Loss of heterozygosity at the alpha-inhibin locus on chromosome 2q is not a feature of human granulosa cell tumors

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.

Methylation and mutation of the inhibin‑α gene in human melanoma cells and regulation of PTEN expression and AKT/PI3K signaling by a demethylating agent

Inhibin suppresses the pituitary secretion of follicle‑stimulating hormone and has been reported to act as a tumor suppressor gene in the gonad in mice. Epigenetic modifications, mutations, changes in the loss of heterozygosity (LOH) of the inhibin‑α gene and regulation of gene expression in response to a demethylating agent [5‑aza‑2'‑deoxycytidine (5‑Aza‑dC)] in human melanoma cells were assessed. In addition, the association between a mutation in the 5'‑untranslated region (5'‑UTR) of the inhibin‑α subunit and the expression of phosphatidylinositol 3,4,5‑trisphosphate‑dependent Rac exchanger 2 (PREX2) and phosphatase and tensin homolog (PTEN) as well as AKT/PI3K signaling was determined. The methylation status of the CpG sites of the inhibin‑α promoter was analyzed by methylation‑specific PCR in bisulfite‑treated DNA. Cell viability was counted using the trypan blue assay, mRNA expression was examined via reverse transcription‑quantitative PCR, and protein expression was examined via western blot analysis. The inhibin‑α promoter was hypermethylated in G361, SK‑MEL‑3, SK‑MEL‑24 and SK‑MEL‑28 cells and moderately methylated in SK‑MEL‑5 cells. Inhibin‑α gene mutations were observed in the 5'‑UTR exon 1 of G361, SK‑MEL‑5, SK‑MEL‑24 and SK‑MEL‑28 cells as well as in exon 2 of SK‑MEL‑3 cells. Allelic imbalance, including LOH, in the inhibin‑α gene was detected in human melanoma cells. Treatment with 5‑Aza‑dC increased inhibin‑α mRNA and protein levels, inhibited cell proliferation, and delayed the doubling times of surviving melanoma cells. In 5‑Aza‑dC‑treated cells, PREX2 protein expression was slightly increased in G361 and SK‑MEL‑24 cells and decreased in SK‑MEL3, SK‑MEL‑5 and SK‑MEL‑28 cells. However, the protein expression of PTEN was decreased in melanoma cells. In addition, AKT and PI3K protein phosphorylation levels increased in all melanoma cells, except of G361 cells, demonstrating decreased PI3K protein phosphorylation. These data provided evidence that methylation, mutation and LOH are observed in the inhibin α‑subunit gene and gene locus in human melanoma cells. Furthermore, the demethylating agent reactivated inhibin‑α gene expression and regulated PREX2 expression. AKT/PI3K signaling increased as PTEN expression decreased. In addition, mutations in the tumor suppressor inhibin‑α, PTEN and p53 genes were not associated with transcriptional silencing, gene expression and cell growth as analyzed through experiments and literature reviews. These data demonstrated that methylation and mutations were associated with the inhibin‑α gene in human melanoma cells and indicated the regulation of PTEN expression and AKT/PI3K signaling by a demethylating agent.

The role of reproductive hormones in epithelial ovarian carcinogenesis

Epithelial ovarian cancer comprises ∼85% of all ovarian cancer cases. Despite acceptance regarding the influence of reproductive hormones on ovarian cancer risk and considerable advances in the understanding of epithelial ovarian carcinogenesis on a molecular level, complete understanding of the biologic processes underlying malignant transformation of ovarian surface epithelium is lacking. Various hypotheses have been proposed over the past several decades to explain the etiology of the disease. The role of reproductive hormones in epithelial ovarian carcinogenesis remains a key topic of research. Primary questions in the field of ovarian cancer biology center on its developmental cell of origin, the positive and negative effects of each class of hormones on ovarian cancer initiation and progression, and the role of the immune system in the ovarian cancer microenvironment. The development of the female reproductive tract is dictated by the hormonal milieu during embryogenesis. Intensive research efforts have revealed that ovarian cancer is a heterogenous disease that may develop from multiple extra-ovarian tissues, including both Müllerian (fallopian tubes, endometrium) and non-Müllerian structures (gastrointestinal tissue), contributing to its heterogeneity and distinct histologic subtypes. The mechanism underlying ovarian localization, however, remains unclear. Here, we discuss the role of reproductive hormones in influencing the immune system and tipping the balance against or in favor of developing ovarian cancer. We comment on animal models that are critical for experimentally validating existing hypotheses in key areas of endocrine research and useful for preclinical drug development. Finally, we address emerging therapeutic trends directed against ovarian cancer.

YAP regulates cell proliferation, migration, and steroidogenesis in adult granulosa cell tumors

The Hippo signaling pathway has been implicated as a conserved regulator of organ size in both Drosophila and mammals. Yes-associated protein (YAP), the central component of the Hippo signaling cascade, functions as an oncogene in several malignancies. Ovarian granulosa cell tumors (GCT) are characterized by enlargement of the ovary, excess production of estrogen, a high frequency of recurrence, and the potential for malignancy and metastasis. Whether the Hippo pathway plays a role in the pathogenesis of GCT is unknown. This study was conducted to examine the expression of YAP in human adult GCTs and to determine the role of YAP in the proliferation and steroidogenesis of GCT cells. Compared with age-matched normal human ovaries, GCT tissues exhibited higher levels of YAP expression. YAP protein was predominantly expressed in the nucleus of tumor cells, whereas the non-tumor ovarian stromal cells expressed very low levels of YAP. YAP was also expressed in cultured primary human granulosa cells and in KGN and COV434 GCT cell lines. siRNA-mediated knockdown of YAP in KGN cells resulted in a significant reduction in cell proliferation (P<0.001). Conversely, overexpression of wild type YAP or a constitutively active YAP (YAP1) mutant resulted in a significant increase in KGN cell proliferation and migration. Moreover, YAP knockdown reduced FSH-induced aromatase (CYP19A1) protein expression and estrogen production in KGN cells. These results demonstrate that YAP plays an important role in the regulation of GCT cell proliferation, migration, and steroidogenesis. Targeting the Hippo/YAP pathway may provide a novel therapeutic approach for GCT.

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.

Transforming growth factor alpha (TGFα) regulates granulosa cell tumor (GCT) cell proliferation and migration through activation of multiple pathways

Granulosa cell tumors (GCTs) are the most common ovarian estrogen producing tumors, leading to symptoms of excessive estrogen such as endometrial hyperplasia and endometrial adenocarcinoma. These tumors have malignant potential and often recur. The etiology of GCT is unknown. TGFα is a potent mitogen for many different cells. However, its function in GCT initiation, progression and metastasis has not been determined. The present study aims to determine whether TGFα plays a role in the growth of GCT cells. KGN cells, which are derived from an invasive GCT and have many features of normal granulosa cells, were used as the cellular model. Immunohistochemistry, Western blot and RT-PCR results showed that the ErbB family of receptors is expressed in human GCT tissues and GCT cell lines. RT-PCR results also indicated that TGFα and EGF are expressed in the human granulosa cells and the GCT cell lines, suggesting that TGFα might regulate GCT cell function in an autocrine/paracrine manner. TGFα stimulated KGN cell DNA synthesis, cell proliferation, cell viability, cell cycle progression, and cell migration. TGFα rapidly activated EGFR/PI3K/Akt and mTOR pathways, as indicated by rapid phosphorylation of Akt, TSC2, Rictor, mTOR, P70S6K and S6 proteins following TGFα treatment. TGFα also rapidly activated the EGFR/MEK/ERK pathway, and P38 MAPK pathways, as indicated by the rapid phosphorylation of EGFR, MEK, ERK1/2, P38, and CREB after TGFα treatment. Whereas TGFα triggered a transient activation of Akt, it induced a sustained activation of ERK1/2 in KGN cells. Long-term treatment of KGN cells with TGFα resulted in a significant increase in cyclin D2 and a decrease in p27/Kip1, two critical regulators of granulosa cell proliferation and granulosa cell tumorigenesis. In conclusion, TGFα, via multiple signaling pathways, regulates KGN cell proliferation and migration and may play an important role in the growth and metastasis of GCTs.

Mutations in inhibin and activin genes associated with human disease

Inhibins and activins are members of the transforming growth factor (TGFβ) superfamily, that includes the TGFβs, inhibins and activins, bone morphogenetic proteins (BMPs) and growth and differentiation factors (GDFs). The family members are expressed throughout the human body, and are involved in the regulation of a range of important functions. The precise regulation of the TGFβ pathways is critical, and mutations of individual molecules or even minor alterations of signalling will have a significant affect on function, that may lead to development of disease or predisposition to the development of disease. The inhibins and activins regulate aspects of the male and female reproductive system, therefore, it is not surprising that most of the diseases associated with abnormalities of the inhibin and activin genes are focused on reproductive disorders and reproductive cancers. In this review, I highlight the role of genetic variants in the development of conditions such as premature ovarian failure, pre-eclampsia, and various reproductive cancers. Given the recent advances in human genetic research, such as genome wide association studies and next generation sequencing, it is likely that inhibins and activins will be shown to play more important roles in a range of human genetic diseases in the future.

Transcriptional silencing of the inhibin-α gene in human gastric carcinoma cells

Although inhibin was first identified as a hormone regulating pituitary FSH secretion, it was later recognized to act as a tumor suppressor in the gonad and adrenal glands. Recently, the alpha subunit of this dimeric hormone (inhibin‑α) was reported to be involved in prostate tumorigenesis. To identify additional roles outside the reproductive axis, we investigated inhibin‑α gene activity and subsequent cell fate in human gastric cancer cells. The results were as follows: all the gastric cancer cells had at least one of a set of abnormalities including hypermethylation of the promoter, mutation of the 5'‑UTR or allelic imbalance including LOH in the inhibin‑α gene. Hypermethylation of the promoter and mutation of the 5'‑UTR in inhibin‑α were observed in SNU‑1, SNU‑5 and SNU‑484 cells. LOH was observed in AGS, KATO III, SNU‑5, SNU‑484 and SNU‑668 cells. Treatment with 5‑AzaC, a demethylating agent, induced demethylation of the inhibin‑α promoter in the SNU‑1, SNU‑5 and SNU‑484 cell lines, with the CpG5 site being strongly influenced by 5‑AzaC. In addition, inhibin‑α mRNA and protein were maintained at low levels in most of the gastric cancer cell lines. These low levels of mRNA and protein expression could be increased in most lines by treatment with 5‑AzaC. These increased inhibin‑α expression levels seemed to be closely associated with apoptosis and suppression of cell growth. Taken together, our results reveal that the inhibin‑α gene is transcriptionally silenced in human gastric cancer cells, and that reactivation of the gene suppresses their growth characteristics. This suggests that inhibin‑α may have a more general tumor suppressor activity outside the reproductive axis.

Loss of betaglycan contributes to the malignant properties of human granulosa tumor cells

Betaglycan is a type III TGFbeta receptor that modulates cellular sensitivity to inhibins and TGFbeta. Previous studies have suggested that betaglycan acts as a tumor suppressor in certain human epithelial cancers. However, the roles of betaglycan in ovarian granulosa cell tumors (GCTs) are poorly understood. The objective of this study was to determine whether human GCTs exhibit betaglycan expression and, if so, what impact this receptor has on tumor biology. Real-time PCR was used to quantify betaglycan transcripts in human GCTs (n = 17) and normal premenopausal ovaries (n = 11). This analysis established that GCTs exhibited a significant 2-fold lower mean betaglycan mRNA level as compared with the normal ovary (P < 0.05). Similarly, two human GCT cell lines, KGN and COV434, exhibited low betaglycan expression and poor responsiveness to TGFbeta and inhibin A in luciferase reporter assays, which was restored by stable transfection of wild-type betaglycan. Betaglycan significantly increased the adhesion of COV434 (P < 0.05) and KGN (P < 0.0001) cells, decreased cellular invasion through Matrigel, and inhibited wound healing. Expression of mutant forms of betaglycan that are defective in TGFbeta and/or inhibin binding in each GCT cell line revealed that the inhibitory effects of betaglycan on wound healing were most strongly linked to the inhibin-binding region of betaglycan. Furthermore, knockdown of INHA mRNA expression abrogated the betaglycan-mediated inhibition of wound healing and invasion, whereas both INHA silencing and TGFbeta neutralization abolished the betaglycan-mediated increase in adhesion to substrate. These data suggest that loss of betaglycan contributes to the pathogenesis of GCTs.

Loss of heterozygosity (LOH) on chromosomes 2q, 3p and 21q in Indian oral squamous cell carcinoma

Around the world, 200,000 people a year are affected by oral cancer, and the incidence of this disease is 10 times higher in India than Japan, mainly due to the custom of chewing tobacco. Loss of heterozygosity (LOH) on the long arm of chromosome 2 (2q), the short arm of chromosome 3 (3p) and the long arm of chromosome 21 (21q) are observed in several human cancers. We identified novel tumor suppressor loci on these regions in primary oral squamous cell carcinomas (OSCCs) in Japanese. However, there has been no detailed analysis of LOH on these chromosomes in Indians. In the present study, we investigated LOH at 2q, 3p and 21q using 9 microsatellite markers in 26 Indian OSCCs. LOH was detected in 25 (96.2%) out of 26 informative samples at one or more of the loci examined. On the basis of the results, two commonly deleted regions were identified and a detailed deletion map was constructed. In the first region, a high frequency of LOH was observed at the D3S1007 locus (53.8%) on 3p25, which is located in the region neighboring the VHL (von Hippel-Lindau) gene. In the second region, LOH was concentrated at the D3S966 locus (50.0%) on 3p21.3, suggesting the presence of a putative tumor suppressor gene (TSG) associated with OSCCs. These results strongly suggest that there are at least two candidate TSGs located on chromosome 3p, and that alteration in them is associated with the tumorigenesis of OSCCs.

Involvement of GATA-4/-5 transcription factors in ovarian carcinogenesis

To clarify the role of GATA transcription factors in ovarian carcinogenesis, we analyzed the expression and methylation states of GATA-4/-5/-6 in eight human ovarian cancer cell lines. GATA-4/-5 were methylated in three and two cell lines without their expression, respectively. Methylation of GATA-4/-5 was also detected in nine and five of 15 primary ovarian cancers, respectively. GATA-6 was not methylated in any cases. We transiently over-expressed GATA-5 in the JHOC-5 cell line using an adenovirus system, resulting in that apoptosis was induced and apoptosis-related genes, such as Apaf-1, were up-regulated. These data suggest that GATA-4/-5 may be involved in ovarian carcinogenesis.

Cancer progression: is inhibin alpha from Venus or Mars?

The inhibin field has been perplexed by the information that inhibin alpha is a tumour suppressor in mice yet is elevated in women with ovarian cancer. Furthermore, we have consistently observed a down-regulation or loss of inhibin alpha in prostate cancer patient samples and cell lines. However, our latest data have prompted us to re-evaluate the role of inhibin alpha in prostate and other cancers. Using the analogy of TGF-beta as a springboard for our hypothesis, we offer a unifying model whereby the previously conflicting observations in mice, men and women can be explained. We propose that initially inhibin alpha is tumour-suppressive and is expressed in benign and early-stage primary cancers. Tumour-suppressive inhibin alpha is then silenced as the tumour progresses but is reactivated as a pro-metastatic factor in advanced, aggressive cancers.

Loss of Heterozygosity and Microsatellite Instability on Chromosome 2q in Human Oral Squamous Cell Carcinoma

Allelic imbalance or loss of heterozygosity (LOH) and microsatellite instability (MSI) have been used to identify regions on chromosomes that may contain putative tumor suppressor genes. To obtain a detailed understanding of genetic alterations in oral cancer, 10 highly polymorphic markers mapped on chromosome 2 were used to examine 25 cases of oral squamous cell carcinoma (SCC). With these, we analyzed chromosome 2q for LOH in 25 primary oral SCCs and constructed a deletion map for this arm of the chromosome. LOH was detected in 16 (64%) of the 25 informative samples at one or more of the loci examined. MSI was observed in 5 (20%) of the 25 cases. Among the loci examined, LOHs were restricted to D2S1328 and D2S206 on chromosomes 2q14-21 and 2q36, respectively, with the former locus showing a rate of 5 (20.8%) and the latter a rate of 6 (25%) of the 24 informative cases. These observations taken in conjunction with data from 40 former cases analyzed at our laboratory suggest that the high incidence of LOH at chromosome 2q is associated with carcinogenesis of oral SCC. The regions that comprise the D2S1328 and D2S206 loci may play an important role in the development of oral SCC, perhaps containing sites that harbor a putative tumor suppressor gene.

Evidence of a role for the INK4 family of cyclin-dependent kinase inhibitors in ovarian granulosa cell tumors

Granulosa cell tumors (GCTs) of the ovary are relatively rare and account for <5% of all ovarian cancers. The molecular pathogenesis of these tumors is not well understood. We tested the hypothesis that cyclin-dependent kinase inhibitors, specifically the inhibitors of the cyclin-dependent kinase 4 (INK4) family, are targets for altered gene expression in GCTs. The status of RB1, INK4A, INK4B, INK4C, INK4D, and ARF in 13 adult and 2 juvenile ovarian GCTs was determined by reverse transcription-polymerase chain reaction of total RNA and exon-specific sequencing of genomic DNA. Tumors showing loss of INK4A expression were assayed further by exon-deletion analysis and methylation-specific PCR. None of the juvenile tumors demonstrated altered expression, but 7/12 (58%) adult GCTs lacked expression of INK4A, INK4B, or both. In one of these cases, we noted a homozygous deletion of the INK4A locus, and in the remaining tumors we found hypermethylation of the promoter region, a mechanism that can lead to gene inactivation. These data support a role for the INK4 family of CDK inhibitors in the biology of GCTs.

Molecular analysis of inhibin A and activin A subunit gene loci in epithelial ovarian cancer

Inhibin A (alpha-betaA) and activin A (betaA-betaA) are biochemically similar proteins that generally have opposite biologic functions. For example, while inhibin (alpha subunit) is proposed to be a tumor suppressor in some types of ovarian cancer, activin appears to stimulate tumor development. Previous reports suggest that a loss of alpha inhibin subunit expression and elevated serum activin levels are associated with human epithelial ovarian cancer (EOC). Our objective was to examine the alpha inhibin subunit gene locus on chromosome 2q for evidence of loss of heterozygosity (LOH) in cases of EOC and to correlate these results with serum activin A levels measured in the same patients. Ovarian tumor and matched healthy tissue samples were collected from 22 women with EOC. DNA was extracted and subjected to PCR analysis using 10 primers, seven from chromosome 2q (alpha inhibin subunit locus) and, as a control, three from chromosome 7p (inhibin/activin betaA subunit). In addition, each patient had a preoperative serum activin A measurement using an ELISA assay. One (1/22) case of EOC demonstrated LOH for one microsatellite marker at the alpha inhibin gene locus. Thirty-six percent (8/22) of patients had an activin A level that was increased above the normal range. We conclude that loss of heterozygosity at the inhibin/activin alpha subunit locus is not frequently associated with EOC. More direct molecular analyses of the inhibin and activin genes are warranted to rule out mutations in cases of epithelial ovarian cancer.

Activins and inhibins in endocrine and other tumors

Inhibin and activin are members of the TGF beta superfamily of growth and differentiation factors. They were first identified as gonadal-derived regulators of pituitary FSH and were subsequently assigned multiple actions in a wide range of tissues. More recently, the inhibin alpha subunit was considered as a tumor suppressor based on functional studies employing transgenic mouse models. This review evaluates the functional and molecular evidence that the inhibin alpha subunit is a tumor suppressor in endocrine cancers. The evaluation highlights the discrepant results from the human and mouse studies, as well as the differences between endocrine tumor types. In addition, we examine the evidence that the activin-signaling pathway is tumor suppressive and identify organ-specific differences in the actions and putative roles of this pathway in endocrine tumors. In summary, there is a considerable body of evidence to support the role of inhibins and activins in endocrine-related tumors. Future studies will define the mechanisms by which inhibins and activins contribute to the process of initiation, promotion, or progression of endocrine-related cancers.

The inhibins and ovarian cancer

Interest in inhibin as a marker of ovarian malignancy was stimulated by the description of elevated immunoreactive inhibin levels in the sera of patients with granulosa cell tumours. Several groups have confirmed the value of serum inhibin in the diagnosis and follow-up of patients with this uncommon malignancy. Immunoreactive inhibin levels are also frequently elevated in patients with mucinous cystadenocarcinoma and less frequently in other forms of ovarian tumour. Assay of sera using the specific dimeric inhibin assays has shown that ovarian tumours are able to secrete dimeric inhibin particularly inhibin B. The less specific alpha-subunit directed assays, however, most frequently show elevated concentrations. Used in combination with CA125 as a dual tumour marker, it appears in principle that inhibin can be a useful diagnostic agent. Immunohistochemistry for the inhibin subunits has been reported with increasing frequency as a helpful method to assess suspected ovarian stromal cell tumours. Its diagnostic accuracy for other types of ovarian adenocarcinoma appears less reliable. Expression of the inhibin subunit mRNAs has been demonstrated in a variety of ovarian malignancies. The observation that inhibin levels are elevated in ovarian cancer has stimulated studies of their relevance to the molecular pathogenesis of these malignancies. Findings to date have been largely negative with no evidence for activating mutations of the FSH receptor or of the post-receptor signalling pathway proteins.

Gene expression in abnormal ovarian structures of ewes homozygous for the inverdale prolificacy gene

Animals heterozygous (I+) for the Inverdale prolificacy gene (FecX(I)) have an increased ovulation rate whereas those homozygous (II) for FecX(I) are infertile with "streak" ovaries and follicular development arrested at the primary (type 2 follicle) stage. The streak ovaries also contain small oocyte-free nodules with granulosa-like cells and often tumor-like structures. It has been hypothesized that these abnormal structures are of granulosa cell origin, and the aim of this study was to determine whether genes normally expressed in granulosa cells are also expressed in the nodules and tumor-like structures. The mRNAs encoding c-kit and its ligand stem cell factor (SCF), FSH receptor (FSH-R), follistatin, alpha-inhibin subunit, and the beta(A)- and beta(B)-activin/inhibin subunits were localized in ovaries of ewes with 0 (++), 1 (I+), or 2 (II) copies of the FecX(I) gene (n = 4-9 animals per genotype per gene) using in situ hybridization. Ontogeny of expression of all mRNAs examined was similar between ++ and I+ ewes. Expression of c-kit mRNA was observed in the oocyte of all follicular types present in ++, I+, and II ewes. Moreover, granulosa cells of type 2 (II) and type 2 and larger follicles (++, I+) expressed SCF mRNA. The mRNAs encoding FSH-R, follistatin, alpha-inhibin subunit, and beta(B)-activin/inhibin subunit were identified in type 3 and larger follicles of ++ and I+ ewes but not in follicles of II ewes that were only at the type 1, 1a, or 2 stages of development. However, the cells within the oocyte-free nodules of II ewes expressed all of these genes. The mRNAs encoding c-kit and beta(A)-activin/inhibin subunit were not observed in granulosa cells until antrum formation (type 5 follicles) or in the nodules of II ewes. Tumors from 4 ewes were obtained and classified as cystic, semisolid, or solid structures containing granulosa-like cells or as solid structures containing predominately fibroblast- and luteal-like cells. Often, two tumors were present on the same ovary. Tumors containing granulosa-like cells (n = 3-4 per gene) expressed the mRNAs encoding alpha-inhibin subunit, beta(A)-, and beta(B)-activin/inhibin subunits, follistatin, and the FSH-R but did not contain detectable amounts of mRNA for c-kit or SCF. Tumors composed predominately of fibroblast- and luteal-like cells expressed very low levels of SCF mRNA; of the other mRNAs examined, none were detected. Also, none of the genes examined were found to be expressed by the surface epithelium, theca externa, fibroblast, or vascular cells within the ovary of animals of any genotype. These findings are consistent with the hypothesis that the somatic cells in oocyte-free nodules and tumor-like tissue in II ewes originate from the granulosa cells of the small follicles.

Adrenal cancer

Adrenal cancer is a rare neoplasm. Up to 1 in 1500 adrenal incidentalomas, however, may hide a carcinoma, which, if diagnosed late or left untreated, is associated with significant morbidity and mortality. Despite extensive investigation of the molecular mechanisms involved in adrenal carcinogenesis and significant improvements in diagnostic imaging, efforts to cure advanced adrenal cancer remain largely unsuccessful. This article reviews the recent advances in molecular understanding, clinical diagnosis, and treatment of adrenal cancer.

Inhibin subunit gene expression in ovarian cancer

OBJECTIVE(S)

Granulosa cell tumors (GCT) and mucinous cystadenocarcinoma of the ovary are associated with elevated circulating levels of immunoreactive inhibin. Measurement of serum inhibin levels provides a useful tumor marker in the management of ovarian tumors. Inhibin is a dimeric ovarian glycoprotein hormone consisting of one alpha and one of two beta subunits. The beta subunits can dimerize to form activin. Activin is bound and its action modulated by another gonadal peptide, follistatin. In this study the patterns of expression of the three inhibin subunit genes, the follistatin gene, and the activin receptor type II gene have been determined.

METHODS

Gene expression was analyzed in RNA prepared from 16 primary ovarian tumors using reverse transcriptase-polymerase chain reaction (RT-PCR). Gene-specific primes were used for RT-PCR; the products were analyzed by Southern blot analysis with gene-specific 32P-labeled probes.

RESULTS

Widespread expression of these genes was found in all of the tumor types examined. Abundant expression of the inhibin alpha subunit gene was observed in the GCT and to a lesser extent in the mucinous and serous tumors. beta subunit expression was also present in the GCT and to a lesser extent in the other tumors. Widespread expression of both the activin receptor type II and the follistatin genes was also observed.

CONCLUSIONS

Expression of the inhibin subunit genes in GCT and some epithelial tumors confirms that these tumors are the source of the increased immunoreactive inhibin seen in the circulation of patients with ovarian tumors. Expression of the activin receptor type II and follistatin genes suggests a paracrine role for activin in these tumors which may be modulated by follistatin, particularly in the GCT.

Preoperative serum level of inhibin A is an independent prognostic factor for the survival of postmenopausal women with epithelial ovarian carcinoma

BACKGROUND

The aim of this study was to determine the prognostic significance of preoperative serum inhibin and activin levels in postmenopausal women with epithelial ovarian carcinoma (EOC) by correlating serum levels with disease parameters, including tumor stage and grade and patient age.

METHODS

Serum levels of inhibin A, inhibin B, pro-alpha C, activin A, and activin B were quantitated with sensitive and specific two-site enzyme-linked immunosorbent assays (ELISAs) in samples collected from 44 postmenopausal women diagnosed with EOC. Serum was obtained within 14 days prior to primary tumor reductive surgery and stored at -55 degrees C. All patients underwent definitive surgical staging and cytoreduction at Mayo Clinic and were followed for at least 5 years or until death. Postoperative adjuvant therapy was selected based on stage of disease. Demographics included 5 Stage I, 2 Stage II, 33 Stage III, and 4 Stage IV tumors, and the predominant histology was serous subtype and poorly differentiated grade.

RESULTS

Inhibin A was detected in 98% of the serum samples (range, 0-12.18 pg/mL). Univariate analysis was used to demonstrate an association between patients with serum inhibin A levels exceeding the median (1.21 pg/mL) and compromised disease free (P = 0.025) and overall (P = 0.006) survival. While the 5 year disease free survival (DFS) for the entire population was 32%, the corresponding DFS rates for patients with inhibin A levels above and below the median were 10% and 43%, respectively. Similarly, the 5-year overall survival (OS) for the entire population was 35%, compared with 16% for patients above and 47% for patients below the median inhibin A level. Stepwise regression analysis that incorporated age, stage, grade, and inhibin A levels identified serum inhibin A levels above the median to be the most cogent predictor of DFS and OS.

CONCLUSIONS

Preoperative serum inhibin A levels provided valuable prognostic information independent of age, stage, and grade in a postmenopausal cohort given standardized treatment for EOC.

Synchronous ovarian and cervical squamous intraepithelial neoplasia: an analysis of HPV status

In contrast to the strong association between human papillomavirus (HPV) and cervical intraepithelial neoplasia (CIN), the relationship between HPV and squamous epithelial lesions of the ovary is less clear. We report a case of synchronous ovarian and cervical squamous intraepithelial neoplasia. To investigate the possible association between HPV and squamous intraepithelial neoplasia/carcinoma in situ (CIS) of the ovary, DNA was extracted from paraffin-embedded tissues including normal cervix, CIN, CIS from both ovaries, and an area of ovarian endometriosis. All samples were positive for HPV 16 E6 except for one of the two samples from the normal cervical squamous epithelium. These results support the hypothesis that HPV may be involved in the development of ovarian squamous intraepithelial neoplasia.

Activating mutation of the stimulatory G protein (gsp) as a putative cause of ovarian and testicular human stromal Leydig cell tumors

Activating mutations of the G protein genes have been associated with the development of several endocrine neoplasms. Such activating mutations, gip2, affecting the alpha-subunit of the G alpha i2 protein were previously described by a single group in 30% of ovarian sex cord stromal tumors. Other activating mutations of the alpha-subunit of the Gs (gsp) have been identified in GH-secreting and nonfunctioning pituitary tumors, autonomous thyroid adenomas, and all affected McCune-Albright tissues, but not in sex cord stromal tumors. In the present study, we investigated the presence of gip2 and gsp mutations in 14 human sex cord stromal tumors. Six Leydig cell tumors (4 ovaries and 2 testes), 2 thecomas, 2 granulosa cell tumors, 3 androblastomas, and 1 gonadoblastoma (sex cord and germ cell) were included in this study. Genomic DNA was obtained from either fresh-frozen tumor tissues or paraffin-embedded sections and in some cases from blood samples. Using PCR, denaturing gradient gel electrophoresis, and direct sequencing, we detected 4 tumors (66.6%) with the gsp mutation (R201C) in our series of ovarian and testicular Leydig cell tumors. In contrast, no gip2 mutations were found in any of the sex cord stromal tumors studied. In conclusion, our findings suggest that the putative oncogene gsp may play a significant role in the molecular mechanism of these tumors.