Impaired estrogen-induced negative feedback on gonadotropin secretion in patients with gonadotropin-secreting and nonfunctioning pituitary adenomas

Is there any gender difference in epidemiology, clinical presentation and co-morbidities of non-functioning pituitary adenomas? A prospective survey of a National Referral Center and review of the literature

PURPOSE

Gender differences in patients diagnosed with non-functioning Pituitary Adenomas (NFPA) in a National Referral Center for Pituitary Tumors at the Federico II University of Naples, Italy.

METHODS

Patients newly diagnosed with non-functioning sellar masses found on pituitary Magnetic Resonance Imaging from January 1st 2016 to December 31th 2018 underwent anthropometric measurements, basal evaluation of pituitary function, and metabolic assessment. Fatty live index (FLI) and visceral adiposity index (VAI) were calculated.

RESULTS

Seventy-three patients (35 males, 51.1 ± 17.0 years; 38 females, 41.8 ± 18.1 years) presented with NFPA. Lesions > 1 cm (85.7% vs. 47.3%; χ² = 10.26, p = 0.001) and hypopituitarism (77.1% vs. 7.9%; χ² = 33.29, p = 0.001) were more frequent in males than females. The highest sizes of pituitary adenomas were significantly associated with male gender (OR = 1.05, p = 0.049; R² = 0.060; IC 1.00-1.10). Headache (62.8% vs. 31.6%; χ² = 5.96, p = 0.015) and visual field deficits (57.1% vs. 26.3%; χ² = 5.93, p = 0.015) were significantly more frequent in males than in females. There was no sex difference in obesity prevalence, but the metabolic syndrome was more common among males than females (60.6% vs. 26.3%; χ² = 7.14, p = 0.001). FLI was also higher in males (69.6 ± 27.3 vs. 49.2 ± 31.3; p < 0.001), while there were no differences in VAI.

CONCLUSIONS

Apart from the possible delay in the diagnosis induced by the gender differences in symptom presentation, the higher prevalence of macroadenomas amongst NFPA in males compared with females let to hypothesize a key role of the sex hormone profile as predictive factors of their biological behavior and metabolic profile. Further studies are, however, mandatory to better support the influence of gender differences on onset, progression, and metabolic consequences of NFPA.

Follicle-Stimulating Hormone-Secreting Pituitary Adenoma Inducing Spontaneous Ovarian Hyperstimulation Syndrome, Treatment Using In Vitro Fertilization and Embryo Transfer: A Case Report

OBJECTIVE

To describe the management of a patient with a pituitary adenoma secreting follicle-stimulating hormone (FSH) associated with spontaneous ovarian hyperstimulation syndrome (sOHSS) who was treated with in vitro fertilization and embryo transfer (IVF-ET).

METHODS

We report a clinical case of a woman of reproductive age with menstrual irregularity, infertility and ovarian hyperstimulation due to recurrent pituitary adenoma secreting FSH, which persisted after transsphenoidal surgery.She underwent the diagnosis by magnetic resonance imaging (MRI) and laboratory tests,and finally she was treated with IVF-ET.

RESULTS

The patient was plagued by a recurrent pituitary adenoma for many years and tried various treatments. After complete transsphenoidal surgery, sOHSS decreased, as shown by a reduction in oestradiol levels and an improvement in the ultrasonography parameters; however, secondary amenorrhea occurred. Finally, pregnancy was achieved through IVF-ET and the symptoms of ovarian hyperstimulation were relieved.

CONCLUSIONS

IVF-ET was found to be effective for the treatment of recurrent pituitary adenoma, thus representing a therapeutic option that should be taken into consideration in such cases.

Gonadotroph adenoma causing ovarian hyperstimulation syndrome in a premenopausal woman

INTRODUCTION

Gonadotroph adenomas occur commonly in middle-aged adults without any specific endocrinological symptoms. To date, only 30 cases of gonadotropinoma causing ovarian hyperstimulation syndrome in pre-menopausal women have been reported.

CASE REPORT

A 37-year old woman with pituitary macroadenoma and hyperprolactinaemia was admitted to the Department of Endocrinology, Diabetology and Isotope Therapy. She presented with recurrent ovarian cysts, menstrual disturbances, headaches, visual impairment and galactorrhea. Her endocrine profile showed normal values of FSH, elevated concentrations of estradiol and suppressed LH levels. Transsphenoidal resection of the tumor tissue resulted in normalization of the hormone values and improvement in the clinical picture.

CONCLUSIONS

Gonadotroph adenomas should be considered in the differential diagnosis in premenopausal women with OHSS.

Reduction of GSTP1 expression by DNA methylation correlates with clinicopathological features in pituitary adenomas

Pi-class glutathione-S-transferase (GSTP1) located on chromosome 11q13 encodes a phase II metabolic enzyme that detoxifies reactive electrophilic intermediates. GSTP1 plays an important role in the protecting cells from cytotoxic and carcinogenic agents and is expressed in normal tissues at variable levels in different cell types. Altered GSTP1 activity and expression have been reported in many tumors and this is largely due to GSTP1 DNA hypermethylation. The role of GSTP1 in pituitary tumorigenesis has not been investigated. In this study, we evaluated the GSTP1 expression level and GSTP1 DNA methylation status in a series of pituitary adenomas. Using immunohistochemistry, we identified expression of GSTP1 in all of the various normal hormone-producing adenohypophysial cell types. In pituitary adenomas, loss or reduced expression of GSTP1 was detected in 27 of 53 tumors (50.9%). Expression of GSTP1 was significantly lower in invasive adenomas than in noninvasive adenomas (P<0.05). Using methylation-specific polymerase chain reaction (MS-PCR), GSTP1 DNA promoter hypermethylation was detected in adenomas (38 of 53, 71.7%) but not in normal tissues. GSTP1 methylation was more frequent in grade II, III, and IV tumors (66.7, 85, and 83%, respectively) than in grade I tumors (33%, P<0.05). In addition, the frequency of GSTP1 methylation was higher in invasive tumors (85%) than in noninvasive tumors (59%; P<0.05). Methylation status correlated with significant downregulation of GSTP1 expression; the frequency of GSTP1 methylation was higher in tumors with reduced-GSTP1 expression (85%) than in tumors with normal or high GSTP1 expression (54%; P<0.05). These data indicate that GSTP1 inactivation through CpG hypermethylation is common in pituitary adenomas and may contribute to aggressive pituitary tumor behavior.

Estrogen regulates KiSS1 gene expression through estrogen receptor alpha and SP protein complexes

Kisspeptins are natural ligands of G protein-coupled receptor-54. Activation of KiSS1/G protein-coupled receptor-54 signaling pathways results in potent activation of the hypothalamus-pituitary-gonadal axis and initiates puberty. Recent data have shown that in female mice, KiSS1 is positively regulated by estradiol (E(2)) in the anteroventral periventricular nucleus, an important reproductive neuroendocrine brain region, but negatively regulated in the arcuate nucleus. However, little is known about the molecular mechanisms governing E(2)-modulated KiSS1 expression. Here, we demonstrate that the expression level of the KiSS1 gene was up-regulated with the administration of E(2) in estrogen receptor alpha (ERalpha)-positive hypothalamic GT1-7 cells. Using transient transfection of human KiSS1 gene promoter coupled to a luciferase reporter, E(2) increases promoter activity in the presence of ERalpha. Deletion analysis of KiSS1 promoter indicates that the E(2)-regulated increase in promoter activity depends on the Sp1 sites of the proximal promoter region. Using both EMSAs and chromatin immunoprecipitation analysis, we determined that both Sp1 and Sp3 proteins constitutively associate with the four putative Sp1 sites in vitro, whereas the association of ERalpha with the KiSS1 promoter is dependent on E(2) exposure. Sp1 and ERalpha form a complex in vivo to mediate the E(2)-induced activation of KiSS1 promoter. Interestingly, Sp1 transactivates KiSS1 promoter activity, whereas Sp3 functions as a transcriptional repressor. Together, these results demonstrate that E(2)-dependent transcriptional activation of KiSS1 gene is mediated by ERalpha through the interaction of Sp1/Sp3 proteins with the GC-rich motifs of KiSS1 promoter, providing a molecular mechanism of how steroid hormone feedback regulates KiSS1 expression.

FSH secretion predominates in vivo and in vitro in patients with non-functioning pituitary adenomas

OBJECTIVE

Non-functioning pituitary adenomas (NFPAs) are characterised by the lack of symptoms of hormone hypersecretory syndromes but in vitro studies have demonstrated that tumour cells may stain for gonadotrophins and/or their alpha- or beta-subunits. In this study, we aimed to examine the pattern of secretion of LH and FSH from a series of pituitary adenomas cultured in vitro and where data were available to relate the results to pre-operative serum gonadotrophin levels.

METHODS

The in vitro secretion of LH and FSH was measured from 46 cultured NFPAs and compared with pre-operative serum gonadotrophin levels in 38 patients. Peritumorous 'normal' pituitary cell cultures from 20 additional pituitary tumour patients were used for comparison with the NFPA group.

RESULTS

A median pre-operative LH:FSH ratio of 0.33:1 was found in 38 patients with NFPAs. Preferential secretion of FSH was also documented from media of 46 NFPAs cultured in vitro with a median LH:FSH ratio of 0.32:1. A significant correlation (r = 0.43, P < 0.01) was observed between serum and media levels of FSH but not LH. Peritumorous 'normal' pituitary cells released LH and FSH in a reversed ratio (median LH:FSH ratio = 3.6:1, P < 0.01 compared with NFPAs).

CONCLUSIONS

This study has evaluated pre-operative serum gonadotrophin levels and in vitro release of hormones in cultures of surgically removed tissue from patients with NFPAs. The data suggest preferential secretion of FSH occurs both in vitro and in vivo. By demonstrating that NFPAs cultured in vitro reflect the in vivo situation of preferential secretion of FSH, it may be possible in future to perform functional studies using this system to elucidate the cellular and molecular mechanisms involved in the development of an imbalance in gonadotroph cells preferentially overproducing FSH in NFPAs.