Analysis of selected oncogenes (AKT1, FOS, BCL2L2, TGFbeta) on chromosome 14 in granulosa cell tumors (GCTs): a comprehensive study on 30 GCTs combining comparative genomic hybridization (CGH) and fluorescence-in situ-hybridization (FISH)

Clinicopathological characteristics and prognostic factors of ovarian granulosa cell tumors: A JSGO-JSOG joint study

OBJECTIVES

The aim of this study was to elucidate the clinicopathological features of ovarian granulosa cell tumors (GCTs) and to identify the prognostic factors.

METHODS

The Japanese Society of Gynecologic Oncology (JSGO) conducted an observational retrospective cohort study of women with GCTs enrolled in the Gynecological Tumor Registry of the Japan Society of Obstetrics and Gynecology (JSOG) between 2002 and 2015. Clinicopathological features, including lymph node metastasis, were evaluated. In addition, we performed a prognostic analysis of patients between 2002 and 2011 for whom survival data were available. Kaplan-Meier and multivariate Cox proportional hazards analyses were performed.

RESULTS

We identified 1426 patients with GCTs. Of the 222 patients who underwent lymph node dissection, 10 (4.5%) had lymph node metastasis. The incidence of lymph node metastasis in patients with pT1, pT2, and pT3 was 2.1%, 13.3%, and 26.7%, respectively (p < 0.001). Prognostic analysis was performed on 674 patients. In the multivariate Cox regression analysis, residual disease after initial surgery (hazard ratio (HR) = 10.39, 95% confidence interval (CI) = 3.15-34.29) and lymph node metastasis (HR = 5.58, 95% CI = 1.62-19.19) were independent risk factors for cancer-specific survival.

CONCLUSIONS

In the initial surgery for GCTs, lymph node dissection can be omitted if the operative finding is pT1. In cases of pT2 or higher, lymph node dissection should be considered. Debulking is critical for achieving no gross residual tumor at the end of the surgery.

Transcription factor-microRNA-target gene networks associated with ovarian cancer survival and recurrence

The identification of reliable transcriptome biomarkers requires the simultaneous consideration of regulatory and target elements including microRNAs (miRNAs), transcription factors (TFs), and target genes. A novel approach that integrates multivariate survival analysis, feature selection, and regulatory network visualization was used to identify reliable biomarkers of ovarian cancer survival and recurrence. Expression profiles of 799 miRNAs, 17,814 TFs and target genes and cohort clinical records on 272 patients diagnosed with ovarian cancer were simultaneously considered and results were validated on an independent group of 146 patients. Three miRNAs (hsa-miR-16, hsa-miR-22*, and ebv-miR-BHRF1-2*) were associated with both ovarian cancer survival and recurrence and 27 miRNAs were associated with either one hazard. Two miRNAs (hsa-miR-521 and hsa-miR-497) were cohort-dependent, while 28 were cohort-independent. This study confirmed 19 miRNAs previously associated with ovarian cancer and identified two miRNAs that have previously been associated with other cancer types. In total, the expression of 838 and 734 target genes and 12 and eight TFs were associated (FDR-adjusted P-value <0.05) with ovarian cancer survival and recurrence, respectively. Functional analysis highlighted the association between cellular and nucleotide metabolic processes and ovarian cancer. The more direct connections and higher centrality of the miRNAs, TFs and target genes in the survival network studied suggest that network-based approaches to prognosticate or predict ovarian cancer survival may be more effective than those for ovarian cancer recurrence. This study demonstrated the feasibility to infer reliable miRNA-TF-target gene networks associated with survival and recurrence of ovarian cancer based on the simultaneous analysis of co-expression profiles and consideration of the clinical characteristics of the patients.

The specificity of the FOXL2 c.402C>G somatic mutation: a survey of solid tumors

BACKGROUND

A somatic mutation in the FOXL2 gene is reported to be present in almost all (97%; 86/89) morphologically defined, adult-type, granulosa-cell tumors (A-GCTs). This FOXL2 c.402C>G mutation changes a highly conserved cysteine residue to a tryptophan (p.C134W). It was also found in a minority of other ovarian malignant stromal tumors, but not in benign ovarian stromal tumors or unrelated ovarian tumors or breast cancers.

METHODOLOGY/PRINCIPAL FINDINGS

Herein we studied other cancers and cell lines for the presence of this mutation. We screened DNA from 752 tumors of epithelial and mesenchymal origin and 28 ovarian cancer cell lines and 52 other cancer cell lines of varied origin. We found the FOXL2 c.402C>G mutation in an unreported A-GCT case and the A-GCT-derived cell line KGN. All other tumors and cell lines analyzed were mutation negative.

CONCLUSIONS/SIGNIFICANCE

In addition to proving that the KGN cell line is a useful model to study A-GCTs, these data show that the c.402C>G mutation in FOXL2 is not commonly found in a wide variety of other cancers and therefore it is likely pathognomonic for A-GCTs and closely related tumors.

Mutation of FOXL2 in granulosa-cell tumors of the ovary

BACKGROUND

Granulosa-cell tumors (GCTs) are the most common type of malignant ovarian sex cord-stromal tumor (SCST). The pathogenesis of these tumors is unknown. Moreover, their histopathological diagnosis can be challenging, and there is no curative treatment beyond surgery.

METHODS

We analyzed four adult-type GCTs using whole-transcriptome paired-end RNA sequencing. We identified putative GCT-specific mutations that were present in at least three of these samples but were absent from the transcriptomes of 11 epithelial ovarian tumors, published human genomes, and databases of single-nucleotide polymorphisms. We confirmed these variants by direct sequencing of complementary DNA and genomic DNA. We then analyzed additional tumors and matched normal genomic DNA, using a combination of direct sequencing, analyses of restriction-fragment-length polymorphisms, and TaqMan assays.

RESULTS

All four index GCTs had a missense point mutation, 402C-->G (C134W), in FOXL2, a gene encoding a transcription factor known to be critical for granulosa-cell development. The FOXL2 mutation was present in 86 of 89 additional adult-type GCTs (97%), in 3 of 14 thecomas (21%), and in 1 of 10 juvenile-type GCTs (10%). The mutation was absent in 49 SCSTs of other types and in 329 unrelated ovarian or breast tumors.

CONCLUSIONS

Whole-transcriptome sequencing of four GCTs identified a single, recurrent somatic mutation (402C-->G) in FOXL2 that was present in almost all morphologically identified adult-type GCTs. Mutant FOXL2 is a potential driver in the pathogenesis of adult-type GCTs.