Reversal of hypogonadotropic hypogonadism with tamoxifen in a patient with hyperprolactinemia resistant to dopamine agonists

[Overcoming therapy resistance in prolactinomas: from perspectives to real clinical practice]

The main treatment option of prolactin-secreting pituitary adenomas is dopamine agonist therapy, which demonstrates prolactin level normalizing and reducing the size of an adenoma in the majority of cases. However, significant amount of patients - about 20% - poorly responds even to high doses of dopamine agonists that is explained by the resistance to therapy. The occurrence of pharmacodynamic characteristics is one of the causes responsible for the development of resistance to typical therapy. Clinical manifestations of persistent hyperprolactinemia are due to following pathological factors: hormonal hypersecretion and the mass-effect of pituitary adenoma. Prevention of irreversible changes is possible only with timely detection of resistance and determination of the optimal personalized treatment algorithm.We report a clinical case of dopamine-agonist resistant microprolactinoma. Patient's health stabilisation, normal level of prolactin and reduction in size of adenoma were achieved due to administration of combined treatment with tamoxifen and dopamine agonists. Hyperprolactinaemia occurring because of prolactin-secreting pituitary adenoma and associated adverse effects are significant problem, decreasing quality of life and demographics in general. This underlines the importance of figuring out causes and identifying predictors of the therapy resistance.The results of the study, illustrated by a clinical example, are presented in the present paper.

Effect of Tamoxifen on the Management of Dopamine Agonist-Resistant Prolactinomas: A Systematic Review

The management of dopamine agonist (DA)-resistant prolactinomas unresponsive to second and third-line treatment is challenging and requires alternative medical therapy. The presence of estrogen receptors on pituitary tumors, and the variable behavior of pituitary tumors in the presence of estrogen, prompted investigation of the role of anti-estrogen in the treatment of DA-resistant prolactinomas. The goal of this paper is to perform a systematic review of the role of tamoxifen in the treatment of DA-resistant prolactinomas. A systematic review was conducted. Inclusion criteria were case reports, case series, and experimental studies using tamoxifen in DA-resistant prolactinomas. Exclusion criteria included review articles, DA-sensitive prolactinomas, and those that were not previously treated with DA. Data were analyzed using descriptive statistics. For continuous data, the mean was used. For dichotomous data, frequencies and percentages were used. Data on 22 patients were extracted from the seven included studies. Twenty patients (90.9%) responded positively to the use of tamoxifen with a mean reduction in prolactin levels of 57.4%. Ten patients (45.5%) showed normalization of prolactin post-tamoxifen administration. Regression of tumor size and stability of tumor growth were reported in four out of 22 cases (18.2%). Combination therapy with DA and tamoxifen increased DA sensitivity and had a clinically significant inhibitory effect on prolactin secretion. Furthermore, tamoxifen may be considered an effective adjuvant for tumor size control. Therefore, further studies are needed to draw more clinically and statistically robust conclusions.

Increased expression of aromatase cytochrome P450 enzyme is associated with prolactinoma invasiveness in post-menopausal women

Objectives

To investigate the expression levels of aromatase cytochrome P450 enzyme (P450AROM) and related molecules—estrogen receptor-beta (ER-β), Ki-67, and p53—in prolactinoma tumor tissue from pre- and post-menopausal women, and to determine the associations of tumor invasiveness with expression levels of these genes.

Methods

This study recruited 90 patients with prolactinoma who underwent adenoidectomy between 2012 and 2017. Information was collected regarding clinical characteristics, hormones, laboratory tests, and magnetic resonance imaging-assessed tumor invasiveness. Expression levels of P450AROM, ER-β, Ki-67, and p53 were examined by immunohistochemistry in prolactinoma tissues.

Results

Increased P450AROM expression was found in invasive prolactinoma tissues in post-menopausal women, compared with its expression in non-invasive prolactinoma tissues. ER-β level was significantly higher in patients resistant to treatment with bromocriptine, a dopamine agonist. However, there were no differences in rate of resistance to treatment (8.2% vs. 3.4%) or expression levels of P450AROM, Ki-67, p53, and ER-β between pre- and post-menopausal patients.

Conclusions

Our results demonstrated that increased P450AROM expression in prolactinoma of post-menopausal women was positively associated with invasiveness. Moreover, ER-β level was higher in both pre- and post-menopausal patients who were resistant to dopamine agonist treatment.

Metformin inhibits growth and prolactin secretion of pituitary prolactinoma cells and xenografts

Metformin (MET) is a diabetes drug that activates AMP-activated protein kinase (AMPK), and is suggested to have anticancer efficacy. Here, we investigated the role of AMPK signalling in prolactinoma (PRLoma), with particular respect to MET and bromocriptine (BC) as a PRLoma treatment. We analysed AMPK phosphorylation, dopamine D2 receptor (D2R), and oestrogen receptor (ER) expression in both BC-sensitive and -resistant PRLoma samples; effects of the AMPK agonist MET (alone or with BC) on in vitro proliferation and apoptosis, xenograft growth and prolactin (PRL) secretion of BC-sensitive and -resistant cells, and ER expression in xenografts. Some BC-resistant PRLomas showed high D2R expression but extremely low AMPK activation. MET significantly inhibited proliferation of cultured PRLoma cells; MET + BC notably restrained their PRL secretion. MET + BC further decreased tumour growth and serum PRL levels in xenografts than BC treatment alone. ER was down-regulated after AMPK activation in both cultured cells and xenografts. Together, we propose that the AMPK signalling pathway down-regulates ERα and ERβ, and suppresses PRLoma growth as well as PRL secretion. Combined MET + BC is a potential treatment for PRLomas.

Comprehensive gene- and pathway-based analysis of depressive symptoms in older adults

Depressive symptoms are common in older adults and are particularly prevalent in those with or at elevated risk for dementia. Although the heritability of depression is estimated to be substantial, single nucleotide polymorphism-based genome-wide association studies of depressive symptoms have had limited success. In this study, we performed genome-wide gene- and pathway-based analyses of depressive symptom burden. Study participants included non-Hispanic Caucasian subjects (n = 6,884) from three independent cohorts, the Alzheimer's Disease Neuroimaging Initiative (ADNI), the Health and Retirement Study (HRS), and the Indiana Memory and Aging Study (IMAS). Gene-based meta-analysis identified genome-wide significant associations (ANGPT4 and FAM110A, q-value = 0.026; GRM7-AS3 and LRFN5, q-value = 0.042). Pathway analysis revealed enrichment of association in 105 pathways, including multiple pathways related to ERK/MAPK signaling, GSK3 signaling in bipolar disorder, cell development, and immune activation and inflammation. GRM7, ANGPT4, and LRFN5 have been previously implicated in psychiatric disorders, including the GRM7 region displaying association with major depressive disorder. The ERK/MAPK signaling pathway is a known target of antidepressant drugs and has important roles in neuronal plasticity, and GSK3 signaling has been previously implicated in Alzheimer's disease and as a promising therapeutic target for depression. Our results warrant further investigation in independent and larger cohorts and add to the growing understanding of the genetics and pathobiology of depressive symptoms in aging and neurodegenerative disorders. In particular, the genes and pathways demonstrating association with depressive symptoms may be potential therapeutic targets for these symptoms in older adults.