Endocrine tumors of the ovary

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.

Molecular manipulation of keratin 8/18 intermediate filaments: modulators of FAS-mediated death signaling in human ovarian granulosa tumor cells

Background

Granulosa cell tumors (GCT) are a rare ovarian neoplasm but prognosis is poor following recurrence. Keratin intermediate filaments expressed in these tumors are a diagnostic marker, yet paradoxically, may also constitute a target for therapeutic intervention. In the current study, we evaluated keratin 8/18 (K8/18) filament expression as a mechanism of resistance to apoptosis in GCT, specifically focusing on regulation of the cell surface death receptor, Fas (FAS).

Methods

The GCT cell line, KGN, was transiently transfected with siRNA to KRT8 and KRT18 to reduce K8/18 filament expression. Expression of K8/18, FAS, and apoptotic proteins (PARP, cleaved PARP) were evaluated by fluorescence microscopy, flow cytometric analysis, and immunoblotting, respectively. The incidence of FAS-mediated apoptosis in KGN cells was measured by caspase 3/7 activity. All experiments were performed independently three to six times, using a fresh aliquot of KGN cells for each experiment. Quantitative data were analyzed by one- or two-way analysis of variance (ANOVA), followed by a Tukey’s post-test for multiple comparisons; differences among means were considered statistically significant at P < 0.05.

Results

Control cultures of KGN cells exhibited abundant K8/18 filament expression (~90 % of cells), and minimal expression of FAS (<25 % of cells). These cells were resistant to FAS-activating antibody (FasAb)-induced apoptosis, as determined by detection of cleaved PARP and measurement of caspase 3/7 activity. Conversely, siRNA-mediated knock-down of K8/18 filament expression enhanced FAS expression (> 70 % of cells) and facilitated FasAb-induced apoptosis, evident by increased caspase 3/7 activity (P < 0.05). Additional experiments revealed that inhibition of protein synthesis, but not MEK1/2 or PI3K signaling, also prompted FasAb-induced apoptosis.

Conclusions

The results demonstrated that K8/18 filaments provide resistance to apoptosis in GCT by impairing FAS expression. The abundance of keratin filaments in these cells and their role in apoptotic resistance provides a greater mechanistic understanding of ovarian tumorgenicity, specifically GCT, as well as a clinically-relevant target for potential therapeutic intervention.

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.

FOXO1/3 and PTEN Depletion in Granulosa Cells Promotes Ovarian Granulosa Cell Tumor Development

The forkhead box (FOX), FOXO1 and FOXO3, transcription factors regulate multiple functions in mammalian cells. Selective inactivation of the Foxo1 and Foxo3 genes in murine ovarian granulosa cells severely impairs follicular development and apoptosis causing infertility, and as shown here, granulosa cell tumor (GCT) formation. Coordinate depletion of the tumor suppressor Pten gene in the Foxo1/3 strain enhanced the penetrance and onset of GCT formation. Immunostaining and Western blot analyses confirmed FOXO1 and phosphatase and tensin homolog (PTEN) depletion, maintenance of globin transcription factor (GATA) 4 and nuclear localization of FOXL2 and phosphorylated small mothers against decapentaplegic (SMAD) 2/3 in the tumor cells, recapitulating results we observed in human adult GCTs. Microarray and quantitative PCR analyses of mouse GCTs further confirmed expression of specific genes (Foxl2, Gata4, and Wnt4) controlling granulosa cell fate specification and proliferation, whereas others (Emx2, Nr0b1, Rspo1, and Wt1) were suppressed. Key genes (Amh, Bmp2, and Fshr) controlling follicle growth, apoptosis, and differentiation were also suppressed. Inhbb and Grem1 were selectively elevated, whereas reduction of Inha provided additional evidence that activin signaling and small mothers against decapentaplegic (SMAD) 2/3 phosphorylation impact GCT formation. Unexpectedly, markers of Sertoli/epithelial cells (SRY [sex determining region Y]-box 9/keratin 8) and alternatively activated macrophages (chitinase 3-like 3) were elevated in discrete subpopulations within the mouse GCTs, indicating that Foxo1/3/Pten depletion not only leads to GCTs but also to altered granulosa cell fate decisions and immune responses. Thus, analyses of the Foxo1/3/Pten mouse GCTs and human adult GCTs provide strong evidence that impaired functions of the FOXO1/3/PTEN pathways lead to dramatic changes in the molecular program within granulosa cells, chronic activin signaling in the presence of FOXL2 and GATA4, and tumor formation.

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.

Circulating sex steroids during pregnancy and maternal risk of non-epithelial ovarian cancer

BACKGROUND

Sex steroid hormones have been proposed to play a role in the development of non-epithelial ovarian cancers (NEOC) but so far no direct epidemiologic data are available.

METHODS

A case-control study was nested within the Finnish Maternity Cohort, the world's largest biorepository of serum specimens from pregnant women. Study subjects were selected among women who donated a blood sample during a singleton pregnancy that led to the birth of their last child preceding diagnosis of NEOC. Case subjects were 41 women with sex cord stromal tumors (SCST) and 21 with germ cell tumors (GCT). Three controls, matching the index case for age, parity at the index pregnancy, and date at blood donation were selected (n = 171). OR and 95% CI associated with concentrations of testosterone, androstenedione, 17-OH-progesterone, progesterone, estradiol, and sex hormone-binding globulin (SHBG) were estimated through conditional logistic regression.

RESULTS

For SCST, doubling of testosterone, androstenedione, and 17-OH-progesterone concentrations were associated with about 2-fold higher risk of SCST [ORs and 95% CI of 2.16 (1.25-3.74), 2.16 (1.20-3.87), and 2.62 (1.27-5.38), respectively]. These associations remained largely unchanged after excluding women within 2-, 4-, or 6-year lag time between blood donation and cancer diagnosis. Sex steroid hormones concentrations were not related to maternal risk of GCT.

CONCLUSIONS

This is the first prospective study providing initial evidence that elevated androgens play a role in the pathogenesis of SCST.

IMPACT

Our study may note a particular need for larger confirmatory investigations on sex steroids and NEOC.

Extinction of FOXL2 expression in aggressive ovarian granulosa cell tumors in children

OBJECTIVE

In the female gonad, FOXL2 is a key factor for proper differentiation of granulosa cells (GC) during folliculogenesis and its expression persists in the ovary after birth. The aim of this multicentric nationwide study was to determine whether FOXL2 expression varies during tumoral proliferation of GC cells in juvenile ovarian GC tumors (OGCT).

DESIGN

Nationwide retrospective study.

SETTING

University Hospital of Montpellier, Department of Hormonology.

PATIENT(S)

Between 1994 and 2004, 26 patients with juvenile OGCT were reported in the TGM95 database of the French Society for Childhood Cancer (SFCE) and from eight pediatric endocrinology centers. Immunohistochemistry was performed using an anti-FOXL2 antibody.

INTERVENTION(S)

Immunohistochemistry studies of FOXL2 on OGCT slides.

MAIN OUTCOME MEASURE(S)

Level of FOXL2 expression within the tumor, International Federation of Gynecology and Obstetrics classification, and tumor recurrences.

RESULT(S)

FOXL2 expression was absent in the GC of 10 patients and was markedly reduced in the cells of 4 patients. Precocious pseudopuberty was more frequently the revealing symptom in the children with conserved FOXL2 expression. Patients with no or reduced expression of FOXL2 more frequently exhibited associated hemorrhagic ascites, higher mitotic activity in the tumor, and significantly more advanced oncologic staging. All patients requiring complementary treatment (n = 7; chemotherapy or complementary surgery) had reduced expression of FOXL2 in the tumor. All recurring OGCT exhibited a complete extinction of FOXL2 expression (n = 3).

CONCLUSION(S)

These results show that FOXL2 is not expressed or is underexpressed in juvenile OGCT with an aggressive pattern of progression, and it thus may be a prognostic factor for these tumors.

No evidence of somatic activating mutations on gonadotropin receptor genes in sex cord stromal tumors

OBJECTIVE

To search for somatic activating mutations of gonadotropin receptor (FSH-R and LH/chorionic gonadotropin receptor [CG-R]) genes as a cause of sex cord stromal tumors.

DESIGN

Molecular studies in human tissue.

SETTING

University hospital. SPECIMEN(S): Eight granulosa cell tumors collected from paraffin-embedded tissue, eight Leydig cell tumors, and three thecomas collected from fresh-frozen or paraffin-embedded tissue.

INTERVENTION(S)

Tumor samples were used for DNA extraction. The entire exon 11 of the LH/CG-R gene and a hot spot for gonadotropin receptor activating mutations on exon 10 of the FSH-R gene were amplified by polymerase chain reaction. The former was analyzed by denaturing gradient gel electrophoresis and automatic direct sequencing, and the latter by automatic direct sequencing.

MAIN OUTCOME MEASURE(S)

Results of denaturing gradient gel electrophoresis and automatic direct sequencing.

RESULT(S)

No somatic activating mutation was detected in exon 11 of the LH/CG-R gene in eight Leydig cell tumors and three thecomas. In addition, no mutations were detected in eight granulosa cell tumors in the hot spot for activating mutations in exon 10 of the FSH-R gene.

CONCLUSION(S)

Somatic activating mutations of gonadotropin receptors seem to play no relevant role in the development of sex cord stromal tumors.

Review of the granulosa-theca cell tumors from the emil Novak ovarian tumor registry

OBJECTIVE

Our purpose was to review patients with granulosa and theca cell tumors as filed in the Emil Novak Ovarian Tumor Registry.

STUDY DESIGN

Our study was a descriptive, retrospective study of 454 case records.

RESULTS

The reviewed diagnoses were for 97 patients with granulosa cell tumors, 116 with theca cell tumors, and 97 with granulosa-theca cell tumors. The remaining cases (n = 144) were reclassified as "nonspecific" gonadal stromal tumors (n = 61), luteomas of pregnancy (n = 7), and 76 "other" cases. These included poorly differentiated cancer, metastatic cancer, mixed mesodermal tumors, and sarcomas. The tumor-related mortality rate for the 310 patients with granulosa, theca, and granulosa-theca cell tumors was 7% (37.3% for granulosa cell tumors only). The surgical stage of disease was the most significant prognostic factor, with a mortality rate of at least 40%, given that the tumor had spread beyond the ovary.

CONCLUSION

Because the differential diagnoses of particularly granulosa cell tumors included several conditions with an extremely poor prognosis, an accurate histologic diagnosis is crucial.

Hormone synthesis and responsiveness of spontaneous granulosa cell tumors in (SWR x SWXJ-9) F1 mice

Granulosa cell tumors spontaneously occur in approximately 10-25% of female (SWR x SWXJ-9) F1 mice. The present studies were designed to test whether tumor-bearing mice produce a distinct hormonal profile by which they could be identified and determine whether cultured tumor cells are responsive to hormones and growth factors that regulate normal granulosa cells. Samples of female mouse blood taken from age 3 to 10 weeks allowed estimation of serum FSH, 17beta-estradiol, and inhibin levels for normal mice and for mice destined to develop tumors. These studies indicated that FSH and 17beta-estradiol values differed between normal and tumor-bearing animals, but overlapped sufficiently that such values could not accurately predict the tumor-bearing state. Inhibin concentrations did differentiate normal from tumor-bearing animals in all cases. Increased levels of inhibin were observed coincident in time with visibly detectable tumors within the ovaries. Compared to inhibin synthesis in vivo, hormonal responsiveness in vitro was much more variable. Steroidogenesis was stimulated in all tumors by dibutyryl-cAMP and low-density lipoprotein (LDL). Some, but not all, tumors responded to IGF1, EGF, FSH, and hCG. In about one-half of the tumors tested, FSH could induce hCG or dibutyryl-cAMP responsiveness. IGF1 pretreatment consistently increased the responsiveness of tumor cells stimulated by dibutyryl-cAMP and LDL. Production of inhibin by isolated tumor cells was detectable and decreased by EGF or dibutyryl-cAMP treatments. We conclude that granulosa tumor cell secretion of inhibin may be under different control than secretion from normal granulosa cells and acts as an excellent marker for these tumors.

Adult granulosa-cell tumor of the ovary: a retrospective study of 45 cases

This study describes 45 cases of adult granulosa-cell tumors seen in our institution between 1976 and 1993. The median age was 46.5 years (12-77) and 18 women were postmenopausal. Vaginal bleeding was present in one-third of cases; other complaints were abdominal pain (28%) and the presence of a pelvic mass (47%). The tumor size was variable (<3 cm to 30 cm, median 11.5 cm). FIGO stages were: stage I: 30 (73%) (19 Ia, seven Ic, four I unknown); stage II: seven (17%) (two IIa, five IIC); stage III: three (7%) (one IIIb, two IIIc). Two adenocarcinomas and 13 cases of hyperplasia were found in 25 endometrial samples available. The initial therapy for all the cases was surgery, consisting in 34 patients of hysterectomy, bilateral salpingo-oophorectomy, +/- tumor resection. Sixteen patients received adjuvant therapy as well: chemotherapy (CT) alone for 12, radiotherapy (RT) alone for two, and CT + RT for two patients. Among the 39 patients who achieved a complete response after initial therapy, 15 patients have relapsed (pelvic recurrences) (38.5%) including six stage Ia (three received only conservative surgery). All the recurrent tumors were resected and 14/15 had CT (13/14 with cisplatin). The overall survival rate was 77.2% at 5 years, 66.5% at 10 years, and 41.2% at 20 years. A statistically significant difference was found between the survival of patients with stage Ia disease (75% at 10 and 15 years) and that of other patients (60% at 10 years, and <50% at 15 years). Serum estradiol and serum inhibin were measured in some patients and the results are described.

Immunohistochemical characterization of extracellular matrix components of granulosa cell tumor of ovary

In order to clarify the characteristics of granulosa cell tumors of the ovary, extracellular matrix components were investigated by immunohistochemical techniques. Twenty-three granulosa cell tumors (GCT; eight juvenile and 15 adult type) were studied in comparison with non-neoplastic granulosa cells of human ovaries. In all 23 cases of GCT, chondroitin 6-sulfate proteoglycan revealed with antibody 3B3 was characteristically observed in the extracellular matrix in the solid nest, as well as in microfollicles. In the juvenile cases, the extracellular matrix also contained large proteoglycan (PG) revealed with antibody 2B1. Macrofollicles as well as microfollicles contained PG chondroitin 6-sulfate side chains with a significant amount of chondroitin 4-sulfate. By biochemical analysis using high pressure liquid chromatography, it was also found that disaccharide composition of glycosaminoglycan fractions extracted from granulosa cell tumor tissues consisted mainly of 2-acetamide-2-deoxyl-3-O-(beta-D-gluco-4-enepyranosyluronic acid)-6-O-sulfo-D-galactose (delta Di-6S). The characteristic feature of granulosa cell tumors is the accumulation of chondroitin sulfate PG, especially chondroitin 6-sulfate PG, which may be synthesized by the tumor cells themselves. Immunohistochemical characterization of the extracellular matrix components (collagen, laminin, heparan sulfate PG, chondroitin 4-sulfate PG) was also studied in relation to chondroitin 6-sulfate PG localization.