Overview of hyperprolactinemia: General approach and reproductive health implications.

Prolactin (PRL) is a polypeptide hormone produced by the lactotrope cells of the anterior pituitary gland. Among its myriads of biological functions, PRL is the main regulator of mammary gland growth and development, as well as of the production and secretion of milk. Hyperprolactinemia represents a frequent consultation cause in medical practice. Nevertheless, elevations in serum PRL are not always pathological. Drug induced hyperprolactinemia is the most common cause, mainly by antipsychotics, followed by other causes such as pituitary neuroendocrine tumors, physiologic conditions, and systemic diseases such as chronic kidney disease and hypothyroidism. When evaluating a patient with hyperprolactinemia it is of utmost importance to consider the diverse etiologies of this condition in order to avoid unnecessary diagnostic workup and treatment. Regarding reproductive health, hyperprolactinemia is a well-documented cause of infertility, as approximately 15-20% of women undergoing infertility evaluation have hyperprolactinemia, which causes secondary amenorrhea, and other menstrual irregularities. Similarly, in men it is a cause of hypogonadism.

Long term outcomes of pituitary adenomas in Multiple Endocrine Neoplasia type 1: a nationwide study.

Introduction: Historically, Multiple Endocrine Neoplasia type 1 (MEN1)-related pituitary adenomas (PAs) were considered more aggressive and treatment-resistant than sporadic PAs. However, recent studies suggest similarities in their behavior. This study aimed to evaluate the long-term outcomes of MEN1 PAs and identify predictive factors. Methods: Nationwide multicenter retrospective cohort study of MEN1-related PAs with a minimum 1-year follow-up, collecting patient demographics, germline MEN1 pathogenic variants (PV), PA size, secretory profile, radiological characteristics, treatments, and outcomes. Results: We analyzed 84 PAs, 69%in females and 31% in males (P<0.001), diagnosed at a mean age of 35.2±14.9 years, mostly through screening (60.7%). Median follow-up was 9 years (IQR:4-16). Prolactin-secreting PAs (PRLomas) (53.5%) and microadenomas (65.5%) were most common. Dopamine agonist treatment was first line for 16 macroPRLomas and 25 microPRLomas, 60.9% of them achieved PRL normalization. There was no significant association observed with tumor size, sex, treatment duration or MEN1 PV. The risk of progression from micro-PA to invasive macro-PA was 7.2% (4/55), after 8 years (IQR:4-13), all of them were microPRLomas. Kaplan-Meier estimation curve showed significantly higher progression probability in microPRLomas than in other microadenomas subtypes (P=0.017) or microNFPAs (P=0.032). No differences were found between sex, age, or germline MEN1 PV. Conclusion: MEN1-related micro-PAs have a low risk of progressing to invasive macro-PAs, regardless of sex, age at diagnosis, or MEN1 germline PV. The risk is higher for microPRLomas over the long term. Therefore, long-term surveillance with reduced frequency, rather than intensive short-term monitoring, may be appropriate for patients with MEN1-related PAs.

A Non-Secreting Pituitary Adenoma That Changed to a Prolactinoma.

Pituitary adenomas (PAs) are the third most common brain tumors in adults right after meningiomas and gliomas. Taking into account their hormonal activity in vivo, they can be divided in functioning PAs, which secrete hormones, and nonfunctioning pituitary adenomas (NFPAs), which are not associated with increased hormone secretion. We present the case of a man diagnosed with pituitary apoplexy. A transsphenoidal surgery was performed with subtotal removal of the mass. Pituitary hormones were measured before and after the procedure on several occasions, showing always normal PRL values, so he was diagnosed with a clinically NFPA. Two years later, the patient noticed a visual deficit. A new magnetic resonance imaging study was performed, showing adenomatous recurrence, and the patient underwent a new surgery. After this, hormonal evaluation revealed high levels of PRL on several occasions. After treatment with cabergoline was started, PRL levels normalized, the visual deficit improved, and there was a slight adenoma reduction. This case report represents an exception to the paradigm that in the presence of a macroadenoma and normal PRL levels (avoiding the "hook effect"), a prolactinoma can be discarded. Moreover, it stresses the importance of comprehensive, regular, and lifelong surveillance of patients with NFPAs and the close monitoring of serum PRL.

Cerebral Computed Tomographic Findings in Schizophrenia: Relationship to Second-Generation Antipsychotics and Hyperprolactinemia.

Antipsychotic medications are essential for managing severe mental illnesses like schizophrenia, which impacts about 1% of the global population. Despite efficacy, in some cases, they can induce hyperprolactinemia, affecting roughly half of the patients. The prevalence of this condition varies with the specific medication used. Although prolactinomas are rare among schizophrenia patients, treating them with dopamine agonists poses conflicts with antipsychotic medication, necessitating careful monitoring and adjustments. The aim of this study was to explore the presence of brain tumors, prolactinomas, and other structural brain changes in schizophrenia patients treated with second-generation antipsychotics using cerebral computed tomography (CT) scans. We conducted a cross-sectional study involving 152 hospitalized patients diagnosed between 1 January 2020 and 31 March 2024. Evaluations included cerebral CT scans, prolactin level assessments, and the monitoring of side effects. Patients, with an average age of 42.79 years and an illness duration of 17.89 years, predominantly received olanzapine (46.05%) and risperidone (36.84%). Side effects, reported by 61.78% of patients, included tremors, dizziness, and weight gain. Abnormal prolactin levels were observed in 53.95% of patients, more prevalent in females on risperidone and in both genders on olanzapine. No prolactinomas were detected on CT scans. Managing hyperprolactinemia in schizophrenia patients undergoing antipsychotic therapy is essential to prevent long-term complications and to ensure treatment compliance.

Cabergoline targets multiple pathways to inhibit PRL secretion and increases stromal fibrosis.

OBJECTIVE: Unravel the potential mechanism(s) of the on- and off-target actions of dopamine agonist therapy in both human prolactinoma tumors and neighboring stromal and immune cells. DESIGN AND METHODS: Five surgically resected prolactinomas (PRLomas) from 3 cabergoline (CBG)-treated patients and 2 treatment-naive patients were analyzed by using single-cell RNA sequencing (scRNA-seq) to compare the cellular composition and transcriptional landscape. RESULTS: Six major cell populations, namely tumor (88.2%), immune (5.6%), stromal (4.9%), progenitor cells (0.6%), proliferating cells (0.4%), and erythrocytes (0.2%), were observed. Tumor cells from CBG-treated patients expressed lower levels of genes that regulated hormone secretion, such as SCG2, VGF, TIMP1, NNAT, and CALD1, consistent with the inhibitory effects of CBG on hormone processing and secretion. Interestingly, we also observed an increased number of CD8+ T cells in the CBG-treated tissues. These cytotoxic CD8+ T cells expressed killing granule components such as perforin and the granzymes GZMB, GNLY, and KLRD1 as well as the inflammatory cytokine CCL5. Immune cell activation of these CD8+ T cells was further analyzed in a compartment-specific manner, and increased CD25 (IL2R) expression was noted in the CD8+ T cells from the CBG-treated samples. Additionally, and confirming prior reports, we noted a higher stromal cell population in the CBG-treated samples. CONCLUSIONS: Our scRNA-seq studies revealed key differences in the transcriptomic features of CBG-treated and CBG-untreated PRLomas in both tumor and microenvironment cellular constituents, and for the first time, describe the previously unknown activation of CD8+ T cells following CBG treatment, which may play a role in the tumoricidal actions of CBG.

Gender Differences in Patients with Prolactinoma: Single-center Ukrainian Experience.

INTRODUCTION: Prolactinomas are the most common type of pituitary gland tumors that secrete overly prolactin. They account for approximately 60% of all hormone-secreting hypophysis tumors. AIM: This study aims to analyze gender differences in patients with prolactinomas who were operated on transsphenoidal surgery and conduct a single-center retrospective analysis of patient data. MATERIAL AND METHODS: This study evaluated the medical records of 109 patients (61 females and 48 males) from 2009 to 2019 at Feofaniya Clinical Hospital of the State Administration of Affairs in Kyiv, Ukraine. The primary criterion for including patients was a Serum Prolactin (PRL) level of over 100 ng/ml and the presence of a pituitary adenoma (PA) as observed on MRI. Additionally, the histological examination needed to confirm the presence of Prolactin-Secreting Pituitary Adenomas (PSPAs) without plurihormonal activity through both microscopy and immunohistochemical (IHC) staining. RESULTS: Significant differences in preoperative PRL levels were not observed. However, males had significantly larger tumor sizes and prevalence of macroadenomas. In male patients, the preoperative PLR levels showed a weak negative correlation with age (r=-0.304, p < 0.036) and a positive correlation with tumor size (r=0.555, p < 0.001) and cavernous sinus invasion (r=0.339, p < 0.018). In females, preoperative PRL was significantly associated only with tumor size and Knosp grade. CONCLUSION: Prolactin-Secreting Pituitary Adenomas (PSPAs) are more common in women than men and are characterized by larger and more invasive tumors with high PRL levels at diagnosis. The PRL level and tumor size before surgery can predict early biochemical remission in both males and females with an accuracy of 58.3% and 68.8%, respectively.

Prognostic factors for surgical treatment of prolactin-secreting pituitary adenomas.

Introduction: Usually, prolactinomas are treated with dopamine agonists (DA). Surgery is considered an option when the patient cannot bear or does not respond positively to DA therapy. Aim: This study aims to determine the early and late outcomes of surgery, with particular emphasis on developing prognostic factors for surgical treatment and analyzing risk factors affecting the recurrence of hyperprolactinemia and prolactinoma. Material and methods: This retrospective study was conducted at the Feofaniya Clinical Hospital of the State Administration of Affairs (Kyiv, Ukraine), evaluating 109 patients' records from 2009 to 2019. The main patients' inclusion criteria were: serum prolactin (PRL) level of more than 100 ng/ml, presence of pituitary adenoma (PA) on MRI, histologically approved PA by microscopy. According to the size of the prolactin-secreting PA (PSPAs) the selected 109 patients were divided into two groups: micro- (≤10 mm, n = 75) and macroadenoma group (10-40 mm, n = 34). Results: 1 month after the operation, PRL levels decreased by 87% (p < 0.001), 12 months-by 93% (p < 0.001). After receiving surgery and DA therapy for 12 months 77.1% of patients achieved biochemical remission. Out of the total number of patients observed, 15.6% (n = 17) had a Knosp score greater than 3. Additionally, in the macroadenoma group, the percentage of patients with a Knosp score greater than 3 was 41,2%, which was significantly higher as compared to the microadenoma group (4%, p < 0.001). In patients with microadenomas a weak reverse correlation between patients' age (r = -0.258, p < 0.026) and positive with tumor size (r = 0.251, p < 0.030) was revealed. In the macroadenoma group significant association was found only between preoperative serum PRL level and tumor size (r = 0.412, p < 0.016). The preoperative PRL can be used as a diagnostic marker for lack of early biochemical remission in patients with PSPAs with diagnostic accuracy 66.9%. Conclusions: This study found that primary transsphenoidal surgery is an effective treatment in reaching PRL level control in patients with both micro- and macroprolactinomas. The correct and thorough selection of candidates for surgery is crucial to achieve postoperative serum PRL normalization in the vast majority of patients.

Drug resistance mechanisms in dopamine agonist-resistant prolactin pituitary neuroendocrine tumors and exploration for new drugs.

BACKGROUND: The treatment of dopamine agonists (DA) resistant prolactinomas remains a formidable challenge, as the mechanism of resistance is still unclear, and there are currently no viable alternative drug therapies available. This study seeks to investigate the mechanism of DA resistance in prolactinomas and identify new potentially effective drugs. METHODS: To explore the mechanism of DA resistance in prolactinomas, this study conducted transcriptome sequencing analysis on 27 cases of DA-resistant prolactinomas and 10 cases of sensitive prolactinomas. In addition, single-cell sequencing analysis was performed on 3 cases of DA-resistant prolactinomas and 3 cases of sensitive prolactinomas. Furthermore, to screen for potential therapeutic drugs, the study successfully established an organoids model for DA-resistant prolactinomas and screened 180 small molecule compounds using 8 organoids. The efficacy of the identified drugs was verified through various assays, including CCK-8, colony formation, CTG, and flow cytometry, and their mechanisms of action were confirmed through WB and IHC. The effectiveness of the identified drugs was evaluated both in vitro and in vivo. RESULTS: The results of transcriptome sequencing and single-cell sequencing analyses showed that DA resistance in prolactinomas is associated with the upregulation of the Focal Adhesion (FA) signaling pathway. Additionally, immunohistochemical validation revealed that FAK and Paxillin were significantly upregulated in DA-resistant prolactinomas. Screening of 180 small molecule compounds using 8 organoids identified Genistein as a potentially effective drug for DA-resistant prolactinomas. Experimental validation demonstrated that Genistein inhibited the proliferation of pituitary tumor cell lines and organoids and promoted apoptosis in pituitary tumor cells. Moreover, both the cell sequencing results and WB validation results of the drug-treated cells indicated that Genistein exerts its anti-tumor effect by inhibiting the FA pathway. In vivo, experiments also showed that Genistein can inhibit subcutaneous tumor formation. CONCLUSION: DA resistance in prolactinomas is associated with upregulation of the Focal Adhesion (FA) signaling pathway, and Genistein can exert its anti-tumor effect by inhibiting the expression of the FA pathway.

Revealing Sexual Dimorphism in Prolactin Regulation From Early Postnatal Development to Adulthood in Murine Models.

Serum prolactin (PRL) levels exhibit a gradual rise both in male and female rats from birth to adulthood, with females consistently displaying higher levels compared to age-matched males. This pattern has traditionally been attributed to the development and maturation of endocrine and neuroendocrine networks responsible for regulating PRL synthesis and secretion. However, the effect of dopamine (DA), which acts as an inhibitory factor on lactotroph function, also increases from birth to puberty, particularly in females. Nonetheless, the secretion of PRL remains higher in females compared to males. On the other hand, the observed sex differences in serum PRL levels during early postnatal development cannot be attributed to the influence of estradiol (E2). While serum E2 levels gradually increase after birth, only after 45 days of life do the disparities in E2 levels between females and males become evident. These observations collectively suggest that neither the maturation of hypothalamic DA regulation nor the rise in E2 levels can account for the progressive and sustained elevation in serum PRL levels and the observed sexual dimorphism during postnatal development. This review highlights the importance of recent discoveries in animal models that shed light on inhibitory mechanisms in the control of PRL secretion within the pituitary gland itself, that is intrapituitary mechanisms, with a specific emphasis on the role of transforming growth factor ß1 and activins in PRL secretion.

Long-term Follow-up of 84 Patients With Giant Prolactinomas-A Swedish Nationwide Study.

PURPOSE: To describe the clinical presentation and treatment outcomes in a nationwide cohort of patients with giant prolactinomas. METHODS: Register-based study of patients with giant prolactinomas [serum prolactin (PRL) > 1000 µg/L, tumor diameter ≥40 mm] identified in the Swedish Pituitary Register 1991-2018. RESULTS: Eighty-four patients [mean age 47 (SD ±16) years, 89% men] were included in the study. At diagnosis, the median PRL was 6305 µg/L (range 1450-253 000), the median tumor diameter was 47 mm (range 40-85), 84% of the patients had hypogonadotropic hypogonadism, and 71% visual field defects. All patients were treated with a dopamine agonist (DA) at some point. Twenty-three (27%) received 1 or more additional therapies, including surgery (n = 19), radiotherapy (n = 6), other medical treatments (n = 4), and chemotherapy (n = 2). Ki-67 was ≥10% in 4/14 tumors. At the last follow-up [median 9 years (interquartile range (IQR) 4-15)], the median PRL was 12 µg/L (IQR 4-126), and the median tumor diameter was 22 mm (IQR 3-40). Normalized PRL was achieved in 55%, significant tumor reduction in 69%, and combined response (normalized PRL and significant tumor reduction) in 43%. In the primary DA-treated patients (n = 79), the reduction in PRL or tumor size after the first year predicted the combined response at the last follow-up (P < .001 and P = .012, respectively). CONCLUSION: DAs effectively reduced PRL and tumor size, but approximately 1 patient out of 4 needed multimodal treatment. Our results suggest that the response to DA after 1 year is useful for identifying patients who need more careful monitoring and, in some cases, additional treatment.

Operative treatment of cystic prolactinomas: a retrospective study.

BACKGROUND: The optimal therapeutic approach for cystic prolactinomas remains unclear. This study aimed to evaluate the remission rates of prolactinoma patients after surgical treatment and the risk factors affecting postoperative remission in cystic prolactinoma patients. METHODS: The clinical data were retrospectively compiled from 141 patients with prolactinomas (including 41 cases of cystic prolactinomas, 21 cases of solid microprolactinomas and 79 cases of solid macroprolactinomas) who underwent transsphenoidal surgery (TSS) between April 2013 and October 2021 at the First Affiliated Hospital of Sun Yat-sen University. RESULTS: Early postoperative remission was achieved in 65.83% (n = 27/41) of cystic prolactinomas, 80.95% (n = 17/21) of solid microprolactinomas and 40.51% (n = 32/79) of solid macroprolactinomas. The mean length of follow up in all patients was 43.95 ± 2.33 months (range: 6-105 months). The follow-up remission rates were 58.54%, 71.43% and 44.30% in cystic, solid micro- and solid macroprolactinomas, respectively. For cystic prolactinomas, the early postoperative remission rates in the patients with preoperative dopamine agonists (DA) treatment were significantly higher than those without preoperative DA treatment (p = 0.033), but the difference in the follow-up remission rates between these two groups was not significant (p = 0.209). Multivariate stepwise logistic regression analysis indicated that tumor size and preoperative prolactin (PRL) levels < 200 ng/ml were independent predictors for early postoperative remission in cystic prolactinomas. CONCLUSION: For cystic prolactinomas, tumor size and preoperative PRL levels were independent predictors of early postoperative remission. Preoperative DA therapy combined with TSS may be more beneficial to cystic prolactinoma patients.

The efficacy and safety of quinagolide in hyperprolactinemia treatment: A systematic review and meta-analysis.

Purpose: Three dopamine agonists [bromocriptine, cabergoline, and quinagolide (CV)] have been used for hyperprolactinemia treatment for decades. Several studies have reviewed the efficacy and safety of bromocriptine and cabergoline. However, no systematic review or meta-analysis has discussed the efficacy and safety of CV in hyperprolactinemia and prolactinoma treatment. Methods: Five medical databases (PubMed, Web of Science, Embase, Scopus, and Cochrane Library) were searched up to 9 May 2022 to identify studies related to CV and hyperprolactinemia. A meta-analysis was implemented by using a forest plot, funnel plot, sensitivity analysis, meta-regression, and Egger's test via software R 4.0 and STATA 12. Results: A total of 1,211 studies were retrieved from the five medical databases, and 33 studies consisting of 827 patients were finally included in the analysis. The pooled proportions of patients with prolactin concentration normalization and tumor reduction (>50%) under CV treatment were 69% and 20%, respectively, with 95% confidence intervals of 61%-76% and 15%-28%, respectively. The pooled proportion of adverse effects was 13%, with a 95% confidence interval of 11%-16%. Conclusion: Our study showed that CV is not less effective than cabergoline and bromocriptine in treating hyperprolactinemia, and the side effects were not significant. Hence, this drug could be considered an alternative first-line or rescue treatment in treating hyperprolactinemia in the future. Systematic review registration: https://www.crd.york.ac.uk/PROSPERO, identifier CRD42022347750.

Neuropsychological Alterations of Prolactinomas' Cognitive Flexibility in Task Switching.

Prolactinomas have been reported to impair cognition in broad aspects. However, few studies investigated the influence of prolactinomas on cognitive flexibility never mentioning the underlying neural and electrophysiological mechanism. We recorded scalp electroencephalography (EEG) in a colour-shape switching task. Patients with prolactinomas showed longer reaction time in switch trials and larger switch costs relative to healthy controls (HCs). Compared to HCs who showed stronger frontal theta activity in switch trials, the generally weak frontal theta activity in patients implied that they could not afford the executive control to configure task sets. Meanwhile, machine-learning based classification revealed that patients manifested non-selective brain patterns in response to different task types (colour vs. shape task) and different task states (switch vs. repeat state), which collectively suggested the cognitive dysfunction in preparation for a changing environment. Compared to HCs who showed stronger frontoparietal synchronization in switch trials, this enhanced frontoparietal connectivity was disrupted among patients with severe prolactinomas. This finding implicated greater hyperprolactinemia was linked to a larger decrease in cognitive performance. Taken together, the present study highlighted frontal theta power, and frontoparietal connectivity at theta band as the electrophysiological markers of the impaired cognitive flexibility and task control in patients with prolactinomas.

MicroRNA-137 inhibits pituitary prolactinoma proliferation by targeting AKT2.

PURPOSE: Prolactinoma is the most common type of pituitary adenoma. Most prolactinoma need medical treatment, but some of them are aggressive and require surgery. In previous decades, some miRNAs have been manifested as oncogenes or tumor suppressors. Consequently, miRNAs' abnormal expression involves tumorigenesis, invasion, and metastasis of different types of tumors, including pituitary tumors. The current study aim to explore the aggressiveness-associated miRNAs in prolactinoma and underlying molecular mechanisms based on the bioinformatic analysis and fundamental experiment studies. METHODS: GSE46294 miRNA expression profile from the Gene Expression Omnibus (GEO) database was downloaded. Differentially expressed miRNAs (DEMs) were filtered from this data. Subsequently, the target genes of downregulated miRNAs were analyzed by Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment. RT-qPCR, western blot, and CCK-8 assays were used to validate the effect of miR-137 on the proliferation of MMQ cells through AKT2. Finally, the binding site of rat miR-137 to AKT2 were predicted by Targetscan and Bibiserv database, and verified by double luciferase reporter assay. RESULTS: Twenty-four changed DEMs (fourteen upregulated and ten downregulated) were identified. Target genes of downregulated DEMs were classified into three groups by GO terms. KEGG pathway enrichment analysis revealed these target genes enriched in the PI3K-Akt pathway. We also confirmed that miR-137 can target AKT2 and inhibit the proliferation of MMQ cells induced by AKT2. CONCLUSION: MiR-137 suppressed prolactinomas' aggressive behavior by targeting AKT2.

Transsphenoidal surgery for prolactinomas in male patients: a retrospective study.

Male patients with prolactinomas usually present with typical hyperprolactinemia symptoms, including sexual dysfunction and infertility. However, clinical factors related to sexual dysfunction and surgical outcomes in these patients remain unclear. This study aimed to investigate the outcomes of male patients with prolactinomas after transsphenoidal surgery and the risk factors affecting sexual dysfunction. This study was conducted on 58 male patients who underwent transsphenoidal surgery for prolactinomas between May 2014 and December 2020 at the First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China. We evaluated the sexual function of patients before and after surgery through International Index of Erectile Function-5 scores, libido, and frequency of morning erection. Of the 58 patients, 48 (82.8%) patients had sexual intercourse preoperatively. Among those 48 patients, 41 (85.4%) patients presented with erectile dysfunction. The preoperative International Index of Erectile Function-5 scores in patients with macroprolactinomas were significantly higher than those in patients with giant prolactinomas (17.63 ± 0.91 vs 13.28 ± 1.43; P = 0.01). Postoperatively, the incidence of erectile dysfunction was 47.9%, which was significantly lower than that preoperatively (85.4%; P = 0.01). Twenty-eight (68.3%) patients demonstrated an improvement in erectile dysfunction. Tumor size and invasiveness were significantly correlated with the improvement of erectile dysfunction. Preoperative testosterone <2.3 ng ml-1 was an independent predictor of improvement in erectile dysfunction. In conclusion, our results indicated that tumor size and invasiveness were important factors affecting the improvement of sexual dysfunction in male patients with prolactinoma. The preoperative testosterone level was an independent predictor related to the improvement of erectile dysfunction.

TLR4 inhibition suppresses growth in oestrogen-induced prolactinoma models.

Prolactinomas have harmful effects on human health. Bromocriptine is the only commercially available drug in China, but about 25% of prolactinoma patients do not respond to it in clinic, its pathogenesis remains unknown. Thus, its pathogenesis needs to be determined to develop new therapeutic methods for prolactinomas. The expression of ERß, TLR4, and prolactin (PRL) in the pituitary gland of C57BL/6 mice and human prolactinoma specimen was examined by immunofluorescence or immunohistochemistry. The role of TLR4 in prolactinoma was determined using estradiol-induced models of C57BL/6 wild-type and TLR4-/- mice. MMQ cells were treated with estradiol, fulvestrant, and lipopolysaccharide (LPS) or transfected with TLR4 siRNA to study the expression of ERß, TLR4, and PRL in these cells. Furthermore, the interaction between ERß and TLR4 was investigated by immunoprecipitation analysis. The expression of PRL and TLR4 was co-located and increased in the pituitary gland of mice and human prolactinoma specimen compared to that in the control specimen. Meanwhile, TLR4 knockout or treatment with the TLR4 inhibitor TAK242 not only significantly inhibited tumor overgrowth but also decreased the expression of PRL in estradiol-treated mice through p38 MAPK pathway regulation. However, MMQ treated with estradiol and LPS enhanced PRL expression than treated with estradiol or LPS alone. Finally, ERß or TLR4 inhibition prevented the estradiol-induced PRL increase by regulating the TLR4/p38 MAPK pathway in vitro. Estradiol promoted prolactinoma development by activating the TLR4/p38 MAPK pathway through ERß, and TLR4 is a potential therapeutic target for prolactinoma treatment.

ß-Catenin is reduced in membranes of human prolactinoma cells and it is inhibited by temozolomide in prolactin secreting tumor models.

INTRODUCTION: Prolactinomas are the most frequent pituitary tumor subtype. Despite most of them respond to medical treatment, a proportion are resistant and become a challenge in clinical management. Wnt/ß-Catenin pathway has been implicated in several cancers including pituitary tumors and other sellar region malignancies. Interestingly, Wnt/ß-Catenin inhibition augments the cytotoxicity of the chemotherapeutic agent Temozolomide (TMZ) in different cancers. TMZ is now being implemented as rescue therapy for aggressive pituitary adenoma treatment. However, the molecular mechanisms associated with TMZ action in pituitary tumors remain unclear. OBJECTIVES: Our aims in the present study were to evaluate differential ß-Catenin expression in human resistant prolactinomas and Wnt/ß-Catenin signaling activation and involvement in Prolactin (PRL) secreting experimental models treated with TMZ. RESULTS: We first evaluated by immunohistochemistry ß-Catenin localization in human resistant prolactinomas in which we demonstrated reduced membrane ß-Catenin in prolactinoma cells compared to normal pituitaries, independently of the Ki-67 proliferation indexes. In turn, in vivo 15 mg/kg of orally administered TMZ markedly reduced PRL production and increased prolactinoma cell apoptosis in mice bearing xenografted prolactinomas. Intratumoral ß-Catenin strongly correlated with Prl and Cyclin D1, and importantly, TMZ downregulated both ß-Catenin and Cyclin D1, supporting their significance in prolactinoma growth and as candidates of therapeutic targets. When tested in vitro, TMZ directly reduced MMQ cell viability, increased apoptosis and produced G2/M cell cycle arrest. Remarkably, ß-Catenin activation and VEGF secretion were inhibited by TMZ in vitro. CONCLUSIONS: We concluded that dopamine resistant prolactinomas undergo a ß-Catenin relocalization in relation to normal pituitaries and that TMZ restrains experimental prolactinoma tumorigenicity by reducing PRL production and ß-Catenin activation. Together, our findings contribute to the understanding of Wnt/ß-Catenin implication in prolactinoma maintenance and TMZ therapy, opening the opportunity of new treatment strategies for aggressive and resistant pituitary tumors.

Dopamine agonist for the rapid improvement of visual field defects in giant and macro-prolactinomas.

PURPOSE: To evaluate effect of first-line dopamine agonist (DA) therapy as an alternative to surgery for visual field defect (VFD) recovery in giant and macro-prolactinoma. METHODS: In this retrospective study, 125 patients with giant and macro-prolactinoma, except those with a history of previous surgery or radiotherapy, were evaluated. Those who underwent visual field examinations using the Humphrey Visual Field analyser upon initial assessment and after treatment were included for analysis. Twelve patients with VFD were included. The effects of DA therapy on both VFD and tumor size were evaluated within the first three months. RESULTS: There were twelve patients analysed: three females and nine males, five giant and seven macroprolactinomas; eight patients received cabergoline (CAB) and four patients received bromocriptine (BRC). The mean adenoma diameter was 35±13mm (range 15-60), and the mean PRL level was 3,523ng/dL (range 312-11,703). Eight patients (67%) complained of blurred vision, while four patients (33%) reported no visual symptoms. After a median duration of three weeks, the VFD completely resolved in ten patients (83%) but only partially improved in two (17%). The mean initial doses of CAB and BRC that provided VFD improvement were 0.5±0.2mg/week and 6.3±1.4mg/day, respectively. After a mean duration of 2.2±0.9months, the mean decrease in adenoma size was 43.6±24.5% (range 10-95%). CONCLUSION: The use of DA as a first-line treatment for at least one month before deciding on surgery is recommended in giant and macro-prolactinomas with VFD. Surgery should be considered only in cases with DA resistance or persistent visual impairment despite medical therapy.

Oophorectomy improves pituitary activin inhibitory function preventing lactotroph hyperplasia development.

Among pituitary adenomas, prolactinomas are the most frequently diagnosed (about 50%). Dopamine agonists are generally effective in the treatment of prolactinomas. However, a subset of about 25% of patients does not respond to these agents. The management of drug-resistant prolactinomas remains a challenge for endocrinologists and new inhibitory treatments are needed. Pituitary activins inhibit lactotroph function. Its expression and action were found reduced in animal models of lactotroph hyperplasia (female mice overexpressing the B subunit of the human chorionic gonadotrophin and female mice knockout for dopamine receptor type 2). In these models, an oophorectomy avoids prolactinoma development. Hormonal replacement with oestradiol and/or progesterone is not enough to reach the tumor size observed in transgenic females. We postulated that the loss of gonadal inhibins after an oophorectomy contributes to prevent hyperplasia development. Here, we demonstrated that an oophorectomy at 2 months age recovers the following in adulthood: (i) pituitary activin expression, (ii) activin receptor expression specifically in lactotroph population, (iii) activin biological activity in lactotrophs with a concomitant reduction of Pit-1 expression. To summarize, when an oophorectomy is performed, inhibins are lost and the inhibitory action of pituitary activins on lactotroph population is recovered, helping to prevent lactotroph hyperplasia development. These results emphasize the importance of the inhibitory action of activins on lactotroph function, positioning activins as a good therapeutic target for the treatment of resistant prolactinomas.

The SF3B1R625H mutation promotes prolactinoma tumor progression through aberrant splicing of DLG1.

BACKGROUND: Recently, a hotspot mutation in prolactinoma was observed in splicing factor 3b subunit 1 (SF3B1R625H), but its functional effects and underlying molecular mechanisms remain largely unexplored. METHODS: Using the CRISPR/Cas9 genome editing system and rat pituitary GH3 cells, we generated heterozygous Sf3b1R625H mutant cells. Sanger and whole-genome sequencing were conducted to verify the introduction of this mutation. Transcriptome analysis was performed in SF3B1-wild-type versus mutant human prolactinoma samples and GH3 cells. RT-PCR and minigene reporter assays were conducted to verify aberrant splicing. The functional consequences of SF3B1R625H were evaluated in vitro and in vivo. Critical makers of epithelial-mesenchymal transition and key components were detected using western blot, immunohistochemistry, and immunofluorescence. Suppressing proteins was achieved using siRNA. RESULTS: Transcriptomic analysis of prolactinomas and heterozygous mutant cells revealed that the SF3B1R625H allele led to different alterations in splicing properties, affecting different genes in different species. SF3B1R625H promoted aberrant splicing and DLG1 suppression in both rat cells and human tumors. In addition, SF3B1R625H and knocking down DLG1 promoted cell migration, invasion, and epithelial-mesenchymal transition through PI3K/Akt pathway. CONCLUSIONS: Our findings elucidate a mechanism through which mutant SF3B1 promotes tumor progression and may provide a potent molecular therapeutic target for prolactinomas with the SF3B1R625H mutation.