The haplotype of two FSHR polymorphisms in ovarian cancer--a potential role of ethnology in risk modification

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.

Expression Levels of Follicle-Stimulating Hormone Receptor and Implication in Diagnostic and Therapeutic Strategy of Ovarian Cancer

BACKGROUND

Follicle-stimulating hormone receptor (FSHR) has been shown to be expressed in ovarian cancer.

METHODS

Here we have summarized the potential therapeutic and diagnostic implication of FSHR in the ovarian cancers based on a review of the literature.

RESULTS

Current research indicates that FSHR comprises several variants: FSHR-1, FSHR-2, FSHR-3 and FSHR-4. Only FSHR-1 and FSHR-3 have biological roles. Although the level of FSHR differs in ovarian cancer tissues, few quantitative correlations have so far been reported on the expression levels of FSHR and carcinogenesis and progression of cancers.

CONCLUSION

A comprehensive understanding of the role of FSHR in the ovarian cancers may help the search for novel therapeutic and diagnostic regimens and improve the management of cancer patients.

Genetic variants as ovarian cancer first-line treatment hallmarks: A systematic review and meta-analysis

BACKGROUND

The potential predictive value of genetic polymorphisms in ovarian cancer first-line treatment is inconsistently reported. We aimed to review ovarian cancer pharmacogenetic studies to update and summarize the available data and to provide directions for further research.

METHODS

A systematic review followed by a meta-analysis was conducted on cohort studies assessing the involvement of genetic polymorphisms in ovarian cancer first-line treatment response retrieved through a MEDLINE database search by November 2016. Studies were pooled and summary estimates and 95% confidence intervals (CI) were calculated using random or fixed-effects models as appropriate.

RESULTS

One hundred and forty-two studies gathering 106871 patients were included. Combined data suggested that GSTM1-null genotype patients have a lower risk of death compared to GSTM1-wt carriers, specifically in advanced stages (hazard ratio (HR), 0.68; 95% CI, 0.48-0.97) and when submitted to platinum-based chemotherapy (aHR, 0.61; 95% CI, 0.39-0.94). ERCC1 rs11615 and rs3212886 might have also a significant impact in treatment outcome (aHR, 0.67; 95% CI, 0.51-0.89; aHR, 1.28; 95% CI, 1.01-1.63, respectively). Moreover, ERCC2 rs13181 and rs1799793 showed a distinct ethnic behavior (Asians: aHR, 1.41; 95% CI, 0.80-2.49; aHR, 1.07; 95% CI, 0.62-1.86; Caucasians: aHR, 0.10; 95% CI, 0.01-0.96; aHR, 0.18; 95% CI, 0.05-0.68, respectively).

CONCLUSION(S)

The definition of integrative predictive models should encompass genetic information, especially regarding GSTM1 homozygous deletion. Justifying additional pharmacogenetic investigation are variants in ERCC1 and ERCC2, which highlight the DNA Repair ability to ovarian cancer prognosis. Further knowledge could aid to understand platinum-treatment failure and to tailor chemotherapy strategies.

Follicle-Stimulating Hormone Receptor (FSHR): A Promising Tool in Oncology?

The cellular pathway of follicle-stimulating hormone (FSH) and its receptor (FSHR) is typically involved in reproduction in mammals. In humans, the FSHR is normally found in cells of the testis and the ovary, while it is scarcely expressed in other normal tissues. The expression of FSH/FSHR is studied in prostate, thyroid, and ovarian cancer tissues. Recently, the expression of FSHR was uniformly documented in malignant vascular endothelial cells from different tumor types, while in normal or inflammatory tissues its expression was scarce, suggesting a potential role of a pan-receptor in cancer. Subsequent studies have attempted to verify this unique specificity of this molecule and further define its features in malignant microenvironments but have had conflicting results, mostly because of differing techniques and immaturity of antibodies. Still, the lack of FSHR expression in most non-cancerous cells, in contrast to its specific correlation with the malignant tissue microenvironment, implies a potential role as both a diagnostic and a therapeutic tool. FSHR might also have a very specific role in malignancies, such as angiogenic and/or growth factor malignancies, but this is yet to be validated. Moreover, the expression of FSHR in endothelial malignant cells could have a predictive impact on disease progression, especially in relation to therapies targeting the tumor vasculature. In this review we look deep into the physiology of the FSH/FSHR pathway and evaluate the potential of FSHR as a predictive and prognostic tool in oncology.

Evaluating the ovarian cancer gonadotropin hypothesis: a candidate gene study

OBJECTIVE

Ovarian cancer is a hormone-related disease with a strong genetic basis. However, none of its high-penetrance susceptibility genes and GWAS-identified variants to date are known to be involved in hormonal pathways. Given the hypothesized etiologic role of gonadotropins, an assessment of how variability in genes involved in the gonadotropin signaling pathway impacts disease risk is warranted.

METHODS

Genetic data from 41 ovarian cancer study sites were pooled and unconditional logistic regression was used to evaluate whether any of the 2185 SNPs from 11 gonadotropin signaling pathway genes was associated with ovarian cancer risk. A burden test using the admixture likelihood (AML) method was also used to evaluate gene-level associations.

RESULTS

We did not find any genome-wide significant associations between individual SNPs and ovarian cancer risk. However, there was some suggestion of gene-level associations for four gonadotropin signaling pathway genes: INHBB (p=0.045, mucinous), LHCGR (p=0.046, high-grade serous), GNRH (p=0.041, high-grade serous), and FSHB (p=0.036, overall invasive). There was also suggestive evidence for INHA (p=0.060, overall invasive).

CONCLUSIONS

Ovarian cancer studies have limited sample numbers, thus fewer genome-wide susceptibility alleles, with only modest associations, have been identified relative to breast and prostate cancers. We have evaluated the majority of ovarian cancer studies with biological samples, to our knowledge, leaving no opportunity for replication. Using both our understanding of biology and powerful gene-level tests, we have identified four putative ovarian cancer loci near INHBB, LHCGR, GNRH, and FSHB that warrant a second look if larger sample sizes and denser genotype chips become available.

Expression and purification of the extracellular domain of the human follicle-stimulating hormone receptor using Escherichia coli

AIM

Although much is known about the structure and biological functions of follicle-stimulating hormone (FSH) receptor (FSHR), the interaction of FSHR and FSH has been challenging to characterize due to the limited quantity of active FSHR protein produced by simple methods. The goal of this study was to express and purify the extracellular domain (ECD) of human FSHR (hFSHR).

METHODS

Total RNA was isolated from normal human ovary tissue. cDNA for hFSHR ECD were amplified and subsequently ligated into the pET32a(+) vector. The plasmid vector construct was confirmed by polymerase chain reaction and sequencing. Expression in Escherichia coli Rosetta (DE3) pLysS strain was induced by isopropyl-thio-β-D-thiogalactoside, and the recombinant products were purified by immuno-affinity chromatography using an Ni-NTA and High-Q column. The recombinant protein was confirmed by western blotting.

RESULTS

Following induction, E. coli expressed a recombinant protein of approximately 65 kDa in size, whereas the non-induced E. coli did not express the recombinant protein. The recombinant fragments purified using a High-Q column demonstrated a single band and an abundant yield. The recombinant protein was soluble and specifically recognized by an antibody for hFSHR. Additionally, four mutation sites were detected that resulted in amino acid shifts at position 112 Asn/Thr, 197 Glu/Ala, 198 Leu/Val and 307 Ala/Thr.

CONCLUSION

The recombinant hFSHR ECD protein was expressed and purified. This method could be easily scaled for increased production and may facilitate additional applications utilizing FSHR in assisted reproductive technology, a contraceptive FSH vaccine and FSHR-targeted therapeutic agents used to treat ovarian cancer.

Pharmacogenetics of follicle-stimulating hormone action

PURPOSE OF REVIEW

To review the current knowledge of genetic variants in the two genes affecting the individual responsiveness to follicle-stimulating hormone (FSH) action-the FSH beta-subunit (FSHB) and the FSH receptor (FSHR), as well as the pharmacogenetic ramifications of the findings.

RECENT FINDINGS

Four common variants in the FSHB and the FSHR genes were shown to exhibit significant effect on FSH action: linked FSHR variants Thr307Ala and Asn680Ser determining common receptor isoforms, and gene expression affecting polymorphisms FSHR -29G/A and FSHB -211G/T. In women, the FSHR Thr307Ala/Asn680Ser polymorphisms show consistent predictive value for estimating the most optimal recombinant FSH dosage in controlled ovarian hyperstimulation (COH). The same variants exhibit a potential for the pharmacogenetic assessment of the treatment of polycystic ovarian syndrome. The FSHR -29G/A variant was also shown to contribute to ovarian response to COH. Pilot studies have suggested the FSHB -211 TT homozygous oligozoospermic men with genetically determined low concentration of FSH, as potentially the best responders to FSH treatment; furthermore, modulation of this response by FSHR polymorphisms is possible.

SUMMARY

Genetic variants in FSHB and FSHR exhibit a potential for pharmacogenetic applications in selecting appropriate treatment options (timing and dosage) in male and female conditions requiring or benefiting from FSH therapy.

Effects of polymorphisms in gonadotropin and gonadotropin receptor genes on reproductive function

Gonadotropins, the action of which is mediated at the level of their gonadal receptors, play a key role in sexual development, reproductive functions and in metabolism. The involvement of the gonadotropins and their receptor genotypes on reproductive function are widely studied. A large number of gonadotropins and their receptors gene polymorphisms are known, but the only one considerable as a clear, absolute genetic marker of reproductive features or disfunctions is the FSHR Asn680Ser polymorphism, since it modulates ovarian response to FSH. The aim of these studies would to be the prediction of the genetic causes of sex-related diseases to enable a customized clinical setting based on individual response of patients undergoing gonadotropin stimulation. In this review we discuss the latest information about the effects of polymorphisms of the gonadotropins and their receptor genes on reproductive functions of both male and female, and discuss their patho-physiological implications.