Functional exploration of the adult ovarian granulosa cell tumor-associated somatic FOXL2 mutation p.Cys134Trp (c.402C>G)

A cellular model provides insights into the pathogenicity of the oncogenic FOXL2 somatic variant p.Cys134Trp

BACKGROUND

FOXL2 is a transcription factor expressed in ovarian granulosa cells. A somatic variant of FOXL2 (c.402 C > G, p.Cys134Trp) is the hallmark of adult-type granulosa cell tumours.

METHODS

We generated KGN cell clones either heterozygous for this variant (MUT) or homozygous for the wild-type (WT) allele by CRISPR/Cas9 editing. They underwent RNA-Seq and bioinformatics analyses to uncover pathways impacted by deregulated genes. Cell morphology and migration were studied.

RESULTS

The differentially expressed genes (DEGs) between WT/MUT and WT/WT KGN cells (DEGs-WT/MUT), pointed to several dysregulated pathways, like TGF-beta pathway, cell adhesion and migration. Consistently, WT/MUT cells were rounder than WT/WT cells and displayed a different distribution of stress fibres and paxillin staining. A comparison of the DEGs-WT/MUT with those found when FOXL2 was knocked down (KD) in WT/WT KGN cells showed that most DEGs-WT/MUT cells were not so in the KD experiment, supporting a gain-of-function (GOF) scenario. MUT-FOXL2 also displayed a stronger interaction with SMAD3.

CONCLUSIONS

Our work, aiming at better understanding the GOF scenario, shows that the dysregulated genes and pathways are consistent with this idea. Besides, we propose that GOF might result from an enhanced interaction with SMAD3 that could underlie an ectopic capacity of mutated FOXL2 to bind SMAD4.

Clinicopathologic Characteristics of a Single-institution Cohort of Ovarian Adult Granulosa Cell Tumors, With Biomarker and Therapeutic Implications Utilizing the Detection of Androgen, Estrogen, and Progesterone Hormone Receptor Expression by Immunohistochemistry

Adult granulosa cell tumors (AGCTs) are rare ovarian tumors with generally good prognosis after surgical resection; however, they do have recurrence potential. Therapeutic and management options for recurrences are currently limited, and the need for expanded adjuvant therapies is increasingly recognized. Anti-hormonal therapy is being explored as an option, which relies on the detection and assessment of hormone receptor expression (androgen, estrogen, and progesterone receptors) as a biomarker and therapeutic target. Our study identifies several clinicopathologic characteristics with significant associations for recurrence of AGCT, which were younger age, higher stage, and larger tumor size. Our study also demonstrates that androgen receptor (AR) expression may be utilized as a potential biomarker for hormonal therapy and that detection of AR expression in AGCT by immunohistochemistry (IHC) varies depending on the antibody clone used for testing. AR was detected in 95% of samples tested with antibodies derived from clone AR27. This detection rate is much higher than previously reported.

A matter of new life and cell death: programmed cell death in the mammalian ovary

BACKGROUND

The mammalian ovary is a unique organ that displays a distinctive feature of cyclic changes throughout the entire reproductive period. The estrous/menstrual cycles are associated with drastic functional and morphological rearrangements of ovarian tissue, including follicular development and degeneration, and the formation and subsequent atrophy of the corpus luteum. The flawless execution of these reiterative processes is impossible without the involvement of programmed cell death (PCD).

MAIN TEXT

PCD is crucial for efficient and careful clearance of excessive, depleted, or obsolete ovarian structures for ovarian cycling. Moreover, PCD facilitates selection of high-quality oocytes and formation of the ovarian reserve during embryonic and juvenile development. Disruption of PCD regulation can heavily impact the ovarian functions and is associated with various pathologies, from a moderate decrease in fertility to severe hormonal disturbance, complete loss of reproductive function, and tumorigenesis. This comprehensive review aims to provide updated information on the role of PCD in various processes occurring in normal and pathologic ovaries. Three major events of PCD in the ovary-progenitor germ cell depletion, follicular atresia, and corpus luteum degradation-are described, alongside the detailed information on molecular regulation of these processes, highlighting the contribution of apoptosis, autophagy, necroptosis, and ferroptosis. Ultimately, the current knowledge of PCD aberrations associated with pathologies, such as polycystic ovarian syndrome, premature ovarian insufficiency, and tumors of ovarian origin, is outlined.

CONCLUSION

PCD is an essential element in ovarian development, functions and pathologies. A thorough understanding of molecular mechanisms regulating PCD events is required for future advances in the diagnosis and management of various disorders of the ovary and the female reproductive system in general.

The forkhead DNA-binding domain binds specific G2-rich RNA sequences

Transcription factors contain a DNA-binding domain ensuring specific recognition of DNA target sequences. The family of forkhead (FOX) transcription factors is composed of dozens of paralogs in mammals. The forkhead domain (FHD) is a segment of about 100 amino acids that binds an A-rich DNA sequence. Using DNA and RNA PCR-SELEX, we show that recombinant FOXL2 proteins, either wild-type or carrying the oncogenic variant C134W, recognize similar DNA-binding sites. This suggests that the oncogenic variant does not alter the intrinsic sequence-specificity of FOXL2. Most importantly, we show that FOXL2 binds G2-rich RNA sequences whereas it virtually fails to bind similar sequences in DNA chemistry. Interestingly, a statistically significant subset of genes responding to the knock-down of FOXL2/Foxl2 harbor such G2-rich sequences and are involved in crucial signaling pathways and cellular processes. In addition, we show that FOXA1, FOXO3a and chimeric FOXL2 proteins containing the FHD of the former are also able to interact with some of the preferred FOXL2-binding sequences. Our results point to an unexpected and novel characteristic of the forkhead domain, the biological relevance of which remains to be explored.

Thyroid-like low-grade nasopharyngeal papillary adenocarcinoma: a clinicopathological and molecular study of four cases

Thyroid-like low-grade nasopharyngeal papillary adenocarcinoma (TLLGNPPA) is a rare nasopharyngeal carcinoma. To date, less than 60 cases of TLLGNPPA have been reported, and its clinical features and pathogenesis remain unclear. In this paper, four cases of TLLGNPPA were reported to clarify the clinicopathological and molecular features of this disease. Histopathological examination revealed that all tumors had papillary glandular arrangement, with a fibrovascular axis in the tumor stroma and focal nuclear groove. All tumors expressed pan-CK, CK7, and CK19, while TG and Pax-8 were negative, and the Ki-67 index was approximately 1-3%. The expression of TTF-1 was diffusely positive in two cases and focally positive in two cases. EBER was not expressed in four cases. Molecular testing was possible in three cases. No common driver event was noted, but unique, mutually exclusive molecular variants were found in each of the three tumors (FGFR4, PDK1, AXIN2, FOXL2, and PIK3C3), one also with copy number variants in MCL1 and STMN1. All four patients underwent surgical resection of the tumor and had no metastasis or recurrence from 7 to 60 months post-resection. Given the assertion that these tumors do not recur or metastasize in addition to their heterogeneous gene mutation spectrum, we propose that TLLGNPPA is a neoplasm with low malignant potential and should no longer to be referred to as an adenocarcinoma.

FOXL2 in adult-type granulosa cell tumour of the ovary: oncogene or tumour suppressor gene?

A recurrent mutation in FOXL2 (c.402C>G; p.C134W) is present in over 95% of adult-type granulosa cell tumours (AGCTs). In contrast, various loss-of-function mutations in FOXL2 lead to the development of blepharophimosis, ptosis, and epicanthus inversus syndrome (BPES). BPES is characterised by an eyelid malformation often accompanied with primary ovarian insufficiency. Two recent studies suggest that FOXL2 C402G is a gain- or change-of-function mutation with altered DNA-binding specificity. Another study proposes that FOXL2 C402G is selectively targeted for degradation, inducing somatic haploinsufficiency, suggesting its role as a tumour suppressor. The latter study relies on data indicative of an FOXL2 allelic imbalance in AGCTs. Here we present RNA-seq data as genetic evidence that no real allelic imbalance is observed at the transcriptomic level in AGCTs. Additionally, there is no loss of protein expression in tumours harbouring the mutated allele. These data and other features of this mutation compared to other oncogenes and tumour suppressor genes argue strongly against FOXL2 being a tumour suppressor in this context. Given the likelihood that FOXL2 C402G is oncogenic, targeting the variant protein or its downstream consequences is the most viable path forward to identifying an effective treatment for this cancer. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

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 Pathognomonic FOXL2 C134W Mutation Alters DNA-Binding Specificity

The somatic missense point mutation c.402C>G (p.C134W) in the FOXL2 transcription factor is pathognomonic for adult-type granulosa cell tumors (AGCT) and a diagnostic marker for this tumor type. However, the molecular consequences of this mutation and its contribution to the mechanisms of AGCT pathogenesis remain unclear. To explore these mechanisms, we engineered V5-FOXL2^WT- and V5-FOXL2^C134W-inducible isogenic cell lines and performed chromatin immunoprecipitation sequencing and transcriptome profiling. FOXL2^C134W associated with the majority of the FOXL2 wild-type DNA elements as well as a large collection of unique elements genome wide. This model enabled confirmation of altered DNA-binding specificity for FOXL2^C134W and identification of unique targets of FOXL2^C134W including SLC35F2, whose expression increased sensitivity to YM155. Our results suggest FOXL2^C134W drives AGCT by altering the binding affinity of FOXL2-containing complexes to engage an oncogenic transcriptional program. SIGNIFICANCE: A mechanistic understanding of FOXL2^C134W-induced regulatory state alterations drives discovery of a rationally designed therapeutic strategy.

FOXL2 homozygous genotype and chromosome instability are associated with recurrence in adult granulosa cell tumors of the ovary

Introduction: Adult granulosa cell tumors (aGCTs) are extremely rare tumors characterized by the presence of the single missense mutation (c.402 C>G, p. C134W) in the FOXL2 gene. These tumors are frequently associated with a slow, indolent disease progression and a high probability of aggressive tumor recurrence. Hence, the identification of molecular markers that are predictive of recurrence and/or aggressive behavior would be a great asset in the management of aGCT. The present study focused on the influence of the FOXL2 genotype (heterozygous or homozygous) and copy number variations (CNVs) in recurrence by comparing the primary tumor with recurrent lesions in the same patient. We performed array comparative genomic hybridization (CGH) experiments and FOXL2 genotyping by allelic discrimination on 40 tumor samples. Results and Discussion: In array CGH results of recurrent tumors, few samples presented the multiple chromosome losses and gains characteristic of chromosome instability (CIN). We also observed that three recurrent tumors and one primary tumor appeared to be homozygous for the FOXL2 c.402C>G mutation. Interestingly, the homozygous FOXL2 genotype was correlated with a shorter time to relapse. A change in the FOXL2 genotype in cases of recurrence was correlated with the appearance of CIN. Conclusion: Despite the small number of matching primary and recurrent tumors analyzed here, the present study is the first to have shown that the FOXL2 homozygous genotype and CIN are prevalent in recurrent aGCTs. The two mechanisms are probably linked, and both almost certainly have a role in the molecular transformation of aGCTs.

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.

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.

Pathogenesis and treatment of adult-type granulosa cell tumor of the ovary

Adult-type granulosa cell tumor is a clinically and molecularly unique subtype of ovarian cancer. These tumors originate from the sex cord stromal cells of the ovary and represent 3-5% of all ovarian cancers. The majority of adult-type granulosa cell tumors are diagnosed at an early stage with an indolent prognosis. Surgery is the cornerstone for the treatment of both primary and relapsed tumor, while chemotherapy is applied only for advanced or non-resectable cases. Tumor stage is the only factor consistently associated with prognosis. However, every third of the patients relapse, typically in 4-7 years from diagnosis, leading to death in 50% of these patients. Anti-Müllerian Hormone and inhibin B are currently the most accurate circulating biomarkers. Adult-type granulosa cell tumors are molecularly characterized by a pathognomonic somatic missense point mutation 402C->G (C134W) in the transcription factor FOXL2. The FOXL2 402C->G mutation leads to increased proliferation and survival of granulosa cells, and promotes hormonal changes. Histological diagnosis of adult-type granulosa cell tumor is challenging, therefore testing for the FOXL2 mutation is crucial for differential diagnosis. Large international collaborations utilizing molecularly defined cohorts are essential to improve and validate new treatment strategies for patients with high-risk or relapsed adult-type granulosa cell tumor. Key Messages: Adult-type granulosa cell tumor is a unique ovarian cancer with an indolent, albeit unpredictable disease course. Adult-type granulosa cell tumors harbor a pathognomonic somatic missense mutation in transcription factor FOXL2. The key challenges in the treatment of patients with adult-type granulosa cell tumor lie in the identification and management of patients with high-risk or relapsed disease.

The disparate origins of ovarian cancers: pathogenesis and prevention strategies

Ovarian cancer is the fifth cause of cancer-related death in women and comprises a histologically and genetically broad range of tumours, including those of epithelial, sex cord-stromal and germ cell origin. Recent evidence indicates that high-grade serous ovarian carcinoma, clear cell carcinoma and endometrioid carcinoma primarily arise from tissues that are not normally present in the ovary. These histogenetic pathways are informing risk-reduction strategies for the prevention of ovarian and ovary-associated cancers and have highlighted the importance of the seemingly unique ovarian microenvironment.

FOXL2 molecular status in adult granulosa cell tumors of the ovary: A study of primary and metastatic cases

Granulosa cell tumors (GCTs) of the ovary are uncommon neoplasms, accounting for ~5% of all malignant ovarian tumors. GCTs are a relatively homogeneous group of tumors, categorized into two distinct subtypes, juvenile GCT and adult GCT (AGCT), likely arising from a limited set of molecular events usually involving the disruption of pathways that regulate granulosa cell proliferation. In the present study, the presence of forkheadbox L2 (FOXL2) c.402C>G mutation was investigated in a series of 42 samples of primary and metastatic AGCT of the ovary. The samples consisted of 37 primary and 5 metastatic ovarian AGCTs from 37 patients. FOXL2 mutational status was evaluated using a pyrosequencing approach on 2.5-µm sections of formalin-fixed paraffin-embedded tissue. FOXL2 c.402C>G mutation was found in 33/37 (89.2%) primary AGCTs and in 4/5 (80.0%) metastases, with the molecular status of the metastases recapitulating that of the primary tumors (4 mutated cases and 1 wild-type case). Overall, FOXL2 mutation is present in the majority of primary and metastatic AGCTs, and could be used as a valid tool in the diagnosis of the disease and in cases of metastatic lesions from an unknown primary origin. Moreover the concordance of FOXL2 molecular status in primary and associated metastases suggests its early appearance and genomic stability in AGCT tumorigenesis.

Insights into granulosa cell tumors using spontaneous or genetically engineered mouse models

Granulosa cell tumors (GCTs) are rare sex cord-stromal tumors that have been studied for decades. However, their infrequency has delayed efforts to research their etiology. Recently, mutations in human GCTs have been discovered, which has led to further research aimed at determining the molecular mechanisms underlying the disease. Mouse models have been important tools for studying GCTs, and have provided means to develop and improve diagnostics and therapeutics. Thus far, several genetically modified mouse models, along with one spontaneous mouse model, have been reported. This review summarizes the phenotypes of these mouse models and their applicability in elucidating the mechanisms of granulosa cell tumor development.

FOXL2 posttranslational modifications mediated by GSK3β determine the growth of granulosa cell tumours

Approximately 97% of patients with ovarian granulosa cell tumours (GCTs) bear the C134W mutation in FOXL2; however, the pathophysiological mechanism of this mutation is unknown. Here we report how this mutation affects GCT development. Sequential posttranslational modifications of the C134W mutant occur where hyperphosphorylation at serine 33 (S33) by GSK3β induces MDM2-mediated ubiquitination and proteasomal degradation. In contrast, S33 of wild-type FOXL2 is underphosphorylated, leading to its SUMOylation and stabilization. This prominent hyperphosphorylation is also observed at S33 of FOXL2 in GCT patients bearing the C134W mutation. In xenograft mice, the S33 phosphorylation status correlates with the oncogenicity of FOXL2, and the inhibition of GSK3β efficiently represses GCT growth. These findings reveal a previously unidentified regulatory mechanism that determines the oncogenic attributes of the C134W mutation via differential posttranslational modifications of FOXL2 in GCT development.

Molecular analyses of juvenile granulosa cell tumors bearing AKT1 mutations provide insights into tumor biology and therapeutic leads

Juvenile granulosa cell tumors (JGCTs) of the ovary are pediatric neoplasms representing 5% of all granulosa cell tumors (GCTs). Most GCTs are of adult type (AGCTs) and bear a mutation in the FOXL2 gene. The molecular basis of JGCTs is poorly understood, although mutations in the GNAS gene have been reported. We have detected in-frame duplications within the oncogene AKT1 in >60% of the JGCTs studied. Here, to evaluate the functional impact of these duplications and the existence of potential co-driver alterations, we have sequenced the transcriptome of four JGCTs and compared them with control transcriptomes. A search for gene variants detected only private alterations probably unrelated with tumorigenesis, suggesting that tandem duplications are the best candidates to underlie tumor formation in the absence of GNAS alterations. We previously showed that the duplications were specific to JGCTs. However, the screening of eight AGCTs samples without FOXL2 mutation showed the existence of an AKT1 duplication in one case, also having a stromal luteoma. The analysis of RNA-Seq data pinpointed a series of differentially expressed genes, involved in cytokine and hormone signaling and cell division-related processes. Further analyses pointed to the existence of a possible dedifferentiation process and suggested that most of the transcriptomic dysregulation might be mediated by a limited set of transcription factors perturbed by AKT1 activation. Finally, we show that commercially available AKT inhibitors can modulate the in vitro activity of various mutated forms. These results shed light on the pathogenesis of JGCTs and provide therapeutic leads for a targeted treatment.

Tyrosine Kinase Inhibitors as Potential Therapeutic Agents in the Treatment of Granulosa Cell Tumors of the Ovary

Objective

Granulosa cell tumors of the ovary (GCTs) represent a specific subset of malignant ovarian tumors, of which there are 2 distinct subtypes, the juvenile and the adult form. Aside from surgery, no reliable therapeutic options currently exist for patients with GCT. This study sought to investigate the potential role of small molecule tyrosine kinase inhibitors (TKIs) as novel therapeutics in the clinical management of GCT.

Materials and Methods

Using TKI with distinct but overlapping multitargeted specificities, cellular proliferation, viability, and apoptosis were evaluated in 2 human GCT-derived cell lines, COV434 and KGN.

Results

Sunitinib, which targets the imatinib-inhibited tyrosine kinases of VEGFR, KIT, PDGFR, and FLT-3, was without effect in COV434 and KGN cell lines. Sorafenib, which has a high affinity for RAF1 and BRAF, dose dependently inhibited cellular proliferation and viability in both cell lines at concentrations equivalent to that seen in other systems. A RAF1 kinase inhibitor was without effect, suggesting that sorafenib is acting via inhibition of BRAF, or that aberrant signaling originates upstream of BRAF in the MAPK pathway. In the presence of a selective Src family inhibitor (SU6656), cell proliferation and cell viability responses dissociated; that is, although SU6656 dose dependently inhibited cell viability, it had limited effect on proliferation and apoptosis.

Conclusions

These findings implicate BRAF in the activated signaling responsible for the growth and viability of GCT and suggest that TKI already in clinical use may be a therapeutic option in the treatment of GCT.

Gynandroblastoma With Juvenile Granulosa Cell Tumor and Concurrent Renal Cell Carcinoma

Gynandroblastoma is an extremely rare primary tumor of the ovary showing morphological evidence of both female (granulosa cell tumor) and male (Sertoli or Sertoli–Leydig tumor) differentiation. We report an unusual case of a 32-year-old female who presented with hyperandrogenism and was found on imaging to have concurrent ovarian and renal masses. Following surgical excision, the ovarian mass was diagnosed as gynandroblastoma, which consisted of 45% juvenile granulosa cell tumor and 55% intermediately differentiated Sertoli–Leydig tumor. The renal mass was diagnosed as a conventional renal clear cell carcinoma. Gynandroblastoma, especially with juvenile granulosa cell tumor, is an extremely rare ovarian tumor. Concurrent gynandroblastoma with another malignant neoplasm has not been reported in the literature.

Identification and Validation of Differential Phosphorylation Sites of the Nuclear FOXL2 Protein as Potential Novel Biomarkers for Adult-Type Granulosa Cell Tumors

Granulosa cell tumor (GCT) is a rare form of ovarian cancer classified as a sex cord-stromal tumor. The c.402C→G missense mutation in the FOXL2 gene that changes cysteine 134 to tryptophan (C134W) is found in more than 97% of adult-type GCTs, and the C134W FOXL2 mutant is hyperphosphorylated. We identified three differential phosphorylation sites, at serine 33 (S33), tyrosine 186 (Y186), and serine 238 (S238), of the C134W mutant by tandem mass spectrometry. Among these sites, antibodies were raised against the pS33 and pY186 epitopes using specific peptides, and they were tested by immunostaining tissue microarrays of archival adult-type GCT specimens, other tumors, and normal tissues. The pS33 antibody showed greater sensitivity and specificity for the detection of adult-type GCTs than that of the other phospho and nonphospho antibodies. The specificity of the pS33 antibody to the pS33 epitope was further confirmed by enriching the pS33 peptide by affinity chromatography using the immobilized antibody, followed by mass spectrometric and western blot analyses from whole cell lysates of the adult-type GCT cell line, KGN. pS33 FOXL2 immunostaining levels were significantly higher in adult-type GCTs than those in other tumors and tissues. The receiver operating characteristic curve analysis of pS33 FOXL2 showed high sensitivity (1.0) and specificity (0.76) to adult-type GCTs with a cutoff score of >30% positive cells, and the area under the curve was 0.96. This suggests the potential of pS33 FOXL2 to serve as a new biomarker for the diagnosis of adult-type GCT.

Combined comparative genomic hybridization and transcriptomic analyses of ovarian granulosa cell tumors point to novel candidate driver genes

Background

Ovarian granulosa cell tumors (GCTs) are the most frequent sex cord-stromal tumors. Several studies have shown that a somatic mutation leading to a C134W substitution in the transcription factor FOXL2 appears in more than 95% of adult-type GCTs. Its pervasive presence suggests that FOXL2 is the main cancer driver gene. However, other mutations and genomic changes might also contribute to tumor formation and/or progression.

Methods

We have performed a combined comparative genomic hybridization and transcriptomic analyses of 10 adult-type GCTs to obtain a picture of the genomic landscape of this cancer type and to identify new candidate co-driver genes.

Results

Our results, along with a review of previous molecular studies, show the existence of highly recurrent chromosomal imbalances (especially, trisomy 14 and monosomy 22) and preferential co-occurrences (i.e. trisomy 14/monosomy 22 and trisomy 7/monosomy 16q). In-depth analyses showed the presence of recurrently broken, amplified/duplicated or deleted genes. Many of these genes, such as AKT1, RUNX1 and LIMA1, are known to be involved in cancer and related processes. Further genomic explorations suggest that they are functionally related.

Conclusions

Our combined analysis identifies potential candidate genes, whose alterations might contribute to adult-type GCT formation/progression together with the recurrent FOXL2 somatic mutation.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1283-0) contains supplementary material, which is available to authorized users.

17β-estradiol inhibits spreading of metastatic cells from granulosa cell tumors through a non-genomic mechanism involving GPER1

Granulosa cell tumor (GCT) is a rare and severe form of sex-cord stromal ovarian tumor that is characterized by its long natural history and tendency to recur years after surgical ablation. Because there is no efficient curative treatment beyond surgery, ~20% of patients die of the consequences of their tumor. However, very little is known of the molecular etiology of this pathology. About 70% of GCT patients present with elevated circulating estradiol (E2). Because this hormone is known to increase tumor growth and progression in a number of cancers, we investigated the possible role of E2 in GCTs. Cell-based studies with human GCT metastases and primary tumor-derived cells, ie KGN and COV434 cells, respectively, aimed at evaluating E2 effect on cell growth, migration and invasion. Importantly, we found that E2 did not affect GCT cell growth, but that it significantly decreased the migration and matrix invasion of metastatic GCT cells. Noteworthy, our molecular studies revealed that this effect was accompanied by the inhibition through non-genomic mechanisms of extracellular signal-regulated kinase 1/2 (ERK1/2), which is constitutively activated in GCTs. By using pharmacological and RNA silencing approaches, we found that E2 action was mediated by G protein-coupled estrogen receptor 1 (GPER1) signaling pathway. Analyses of GPER1 expression on tissue microarrays from human GCTs confirmed its expression in ~90% of GCTs. Overall, our study reveals that E2 would act via non-classical pathways to prevent metastasis spreading in GCTs and also reveals GPER1 as a possible target in this disease.

A Hot-spot of In-frame Duplications Activates the Oncoprotein AKT1 in Juvenile Granulosa Cell Tumors

BACKGROUND

Ovarian granulosa cell tumors are the most common sex-cord stromal tumors and have juvenile (JGCTs) and adult forms. In a previous study we reported the occurrence of activating somatic mutations of Gαs, which transduces mitogenic signals, in 30% of the analyzed JGCTs.

METHODS

We have searched for alterations in other proteins involved in ovarian mitogenic signaling. We focused on the PI3K-AKT axis. As we found mutations in AKT1, we analyzed the subcellular localization of the mutated proteins and performed functional explorations using Western-blot and luciferase assays.

FINDINGS

We detected in-frame duplications affecting the pleckstrin-homology domain of AKT1 in more than 60% of the tumors occurring in girls under 15 years of age. The somatic status of the mutations was confirmed when peritumoral DNA was available. The JGCTs without duplications carried point mutations affecting highly conserved residues. Several of these substitutions were somatic lesions. The mutated proteins carrying the duplications had a non-wild-type subcellular distribution, with a marked enrichment at the plasma membrane. This led to a striking degree of AKT1 activation demonstrated by a strong phosphorylation level and by reporter assays.

INTERPRETATION

Our study incriminates somatic mutations of AKT1 as a major event in the pathogenesis of JGCTs. The existence of AKT inhibitors currently tested in clinical trials opens new perspectives for targeted therapies for these tumors, which are currently treated with standard non-specific chemotherapy protocols.

HER2 and GATA4 are new prognostic factors for early-stage ovarian granulosa cell tumor-a long-term follow-up study

Granulosa cell tumors (GCTs) carry a risk of recurrence also at an early stage, but reliable prognostic factors are lacking. We assessed clinicopathological prognostic factors and the prognostic roles of the human epidermal growth factor receptors (HER 2–4) and the transcription factor GATA4 in GCTs. We conducted a long-term follow-up study of 80 GCT patients with a mean follow-up time of 16.8 years. A tumor-tissue microarray was immunohistochemically stained for HER2–4 and GATA4. Expression of HER2–4 mRNA was studied by means of real time polymerase chain reaction and HER2 gene amplification was analyzed by means of silver in situ hybridization. The results were correlated to clinical data on recurrences and survival. We found that GCTs have an indolent prognosis, with 5-year disease-specific survival (DSS) being 97.5%. Tumor recurrence was detected in 24% of the patients at a median of 7.0 years (range 2.6–18 years) after diagnosis. Tumor stage was not prognostic of disease-free survival (DFS). Of the molecular prognostic factors, high-level expression of HER2, and GATA4, and high nuclear atypia were prognostic of shorter DFS. In multivariate analyses, high-level coexpression of HER2 and GATA4 independently predicted DFS (hazard ratio [HR] 8.75, 95% CI 2.20–39.48, P = 0.002). High-level expression of GATA4 also predicted shorter DSS (HR 3.96, 95% CI 1.45–12.57, P = 0.006). In multivariate analyses, however, tumor stage (II–III) and nuclear atypia were independent prognostic factors of DSS. In conclusion HER2 and GATA4 are new molecular prognostic markers of GCT recurrence, which could be utilized to optimize the management and follow-up of patients with early-stage GCTs.

FOXL2 suppresses proliferation, invasion and promotes apoptosis of cervical cancer cells

FOXL2 is a transcription factor that is essential for ovarian function and maintenance, the germline mutations of which give rise to the blepharophimosis ptosis epicanthus inversus syndrome (BPES), often associated with premature ovarian failure. Recently, its mutations have been found in ovarian granulosa cell tumors (OGCTs). In this study, we measured the expression of FOXL2 in cervical cancer by immunohistochemistry and its mRNA level in cervical cancer cell lines Hela and Siha by RT-PCR. Then we overexpressed FOXL2 in Hela cells and silenced it in Siha cells by plasmid transfection and verified using western blotting. When FOXL2 was overexpressed or silenced, cells proliferation and apoptosis were determined by Brdu assay and Annexin V/PI detection kit, respectively. In addition, we investigated the effects of FOXL2 on the adhesion and invasion of Hela and Siha cells. Finally, we analyzed the influences of FOXL2 on Ki67, PCNA and FasL by flow cytometry. The results showed that FOXL2 was highly expressed in cervical squamous cancer. Overexpressing FOXL2 suppressed Hela proliferation and facilitated its apoptosis. Silencing FOXL2 enhanced Siha proliferation and inhibited its apoptosis. Meanwhile, silencing FOXL2 promoted Siha invasion, but it had no effect on cells adhesion. In addition, overexpressing FOXL2 decreased the expression of Ki67 in Hela and Siha cells. Therefore, our results suggested that FOXL2 restrained cells proliferation and enhanced cells apoptosis mainly through decreasing Ki67 expression.

FOXL2: a central transcription factor of the ovary

Forkhead box L2 (FOXL2) is a gene encoding a forkhead transcription factor preferentially expressed in the ovary, the eyelids and the pituitary gland. Its germline mutations are responsible for the blepharophimosis ptosis epicanthus inversus syndrome, which includes eyelid and mild craniofacial defects associated with primary ovarian insufficiency. Recent studies have shown the involvement of FOXL2 in virtually all stages of ovarian development and function, as well as in granulosa cell (GC)-related pathologies. A central role of FOXL2 is the lifetime maintenance of GC identity through the repression of testis-specific genes. Recently, a highly recurrent somatic FOXL2 mutation leading to the p.C134W subtitution has been linked to the development of GC tumours in the adult, which account for up to 5% of ovarian malignancies. In this review, we summarise data on FOXL2 modulators, targets, partners and post-translational modifications. Despite the progresses made thus far, a better understanding of the impact of FOXL2 mutations and of the molecular aspects of its function is required to rationalise its implication in various pathophysiological processes.

Identification of the forkhead transcriptional factor 2 (FOXL2) gene mutations in four Chinese families with blepharophimosis syndrome

PURPOSE

To determine the genetic origin of disease in four Chinese families with blepharophimosis syndrome.

METHODS

Four Han Chinese families with blepharophimosis syndrome were ascertained and patients underwent complete physical and ophthalmic examinations. Blood samples were collected and genomic DNA was extracted. Sequence analysis of the forkhead transcriptional factor 2 (FOXL2) gene was performed by direct sequencing and mutations were analyzed.

RESULTS

Three mutations in FOXL2 were found in four families, including c.672_701dup30 (p.Ala224_Ala234dup10), c.313C>A (p.N105H), and c.430G>T (p.R144W). The c.672_701dup30 (p.Ala224_Ala234dup10) mutation was reported previously and predicted to result in expansions of the polyalanine tract. The mutations of c.313C>A (p. N105H) and c.430G>T (p.R144W) are two novel missense mutations.

CONCLUSIONS

Our study further supports the view that the expansion of the polyalanine tract is the hotspot of mutations within FOXL2. The two novel missense mutations detected in this study will expand the mutation spectrum of the FOXL2 gene and contribute to the research on the molecular pathogenesis of FOXL2.

Essential but differential role of FOXL2wt and FOXL2C134W in GDF-9 stimulation of follistatin transcription in co-operation with Smad3 in the human granulosa cell line COV434

The FOXL2(C134W) mutation has been identified in virtually all adult granulosa cell tumors (GCTs). Here we show that the exogenous FOXL2 expression is necessary for GDF-9 stimulation of follistatin transcription in the human GCT cell line, COV434 that lacks endogenous FOXL2 expression. Interestingly, in the presence of Smad3 co-expression, FOXL2(C134W) negated GDF-9 stimulation of follistatin transcription. However, mutation of the Smad binding element (SBE) located in the intronic enhancer elements in the follistatin gene restored normal FOXL2 activity to FOXL2(C134W), thus the altered activity of FOXL2(C134W) is dependent on the ability of Smad3 to directly bind the SBE. Mutation of the FOXL2 binding element (FBE) or the FBE and SBE completely prevented GDF-9 activity, suggesting that the FBE is essential for GDF-9 stimulation in COV434. Overall, our study supports the view that altered interaction of FOXL2(C134W) with co-factors may underlie the pathogenesis of this mutation in GCTs.

Granulosa cell tumor mutant FOXL2C134W suppresses GDF-9 and activin A-induced follistatin transcription in primary granulosa cells

A single somatic FOXL2 mutation (FOXL2(C134W)) was identified in almost all granulosa cell tumor (GCT) patients. In the pituitary, FOXL2 and Smad3 coordinately regulate activin stimulation of follistatin transcription. We explored whether a similar regulation occurs in the ovary, and whether FOXL2(C134W) has altered activity. We show that in primary granulosa cells, GDF-9 and activin increase Smad3-mediated follistatin transcription. In contrast to findings in the pituitary, FOXL2 negatively regulates GDF-9 and activin-stimulated follistatin transcription in the ovary. Knockdown of endogenous FOXL2 confirmed this inhibitory role. FOXL2(C134W) displayed enhanced inhibitory activity, completely ablating GDF-9 and activin-induced follistatin transcription. GDF-9 and activin activity was lost when either the smad binding element or the forkhead binding element were mutated, indicating that both sites are required for Smad3 actions. This study highlights that FOXL2 negatively regulates follistatin expression within the ovary, and that the pathogenesis of FOXL2(C134W) may involve an altered interaction with Smad3.

Overexpression of wild-type but not C134W mutant FOXL2 enhances GnRH-induced cell apoptosis by increasing GnRH receptor expression in human granulosa cell tumors

The etiology of granulosa cell tumors (GCTs) is largely unknown. The primary mode of treatment is surgical, however not all women are cured by surgery alone. Thus, it is important to develop improved treatments through a greater understanding of the molecular mechanisms that contribute to this disease. Recently, it has been shown that a FOXL2 402C>G (C134W) mutation is present in 97% of human adult-type GCTs, suggesting an important role for this mutation in the development of GCTs. We have shown previously that gonadotropin-releasing hormone (GnRH)-I and -II induce apoptosis in cultured normal human granulosa cells. Moreover, it has been reported that FOXL2 can bind to the promoter of the mouse GnRH receptor gene and regulate its transcription. Thus, we hypothesized that C134W mutant FOXL2 could modulate the pro-apoptotic effects of GnRH via aberrant regulation of GnRH receptor levels. Using KGN cells, a human GCT-derived cell line which harbors the FOXL2 402C>G mutation, we show that treatment with GnRH-I and -II induces cell apoptosis, and that small interfering RNA-mediated depletion of GnRH receptor abolishes these effects. Overexpression of wild-type FOXL2 increases both mRNA and protein levels of GnRH receptor and consequently enhances GnRH-induced apoptosis. Importantly, neither the expression levels of GnRH receptor nor GnRH-induced apoptosis were affected by overexpression of the C134W mutant FOXL2. Interestingly, knockdown of endogenous FOXL2 down-regulates GnRHR expression in normal human granulosa cells with wild-type FOXL2, but not in KGN cells. These results suggest that the FOXL2 402C>G mutation may contribute to the development of human adult-type GCTs by reducing the expression of GnRH receptor, thus conferring resistance to GnRH-induced cell apoptosis.

Betaglycan alters NFκB-TGFβ2 cross talk to reduce survival of human granulosa tumor cells

The molecular pathways controlling granulosa cell tumor (GCT) survival are poorly understood. In many cell types, nuclear factor-κB (NFκB) and TGFβ coordinately regulate cell survival to maintain tissue homeostasis. Because GCT cell lines exhibit constitutively activated NFκB, we hypothesized that NFκB blocks TGFβ-mediated cell death in GCT cells. To test this hypothesis, we used the human GCT cell line KGN, which exhibits loss of betaglycan, a TGFβ co-receptor. After inhibition of NFκB in KGN cells, re-expression of betaglycan resulted in a decrease in cell viability, which was further decreased by TGFβ2. Intriguingly, TGFβ2 increased NFκB reporter activity in control cells, but betaglycan expression suppressed both basal and TGFβ2-stimulated NFκB activity. Chemical inhibition of Mothers against decapentaplegic homolog 2/3 (SMAD2/3) signaling or SMAD2/3 gene silencing revealed that both SMADs contributed to cell survival. Furthermore, inhibiting NFκB activity resulted in a specific reduction in SMAD3 expression. Conversely, overexpression of SMAD3 increased basal NFκB activity and countered betaglycan-mediated suppression of NFκB activity. Finally, ERK1/2 activation emerged as the point of convergence of NFκB, SMAD3, and TGFβ2/betaglycan governance of GCT cell viability. Key findings in KGN cells were reproduced in a second GCT cell line, COV434. Collectively, our data establish that both SMAD2/3 and NFκB signaling pathways support GCT cell viability and suggest the existence of a positive feedback loop between NFκB and SMAD3 signaling in late-stage GCT. Furthermore, our data suggest that loss of betaglycan during tumor progression in GCT alters the functional outcomes generated by NFκB and TGFβ pathway cross talk.

Fine map of the Gct1 spontaneous ovarian granulosa cell tumor locus

The spontaneous development of juvenile-onset, ovarian granulosa cell (GC) tumors in the SWR/Bm (SWR) inbred mouse strain is a model for juvenile-type GC tumors that appear in infants and young girls. GC tumor susceptibility is supported by multiple Granulosa cell tumor (Gct) loci, but the Gct1 locus on Chr 4 derived from SWR strain background is fundamental for GC tumor development and uniquely responsive to the androgenic precursor dehydroepiandrosterone (DHEA). To resolve the location of Gct1 independently from other susceptibility loci, Gct1 was isolated in a congenic strain that replaces the distal segment of Chr 4 in SWR mice with a 47 × 10(6)-bp genomic segment from the Castaneus/Ei (CAST) strain. SWR females homozygous for the CAST donor segment were confirmed to be resistant to DHEA- and testosterone-induced GC tumorigenesis, indicating successful exchange of CAST alleles (Gct1 ( CA )) for SWR alleles (Gct1 ( SW )) at this tumor susceptibility locus. A series of nested, overlapping, congenic sublines was created to fine-map Gct1 based on GC tumor susceptibility under the influence of pubertal DHEA treatment. Twelve informative lines have resolved the Gct1 locus to a 1.31 × 10(6)-bp interval on mouse Chr 4, a region orthologous to human Chr 1p36.22.

Mouse forkhead L2 maintains repression of FSH-dependent genes in the granulosa cell

The forkhead transcription factor forkhead box L2 (FOXL2) is expressed in granulosa cells of small and medium follicles in the mouse ovary.Foxl2female knockout mice exhibit primordial follicle depletion and primary ovarian failure, but evidence from adult female conditionalFoxl2knockout mice suggests that FOXL2 may also play a significant role in maintenance of ovarian differentiation at stages beyond the primordial follicle and initial wave of folliculogenesis. We previously showed that human FOXL2 functions as a transcriptional repressor of several key genes involved in granulosa cell proliferation and differentiation, including steroidogenic acute regulatory protein (STAR), P450aromatase (CYP19A1(CYP19)), P450scc (CYP11A1(CYP11A)), and cyclin D2 (CCND2). To elucidate the role of mouse FOXL2, we determined its role in transcriptional regulation in Chinese hamster ovary (CHO) cells and then confirmed our findings in mouse granulosa cells. We found that mouse FOXL2 represses the activities of the mouseStar,Cyp19a1,Cyp11a1promoters in CHO cells, but may not repress theCcnd2promoter, and identified the minimal mouseStar,Cyp19a1, andCyp11a1promoter regions responsive to FOXL2 regulation. We then knocked downFoxl2in mouse granulosa cells using siRNA, which resulted in significantly increased expression levels of mouseStar,Cyp19a1, andCyp11a1but notCcnd2. To increaseFoxl2expression levels, we generated a mouseFoxl2lentiviral construct and used it to infect mouse granulosa cells. Following lentiviral infection, the expression levels of mouseStar,Cyp19a1, andCyp11a1, but notCcnd2, decreased significantly. These data confirm that mouse FOXL2 functions as a transcriptional repressor of key granulosa cell genes that influence ovarian development.

The transcriptional targets of mutant FOXL2 in granulosa cell tumours

Background

Despite their distinct biology, granulosa cell tumours (GCTs) are treated the same as other ovarian tumours. Intriguingly, a recurring somatic mutation in the transcription factor Forkhead Box L2 (FOXL2) 402C>G has been found in nearly all GCTs examined. This investigation aims to identify the pathogenicity of mutant FOXL2 by studying its altered transcriptional targets.

Methods

The expression of mutant FOXL2 was reduced in the GCT cell line KGN, and wildtype and mutant FOXL2 were overexpressed in the GCT cell line COV434. Total RNA was hybridised to Affymetrix U133 Plus 2 microarrays. Comparisons were made between the transcriptomes of control cells and cells altered by FOXL2 knockdown and overexpression, to detect potential transcriptional targets of mutant FOXL2.

Results

The overexpression of wildtype and mutant FOXL2 in COV434, and the silencing of mutant FOXL2 expression in KGN, has shown that mutant FOXL2 is able to differentially regulate the expression of many genes, including two well known FOXL2 targets, StAR and CYP19A. We have shown that many of the genes regulated by mutant FOXL2 are clustered into functional annotations of cell death, proliferation, and tumourigenesis. Furthermore, TGF-β signalling was found to be enriched when using the gene annotation tools GATHER and GeneSetDB. This enrichment was still significant after performing a robust permutation analysis.

Conclusion

Given that many of the transcriptional targets of mutant FOXL2 are known TGF-β signalling genes, we suggest that deregulation of this key antiproliferative pathway is one way mutant FOXL2 contributes to the pathogenesis of adult-type GCTs. We believe this pathway should be a target for future therapeutic interventions, if outcomes for women with GCTs are to improve.

Refined mapping of a quantitative trait locus on chromosome 1 responsible for mouse embryonic death

Recurrent spontaneous abortion (RSA) is defined as the loss of three or more consecutive pregnancies during the first trimester of embryonic intrauterine development. This kind of human infertility is frequent among the general population since it affects 1 to 5% of women. In half of the cases the etiology remains unelucidated. In the present study, we used interspecific recombinant congenic mouse strains (IRCS) in the aim to identify genes responsible for embryonic lethality. Applying a cartographic approach using a genotype/phenotype association, we identified a minimal QTL region, of about 6 Mb on chromosome 1, responsible for a high rate of embryonic death (∼30%). Genetic analysis suggests that the observed phenotype is linked to uterine dysfunction. Transcriptomic analysis of the uterine tissue revealed a preferential deregulation of genes of this region compared to the rest of the genome. Some genes from the QTL region are associated with VEGF signaling, mTOR signaling and ubiquitine/proteasome-protein degradation pathways. This work may contribute to elucidate the molecular basis of a multifactorial and complex human disorder as RSA.

Adult ovarian granulosa cell tumor transcriptomics: prevalence of FOXL2 target genes misregulation gives insights into the pathogenic mechanism of the p.Cys134Trp somatic mutation

Ovarian granulosa cell tumors (OGCT) are the most frequent kind of sex cord-stromal tumors, and represent ∼2-5% of all ovarian malignancies. OGCTs exist as two entities, juvenile and adult types, with specific clinical and pathological characteristics. The molecular pathogenesis of these tumors has just begun to be unraveled. Indeed, recent studies have indicated that mutation and/or misregulation of the key ovarian transcription factor FOXL2 has a role in OGCT formation, although the mechanisms remain unclear. To better understand the molecular characteristics of OGCT, we studied the transcriptomic profiles of ten human adult-type OGCT samples, as well as ethnically matched granulosa cell (GC) controls. We find that the OGCT samples analyzed herein exhibit several hallmarks of cancer, including increased expression of genes linked to cell proliferation, but decreased expression of those conferring sensitivity to cell death. Moreover, genes differentially expressed in OGCTs are significantly enriched for known FOXL2 target genes, consistently with the prevalence of FOXL2 somatic mutation in these tumors. Expression of these targets is altered in a way expected to promote malignant transformation, for instance, through induction of genes associated with faster cell cycling and downregulation of genes associated with cell death. Over time, such defects may be responsible at least partly for the malignant transformation of healthy GCs into OGCT. These insights into the molecular pathogenesis of OGCTs may open the way to new efforts in the development of more targeted therapeutic strategies for OGCT patients.

The transcription factor FOXL2: at the crossroads of ovarian physiology and pathology

FOXL2 is a gene encoding a forkhead transcription factor. Its mutations or misregulation have been shown to cause the blepharophimosis-ptosis-epicanthus inversus (BPES) syndrome and more recently have been associated with the development of Ovarian Granulosa Cell Tumors (OGCT). BPES is a genetic disorder involving mild craniofacial abnormalities often associated with premature ovarian failure. OGCTs are endocrine malignancies, accounting for 2-5% of ovarian cancers, the treatment of which is still challenging. In this review we summarize recent data concerning FOXL2 transcriptional targets and molecular partners, its post-translational modifications, its mutations and its involvement in newly discovered pathophysiological processes. In the ovary, FOXL2 is involved in the regulation of cholesterol and steroid metabolism, apoptosis, reactive oxygen species detoxification and cell proliferation. Interestingly, one of the main roles of FOXL2 is also to preserve the identity of ovarian granulosa cells even at the adult stage and to prevent their transdifferentiation into Sertoli-like cells. All these recent advances indicate that FOXL2 is central to ovarian development and maintenance. The elucidation of the impact of FOXL2 germinal and somatic mutations will allow a better understanding of the pathogenesis of BPES and of OGCTs.

FOXL2 mutation and large-scale genomic imbalances in adult granulosa cell tumors of the ovary

Adult granulosa cell tumors (AGCTs) are a rare class of ovarian tumors with recurrent cytogenetic abnormalities including trisomy 12, trisomy 14, monosomy 16/deletion 16q, and monosomy 22. Over 90% contain a missense point mutation (C134W) in the FOXL2 gene at 3q22.3. The relationship between FOXL2 mutation and cytogenetic abnormalities is unclear, although both are presumably early events in tumorigenesis. In addition, FOXL2 C134W mutant allele imbalance has been noted in a minority of AGCTs, but the mechanism for allelic imbalance has not yet been described. We used a microarray platform designed for formalin-fixed, paraffin-embedded (FFPE) tissue specimens, the Affymetrix OncoScan FFPE Express 330K Molecular Inversion Probe (MIP) array, to explore the correlation between genomic imbalances detected by microarray and FOXL2 mutation status detected by pyrosequencing in a series of 21 archived AGCTs. Tumors were characterized by histopathologic features, stage, and alpha-inhibin expression by immunohistochemistry. All tumors were positive for inhibin, and 18/21 tumors contained a FOXL2 mutation. The most common genomic imbalances were a gain of 14q, a loss of 16q, and a loss of 22q. Three tumors showed evidence of FOXL2 mutant allele imbalance by pyrosequencing; microarray revealed a 32.5 Mb deletion encompassing FOXL2 in 1 case and a 70.9 Mb stretch of homozygosity encompassing FOXL2 in the other case. The third case, with a FOXL2 mutant allele imbalance, showed a diminished mutant allele population (32%) despite high estimated tumor content (>90%), suggesting tumor heterogeneity for the mutation. This study provides the first correlation of FOXL2 mutation status and genomic imbalances in AGCTs, and it further elucidates the mechanisms for mutant allele imbalance in cancer.

Giant multilocular sex cord tumor with annular tubules associated with precocious puberty

We report a case of sex cord tumor with annular tubules featuring a giant multilocular cyst, grossly similar to cystadenoma, in the ovary of an 8.5 year old girl. Estrogen-related symptoms, including precocious puberty and irregular uterine bleeding, immediately improved after tumor resection.