT-PCR of selected candidate genes. Furthermore, we interrogated the in situ localization of selected corresponding proteins using immunofluorescence.

MAIN RESULTS AND THE ROLE OF CHANCE

Our differentially expressed gene analysis revealed a number of transcripts in the granulosa cells to be significantly down- (736 genes) or up- (294 genes) regulated during the human primordial-to-primary follicle transition. The IPA analysis revealed enriched canonical signalling pathways not previously associated with granulosa cells from human primordial and primary follicles. Immunofluorescent staining of human ovarian tissue explored the intra-ovarian localization of FOG2, and FOXL2, which revealed the presence of forkhead box L2 (FOXL2) in both oocytes and granulosa cells in primary follicles, with a more enriched staining in the granulosa cells in primary follicles. Friend of GATA 2 (FOG2) stained strongly in oocytes in primordial follicles, with a shift towards granulosa cell as follicle stage advanced.

LARGE SCALE DATA

http://users-birc.au.dk/biopv/published_data/ernst_et_al_GC_2017/.

LIMITATIONS REASONS FOR CAUTION

This is a descriptive study, and no functional assays were employed. The study was based on a limited number of patients, and it is acknowledged that natural biological variance exists in human samples. Strict filters were applied to accommodate the in silico extraction of the granulosa cell contribution. In support of this, quantitative RT-PCR was used to confirm selected candidate genes, and immunofluorescent staining was employed to interrogate the intra-ovarian distribution of selected corresponding proteins. Moreover, it is unknown whether the primordial follicles analysed represent those still in the resting pool, or those from the cohort that have entered the growing pool.

WIDER IMPLICATIONS OF THE FINDINGS

We present, for the first time, a detailed description of global gene activity in the human granulosa cell compartment of primordial and primary follicles. These results may be utilized in the development of novel clinical treatment strategies aimed at improving granulosa cell function.

STUDY FUNDING/COMPETING INTEREST(S)

E.H.E. was supported by the Health Faculty, Aarhus University and Kong Christian Den Tiendes Fond. K.L.H. was supported by a grant from Fondens til Lægevidenskabens Fremme and Kong Christian Den Tiendes Fond. No authors have competing interests to declare.

Forkhead box transcription factor L2 activates Fcp3C to regulate insect chorion formation

Most animals are oviparous. However, the genes regulating egg shell formation remain not very clear. In this study, we found that Nilaparvata lugens Forkhead box transcription factor L2 (NlFoxL2) directly activated follicle cell protein 3C (NlFcp3C) to regulate chorion formation. NlFoxL2 and NlFcp3C had a similar expression pattern, both highly expressed in the follicular cells of female adults. Knockdown of NlFoxL2 or NlFcp3C also resulted in the same phenotypes: obesity and female infertility. RNA interference (RNAi) results suggested that NlFcp3C is a downstream gene of NlFoxL2. Furthermore, transient expression showed that NlFoxL2 could directly activate the NlFcp3C promoter. These results suggest that NlFcp3C is a direct target gene of NlFoxL2. Depletion of NlFoxL2 or NlFcp3C prevented normal chorion formation. Our results first revealed the functions of Fcp3C and FoxL2 in regulation of oocyte maturation in an oviparous animal.

Mitochondrial membrane depolarization enhances TRAIL-induced cell death in adult human granulosa tumor cells, KGN, through inhibition of BIRC5

BACKGROUND

Cellular metabolic changes that accompany malignant transformation have been heralded as hallmark features of cancer. However, metabolic signatures between neoplasms can be unique, allowing for distinctions in malignancy, invasion and chemoresistance between cancer types and subtypes. Mitochondria are central metabolic mediators, as cellular bioenergetics veers from oxidative phosphorylation to glycolysis. Herein, we evaluate the role of mitochondria in maintenance of cellular metabolism, proliferation, and survival in the adult granulosa tumor cell line, KGN, as well as three epithelial ovarian cancer cell lines to determine distinctions in specific features.

RESULTS

Notably, KGN cells were susceptible to TRAIL- and cisplatin-induced death following pretreatment with the metabolic inhibitor FCCP, but not oligomycin A. Collapse of mitochondrial membrane potential was found concomitant with cell death via apoptosis, independent from extrinsic canonical apoptotic routes. Rather, treatment with FCCP resulted in elevated cytochrome c release from mitochondria and decreased responsiveness to BIRC5. Following knockdown of BIRC5, mitochondrial membrane depolarization further sensitized KGN cells to induction of apoptosis via TRAIL.

CONCLUSIONS

These results indicate an essential role, distinct from metabolism, for mitochondrial membrane potential in KGN cells to sense and respond to external mediators of apoptotic induction.

TERT promoter mutation in adult granulosa cell tumor of the ovary

The telomerase reverse transcriptase (TERT) gene is highly expressed in stem cells and silenced upon differentiation. Cancer cells can attain immortality by activating TERT to maintain telomere length and telomerase activity, which is a crucial step of tumorigenesis. Two somatic mutations in the TERT promoter (C228T; C250T) have been identified as gain-of-function mutations that promote transcriptional activation of TERT in multiple cancers, such as melanoma and glioblastoma. A recent study investigating TERT promoter mutations in ovarian carcinomas found C228T and C250T mutations in 15.9% of clear cell carcinomas. However, it is unknown whether these mutations are frequent in other ovarian cancer subtypes, in particular, sex cord-stromal tumors including adult granulosa cell tumors. We performed whole-genome sequencing on ten adult granulosa cell tumors with matched normal blood and identified a TERT C228T promoter mutation in 50% of tumors. We found that adult granulosa cell tumors with mutated TERT promoter have increased expression of TERT mRNA and exhibited significantly longer telomeres compared to those with wild-type TERT promoter. Extension cohort analysis using allelic discrimination revealed the TERT C228T mutation in 51 of 229 primary adult granulosa cell tumors (22%), 24 of 58 recurrent adult granulosa cell tumors (41%), and 1 of 22 other sex cord-stromal tumors (5%). There was a significant difference in overall survival between patients with TERT C228T promoter mutation in the primary tumors and those without it (p = 0.00253, log-rank test). In seven adult granulosa cell tumors, we found the TERT C228T mutation present in recurrent tumors and absent in the corresponding primary tumor. Our data suggest that TERT C228T promoter mutations may have an important role in progression of adult granulosa cell tumors.

Ovarian adult-type granulosa cell tumor: focusing on endocrine-based therapies

Adult-type granulosa cell tumors (GCTs), although rare, are the most commonly diagnosed neoplasms arising in the endocrine-active ovarian stroma. They are characterized by excessive production of estrogens, antimullerian hormone and inhibins. In 2009, a specific mutation in FOXL2 was identified to be pathognomonic of GCTs. How dysregulation of this transcription factor, resulting in upregulation of aromatase, leads to unchecked proliferation, and progression to a malignancy, remains unclear. The key pathological and clinical feature of GCTs that affects their usually favorable outcomes is a diagnosis of greater than Stage 1 disease at presentation. Chemotherapy is given as adjuvant upon an advanced stage diagnosis; however, its effect on survival upon recurrence is modest. On the other hand, aromatase inhibitors also lead to tumor regression and are suitable for long-term maintenance.

FOXL2C134W-Induced CYP19 Expression via Cooperation With SMAD3 in HGrC1 Cells

Germline knockout studies in female mice demonstrated an essential role for forkhead box L2 (FOXL2) in early follicle development, whereas an inducible granulosa cell (GC)-specific deletion of Foxl2 in adults has shown ovary-to-testis somatic sex reprogramming. In women, over 120 different germline mutations in the FOXL2 gene have been shown to cause blepharophimosis/ptosis/epicantus inversus syndrome associated with or without primary ovarian insufficiency. By contrast, a single somatic mutation (FOXL2C134W) accounts for almost all adult-type GC tumors (aGCTs). To test the hypothesis that FOXL2C134W differentially regulates the expression of aGCT markers, we investigated the effect of FOXL2C134W on inhibin B and P450 aromatase expression using a recently established human GC line (HGrC1), which we now show to bear two normal alleles of FOXL2. Neither FOXL2wt nor FOXL2C134W regulate INHBB messenger RNA (mRNA) expression. However, FOXL2C134W selectively displays a 50-fold induction of CYP19 mRNA expression dependent upon activin A. Mechanistically, the CYP19 promoter is activated in a similar way by FOXL2C134W interaction with SMAD3, but not by FOXL2wt. SMAD2 had no effect. Moreover, FOXL2C134W interactions with SMAD3 and with the FOX binding element located at -199 bp upstream of the ATG initiation codon of CYP19 are more sustainable than FOXL2wt. Thus, FOXL2C134W potentiates CYP19 expression in HGrC1 cells via enhanced recruitment of SMAD3 to a proximal FOX binding element. These findings may explain the pathophysiology of estrogen excess in patients with aGCT.

The molecular mechanism of ovarian granulosa cell tumors

Over these years, more and more sex cord-stromal tumors have been reported. Granulosa cell tumor (GCT) is a rare tumor in ovaries, accounts for 2% to 5% of ovarian cancers. The main different feature of GCTs from other ovarian cancers is that GCTs can lead to abnormally secreted hormones (estrogen, inhibin and Müllerian inhibiting substance). The GCT is divided into two categories according to the age of patients, namely AGCT (adult granulosa cell tumor) and JGCT (Juvenile granulosa cell tumor). AGCT patients accounts for 95%. Although the pathogenesis is not clear, FOXL2 (Forkhead box L2) mutation was considered as the most critical factor in AGCT development. The current treatment is dominated by surgery. Target therapy remains in the adjuvant therapy stage, such as hormone therapy. During these years, other pathogenic factors were also explored, such as PI3K/AKT (phosphatidylinositol-3-kinase; serine/threonine kinase), TGF-β (Transforming growth factor beta) signaling pathway, Notch signaling pathway, GATA4 and VEGF (vascular endothelial growth factor). These factors and signaling pathway play important roles in GCT cell proliferation, apoptosis, or angiogenesis. The purpose of this review is to summarize the possible pathogenic factors and signaling pathways, which may shed lights on developing potential therapeutic targets for GCT.

Novel FOXL2 mutations cause blepharophimosis-ptosis-epicanthus inversus syndrome with premature ovarian insufficiency

Background

Blepharophimosis‐ptosis‐epicanthus inversus syndrome (BPES) is a malformation of the eyelids. Forkhead Box L2 (FOXL2) is the only gene known to be associated with BPES.

Methods

We identified two Han Chinese BPES families with premature ovarian insufficiency (POI). Sanger sequencing and in vitro functional analysis were performed to identify the genetic cause.

Results

Sanger sequencing identified two novel mutations (c.462_468del, c.988_989insG) in FOXL2, one in each family. The in vitro functional analysis confirmed that both novel mutations were associated with impaired transactivation of downstream genes. Specifically, the single‐base insertion, c.988_989insG, led to subcellular mislocalization and aggregation of the encoded protein, which validated the hypothesis that the two novel FOXL2 mutations are deleterious and associated with POI in the two BPES families.

Conclusion

The novel mutations identified in the present study will enhance the present knowledge of the mutation spectrum of FOXL2. The in vitro experiments provide further insights into the molecular mechanism by which the two new variants mediate disease pathogenesis and may contribute to elucidating the genotype‐phenotype correlation between the two novel FOXL2 mutations and POI.

Ovarian sex cord-stromal tumours: an update in recent molecular advances

Sex cord-stromal tumours (SCSTs) consist of a heterogeneous group of neoplasms with diverse clinicopathological features and biological behaviour. They often present as a diagnostic challenge as they have varied and occasionally overlapping histomorphology and some may even mimic non-SCSTs. An accurate diagnosis is important for therapeutic and prognostic purposes. The use of a panel of immunohistochemical markers which are sensitive and specific for sex cord-stromal differentiation such as α-inhibin, calretinin, SF-1 and FOXL2, may be helpful in confirming the cellular lineage of these tumours, but is of limited utility in distinguishing between the different tumour types within this category. Additionally, the development of new therapeutic strategies in patients with SCSTs is also hampered by the infrequent occurrence of these neoplasms. Recent molecular analyses of some SCSTs has led to the discovery of novel molecular events, which may have important diagnostic, prognostic and therapeutic implications. The salient pathological features, management issues and recently described genetic aberrations in adult and juvenile granulosa cell tumours as well as Sertoli-Leydig cell tumours are discussed in this review, with particular emphasis on the clinical significance of FOXL2 and DICER1 mutations. An in-depth understanding of the molecular pathogenesis underlying SCSTs may aid in improving tumour classification and disease prognostication and also potentially lead to the discovery of more effective treatment strategies.

SMAD3 Activation: A Converging Point of Dysregulated TGF-Beta Superfamily Signaling and Genetic Aberrations in Granulosa Cell Tumor Development?

Ovarian granulosa cell tumors (GCTs) are rare gynecologic tumors in women. Due to the rarity and limited research efforts invested, the etiology of GCTs remains poorly defined. A landmark study has discovered the mutation of forkhead box L2 (FOXL2) as a genetic hallmark of adult GCTs in the human. However, our understanding of the role of cell signaling in GCT development is far from complete. Increasing lines of evidence highlight the importance of TGF-beta (TGFB) superfamily signaling in the pathogenesis of GCTs. This review draws on findings using genetically modified mouse models and human patient specimens and cell lines to reveal SMAD3 activation as a potentially key converging point of dysregulated TGFB superfamily signaling and genetic aberrations in GCT development. It is anticipated that deciphering the role of TGFB superfamily signaling cascades in ovarian tumorigenesis will help develop new therapeutic approaches for GCTs by targeting core signaling elements essential for tumor initiation, growth, and progression.

Foxl2 and Its Relatives Are Evolutionary Conserved Players in Gonadal Sex Differentiation

Foxl2 is a member of the large family of Forkhead Box (Fox) domain transcription factors. It emerged during the last 15 years as a key player in ovarian differentiation and oogenesis in vertebrates and especially mammals. This review focuses on Foxl2 genes in light of recent findings on their evolution, expression, and implication in sex differentiation in animals in general. Homologs of Foxl2 and its paralog Foxl3 are found in all metazoans, but their gene evolution is complex, with multiple gains and losses following successive whole genome duplication events in vertebrates. This review aims to decipher the evolutionary forces that drove Foxl2/3 gene specialization through sub- and neo-functionalization during evolution. Expression data in metazoans suggests that Foxl2/3 progressively acquired a role in both somatic and germ cell gonad differentiation and that a certain degree of sub-functionalization occurred after its duplication in vertebrates. This generated a scenario where Foxl2 is predominantly expressed in ovarian somatic cells and Foxl3 in male germ cells. To support this hypothesis, we provide original results showing that in the pea aphid (insects) foxl2/3 is predominantly expressed in sexual females and showing that in bovine ovaries FOXL2 is specifically expressed in granulosa cells. Overall, current results suggest that Foxl2 and Foxl3 are evolutionarily conserved players involved in somatic and germinal differentiation of gonadal sex.