Extragonadal FSHR Expression and Function-Is It Real?

Effects of follicle-stimulating hormone on energy balance and tissue metabolic health after loss of ovarian function

Loss of ovarian function imparts increased susceptibility to obesity and metabolic disease. These effects are largely attributed to decreased estradiol (E2), but the role of increased follicle-stimulating hormone (FSH) in modulating energy balance has not been fully investigated. Previous work that blocked FSH binding to its receptor in mice suggested this hormone may play a part in modulating body weight and energy expenditure after ovariectomy (OVX). We used an alternate approach to isolate the individual and combined contributions of FSH and E2 in mediating energy imbalance and changes in tissue-level metabolic health. Female Wistar rats were ovariectomized and given the gonadotropin releasing hormone (GnRH) antagonist degarelix to suppress FSH production. E2 and FSH were then added back individually and in combination for a period of 3 wk. Energy balance, body mass composition, and transcriptomic profiles of individual tissues were obtained. In contrast to previous studies, suppression and replacement of FSH in our paradigm had no effect on body weight, body composition, food intake, or energy expenditure. We did, however, observe organ-specific effects of FSH that produced unique transcriptomic signatures of FSH in retroperitoneal white adipose tissue. These included reductions in biological processes related to lipogenesis and carbohydrate transport. In addition, rats administered FSH had reduced liver triglyceride concentration (P < 0.001), which correlated with FSH-induced changes at the transcriptomic level. Although not appearing to modulate energy balance after loss of ovarian function in rats, FSH may still impart tissue-specific effects in the liver and white adipose tissue that might affect the metabolic health of those organs.NEW & NOTEWORTHY We find no effect of follicle-stimulating hormone (FSH) on energy balance using a novel model in which rats are ovariectomized, subjected to gonadotropin-releasing hormone antagonism, and systematically given back FSH by osmotic pump. However, tissue-specific effects of FSH on adipose tissue and liver were observed in this study. These include unique transcriptomic signatures induced by the hormone and a stark reduction in hepatic triglyceride accumulation.

New insights into the role of LH in early ovarian follicular growth: a possible tool to optimize follicular recruitment

Evidence shows that LH participates in enhancing transition from the early stage to the antral stage of folliculogenesis. It has been demonstrated that functional LH receptors are expressed, albeit at a very low level and even in smaller follicles, during the phase that was traditionally considered to be gonadotrophin independent, suggesting a role for LH in accelerating the rate of progression of non-growing and primary follicles to the preantral/antral stage. Hypogonadotropic hypogonadism, together with other clinical conditions of pituitary suppression, has been associated with reduced functional ovarian reserve. The reduction in LH serum concentration is associated with a low concentration of anti-Müllerian hormone. This is the case in hypothalamic amenorrhoea, pregnancy, long-term GnRH-analogue therapy and hormonal contraception. The effect seems to be reversible, such that after pregnancy and after discontinuation of drugs, the functional ovarian reserve returns to the baseline level. Evidence suggests that women with similar primordial follicle reserves could present with different numbers of antral follicles, and that gonadotrophins may play a fundamental role in permitting a normal rate of progression of follicles through non-cyclic folliculogenesis. The precise role of gonadotrophins in early folliculogenesis, as well as their use to modify the functional ovarian reserve, must be investigated.

Gonadotropins in the Management of Couple Infertility: Toward the Rational Use of an Empirical Therapy

Although epidemiology shows that both men and woman can experience infertility, the female partner usually experiences most of the diagnostic and therapeutic burden. Thus, management of couple infertility is a unique example of gender inequality. The use of exogenous gonadotropins in assisted reproductive technology (ART) to induce multifollicular growth is well consolidated in women, but the same is not done with the same level of confidence and purpose in infertile men. Indeed, the treatment of idiopathic male infertility is based on an empirical approach that involves administration of the follicle-stimulating hormone (FSH) in dosages within the replacement therapy range. This treatment has so far been attempted when the endogenous FSH serum levels are within the reference ranges. According to the most recent evidence, a "substitutive" FSH administration may not be effective enough, while a stimulatory approach could boost spermatogenesis over its basal levels without adverse extragonadal effects. This article aims to describe the rationale behind the empirical application of gonadotropins in couple infertility, highlighting the need for a change in the therapeutic approach, especially for the male partner.

Polymorphisms in FSHR modulating susceptibility to polycystic ovary syndrome: an updated meta-analysis

BACKGROUND

Two polymorphisms, rs6165 and rs6166 located in the intracellular domain of FSHR has been reported to affect folliculogenesis, steroidogenesis and oocyte maturation. Several studies have highlighted the role of FSHR polymorphisms in PCOS but the findings are conflicting. A meta-analysis was carried out to decipher the emerging perspectives.

METHODOLOGY

A comprehensive literature search was made using PubMed, PCOSkb, and Google Scholar. New Ottawa Scale has been utilized to evaluate the quality of each article. To evaluate the strength of association under different genetic models of rs6165 and rs6166 polymorphisms, odds ratio with a 95% confidence interval (CI) was calculated.

RESULTS

A total of 20 articles were selected for the present study. In pooled analysis and after the stratification by ethnicity, polymorphism rs6165 remains unrelated to the onset of PCOS. Besides, rs6166 exhibits significant protection in the Indian population under recessive, additive, and allele models (OR = 0.7, CI: 0.54-0.9, p = 0.006, OR = 0.65, CI: 0.48-0.89, p = 0.006, OR = 0.82, CI: 0.7-0.95, p = 0.01, respectively) and low to moderate risk in the Caucasian population under allele model (OR = 1.17, CI: 1.04-1.32, p = 0.01).

CONCLUSION

This meta-analysis suggests that GG genotype of rs6166 provides protection against PCOS, in a population-specific manner.

Effects of Chinese herbal feed additives on the sperm quality and reproductive capacity in breeding boars

Currently, Chinese herbal feed additives (CHFA) are commonly utilized in domestic pig farms. However, their impact on the sperm quality and reproductive capacity of imported breeding boars has yet to be thoroughly explored. In this study, the effect of CHFA on the sperm quality and reproductive capacity of the imported Duroc boars was investigated. Sixteen boars were randomly divided into control group and experimental (CHFA treated) group and fed normal or CHFA-levels containing diets, respectively. The sperm quality and reproductive hormone levels were periodically tested, and the reproductive capacity with breeding sows were evaluated. The results showed that the CHFA treated group boars significantly improved sperm volume, sperm concentration, and motility and reduced the sperm abnormalities. Furthermore, the serum levels of reproductive hormone such as follicle-stimulating hormone (FSH), luteinizing hormone (LH), and testosterone (T) in the CHFA treated group were significantly higher than those in the control group. Although there was no significant difference in the initial birth weight of piglets between the two groups, the CHFA treated group had a significantly higher average number of piglets born, the average number of piglets born alive, the number of piglets weaned at 28 days, and the weaning weight compared to the control group. These findings suggest that CHFA can significantly improve the sperm quality of breeding boars and enhance their reproductive hormone levels as well as the reproductive capacity, providing direct evidence for the further application of CHFA in the management of breeding boars in China.

Extra-Gonadal and Non-Canonical Effects of FSH in Males

Recombinant follicle-stimulating hormone (FSH) is commonly used for the treatment of female infertility and is increasingly being used in males as well, as recommended by notable guidelines. FSH is composed of an α subunit, shared with other hormones, and a β subunit, which confers specificity of biological action by interacting with its surface receptor (FSHR), predominantly located in granulosa and Sertoli cells. However, FSHRs also exist in extra-gonadal tissues, indicating potential effects beyond male fertility. Emerging evidence suggests that FSH may have extra-gonadal effects, including on bone metabolism, where it appears to stimulate bone resorption by binding to specific receptors on osteoclasts. Additionally, higher FSH levels have been associated with worse metabolic and cardiovascular outcomes, suggesting a possible impact on the cardiovascular system. FSH has also been implicated in immune response modulation, as FSHRs are expressed on immune cells and may influence inflammatory response. Furthermore, there is growing interest in the role of FSH in prostate cancer progression. This paper aims to provide a comprehensive analysis of the literature on the extra-gonadal effects of FSH in men, with a focus on the often-conflicting results reported in this field. Despite the contradictory findings, the potential for future development in this area is substantial, and further research is needed to elucidate the mechanisms underlying these effects and their clinical implications.

Cytogenetic screening of chromosomal abnormalities and genetic analysis of FSH receptor Ala307Thr and Ser680Asn genes in amenorrheic patients

Objective

Amenorrhea is a rare reproductive medical condition defined by the absence of menstruation during puberty or later life. This study aims to establish the frequency and pattern of chromosomal abnormalities (CA) in both primary amenorrhea (PA) and secondary amenorrhea (SA), and further to detect the genetic changes in exon 10 at nucleotide positions 919 and 2039 of the genotypes Thr307Ala, and Asn680Ser, respectively.

Design settings and patients

This cross-sectional study was conducted on a sample of seventy amenorrhoeic women according to the Helsinki declaration rules of medical ethics, as divided into 40 (57.14%) with PA and 30 (42.86%) with SA, and 30 healthy women with normal menstruation as the control. The chromosomal karyotyping was performed according to the ISCN, 2020. PCR products were submitted to RFLP and Sanger sequencing for women with normal karyotype and high FSH serum levels.

Results

The classical Turner Syndrome was the most common CA in PA, followed by isochromosome X [46, Xi(X)(q10)], mosaicism of Turner and isochromosome X [45, X /46, Xi(X)(q10)], sex reversal (46, XY) and (46, XX,-3,+der3,-19,del 19 p). Abnormal SA cases were characterized by mosaicism Turner syndrome (45,X/46,XX) and (46,XX,-3,+der3,X,+derX). The homozygous genotypes AA and GG of Ala307Thr (rs6165) in the FSHR gene are most common in PA, while the homozygous genotype AA is more common in SA. GG and AG genotypes of Ser680Asn (rs6166) are more frequent in Iraqi patients with PA and SA compared to the healthy control women. Both PCR-RFLP and Sanger sequencing indicated a marked matching between genotypes.

Conclusions

The study emphasizes the need for cytogenetic analysis to determine the genetic basis of PA and SA. Further, genotyping for women with normal karyotype and high FSH serum concentrations via PCR-RFLP should be considered for the precise diagnosis and development of appropriate management of and counselling for these patients.

Pharmacodynamic structure of deer antler base protein and its mammary gland hyperplasia inhibition mechanism by mediating Raf-1/MEK/ERK signaling pathway activation

Mammary gland hyperplasia (MGH) is a common mammary disease whose main pathogenesis is the disruption of estradiol (E₂) and progesterone (P) secretion, thereby causing overproliferation of mammary epithelial cells and mammary gland tissue hyperplasia. Deer antler base is a traditional Chinese medicine that has been used for many years to treat MGH. However, its pharmacological mechanism and pharmacodynamic material basis are unclear. In this study, we for the first time used the graded salting method to classify deer antler base protein (CNCP) as CNCP-A, CNCP-B, and CNCP-C and explored the pharmacological mechanism of the anti-MGH properties of CNCP. We found that CNCP could regulate the hormonal levels of E₂, P, and follicle stimulating hormone (FSH) and improve the histopathological condition. The potential mechanism might be related to the recombinant C-Raf proto oncogene serine/threonine protein kinase/mitogen-activated protein/extracellular regulated protein kinase (Raf-1/MEK/ERK) signaling pathway. By upregulating the protein expression of the follicle stimulating hormone receptor (FSHR), cyclic adenosine monophosphate (cAMP) and protein kinase A (PKA) inhibited the activation of the downstream Raf-1/MEK/ERK signaling pathway, which in turn inhibited the proliferation of mammary epithelial cells. We analyzed the physicochemical properties of CNCP-A, CNCP-B, and CNCP-C and obtained CNCP-C-I by column chromatographic purification of the best pharmacophore protein CNCP. Using high-performance liquid gel filtration chromatography (HPGFC), we determined the molecular weight of CNCP-C-I and identified it by high-performance liquid tandem mass spectrometry (LC-MS/MS) to obtain the first match for a high confidence protein KRT1. This study provides a theoretical basis for the development of effective traditional Chinese medicines with low toxicity levels for the prevention and treatment of mammary gland diseases.

Non-reproductive effects of follicle-stimulating hormone in young men

OBJECTIVE

Follicle-stimulating hormone (FSH) receptor expression has been reported in many extra-gonadal tissues, raising the question of non-reproductive effects of FSH. Because of increasing usage of FSH in treatment of male infertility, deeper knowledge of possible harmful off-target effects of FSH is warranted.

METHODS

In total, 33 healthy young men (mean age 30 years) were included in the study. All received an s.c. injection of gonadotropin-releasing hormone (GnRH) antagonist and n = 16 were randomized to 300 IU recombinant FSH (300 IE 3 times/week) for 5 weeks at first visit (V1) whereas n = 17 served as controls. Blood samples were taken at (V1), after 3 weeks (V2), and after 5 weeks (V3), when the study ended. At V2, all subjects received 1000 mg testosterone undecanoate i.m. A standard set of bio- and inflammatory markers were compared between the groups using the Mann-Whitney test adjusted for multiple testing.

RESULTS

As compared to controls, the FSH treated men had higher SHBG and albumin concentrations at V2 (p = 0.024 and 0.027, respectively), and lower levels of alanine aminotransferase (p = 0.026) and magnesium (p = 0.028) at V3. However, none of the results remained statistically significant after Bonferroni correction (p > 0.0011).

CONCLUSIONS

FSH had no significant effects on non-reproductive organs when given in standard therapeutic doses to young men for 5 weeks. Therefore, the FSH treatment can be considered safe in otherwise healthy young men, constituting candidates for the infertility treatment with FSH.

Inadequate detection of the FSHR complicates future research on extragonadal FSHR localization

INTRODUCTION

Recently, follicle stimulating hormone (FSH) through interaction with its receptor (FSHR) has been proposed to play a role in postmenopausal osteoporosis and cardiovascular disease, rather than the loss of estrogen. To explore this hypothesis, unravelling which cells express extragonadal FSHR on protein level is key.

METHODS

We used two commercial anti-FSHR antibodies and validated them by performing immunohistochemistry on positive (ovary, testis) and negative controls (skin).

RESULTS

The monoclonal anti-FSHR antibody could not identify the FSHR in ovary or testis. The polyclonal anti-FSHR antibody stained the granulosa cells (ovary) and Sertoli cells (testis), yet there was equally intense staining of other cells/extracellular matrix. Furthermore, the polyclonal anti-FSHR antibody also stained skin tissue extensively, suggesting that the antibody stains more than just FSHR.

DISCUSSION

The findings in this study may add accuracy to literature on extragonadal FSHR localization and warrants attention to the use of inadequate anti-FSHR antibodies to value the potential role of FSH/FSHR in postmenopausal disease.

Follicle-Stimulating Hormone Promotes the Development of Endometrial Cancer In Vitro and In Vivo

Endocrine disruptors as risk factors for endometrial cancer (EC) are positively correlated with serum follicle-stimulating hormone (FSH) levels. Additionally, increased FSH is associated with EC. However, its exact mechanism is not yet clear. Therefore, this study investigated how FSH affects the occurrence of EC. Using immunohistochemistry (IHC), immunofluorescence (IF), and Western blot (WB), we found that FSH receptor (FSHR) was expressed in both EC tissues and cell lines. To explore the effect of FSH on EC in vitro, Ishikawa (ISK) cells were cultured in different doses of FSH, and it was found that FSH could promote the proliferation and migration of ISK cells. Furthermore, the detection of key molecules of migration and apoptosis by WB showed that FSH promoted cell migration and inhibited apoptosis. Additionally, FSH decreased AMPK activation. To clarify the effect of FSH on EC in vivo, we subcutaneously planted ISK cells into ovariectomized mice and then gave two of the groups oestradiol (E2). In comparison with the OE (ovariectomy plus E2) and sham groups, the growth rates and weights of the tumors in the OE plus FSH group were significantly higher. The findings above suggest that FSH promotes the proliferation and metastasis of EC, providing a new strategy for the treatment of EC.

Expression and function of the luteinizing hormone choriogonadotropin receptor in human endometrial stromal cells

The human luteinising hormone choriogonadotropin receptor (LHCGR) is a G-protein coupled receptor activated by both human chorionic gonadotropin (hCG) and luteinizing hormone (LH), two structurally related gonadotropins with essential roles in ovulation and maintenance of the corpus luteum. LHCGR expression predominates in ovarian tissues where it elicits functional responses through cyclic adenosine mononucleotide (cAMP), Ca²⁺ and extracellular signal-regulated kinase (ERK) signalling. LHCGR expression has also been localized to the human endometrium, with purported roles in decidualization and implantation. However, these observations are contentious. In this investigation, transcripts encoding LHCGR were undetectable in bulk RNA sequencing datasets from whole cycling endometrial tissue and cultured human endometrial stromal cells (EnSC). However, analysis of single-cell RNA sequencing data revealed cell-to-cell transcriptional heterogeneity, and we identified a small subpopulation of stromal cells with detectable LHCGR transcripts. In HEK-293 cells expressing recombinant LHCGR, both hCG and LH elicited robust cAMP, Ca²⁺ and ERK signals that were absent in wild-type HEK-293 cells. However, none of these responses were recapitulated in primary EnSC cultures. In addition, proliferation, viability and decidual transformation of EnSC were refractory to both hCG and LH, irrespective of treatment to induce differentiation. Although we challenge the assertion that LHCGR is expressed at a functionally active level in the human endometrium, the discovery of a discrete subpopulation of EnSC that express LHCGR transcripts may plausibly account for the conflicting evidence in the literature.

ABCA1 is associated with the development of acquired chemotherapy resistance and predicts poor ovarian cancer outcome

Aim: This study investigated the ATP binding cassette (ABC) transporter (ABCA1, ABCB1, ABCB3, ABCC2 and ABCG2) expression in high grade serous ovarian cancer (HGSOC) tissues, cell lines and primary cells to determine their potential relationship with acquired chemotherapy resistance and patient outcome. Methods: ABC transporter mRNA and protein expression (ABCA1, ABCB1, ABCB3, ABCC2 and ABCG2) was assessed in publicly available datasets and in a tissue microarray (TMA) cohort of HGSOC at diagnosis, respectively. ABC transporter mRNA expression was also assessed in chemosensitive ovarian cancer cell lines (OVCAR-5 and CaOV3) versus matching cell lines with acquired carboplatin resistance and in primary HGSOC cells from patients with chemosensitive disease at diagnosis (n = 10) as well as patients with acquired chemotherapy resistance at relapse (n = 6). The effects of the ABCA1 inhibitor apabetalone in carboplatin-sensitive and -resistant cell lines were also investigated. Results: High ABCA1 mRNA and protein expression was found to be significantly associated with poor patient outcome. ABCA1 mRNA and protein levels were significantly increased in ovarian cancer cell lines (OVCAR-5 CBPR and CaOV3 CBPR) with acquired carboplatin resistance. ABCA1 mRNA was significantly increased in primary HGSOC cells obtained from patients with acquired chemotherapy resistance. Apabetalone treatment reduced ABCA1 protein expression and increased the sensitivity of both parental and carboplatin-resistant ovarian cancer cells to carboplatin. Conclusion: These results suggest that inhibiting ABCA1 transporter may be useful in overcoming acquired chemotherapy resistance and improving outcome for patients with HGSOC.

Effect of human follicle-stimulating hormone on immunomodulatory function of decidual mesenchymal stem cells by reducing interleukin-6 levels

Objective

Women with an elevated basal FSH indicate diminished ovarian reserve and reduced oocyte and embryo numbers. DMSCs are likely to be involved in immune tolerance of pregnancy maintenance. We investigate the effect of follicle-stimulating hormones on the immunomodulatory functions of DMSCs.

Methods

DMSCs were primary cultured from decidual tissue. Pretreated DMSCs with mitomycin C, combined with CD4⁺ T lymphocytes, DMSCs + CD4⁺T co-culture system was established. Different physiological dose FSH (3 ng/ml,10 ng/ml,30 ng/ml,100 ng/ml) were used to co-culture system. Cytokines (IFN-γ, IL-2, IL-4, IL-6, IL-10, TNF-α) and other proteins (FSHR, MyD88) were measured.

Results

Compared with the control group (FSH (0 ng/mL) + CD4⁺T + DMSCs), the FSH concentration was 10, 30, and 100 ng/ml, IL-6 levels were significantly reduced (P < 0.05). IL-6, MyD88 protein expression was remarkably decreased (P < 0.05).

Conclusion

FSH/FSHR could negatively regulate the immunosuppressive function of DMSCs by reducing secretion of IL-6 levels through MyD88 pathways, but upstream and downstream signalling pathways require further validation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13048-022-00993-3.

Regulation of antral follicular growth by an interplay between gonadotropins and their receptors

Knowledge of the growth and maturation of human antral follicles is based mainly on concepts and deductions from clinical observations and animal models. To date, new experimental approaches and in vitro data contributed to a deep comprehension of gonadotropin receptors' functioning and may provide new insights into the mechanisms regulating still unclear physiological events. Among these, the production of androgen in the absence of proper LH levels, the programming of follicular atresia and dominance are some of the most intriguing. Starting from evolutionary issues at the basis of the gonadotropin receptor signal specificity, we draw a new hypothesis explaining the molecular mechanisms of the antral follicular growth, based on the modulation of endocrine signals by receptor-receptor interactions. The "heteromer hypothesis" explains how opposite death and life signals are delivered by gonadotropin receptors and other membrane partners, mediating steroidogenesis, apoptotic events, and the maturation of the dominant follicle.

Overview of follicle stimulating hormone and its receptors in reproduction and in stem cells and cancer stem cells

Follicle stimulating hormone (FSH) and its receptor (FSHR) have been reported to be responsible for several physiological functions and cancers. The responsiveness of stem cells and cancer stem cells towards the FSH-FSHR system make the function of FSH and its receptors more interesting in the context of cancer biology. This review is comprised of comprehensive information on FSH-FSHR signaling in normal physiology, gonadal stem cells, cancer cells, and potential options of utilizing FSH-FSHR system as an anti-cancer therapeutic target.

The Relationship Between Bone and Reproductive Hormones Beyond Estrogens and Androgens

Reproductive hormones play a crucial role in the growth and maintenance of the mammalian skeleton. Indeed, the biological significance for this hormonal regulation of skeletal homeostasis is best illustrated by common clinical reproductive disorders, such as primary ovarian insufficiency, hypothalamic amenorrhea, congenital hypogonadotropic hypogonadism, and early menopause, which contribute to the clinical burden of low bone mineral density and increased risk for fragility fracture. Emerging evidence relating to traditional reproductive hormones and the recent discovery of newer reproductive neuropeptides and hormones has deepened our understanding of the interaction between bone and the reproductive system. In this review, we provide a contemporary summary of the literature examining the relationship between bone biology and reproductive signals that extend beyond estrogens and androgens, and include kisspeptin, gonadotropin-releasing hormone, follicle-stimulating hormone, luteinizing hormone, prolactin, progesterone, inhibin, activin, and relaxin. A comprehensive and up-to-date review of the recent basic and clinical research advances is essential given the prevalence of clinical reproductive disorders, the emerging roles of upstream reproductive hormones in bone physiology, as well as the urgent need to develop novel safe and effective therapies for bone fragility in a rapidly aging population.

An overview of FSH-FSHR biology and explaining the existing conundrums

FSH was first identified in 1930 and is central to mammalian reproduction. It is indeed intriguing that despite being researched upon for about 90 years, there is still so much more to learn about FSH-FSHR biology. The purpose of this review is to provide an overview of current understanding of FSH-FSHR biology, to review published data on biological and clinical relevance of reported mutations, polymorphisms and alternately spliced isoforms of FSHR. Tissue-resident stem/progenitor cells in multiple adult tissues including ovaries, testes and uterus express FSHR and this observation results in a paradigm shift in the field. The results suggest a direct action of FSH on the stem cells in addition to their well-studied action on Granulosa and Sertoli cells in the ovaries and testes respectively. Present review further addresses various concerns raised in recent times by the scientific community regarding extragonadal expression of FSHR, especially in cancers affecting multiple organs. Similar population of primitive and pluripotent tissue-resident stem cells expressing FSHR exist in multiple adult tissues including bone marrow and reproductive tissues and help maintain homeostasis throughout life. Any dysfunction of these stem cells results in various pathologies and they also most likely get transformed into cancer stem cells and initiate cancer. This explains why multiple solid as well as liquid tumors express OCT-4 and FSHR. More research efforts need to be focused on alternately spliced FSHR isoforms.

Endogenous, tissue-resident stem/progenitor cells in gonads and bone marrow express FSHR and respond to FSH via FSHR-3

Follicle stimulating hormone (FSH) is secreted by the anterior pituitary and acts on the germ cells indirectly through Granulosa cells in ovaries and Sertoli cells in the testes. Extragonadal action of FSH has been reported but is still debated. Adult tissues harbor two populations of stem cells including a reserve population of primitive, small-sized, pluripotent very small embryonic-like stem cells (VSELs) and slightly bigger, tissue-specific progenitors which include ovarian stem cells (OSCs) in ovaries, spermatogonial stem cells (SSCs) in testes, endometrial stem cells (EnSCs) in uterus and hematopoietic stem cells (HSCs) in the bone marrow. Data has accumulated in animal models showing FSHR expression on both VSELs and progenitors in ovaries, testes, uterus and bone marrow and eventually gets lost as the cells differentiate further. FSH exerts a direct action on the stem/progenitor cells via alternatively spliced FSHR-3 rather than the canonical FSHR-1. FSH stimulates VSELs to undergo asymmetrical cell divisions to self-renew and give rise to the progenitors that in turn undergo symmetrical cell divisions and clonal expansions followed by differentiation into specific cell types. Excessive self-renewal of VSELs results in cancer and this explains ubiquitous expression of embryonic markers including nuclear OCT-4 along with FSHR in cancerous tissues. Focus of this review is to compile published data to support this concept. FSHR expression in stem/progenitor cells was confirmed by immuno-fluorescence, Western blotting, in situ hybridization and by quantitative RT-PCR. Two different commercially available antibodies (Abcam, Santacruz) were used to confirm specificity of FSHR expression along with omission of primary antibody and pre-incubation of antibody with immunizing peptide as negative controls. Western blotting allowed detection of alternatively spliced FSHR isoforms. Oligoprobes and primers specific for Fshr-1 and Fshr-3 were used to study these alternately-sliced isoforms by in situ hybridization and their differential expression upon FSH treatment by qRT-PCR. To conclude, stem/progenitor cells in adult tissues express FSHR and directly respond to FSH via FSHR-3. These findings change the field of FSH-FSHR biology, call for paradigm shift, explain FSHR expression on cancer cells in multiple organs and provide straightforward explanations for various existing conundrums including extragonadal expression of FSHR.

Seasonal reproduction and gonadal function: A focus on humans starting from animal studies

Photoperiod impacts reproduction in many species of mammals. Mating occurs at specific seasons to achieve reproductive advantages, such as optimization of offspring survival. Light is the main regulator of these changes during the photoperiod. Seasonally breeding mammals detect and transduce light signals through extraocular photoreceptor, regulating downstream melatonin-dependent peripheral circadian events. In rodents, hormonal reduction and gonadal atrophy occur quickly, and consensually with short-day periods. It remains unclear whether photoperiod influences human reproduction. Seasonal fluctuations of sex hormones have been described in humans, although they seem to not imply adaptative seasonal pattern in human gonads. This review discusses current knowledge about seasonal changes in the gonadal function of vertebrates, including humans. The photoperiod-dependent regulation of hypothalamic-pituitary-gonadal axis, as well as morphological and functional changes of the gonads are evaluated herein. Endocrine and morphological variations of reproductive functions, in response to photoperiod, are of interest as they may reflect the nature of past population selection for adaptative mechanisms that occurred during evolution.

Hsa-mir-548 family expression in human reproductive tissues

BACKGROUND

Hsa-miR-548ba expressed in ovarian granulosa cells targets PTEN and LIFR, which are essential for ovarian follicle activation and growth. The expression pattern of hsa-miR-548ba correlates with its host gene follicle-stimulating hormone receptor (FSHR), and FSH has a positive influence on hsa-miR-548ba expression. However, hsa-miR-548ba is a member of a large hsa-mir-548 family with potentially overlapping targets. The current study aims to investigate the co-expression of hsa-mir-548 family members in FSHR-positive reproductive tissues and to explore the potential co-regulation of pathways.

RESULTS

For the above-described analysis, small RNA sequencing data from public data repositories were used. Sequencing results revealed that hsa-miR-548ba was expressed at the highest level in the ovarian granulosa cells and uterine myometrial samples together with another twelve and one hsa-miR-548 family members, respectively. Pathway enrichment analysis of microRNA targets in the ovarian samples revealed the hsa-miR-548ba and hsa-miR-548b-5p co-regulation of RAB geranylgeranylation in mural granulosa cells. Moreover, other hsa-mir-548 family members co-regulate pathways essential for ovarian functions (PIP3 activates AKT signalling and signalling by ERBB4). In addition to hsa-miR-548ba, hsa-miR-548o-3p is expressed in the myometrium, which separately targets the peroxisome proliferator-activated receptor alpha (PPARA) pathway.

CONCLUSION

This study reveals that hsa-mir-548 family members are expressed in variable combinations in the reproductive tract, where they potentially fulfil different regulatory roles. The results provide a reference for further studies of the hsa-mir-548 family role in the reproductive tract.

Actions and Roles of FSH in Germinative Cells

Follicle stimulating hormone (FSH) is produced by the pituitary gland in a coordinated hypothalamic-pituitary-gonadal (HPG) axis event, plays important roles in reproduction and germ cell development during different phases of reproductive development (fetal, neonatal, puberty, and adult life), and is consequently essential for fertility. FSH is a heterodimeric glycoprotein hormone of two dissociable subunits, α and β. The FSH β-subunit (FSHβ) function starts upon coupling to its specific receptor: follicle-stimulating hormone receptor (FSHR). FSHRs are localized mainly on the surface of target cells on the testis and ovary (granulosa and Sertoli cells) and have recently been found in testicular stem cells and extra-gonadal tissue. Several reproduction disorders are associated with absent or low FSH secretion, with mutation of the FSH β-subunit or the FSH receptor, and/or its signaling pathways. However, the influence of FSH on germ cells is still poorly understood; some studies have suggested that this hormone also plays a determinant role in the self-renewal of germinative cells and acts to increase undifferentiated spermatogonia proliferation. In addition, in vitro, together with other factors, it assists the process of differentiation of primordial germ cells (PGCLCs) into gametes (oocyte-like and SSCLCs). In this review, we describe relevant research on the influence of FSH on spermatogenesis and folliculogenesis, mainly in the germ cell of humans and other species. The possible roles of FSH in germ cell generation in vitro are also presented.

Mechanistic insight into how gonadotropin hormone receptor complexes direct signaling†

Gonadotropin hormones and their receptors play a central role in the control of male and female reproduction. In recent years, there has been growing evidence surrounding the complexity of gonadotropin hormone/receptor signaling, with it increasingly apparent that the Gαs/cAMP/PKA pathway is not the sole signaling pathway that confers their biological actions. Here we review recent literature on the different receptor-receptor, receptor-scaffold, and receptor-signaling molecule complexes formed and how these modulate and direct gonadotropin hormone-dependent intracellular signal activation. We will touch upon the more controversial issue of extragonadal expression of FSHR and the differential signal pathways activated in these tissues, and lastly, highlight the open questions surrounding the role these gonadotropin hormone receptor complexes and how this will shape future research directions.

Effectiveness Assessment of a Modified Preservation Solution Containing Thyrotropin or Follitropin Based on Biochemical Analysis in Perfundates and Homogenates of Isolated Porcine Kidneys after Static Cold Storage

In this paper, we assess the nephroprotective effects of thyrotropin and follitropin during ischaemia. The studies were performed in vitro in a model of isolated porcine kidneys stored in Biolasol (FZNP, Biochefa, Sosnowiec, Poland) and modified Biolasol (TSH: 1 µg/L; FSH 1 µg/L). We used the static cold storage method. The study was carried out based on 30 kidneys. The kidneys were placed in 500 mL of preservation solution chilled to 4 °C. The samples for biochemical tests were collected during the first kidney perfusion (after 2 h of storage) and during the second perfusion (after 48 h of storage). The results of ALT, AST, and LDH activities confirm the effectiveness of Biolasol + p-TSH in maintaining the structural integrity of renal cell membranes. Significantly reduced biochemical parameters of kidney function, i.e., creatinine and protein concentrations were also observed after 48 h storage. The protective effect of Biasol + p-TSH is most pronounced after 2 h of storage, suggesting a mild course of damage thereafter. A mild deterioration of renal function was observed after 48 h. The results of our analyses did not show any protective effect of Biolasol + p-FSH on the kidneys during ischaemia.

Effect of kisspeptin (KISS) and RFamide-related peptide-3 (RFRP-3) on the synthesis and secretion of FSH in vitro by pituitary cells in pigs

Kisspeptins (KISSs) and RFamide-related peptide-3 (RFRP-3) affect the synthesis and secretion of luteinizing hormone (LH) and modulate female reproductive processes. The presence of KISS and RFRP-3 in the porcine pituitary gland and their contribution to the regulation of follicle-stimulating hormone (FSH) synthesis and secretion is unknown. This study analyzed the presence of KISS and RFRP-3 in the pituitary of estrous-cyclic pigs on days 2 to 3, 10 to 11, 12 to 13, 15 to 16 and 19 to 20 and early pregnant pigs on days 10 to 11, 12 to 13 and 15 to 16, and evaluated the effect of KISS and RFRP-3 on β-Fsh mRNA expression and FSH secretion in vitro by pituitary cells collected on selected days of the estrous cycle. The cells were cultured in vitro and treated with KISS (10^-6 M, 10^-7 M) and RFRP-3 (10^-6 M, 10^-7 M) or gonadotropin-releasing hormone (GnRH; 100 ng/mL) alone and in combinations (4 h or 24 h). The relative abundance of Kiss and Rfrp-3 and their receptor mRNA transcripts, as well as the KISS and RFRP-3 proteins, were found in the pituitaries of estrous-cyclic and early pregnant pigs. KISS after 4 h increased the secretion of FSH in estrous cyclic pigs mostly during the early-luteal phase and luteolysis. RFRP-3 inhibited the synthesis and secretion of FSH in estrous-cyclic pigs on days 19 to 20 and the secretion of FSH on days 2 to 3 and 10 to 12 of the estrous cycle compared with GnRH-treated cells. KISS in co-treatment with GnRH after 24 h enhanced FSH release on days 2 to 3 and 15 to 16 of the estrous cycle. In conclusion, KISS and RFRP-3 systems are present in the pituitary of estrous-cyclic and pregnant pigs. In estrous-cyclic pigs, KISS and RFRP-3 may affect the synthesis and secretion of FSH by pituitary cells.

Recent advances in understanding gonadotropin signaling

Gonadotropins are glycoprotein sex hormones regulating development and reproduction and bind to specific G protein–coupled receptors expressed in the gonads. Their effects on multiple signaling cascades and intracellular events have recently been characterized using novel technological and scientific tools. The impact of allosteric modulators on gonadotropin signaling, the role of sugars linked to the hormone backbone, the detection of endosomal compartments supporting signaling modules, and the dissection of different effects mediated by these molecules are areas that have advanced significantly in the last decade. The classic view providing the exclusive activation of the cAMP/protein kinase A (PKA) and the steroidogenic pathway by these hormones has been expanded with the addition of novel signaling cascades as determined by high-resolution imaging techniques. These new findings provided new potential therapeutic applications. Despite these improvements, unanswered issues of gonadotropin physiology, such as the intrinsic pro-apoptotic potential to these hormones, the existence of receptors assembled as heteromers, and their expression in extragonadal tissues, remain to be studied. Elucidating these issues is a challenge for future research.

A Novel Hypothesis: A Role for Follicle Stimulating Hormone in Abdominal Aortic Aneurysm Development in Postmenopausal Women

An abdominal aortic aneurysm (AAA) is a dilatation of the abdominal aorta, which can potentially be fatal due to exsanguination following rupture. Although AAA is less prevalent in women, women with AAA have a more severe AAA progression compared to men as reflected by enhanced aneurysm growth rates and a higher rupture risk. Women are diagnosed with AAA at an older age than men, and in line with increased osteoporosis and cardiovascular events, the delayed AAA onset has been attributed to the reduction of the protective effect of oestrogens during the menopausal transition. However, new insights have shown that a high follicle stimulating hormone (FSH) level during menopause may also play a key role in those diseases. In this report we hypothesize that FSH may aggravate AAA development and progression in postmenopausal women via a direct and/or indirect role, promoting aorta pathology. Since FSH receptors (FSHR) are reported on many other cell types than granulosa cells in the ovaries, it is feasible that FSH stimulation of FSHR-bearing cells such as aortic endothelial cells or inflammatory cells, could promote AAA formation directly. Indirectly, AAA progression may be influenced by an FSH-mediated increase in osteoporosis, which is associated with aortic calcification. Also, an FSH-mediated decrease in cholesterol uptake by the liver and an increase in cholesterol biosynthesis will increase the cholesterol level in the circulation, and subsequently promote aortic atherosclerosis and inflammation. Lastly, FSH-induced adipogenesis may lead to obesity-mediated dysfunction of the microvasculature of the aorta and/or modulation of the periaortic adipose tissue. Thus the long term increased plasma FSH levels during the menopausal transition may contribute to enhanced AAA disease in menopausal women and could be a potential novel target for treatment to lower AAA-related events in women.

Follicle-Stimulating Hormone Induces Lipid Droplets via Gαi/o and β-Arrestin in an Endometrial Cancer Cell Line

Follicle-stimulating hormone (FSH) and its G protein-coupled receptor, FSHR, represents a paradigm for receptor signaling systems that activate multiple and complex pathways. Classically, FSHR activates Gαs to increase intracellular levels of cAMP, but its ability to activate other G proteins, and β-arrestin-mediated signaling is well documented in many different cell systems. The pleiotropic signal capacity of FSHR offers a mechanism for how FSH drives multiple and dynamic downstream functions in both gonadal and non-gonadal cell types, including distinct diseases, and how signal bias may be achieved at a pharmacological and cell system-specific manner. In this study, we identify an additional mechanism of FSH-mediated signaling and downstream function in the endometrial adenocarcinoma Ishikawa cell line. While FSH did not induce increases in cAMP levels, this hormone potently activated pertussis toxin sensitive Gαi/o signaling. A selective allosteric FSHR ligand, B3, also activated Gαi/o signaling in these cells, supporting a role for receptor-mediated activation despite the low levels of FSHR mRNA. The low expression levels may attribute to the lack of Gαs/cAMP signaling as increasing FSHR expression resulted in FSH-mediated activation of the Gαs pathway. Unlike prior reports for FSH-mediated Gαs/cAMP signaling, FSH-mediated Gαi/o signaling was not affected by inhibition of dynamin-dependent receptor internalization. While chronic FSH did not alter cell viability, FSH was able to increase lipid droplet size. The β-arrestins are key adaptor proteins known to regulate FSHR signaling. Indeed, a rapid, FSH-dependent increase in interactions between β-arrestin1 and Gαi1 was observed via NanoBiT complementation in Ishikawa cells. Furthermore, both inhibition of Gαi/o signaling and siRNA knockdown of β-arrestin 1/2 significantly reduced FSH-induced lipid droplet accumulation, implying a role for a Gαi/o/β-arrestin complex in FSH functions in this cell type. As FSH/FSHR has been implicated in distinct hormone-dependent cancers, including endometrial cancer, analysis of the cancer genome database from 575 human endometrial adenocarcinoma tumors revealed that a subpopulation of samples expressed FSHR. Overall, this study highlights a novel mechanism for FSHR signal pleiotropy that may be exploited for future personalized therapeutic approaches.

Reduced Gonadotrophin Receptor Expression Is Associated with a More Aggressive Ovarian Cancer Phenotype

Follicle-stimulating hormone (FSH) and luteinising hormone (LH) play important roles in regulating cell growth and proliferation in the ovary. However, few studies have explored the expression of FSH and LH receptors (FSHR and LHCGR) in ovarian cancer, and their functional roles in cancer progression remain inconclusive. This study investigated the potential impact of both mRNA (FSHR, LHCGR) and protein (FSHR, LHCGR) expression on ovarian cancer progression using publicly available online databases, qRT-PCR (high grade serous ovarian cancers, HGSOC, n = 29 and benign ovarian tumors, n = 17) and immunohistochemistry (HGSOC, n = 144). In addition, we investigated the effect of FSHR and LHCGR siRNA knockdown on the pro-metastatic behavior of serous ovarian cancer cells in vitro. High FSHR or high LHCGR expression in patients with all subtypes of high-grade ovarian cancer was significantly associated with longer progression-free survival (PFS) and overall survival (OS). High FSHR protein expression was associated with increased PFS (p = 0.050) and OS (p = 0.025). HGSOC patients with both high FSHR and high LHCGR protein levels had the best survival outcome, whilst both low FSHR and low LHCGR expression was associated with poorest survival (p = 0.019). Knockdown of FSHR significantly increased the invasion of serous ovarian cancer cells (OVCAR3 and COV362) in vitro. LHCGR knockdown also promoted invasion of COV362 cells. This study highlights that lower FSHR and LHCGR expression is associated with a more aggressive epithelial ovarian cancer phenotype and promotes pro-metastatic behaviour.

FSH-R Human Early Male Genital Tract, Testicular Tumors and Sperm: Its Involvement in Testicular Disorders

The follicle-stimulating hormone receptor (FSH-R) expression was always considered human gonad-specific. The receptor has also been newly detected in extragonadal tissues. In this finding, we evaluated FSH-R expression in the human male early genital tract, in testicular tumors, and in sperm from healthy and varicocele patients. In sperm, we also studied the mechanism of FSH-R action. Immunohystochemistry and Western blot analysis showed FSH-R presence in the first pathways of the human genital tract, in embryonal carcinoma, and in sperm, but it was absent in seminoma and in lower varicocele. In sperm, FSH/FSH-R activity is mediated by G proteins activating the PKA pathway, as we observed by using the H89. It emerged that increasing FSH treatments induced motility, survival, capacitation, and acrosome reaction in both sperm samples. The different FSH-R expression in tumor testicular tissues may be discriminate by tumor histological type. In spermatozoa, FSH-R indicates a direct action of FSH in these cells, which could be beneficial during semen preparation for in vitro fertilization procedures. For instance, FSH positive effects could be relevant in idiopathic infertility and in the clinic surgery of varicocele. In conclusion, FSH-R expression may be considered a molecular marker of testicular disorders.

Follicle-stimulating hormone impairs dental pulp stem cells odontogenic differentiation

In addition to bone, the dentin‐pulp complex is also influenced by menopause, showing a decreased regenerative capacity. High levels of follicle‐stimulating hormone (FSH) during menopause could directly regulate bone metabolism. Here, the role of FSH in the odontogenic differentiation of the dentin‐pulp complex was investigated. Dental pulp stem cells (DPSCs) were isolated. CCK‐8 assays, cell apoptosis assays, Western blotting (WB), real‐time RT‐PCR, alkaline phosphatase activity assays, and Alizarin Red S staining were used to clarify the effects of FSH on the proliferation, apoptosis and odontogenic differentiation of the DPSCs. MAPK pathway‐related factors were explored by WB assays. FSH and its inhibitor were used in OVX rats combined with a direct pulp‐capping model. HE and immunohistochemistry were used to detect reparative dentin formation and related features. The results indicated that FSH significantly decreased the odontogenic differentiation of the DPSCs without affecting cell proliferation and apoptosis. Moreover, FSH significantly activated the JNK signalling pathway, and JNK inhibitor partly rescued the inhibitory effect of FSH on DPSC differentiation. In vivo, FSH treatment attenuated the dentin bridge formation and mineralization‐related protein expression in the OVX rats. Our findings indicated that FSH reduced the odontogenic capacity of the DPSCs and was involved in reparative dentinogenesis during menopause.

Follicle-stimulating hormone receptors expression in ovine corpora lutea during luteal phase: effect of nutritional plane and follicle-stimulating hormone treatment

Corpus luteum (CL), a transient endocrine gland critical for reproductive cyclicity and pregnancy maintenance, is controlled by numerous regulatory factors. Although LH is widely recognized as the major regulator, other factors may also affect luteal functions. It has been demonstrated that FSH receptors (FSHR) are expressed not only in ovarian follicles but also in other tissues within the reproductive tract, including the CL. To evaluate FSHR expression in nontreated (nonsuperovulated; experiment 1) or FSH-treated (superovulated; experiment 2) sheep fed a control (C; maintenance), excess (O; 2 × C), or restricted (U; 0.6 × C) diet, CL were collected at the early, mid and/or late luteal phases (n = 5-7 per group). Protein and messenger RNA (mRNA) expression of FSHR were detected in the CL from all groups using immunohistochemistry followed by image analysis and quantitative RT-PCR, respectively. Follicle-stimulating hormone receptor was immunolocalized to steroidogenic small and large and nonsteroidogenic luteal cells. In both experiments, FSHR protein expression was not affected by stage of luteal development or diet. In experiment 1, expression of mRNA for all FSHR variants was greater (P <0.02 to 0.0003) at the late phase than mid or early luteal phase, and in experiment 2, it was greater (P < 0.001) at the mid than early luteal phase. Plane of nutrition did not affect FSHR mRNA expression. Comparison of FSH-treated with nontreated ewes demonstrated that FSH increased FSHR protein expression by 1.5- to 2-fold (P < 0.0001) in all groups, and mRNA expression by 7- to 30-fold (P < 0.001) for (1) FSHR-1 in all groups except U at the early luteal phase, (2) FSHR-2 in C, O, and U at the mid-phase, but not early luteal phase, and (3) FSHR-3 in U at the mid-luteal phase. Our data demonstrate that (1) FSHRs are expressed in ovine CL at several stages of luteal development, (2) FSHR protein expression does not change during the luteal phase and is not affected by diet, (3) FSHR mRNA expression not only depends on the stage of the estrous cycle but also not affected by diet in nonsuperovulated or superovulated ewes, and (4) in vivo FSH treatment enhanced FSHR protein and/or mRNA expression in the CL depending on diet and phase of the estrous cycle. Presence of FSHR in the CL indicates a regulatory role of FSH in luteal function in sheep. As very little is known about the possible role of FSH and FSHR in luteal functions, further studies should be undertaken to elucidate the endocrine, molecular, and cellular mechanisms of FSH effects on the CL.

Cloning and expression analysis of the follicle-stimulating hormone receptor (FSHR) gene in the reproductive axis of female yaks (Bos grunniens)

Follicle-stimulating hormone receptor (FSHR) plays a central role in promoting follicle maturation through the follicle-stimulating hormone (FSH)-mediated cAMP pathway in animals. The objectives of the present study were to clone the FSHR gene of yaks (Bos grunniens) and compare differences in FSHR mRNA expression in the reproductive axis between yaks and cattle. Hypothalamus, anterior pituitary, oviduct, ovary, and uterus tissue samples were collected from adult female yaks (n = 5) and cattle (n = 5) during the follicular phase. Using reverse transcriptase-polymerase chain reaction (RT-PCR), we found that the FSHR coding region of the yak is 2088 bp and encodes 695 amino acids. Its amino acid sequence showed 99.38%-72.22% similarity to the homologous genes of cattle, goats, sheep, cats, donkeys, horses, humans, chickens, monkeys, mice, rats, and wild boar. Real-time PCR analysis revealed that the FSHR gene was expressed in all tissues examined. Expression of the FSHR gene in the yak was higher in the uterus than other tissues (P < 0.05) but, in cattle, was higher in the ovary than other tissues (P < 0.05). The FSHR gene expression level in the cattle ovary was significantly higher than that in the yak ovary (P < 0.01). These results indicate that the FSHR gene is relatively conserved in the course of animal evolution. The variation in sequence and expression level of FSHR between the two species might be associated with the difference in their reproduction.

β-arrestin 2 Is a Prognostic Factor for Survival of Ovarian Cancer Patients Upregulating Cell Proliferation

Establishing reliable prognostic factors as well as specific targets for new therapeutic approaches is an urgent requirement in advanced ovarian cancer. For several tumor entities, the ubiquitously spread scaffold protein β-arrestin 2, a multifunctional scaffold protein regulating signal transduction and internalization of activated G protein-coupled receptors (GPCRs), has been considered with rising interest for carcinogenesis. Therefore, we aimed to elucidate the prognostic impact of β-arrestin 2 and its functional role in ovarian cancer. β-arrestin 2 expression was analyzed in a subset of 156 samples of ovarian cancer patients by immunohistochemistry. Cytoplasmic expression levels were correlated with clinical as well as pathological characteristics and with prognosis. The biologic impact of β-arrestin 2 on cell proliferation and survival was evaluated, in vitro. Following transient transfection by increasing concentrations of plasmid encoding β-arrestin 2, different cell lines were evaluated in cell viability and death. β-arrestin 2 was detected in all histological ovarian cancer subtypes with highest intensity in clear cell histology. High β-arrestin 2 expression levels correlated with high-grade serous histology and the expression of the gonadotropin receptors FSHR and LHCGR, as well as the membrane estrogen receptor GPER and hCGβ. Higher cytoplasmic β-arrestin 2 expression was associated with a significantly impaired prognosis (median 29.88 vs. 50.64 months; P = 0.025). Clinical data were confirmed in transfected HEK293 cells, human immortalized granulosa cell line (hGL5) and the ovarian cancer cell line A2780 in vitro, where the induction of β-arrestin 2 cDNA expression enhanced cell viability, while the depletion of the molecule by siRNA resulted in cell death. Reflecting the role of β-arrestin 2 in modulating GPCR-induced proliferative and anti-apoptotic signals, we propose β-arrestin 2 as an important prognostic factor and also as a promising target for new therapeutic approaches in advanced ovarian cancer.