No activating mutations of FSH receptor in four children with ovarian juvenile granulosa cell tumors and the association of these tumors with central precocious puberty

Central precocious puberty secondary to peripheral precocious puberty due to a pineal germ cell tumor: a case and review of literature

BACKGROUND

The pineal lesion affecting melatonin is a rare cause of central precocious puberty by decreasing the inhibition of hypothalamic-pituitary-gonadal axis. Germ cell tumor secreting human chorionic gonadotropin is a rare cause of peripheral puberty.

CASE PRESENTATION

A 5.8-year-old male presented facial hair and phallic growth, deepened voice, and accelerated growth velocity for 6 months. The elevated human chorionic gonadotropin level with undetectable gonadotropin levels indicated peripheral precocious puberty. Brain imaging revealed a pineal mass and further pathology indicated the diagnosis of teratoma. During chemoradiotherapy with operation, the elevated human chorionic gonadotropin level reduced to normal range, while the levels of gonadotropins and testosterone increased. Subsequently, progressing precocious puberty was arrested with gonadotrophin-releasing hormone analog therapy. Previous cases of transition from peripheral precocious puberty to central precocious puberty were reviewed. The transitions were caused by the suddenly reduced feedback inhibition of sex steroid hormones on gonadotropin releasing hormone and gonadotropins.

CONCLUSIONS

For patients with human chorionic gonadotropin-secreting tumors, gonadotropin levels increase prior to sex steroid decrease, seems a sign of melatonin-related central PP related to melatonin.

Functional characterization of naturally-occurring constitutively activating/inactivating mutations in equine follicle-stimulating hormone receptor (eFSHR)

Objective

Follicle-stimulating hormone (FSH) is the central hormone involved in mammalian reproduction, maturation at puberty, and gamete production that mediates its function by control of follicle growth and function. The present study investigated the mutations involved in the regulation of FSH receptor (FSHR) activation.

Methods

We analyzed seven naturally-occurring mutations that were previously reported in human FSHR (hFSHR), in the context of equine FSHR (eFSHR); these include one constitutively activation variant, one allelic variant, and five inactivating variants. These mutations were introduced into wild-type eFSHR (eFSHR-wt) sequence to generate mutants that were designated as eFSHR-D566G, -A306T, -A189V, -N191I, -R572C, -A574V, and -R633H. Mutants were transfected into PathHunter EA-parental CHO-K1 cells expressing β-arrestin. The biological function of mutants was analyzed by quantitating cAMP accumulation in cells incubated with increasing concentrations of FSH.

Results

Cells expressing eFSHR-D566G exhibited an 8.6-fold increase in basal cAMP response, as compared to that in eFSHR-wt. The allelic variation mutant eFSHR-A306T was not found to affect the basal cAMP response or EC50 levels. On the other hand, eFSHR-D566G and eFSHR-A306T displayed a 1.5- and 1.4-fold increase in the maximal response, respectively. Signal transduction was found to be completely impaired in case of the inactivating mutants eFSHR-A189V, -R572C, and -A574V. When compared with eFSHR-wt, eFSHR-N191I displayed a 5.4-fold decrease in the EC50 levels (3910 ng/mL) and a 2.3-fold decrease in the maximal response. In contrast, cells expressing eFSHR-R633H displayed in a similar manner to that of the cells expressing the eFSHR-wt on signal transduction and maximal response.

Conclusion

The activating mutant eFSHR-D566G greatly enhanced the signal transduction in response to FSH, in the absence of agonist treatment. We suggest that the state of activation of the eFSHR can modulate its basal cAMP accumulation.

Constitutive Activation and Inactivation of Mutations Inducing Cell Surface Loss of Receptor and Impairing of Signal Transduction of Agonist-Stimulated Eel Follicle-Stimulating Hormone Receptor

In the present study, we investigated the signal transduction of mutants of the eel follicle-stimulating hormone receptor (eelFSHR). Specifically, we examined the constitutively activating mutant D540G in the third intracellular loop, and four inactivating mutants (A193V, N195I, R546C, and A548V). To directly assess functional effects, we conducted site-directed mutagenesis to generate mutant receptors. We measured cyclic adenosine monophosphate (cAMP) accumulation via homogeneous time-resolved fluorescence assays in Chinese hamster ovary (CHO-K1) cells and investigated cell surface receptor loss using an enzyme-linked immunosorbent assay in human embryonic kidney (HEK) 293 cells. The cells expressing eelFSHR-D540G exhibited a 23-fold increase in the basal cAMP response without agonist treatment. The cells expressing A193V, N195I, and A548V mutants had completely impaired signal transduction, whereas those expressing the R546C mutant exhibited little increase in cAMP responsiveness and a small increase in signal transduction. Cell surface receptor loss in the cells expressing inactivating mutants A193V, R546C, and A548V was clearly slower than in the cell expressing the wild-type eelFSHR. However, cell surface receptor loss in the cells expressing inactivating mutant N195I decreased in a similar manner to that of the cells expressing the wild-type eelFSHR or the activating mutant D540G, despite the completely impaired cAMP response. These results provide important information regarding the structure–function relationships of G protein-coupled receptors during signal transduction.

The Asn680Ser polymorphism of the follicle stimulating hormone receptor gene and ovarian cancer risk: a meta-analysis

PURPOSE

The purpose of this study was to conduct a meta-analysis to assess the association between FSHR Asn680Ser polymorphism and ovarian cancer susceptibility.

METHODS

A literature search was conducted in PubMed, Embase and the China National Knowledge Infrastructure (CNKI) for all relevant studies published up to September 2013. The pooled odds ratios (ORs) with the corresponding 95 % confidence intervals (95 % CIs) were calculated to evaluate the association.

RESULTS

Four case-control studies including 474 ovarian cancer cases and 659 controls met the inclusion criteria. The pooled analyses showed that FSHR Asn680Ser polymorphism was associated with the risk of ovarian cancer (Ser vs Asn: OR=1.295, 95 % CI 1.057-1.498, P=0.01; Ser/Ser + Asn/Ser vs Asn/Asn: OR=1.611, 95 % CI 1.027-2.528, P=0.038). Subgroup analyses by ethnicity (Caucasian and Asian) further revealed significant associations among Asians (Ser vs Asn: OR=1.386, 95 % CI 1.066-1.802, P=0.015; Ser/Ser + Asn/Ser vs Asn/Asn: OR=1.893, 95 % CI 1.329-2.689, P=0.000) but not Caucasians. There was no obvious risk of publication bias.

CONCLUSIONS

The meta-analysis suggests that FSHR Asn680Ser polymorphism may be a risk factor for ovarian cancer in Asians. Due to the limited quantity of the included studies, further studies are needed to validate the above conclusions.

FSH-FSHR3-stem cells in ovary surface epithelium: basis for adult ovarian biology, failure, aging, and cancer

Despite extensive research, genetic basis of premature ovarian failure (POF) and ovarian cancer still remains elusive. It is indeed paradoxical that scientists searched for mutations in FSH receptor (FSHR) expressed on granulosa cells, whereas more than 90% of cancers arise in ovary surface epithelium (OSE). Two distinct populations of stem cells including very small embryonic-like stem cells (VSELs) and ovarian stem cells (OSCs) exist in OSE, are responsible for neo-oogenesis and primordial follicle assembly in adult life, and are modulated by FSH via its alternatively spliced receptor variant FSHR3 (growth factor type 1 receptor acting via calcium signaling and the ERK/MAPK pathway). Any defect in FSH-FSHR3-stem cell interaction in OSE may affect folliculogenesis and thus result in POF. Ovarian aging is associated with a compromised microenvironment that does not support stem cell differentiation into oocytes and further folliculogenesis. FSH exerts a mitogenic effect on OSE and elevated FSH levels associated with advanced age may provide a continuous trigger for stem cells to proliferate resulting in cancer, thus supporting gonadotropin theory for ovarian cancer. Present review is an attempt to put adult ovarian biology, POF, aging, and cancer in the perspective of FSH-FSHR3-stem cell network that functions in OSE. This hypothesis is further supported by the recent understanding that: i) cancer is a stem cell disease and OSE is the niche for ovarian cancer stem cells; ii) ovarian OCT4-positive stem cells are regulated by FSH; and iii) OCT4 along with LIN28 and BMP4 are highly expressed in ovarian cancers.

Follicle stimulating hormone modulates ovarian stem cells through alternately spliced receptor variant FSH-R3

BACKGROUND

We have earlier reported that follicle stimulating hormone (FSH) modulates ovarian stem cells which include pluripotent, very small embryonic-like stem cells (VSELs) and their immediate descendants 'progenitors' termed ovarian germ stem cells (OGSCs), lodged in adult mammalian ovarian surface epithelium (OSE). FSH may exert pleiotropic actions through its alternatively spliced receptor isoforms. Four isoforms of FSH receptors (FSHR) are reported in literature of which FSH-R1 and FSH-R3 have biological activity. Present study was undertaken to identify FSHR isoforms mediating FSH action on ovarian stem cells, using sheep OSE cells culture as the study model.

METHODS

Cultures of sheep OSE cells (a mix of epithelial cells, VSELs, OGSCs and few contaminating red blood cells) were established with and without FSH 5IU/ml treatment. Effect of FSH treatment on self-renewal of VSELs and their differentiation into OGSCs was studied after 15 hrs by qRT-PCR using markers specific for VSELs (Oct-4A, Sox-2) and OGSCs (Oct-4). FSH receptors and its specific transcripts (R1 and R3) were studied after 3 and 15 hrs of FSH treatment by immunolocalization, in situ hybridization and qRT-PCR. FSHR and OCT-4 were also immuno-localized on sheep ovarian sections, in vitro matured follicles and early embryos.

RESULTS

FSH treatment resulted in increased stem cells self-renewal and clonal expansion evident by the appearance of stem cell clusters. FSH receptors were expressed on ovarian stem cells whereas the epithelial cells were distinctly negative. An increase in R3 mRNA transcripts was noted after 3 hrs of FSH treatment and was reduced to basal levels by 15 hrs, whereas R1 transcript expression remained unaffected. Both FSHR and OCT-4 were immuno-localized in nuclei of stem cells, showed nuclear or ooplasmic localization in oocytes of primordial follicles and in cytoplasm of granulosa cells in growing follicles.

CONCLUSIONS

FSH modulates ovarian stem cells via FSH-R3 to undergo potential self-renewal, clonal expansion as 'cysts' and differentiation into oocytes. OCT-4 and FSHR proteins (required initially to maintain pluripotent state of VSELs and for FSH action respectively) gradually shift from nuclei to cytoplasm of developing oocytes and are later possibly removed by surrounding granulosa cells as the oocyte prepares itself for fertilization.

Central precocious puberty and granulosa cell ovarian tumor in an 8-year old female

Ovarian tumors associated with hormonal changes of the peripheral iso-sexual precocious puberty are of common presentation. We describe here a rare case of juvenile granulosa cell tumor in a female with central precocious puberty (CPP). An 8-year old girl with CPP presented with vaginal bleeding four months after the diagnosis and before starting treatment with gonadotropin-releasing hormone (GnRH)-analogs. Suppression of basal follicle-stimulating hormone (FSH) level, elevation of serum estradiol, progesterone and Cancer Antigen-125 were documented. Abdominal ultrasound examination (US) and magnetic resonance imaging showed a pelvic mass affecting the left ovary. A left salpingo-oophorectomy was performed and the mass was totally resected. Juvenile granulosa cell ovarian tumor was diagnosed. One month post surgery, estradiol and progesterone decreased to values of the first evaluation and FSH increased; Cancer Antigen-125 resulted normal while ultrasound pelvic examination showed absence of pelvic masses. In our patient, the tumor had grown very quickly since hormonal data demonstrated a CPP without any evidence of ovarian mass on US only four months before diagnosis. The overstimulation of the FSH or aberrant activation of FSH receptors may have contributed to the development of the mass.

The new molecular biology of granulosa cell tumors of the ovary

Granulosa cell tumors (GCTs) of the ovary belong to the group of ovarian sex-cord stromal tumors and represent 5 to 10% of ovarian malignancies. GCTs exhibit several morphological, biochemical and hormonal features of normal proliferating pre-ovulatory granulosa cells, such as estrogen biosynthesis. Prognostic factors of this condition are lacking, and alternative treatment options to preserve future fertility are needed. Several groups have shown that two genetic factors implicated in GCTs are of particular interest. The gsp oncogene is a constitutive activating mutation of the prognosis of the tumor. FOXL2 is a transcription factor gene involved in ovarian development and function, whose expression is reduced and which is mutated in the majority of GCTs. FOXL2 appears to play a major role in cell cycle regulation. These recent findings open new pathophysiological insights into GCT development as well as revisitation of granulosa cell and ovarian function.