Medical treatment of prolactinomas

The Relationship Between the Ganglion Cell-Inner Plexiform Layer, Retinal Nerve Fiber Layer, and Photopic Negative Response in Newly Diagnosed Pituitary Macroadenoma: 12-Month Prospective Follow-Up Study

BACKGROUND/OBJECTIVES

This prospective study evaluates the relationship between the ganglion cell-inner plexiform layer (GCIPL), retinal nerve fiber layer (RNFL), and photopic negative response (PhNR) in patients with newly diagnosed pituitary macroadenomas over 12 months.

METHODS

A total of 40 patients (80 eyes) were included, divided into a treatment group of 27 patients (54 eyes), receiving pharmacological and/or surgical intervention, and an observation group of 13 patients (26 eyes), with non-functional pituitary adenomas (NFPAs) that did not require treatment.

RESULTS

Key findings indicate a significant improvement in best corrected visual acuity (BCVA) after 12 months in the treatment group (p = 0.02) and a significant reduction in RNFL thickness in multiple quadrants (p < 0.01). Moreover, PhNR amplitude and W-ratio significantly increased in the treatment group (p < 0.0001). In the observation group, only GCIPL Inferior (p = 0.0470) and PhNR W-ratio (p = 0.0015) showed significant differences. Between-group comparisons showed significant differences in RNFL Nasal quadrant at baseline (p = 0.0017) and after 12 months (p = 0.0150). PhNR amplitude and W-ratio also differed significantly between groups at 12 months (p = 0.0012 and p = 0.0016, respectively). Correlations between OCT and ERG parameters were weak at baseline and diminished over time.

CONCLUSIONS

These findings suggest that GCIPL, RNFL, and PhNR analyses may be useful for monitoring disease progression and guiding treatment decisions in patients with pituitary macroadenomas.

TRIM21-mediated ubiquitination and phosphorylation of ERK1/2 promotes cell proliferation and drug resistance in pituitary adenomas

BACKGROUND

Pituitary adenomas (PAs) are common intracranial tumors and the TRIM family plays a crucial role in cell proliferation and therapeutic resistance of tumors. However, the role of the TRIM family in PAs is not well recognized.

METHODS

CRISPR screening explored the role of the TRIM family in cell proliferation and drug resistance in PAs. In vitro and in vivo experiments were performed to evaluate the effects of Tripartite Motif Containing 21 (TRIM21). RNA-sequencing, mass spectrometry, immunoprecipitation, and ubiquitination experiments were performed to explore the molecular mechanism. NanoBiT assays were used to screen the drugs reducing TRIM21 expression.

RESULTS

CRISPR-Cas9 screens identified that TRIM21 facilitated cell proliferation and drug resistance in PAs. Mechanistically, TRIM21 interacted with ERK1/2 through PRY-SPRY domain, leading to ERK1/2 K27-linked ubiquitination. The ERK1/2 ubiquitination promotes the interaction between ERK1/2 and MEK1/2, thereby facilitating the phosphorylation of ERK1/2. However, an excess presence of TRIM21 suppressed the phosphorylation of ERK1/2 and cell proliferation via activating ERK1/2 negative feedback pathways. Importantly, TRIM21 was upregulated in dopamine-resistant prolactinomas and cabergoline-resistant MMQ cells. Furthermore, drug screening identified that Fimepinostat and Quisinostat, can reduce the protein levels of TRIM21, inhibit tumor progression, and increase drug sensitivity.

CONCLUSIONS

TRIM21 may represent a therapeutic target for tumors, and inhibiting TRIM21 could be a potential strategy for tumor treatment.

It Keeps Getting Bigger: A Patient With a Hypothalamic Tumor and Hyperprolactinemia

Internists might occasionally see patients with prolactinomas and non-prolactin-secreting intracranial tumors under their care. This report presents an interesting and rare case of a woman with end-stage renal disease, who presented with hallucinations and a suprasellar mass. Her symptoms and prolactin levels, however, did not improve with adherent, inpatient, dopamine agonist treatment. She was eventually palliated and demised shortly after compassionate discharge. It is imperative that physicians maintain a high index of suspicion of alternative diagnoses (such as metastatic disease or high-grade glioma) when hypothalamic masses and raised prolactin levels do not significantly decline with dopamine agonism.

Elucidating Clinical Queries for Tailored Therapy in Patients with Prolactinoma

Prolactinomas are the most prevalent type of pituitary neuroendocrine adenomas, primarily affecting women of reproductive age. Unlike other pituitary tumors, the first-line management has traditionally been pharmacological rather than surgical. This preference is due to the effectiveness of dopamine agonists (DAs), which typically reduce tumor size and normalize prolactin levels in most patients. However, this does not imply that there is no room for improvement; the duration of treatment and medication side effects often lead to compliance issues among patients. Recent advances in surgical techniques and molecular biology have paved the way for the development of precision medicine, allowing for more flexible and personalized treatment strategies for prolactinomas. This review aims to enhance clinical decision-making and patient care for endocrinologists by focusing on several key factors: predictive markers of DA sensitivity, clinical characteristics and suitability for transsphenoidal adenomectomy as a potential first-line treatment, factors determining the successful withdrawal of DAs after prolonged use, safety concerns during pre/post-pregnancy and breastfeeding, and determinants of tumor aggressiveness. Through tailored therapy-a patient-focused, multidisciplinary approach- we aim to improve the management of prolactinoma patients.

Risk Assessment of Diabetes Mellitus During and After Pregnancy in Women With Prolactinomas

CONTEXT

Prolactin (PRL) is a crucial mediator of glucoinsulinemic metabolism.

OBJECTIVE

This work aims to dissect glucose metabolism during and after pregnancy in patients with prolactinomas.

METHODS

A total of 52 patients treated with cabergoline (CAB) were evaluated before conception, during pregnancy, and up to 10 years after delivery. During pregnancy, CAB was discontinued, while it was restarted in 57.7% of patients after delivery, due to recurrent hyperprolactinemia (RH). Hormonal (serum PRL) and metabolic (glycated hemoglobin A1c [HbA1c], fasting glucose [FG], glucose tolerance) parameters were assessed.

RESULTS

During pregnancy, PRL gradually increased, while FG remained stable. An inverse correlation between PRL and FG was found in the first (P = .032) and third (P = .048) trimester. PRL percentage increase across pregnancy was inversely correlated with third-trimester FG. Serum PRL before conception emerged as a predictive biomarker of third-trimester FG (t = 2.603; P = .048). Older patients with lower HbA1c in the first trimester and lower FG at 3 years post partum delivered infants with reduced birth weight. Breastfeeding up to 6 months correlated with lower FG at 4 and 10 years post partum. A positive correlation between BMI and FG at 10 years after delivery (P = .03) was observed, particularly in overweight/obese patients requiring higher CAB doses. Patients with RH who had to restart CAB showed shorter breastfeeding duration and higher FG at 2 years post partum.

CONCLUSION

Low PRL levels before pregnancy may be detrimental to FG during pregnancy. CAB duration and dose may influence long-term glucose tolerance, besides family history and BMI. Preconception metabolic management should be recommended to reduce the risk of gestational and type 2 diabetes mellitus.

The Role of Endoscopic Transsphenoidal Surgery in Microprolactinomas: A Retrospective Study

OBJECTIVE

Most patients with microprolactinomas require lifetime treatment with a dopamine agonist. Many patients in our center have sought endoscopic transsphenoidal surgery as an alternative therapy.

METHODS

This study was a retrospective cohort analysis of 42 patients with microprolactinoma who underwent endoscopic transsphenoidal surgery between January 2010 and December 2023 performed by experienced neurosurgeons in our center.

RESULTS

The mean follow-up duration was 30.17 months (range, 13.00-45.40 months). The short-term (postoperative day 1) remission rate was 95.24%, and the long-term (>1-year follow-up) remission rate was 92.86%. The pattern of prolactin level changes on postoperative day 1 was significantly associated with recurrence. In the hypoprolactinemia group, all 29 patients achieved remission at the 1-year follow-up. In patients with normal prolactin levels, 10 of 11 patients achieved remission, while 1 of 11 patients had recurrence at the 1-year follow-up. In the hyperprolactinemia group, 2 of 2 patients had recurrence at the 1-year follow-up. Moreover, adenoma location was significantly associated with recurrence. In the recurrent group (3 patients), 2 patients belonged to the uncertain group, while the third patient belonged to the lateral group. The surgical complications were temporary and resolved shortly after surgery.

CONCLUSIONS

According to our findings, endoscopic transsphenoidal surgery performed on patients with microprolactinomas at advanced pituitary tumor centers could be an option with high success rates and low complications. Moreover, improving magnetic resonance imaging techniques and/or multidisciplinary team discussion before surgery for microprolactinoma could improve tumor remission after surgery.

[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.

The Role of Aromatase Inhibitors in Male Prolactinoma

BACKGROUND

dopamine agonists are the recommended treatment for male prolactinomas, but some patients may develop dopamine-agonist-resistant hyperprolactinemia, leading to persistent hypogonadism that requires treatment with testosterone. However, testosterone replacement therapy may be associated with a decrease in the efficacy of dopamine agonists due to the aromatization of testosterone to estradiol, which can stimulate the proliferation and hyperplasia of lactotroph cells in the pituitary, inducing resistance to dopamine agonists.

OBJECTIVE

this paper systematically reviewed the role of aromatase inhibitors for men with prolactinoma and dopamine-agonist-resistant or persistent hypogonadism following treatment.

METHOD

we performed a systematic review of all studies (according to PRISMA guidelines), assessing the role of aromatase inhibitors, including anastrozole and letrozole, for male prolactinoma. An English-language search for relevant studies was conducted on PubMed from its inception to 1 December 2022. The reference lists of the relevant studies were also reviewed.

RESULTS

our systematic review identified six articles (nine patients), including five case reports and a single case series, on the use of aromatase inhibitors for male prolactinomas. Reducing estrogen levels with an aromatase inhibitor improved sensitivity to dopamine agonists, as the addition of anastrozole or letrozole improves the control of prolactin levels and may lead to the shrinkage of tumors.

CONCLUSION

aromatase inhibitors are of potential value to patients with dopamine-agonist-resistant prolactinoma, or when hypogonadism persists while using high-dose dopamine agonists.

Endoscopic Transnasal Approach for Microprolactinomas with Experience of 105 Cases in a Single Center: Paradigmal Shift for Conventional Medical Therapy

OBJECTIVE

The classically recommended first-line therapy for microprolactinomas is medical therapy. In the presence of drug resistance and intolerance after the use of dopamine agonists or when the patients prefer surgery instead of medication, surgical treatment is considered as second-line treatment. The high hormonal remission and low complication rates after surgery for microprolactinomas suggest that the surgical outcome of endoscopic surgeries may be better than medical therapy in well-selected patients. This study reports a large series of patients with microprolactinoma treated by endoscopic transnasal approach and evaluates the efficiency of surgical treatment.

METHODS

Our study is a retrospective cohort analysis of patients with microprolactinoma operated on by an endoscopic transnasal approach between August 1997 and February 2022 by an experienced pituitary surgeon in a single tertiary center. Inclusion criteria for microprolactinoma were based on increased prolactin levels, microadenoma (<10 mm in diameter) on pituitary magnetic resonance imaging, and histopathologically verified lactotroph adenoma.

RESULTS

The mean follow-up was 74.90 months (range, 6-207). The postoperative day 1 remission rate was 85.7% and the long-term remission rate was 74.3%. The long-term remission rates of the patients in the preference group were significantly higher than those of the patients in the resistant or intolerance group (P = 0.002). Patients who used dopamine agonists for more than 3 years had a lower remission rate compared with patients who used dopamine agonists for a shorter period or who did not use it (P = 0.01). The surgical complication rate was 4.76%.

CONCLUSIONS

According to our findings, endoscopic transnasal surgery performed by an experienced neurosurgeon in well-selected patients with microprolactinoma can be offered with cure rates superior to medical therapy and may be an alternative first-line treatment option to dopamine agonists.

DRD2 expression based on 18F-fallypride PET/MR predicts the dopamine agonist resistance of prolactinomas: a pilot study

PURPOSE

The dopamine agonists (DA) have been used widely to treat prolactinomas. However, it is difficult to predict whether the patient will be responsive to DA treatment.

METHODS

We aimed to investigate whether the in vivo expression of DRD2 based on ¹⁸F-fallypride PET/MR could predict the therapeutic effect of DA on prolactinomas. Seven patients with prolactinomas completed ¹⁸F-fallypride PET/MR. Among them, three patients underwent surgery and further tumor immunohistochemistry. Imaging findings and immunohistochemical staining were compared with treatment outcomes.

RESULTS

¹⁸F-fallypride PET/MR was visually positive in 7 of 7 patients, and DRD2 target specificity could be confirmed by immunohistochemical staining. A significantly lower tracer standard uptake value (SUV) could be detected in the resistant patients (n = 3) than in the sensitive patients (n = 4; SUV_mean, 4.67 ± 1.32 vs. 13.57 ± 2.42, p < 0.05). DRD2 expression determined by ¹⁸F-fallypride PET/MR corresponded with the DA treatment response.

CONCLUSION

¹⁸F-fallypride PET/MR may be a promising technique for predicting DA response in patients with prolactinoma.

Predicting hypogonadotropic hypogonadism persistence in male macroprolactinoma

PURPOSE

To study the baseline characteristics predicting hypogonadotropic hypogonadism (HH) persistence in men with macroprolactinoma that achieved prolactin normalization.

DESIGN

Retrospective cohort study.

METHODS

Male patients diagnosed with macroprolactinoma and HH that received cabergoline treatment with subsequent prolactin normalization were included: men that achieved eugonadism, and men that remained hypogonadal. Patient's demographic, clinical and biochemical parameters, sellar imaging, and visual fields tests were obtained. Univariate and multivariate models were used to identify predictors of HH persistence.

RESULTS

Fifty-eight male patients (age 49.2 ± 12.6 years) with a median baseline prolactin of 1154 ng/mL (IQR 478-2763 ng/mL) and adenoma (maximal) diameter of 25.9 ± 14.8 mm were followed for a median of 5.6 years (IQR 3.0-10.7). Twelve men (21%) suffered from HH persistence at the end of follow-up and 46 men achieved eugonadism. Forty-two out of 46 men (91%) accomplished eugonadism within the first year following prolactin normalization. In a multivariate logistic regression model, hypopituitarism (OR 10.1; 95% CI 1.10-101.94), visual field defect (OR 9.9; 95% CI 1.07-92.33), and low baseline testosterone levels (OR 0.5; 95% CI 0.29-0.93) were independent predictors of HH persistence.

CONCLUSION

In our cohort of men with macroprolactinoma that reached prolactin normalization with cabergoline treatment, 21% had HH persistence. Pituitary hormone deficiency, visual field defects, and low baseline testosterone levels were independently associated with HH persistence. 91% of men achieved eugonadism within the first year following prolactin normalization. These findings may support informed clinical decision-making regarding the initiation of testosterone replacement in men with macroprolactinomas.

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.

Surgery as a first-line option for prolactinomas

INTRODUCTION

Treatment of prolactinomas with dopamine agonists has been the established first-line treatment option for many years, with surgery reserved for refractory cases or medication intolerance. This approach may not be the best option in many cases.

AREAS COVERED

Review of the epidemiology, biology, and treatment options available for prolactinomas, including best available data on outcomes, costs, and morbidities for each therapy. These data are then used to propose a 'surgery-first' treatment approach for a subset of prolactinomas as an alternative to primary medical management.

EXPERT OPINION

Based on the available data, there is a strong rationale that transsphenoidal surgery should be considered a first-line treatment option for both micro- and macro-prolactinomas that do not demonstrate high grade cavernous sinus invasion on MRI imaging, with dopamine agonists administered as a secondary therapy for tumors not in remission following surgery, and for giant tumors. This 'surgery-first' approach assumes the availability of skilled and experienced pituitary surgeons to ensure optimal outcomes. This approach should result in high cure rates and reduced DA requirements for patients not cured from initial surgery. Further, it will reduce medical costs over a patient's lifetime and the chronic morbidities associated with protracted dopamine agonist usage.

Resistant prolactinomas: a case series of 26 patients

PURPOSE

Prolactin (PRL)-secreting tumors are the most common functional pituitary adenomas. They usually respond to dopamine agonist (DA) treatment, with PRL normalization and adenoma shrinkage. Our aim was to characterize patients with prolactinoma resistant to DA treatment.

METHODS

This retrospective case series included patients diagnosed with DA-resistant prolactinomas between 1993-2017 in three medical centers. Resistance was defined as PRL levels above three times the upper limit of normal (ULN) despite a weekly dose of ≥2 mg cabergoline (CAB). Clinical and biochemical information, and response to treatment, were retrieved from medical records.

RESULTS

Twenty-six patients were identified; 20 males. Of 25 macroadenomas, three were giant tumors (>40 mm) and 15 (57.7%) were invasive. The mean age at diagnosis was 31.8 ± 14.9 years (range: 13-62). The median maximal CAB dose was 3.5 mg/week (IQR, 2.5-5). Half the patients received only CAB in escalating doses, nine received CAB and underwent transsphenoidal surgery, and four underwent surgery and radiotherapy in addition to CAB treatment. PRL levels at baseline between patients treated only with CAB and those operated were (91.6 [51.1-296.7] vs. 73.1 [22.6-170.9] XULN p = 0.355), and under maximal CAB dose PRL levels between patients treated only with CAB and those operated were similar (5.77 [1.27-11.27] vs 5.27 (2.9-26) XULN p = 0.317). At the last visit patients who received combined therapy achieved lower PRL levels than those treated with DA only (5.22 [1.7-21.6] vs 1.1 [0.44-3.99] XULN p = 0.017) PRL normalization was attained in seven patients and levels below 3 × ULN in fourteen patients; the overall response was 56%.

CONCLUSIONS

Resistant prolactinomas usually require a multi-modal treatment strategy. We were able to control 14/25 (56%) of resistant tumors.

Current and Emerging Medical Therapies in Pituitary Tumors

Pituitary tumors (PT) represent in, the majority of cases, benign tumors for which surgical treatment still remains, except for prolactin-secreting PT, the first-line therapeutic option. Nonetheless, the role played by medical therapies for the management of such tumors, before or after surgery, has evolved considerably, due in part to the recent development of well-tolerated and highly efficient molecules. In this review, our aim was to present a state-of-the-art of the current medical therapies used in the field of PT and the benefits and caveats for each of them, and further specify their positioning in the therapeutic algorithm of each phenotype. Finally, we discuss the future of PT medical therapies, based on the most recent studies published in this field.

Outcome of giant pituitary tumors requiring surgery

OBJECTIVE

The management of giant pituitary tumors is complex, with few publications and recommendations. Consequently, patient's care mainly relies on clinical experience. We report here a first large series of patients with giant pituitary tumors managed by a multidisciplinary expert team, focusing on treatments and outcome.

METHODS

A retrospective cohort study was conducted. Giant pituitary tumors were defined by a main diameter > 40mm. Macroprolactinomas sensitive to dopamine agonists were excluded. All patients were operated by a single neurosurgical team. After surgery, multimodal management was proposed, including hormone replacement, radiotherapy and anti-tumor medical therapies. Outcome was modeled using Kaplan-Meyer representation. A logistic regression model was built to identify the risk factors associated with surgical complications.

RESULTS

63 consecutive patients presented a giant adenoma, most often with visual defects. Patients were operated once, twice or three times in 59%, 40% and 1% of cases respectively, mainly through endoscopic endonasal approach. Giant adenomas included gonadotroph, corticotroph, somatotroph, lactotroph and mixed GH-PRL subtypes in 67%, 14%, 11%, 6% and 2% of patients respectively. Vision improved in 89% of patients with prior visual defects. Severe surgical complications occurred in 11% of patients, mainly for tumors > 50 mm requiring microscopic transcranial approach. Additional radiotherapy was needed for 29% of patients, 3 to 56 months after first surgery. For 6% of patients, Temozolomide treatment was required, 19 to 66 months after first surgery.

CONCLUSIONS

Giant pituitary tumors require multimodal management, with a central role of surgery. Most often, tumor control can be achieved by expert multidisciplinary teams.

MicroRNA-Mediated Drug Repurposing Unveiled Potential Candidate Drugs for Prolactinoma Treatment

INTRODUCTION

Prolactinomas, also called lactotroph adenomas, are the most encountered type of hormone-secreting pituitary neuroendocrine tumors in the clinic. The preferred first-line therapy is a medical treatment with dopamine agonists (DAs), mainly cabergoline, to reduce serum prolactin levels, tumor volume, and mass effect. However, in some cases, patients have displayed DA resistance with aggressive tumor behavior or are faced with recurrence after drug withdrawal. Also, currently used therapeutics have notorious side effects and impair the life quality of the patients.

METHODS

Since the amalgamation of clinical and laboratory data besides tumor histopathogenesis and transcriptional regulatory features of the tumor emerges to exhibit essential roles in the behavior and progression of prolactinomas; in this work, we integrated mRNA- and microRNA (miRNA)-level transcriptome data that exploit disease-specific signatures in addition to biological and pharmacological data to elucidate a rational prioritization of pathways and drugs in prolactinoma.

RESULTS

We identified 8 drug candidates through drug repurposing based on mRNA-miRNA-level data integration and evaluated their potential through in vitro assays in the MMQ cell line. Seven repurposed drugs including 5-fluorocytosine, nortriptyline, neratinib, puromycin, taxifolin, vorinostat, and zileuton were proposed as potential drug candidates for the treatment of prolactinoma. We further hypothesized possible mechanisms of drug action on MMQ cell viability through analyzing the PI3K/Akt signaling pathway and cell cycle arrest via flow cytometry and Western blotting.

DISCUSSION

We presented the transcriptomic landscape of prolactinoma through miRNA and mRNA-level data integration and proposed repurposed drug candidates based on this integration. We validated our findings through testing cell viability, cell cycle phases, and PI3K/Akt protein expressions. Effects of the drugs on cell cycle phases and inhibition of the PI3K/Akt pathway by all drugs gave us promising output for further studies using these drugs in the treatment of prolactinoma. This is the first study that reports miRNA-mediated repurposed drugs for prolactinoma treatment via in vitro experiments.

Tumor invasion to the spinal region after primary surgery: A case report

Background

It is believed that pituitary carcinoma is a rare disorder and arise from the transformation of benign invasive macroadenomas, and the process of this transformation takes place slowly.

Case Presentation

A 51-year-old man presented with the clinical features of Cushing syndrome and walking impairment who was diagnosed with metastatic corticotroph pituitary carcinoma to the spine region, 6 years after the initial resection of a primary invasive pituitary adenoma. He made a visit to neurosurgery and endocrinology clinic with the chief complaint of weight gain, facial and extremities swelling, paresthesia, weakness, motion and speaking impairments, and HTN which all appeared through the last 1 year; hormonal laboratory tests showed urine free cortisol (UFC) 197.8 and 367. 30 ug/24hrs (36-137), cortisol 8 am after 1 mg overnight dexamethasone test 375 ng/mL (50-250) and ACTH 59 pg/mL. MRI study revealed a mass in the brainstem with the compression effect on spinal region, pituitary imagine does not differ from the last MRI. He underwent a neurosurgery for spinal mass resection, which was successful and the total mass was resected. After surgery, the patient's condition became better.

Conclusion

Pituitary carcinoma is a rare entity impossible to recognize as a primary tumor because its diagnosis by definition requires the presence of metastasis. Clinical awareness of the rare possibility for aggressive adenomas will progress, to metastasize is essential to appropriately monitor patients for possible early detection and treatment of pituitary carcinoma.

Tumor stem-like cells isolated from MMQ cells resist to dopamine agonist treatment

Although tumor stem-like cells (TSLCs) have been studied in a range of malignant tumors, evidence for the presence of these cells in pituitary adenomas needs further exploration. Here, we identified a small subset of sphere-forming cells possess tumor stem-like cell properties in rat prolactinoma MMQ cells, which resist to dopamine agonist treatment. Comparing to MMQ cells, sphere-forming cells showed higher cell viability after dopamine agonist (DA) treatment. Furthermore, the cells showed lower expression of prolactin (PRL) and dopamine 2 receptor (D2R). On the contrary, the daughter tumor cells differentiated from these cells restored the sensitivity to DA and showed high expression of PRL and D2R. The lower D2R expression and DA resistance might be due to DNA hypermethylation of D2R promoter. Our study demonstrates that the sphere-forming cells isolated from MMQ cells possess the trait of TSLCs and resist to DA treatment, which offers the opportunity to further investigate the mechanisms underlying tumor recurrence based on TSLCs.

Comparison of the effects of medical and surgical treatments in giant prolactinoma: a single-center experience

PURPOSE

Giant prolactinomas, which have extremely large sizes and high prolactin (PRL) values, are rarely seen. Although medical therapy is effective, surgical treatment is more frequently applied due to slightly lower response rates and compression symptoms. This study aimed to compare the medical and surgical treatment results in giant prolactinomas.

METHODS

Thirty-nine patients who were followed up in our center for giant prolactinoma were included in the study, and the response rates of the patients were evaluated after the medical and surgical treatments. The treatment responses were compared in terms of tumor volume, PRL level, visual field, and pituitary function.

RESULTS

The outcomes of the 66 treatment periods (medical n = 42; surgical n = 24) in 39 patients (mean age, 47.2 years; men, 89.7%) were evaluated. The most common presentations were hypogonadism and visual defects. The mean longest tumor diameter at diagnosis was 52.2 ± 11.8 mm, and the median PRL levels were 5000 ng/mL. PRL level normalization was achieved in 69% with medical therapy, and a curative response was obtained in only two patients with surgery. Tumor volume reduction was 67% (no cure) in the medical and 75% (13% cure) in the surgical groups (p = 0.39). Improvement of visual field was 70.8% in the medical and 84.2% in the surgical group (p = 0.12).

CONCLUSION

In our study, it was observed that medical therapy was effective and safe in patients with giant prolactinomas. The use of surgical treatment should be limited to prolactinomas with compression or post-resistance to medical treatment in serious cases.

Hyperprolactinemia after menopause: Diagnosis and management

Most prolactinomas are diagnosed in women of reproductive age and are generally microadenomas. Prolactinomas diagnosed in postmenopausal women are less common and are not usually associated with the typical syndrome induced by prolactin excess, including infertility and oligo-amenorrhea. This implies that the diagnosis of prolactinomas after menopause may be delayed and require greater clinical effort. Limited data are available on the management and prognosis of prolactinomas in postmenopausal women. However, the physiologic decline of prolactin levels during menopause and the lack of fertility concerns, which represent specific indications for medical treatment with dopamine agonists, might require a careful reassessment of therapeutic management in such patients. Postmenopausal women with microprolactinoma may be successfully withdrawn from medical therapy with dopamine agonists, whereas in those with macroprolactinomas greater caution is advisable before dopamine agonists are discontinued, considering the potential, although rare, tumor enlargement. This review focuses on the diagnostic challenges and therapeutic management of prolactinomas in postmenopausal women.

Brusatol Inhibits Tumor Growth and Increases the Efficacy of Cabergoline against Pituitary Adenomas

Cabergoline (CAB) is the first choice for treatment of prolactinoma and the most common subtype of pituitary adenoma. However, drug resistance and lack of effectiveness in other pituitary tumor types remain clinical challenges to this treatment. Brusatol (BT) is known to inhibit cell growth and promote apoptosis in a variety of cancer cells. In our present studies, we investigate the effects of BT on pituitary tumor cell proliferation in vitro and in vivo. BT treatment resulted in an increase in Annexin V-expressing cells and promoted the expression of apoptosis-related proteins in rat and human pituitary tumor cells. Investigation of the mechanism underlying this effect revealed that BT increased the production of reactive oxygen species (ROS) and inhibited the phosphorylation of 4EBP1 and S6K1. Furthermore, treatment with a combination of BT and CAB resulted in greater antitumor effects than either treatment alone in nude mice and pituitary tumor cells. Collectively, our results suggest that the BT-induced ROS accumulation and inhibition of mTORC1 signaling pathway leads to inhibition of tumor growth. Combined use of CAB and BT may increase the clinical effectiveness of treatment for human pituitary adenomas.

Exploiting D2 receptor β-arrestin2-biased signalling to suppress tumour growth of pituitary adenomas

BACKGROUND AND PURPOSE

Dopamine agonists targeting D₂ receptor have been used for decades in treating pituitary adenomas. There has been little clear evidence implicating the canonical G protein signalling as the mechanism by which D₂ receptor suppresses the growth of pituitary tumours. We hypothesize that β-arrestin2-dependent signalling is the molecular mechanism dictating D₂ receptor inhibitory effects on pituitary tumour growth.

EXPERIMENTAL APPROACH

The involvement of G protein and β-arrestin2 in bromocriptine-mediated growth suppression in rat MMQ and GH3 tumour cells was assessed. The anti-growth effect of a β-arrestin2-biased agonist, UNC9994, was tested in cultured cells, tumour-bearing nude mice and primary cultured human pituitary adenomas. The effect of G protein signalling on tumour growth was also analysed by using a G protein-biased agonist, MLS1547, and a Gβγ inhibitor, gallein, in vitro.

KEY RESULTS

β-arrestin2 signalling but not G protein pathways mediated the suppressive effect of bromocriptine on pituitary tumour growth. UNC9994 inhibited pituitary tumour cell growth in vitro and in vivo. The suppressive function of UNC9994 was obtained by inducing intracellular reactive oxygen species generation through downregulating mitochondrial complex I subunit NDUFA1. The effects of Gαi/o signalling and Gβγ signalling via D₂ receptor on pituitary tumour growth were cell-type-dependent.

CONCLUSION AND IMPLICATIONS

Given the very low expression of Gαi/o proteins in pituitary tumours and the complexity of the responses of pituitary tumours to G protein signalling pathways, our study reveals D₂ receptor β-arrestin2-biased ligand may be a more promising choice to treat pituitary tumours with improved therapeutic selectivity.

Identification of an optimal prolactin threshold to determine prolactinoma size using receiver operating characteristic analysis

Prolactinomas represent the most common type of secretory pituitary neoplasms, with a therapeutic management that varies considerably based on tumour size and degree of hyperprolactinemia. The aim of the current study was to evaluate the relationship between serum prolactin (PRL) concentrations and prolactinoma size, and to determine a cut-off PRL value that could differentiate micro- from macro-prolactinomas. A retrospective cohort study of 114 patients diagnosed with prolactinomas between 2007 and 2017 was conducted. All patients underwent gadolinium enhanced pituitary MRI and receiver operating characteristic (ROC) analyses were performed. 51.8% of patients in this study were men, with a mean age at the time of diagnosis of 42.32 ± 15.04 years. 48.2% of the total cohort were found to have microadenomas. Baseline serum PRL concentrations were strongly correlated to tumour dimension (r = 0.750, p = 0.001). When performing the ROC curve analysis, the area under the curve was 0.976, indicating an excellent accuracy of the diagnostic method. For a value of 204 μg/L (4338 mU/L), sensitivity and specificity were calculated at 0.932 and 0.891, respectively. When a cut off value of 204 μg/L (4338 mU/L) was used, specificity was 93.2%, and sensitivity 89.1%, acceptable to reliably differentiate between micro- and macro- adenomas.

Resistance to Dopamine Agonists in Pituitary Tumors: Molecular Mechanisms

Pituitary neuroendocrine tumors (PitNET) are commonly benign tumors accounting for 10-25% of intracranial tumors. Prolactin-secreting adenomas represent the most predominant type of all PitNET and for this subtype of tumors, the medical therapy relies on the use of dopamine agonists (DAs). DAs yield an excellent therapeutic response in reducing tumor size and hormonal secretion targeting the dopamine receptor type 2 (D2DR) whose higher expression in prolactin-secreting adenomas compared to other PitNET is now well established. Moreover, although DAs therapy does not represent the first-line therapy for other PitNET, off-label use of DAs is considered in PitNET expressing D2DR. Nevertheless, DAs primary or secondary resistance, occurring in a subset of patients, may involve several molecular mechanisms, presently not fully elucidated. Dopamine receptors (DRs) expression is a prerequisite for a proper DA function in PitNET and several molecular events may negatively modify DR membrane expression, through the DRs down-regulation and intracellular trafficking, and DR signal transduction pathway. The current mini-review will summarise the presently known molecular events that underpin the unsuccessful therapy with DAs.

Multimodal Non-Surgical Treatments of Aggressive Pituitary Tumors

Up to 35% of aggressive pituitary tumors recur and significantly affect mortality and quality of life. Management can be challenging and often requires multimodal treatment. Current treatment options, including surgery, conventional medical therapies such as dopamine agonists, somatostatin receptor agonists and radiotherapy, often fail to inhibit pituitary tumor growth. Recently, anti-tumor effects of chemotherapeutic drugs such as Temozolomide, Capecitabine, and Everolimus, as well as peptide receptor radionuclide therapy on aggressive pituitary tumors have been increasingly investigated and yield mixed, although sometimes promising, outcomes. The purpose of this review is to provide thorough information on non-surgical medical therapies and their efficacies and used protocols for aggressive pituitary adenomas from pre-clinical level to clinical use.

Predictors of Chronic LH-Testosterone Axis Suppression in Male Macroprolactinomas With Normoprolactinemia on Cabergoline

CONTEXT

Data are limited regarding prevalence, predictors, and mechanisms of persistent hypogonadotropic hypogonadism (HH) in males with a macroprolactinoma who achieve normoprolactinemia on dopamine-agonist therapy. None of the previous studies provide cutoffs to predict the achievement of eugonadism.

OBJECTIVE

The objective of this work is to evaluate the prevalence of persistent HH and its determinants in men with a macroprolactinoma who achieve normoprolactinemia on cabergoline monotherapy.

DESIGN AND SETTING

This retrospective study with prospective cross-sectional evaluation took place at a tertiary health care center.

PATIENTS

Study participants included men with a macroprolactinoma and baseline HH who achieved normoprolactinemia on cabergoline monotherapy.

MAIN OUTCOME MEASURES

Outcome measures of this study included the prevalence of persistent HH and its predictors.

RESULTS

Thirty participants (age, 38.3 ± 10.1 years) with baseline tumor size of 4.08 ± 1.48 cm and median (interquartile range) prolactin of 2871 ng/mL (range, 1665-8425 ng/mL) were included. Eight of 30 participants achieved eugonadism after a median follow-up of 3 years. Patients with persistent HH had suppression of the luteinizing hormone (LH)-testosterone axis with sparing of other anterior pituitary hormonal axes, including follicle-stimulating hormone-inhibin B. Baseline prolactin (1674 vs 4120 ng/mL; P = .008) and maximal tumor diameter (2.55 ± 0.36 vs 4.64 ± 1.32 cm; P = .003) were lower in patients who achieved eugonadism. Baseline maximal tumor diameter less than or equal to 3.2 cm (sensitivity: 75%, specificity: 63.6%) and serum prolactin less than or equal to 2098 ng/mL (sensitivity: 87.5%, specificity: 77.3%) best predicted reversal of HH.

CONCLUSION

Recovery of the LH-testosterone axis occurred in 26.7% of men with a macroprolactinoma who achieved normoprolactinemia on cabergoline monotherapy. Higher baseline tumor size and serum prolactin predict persistent HH. Our data favor chronic functional modification of the hypothalamic-pituitary-gonadal axis over gonadotroph damage as the cause of persistent HH.

Hyperprolactinemia in clinical non-functional pituitary macroadenomas: A STROBE-compliant study

Hyperprolactinemia is a prevalent endocrine disorder presented in patients with non-functional pituitary adenomas (NFPAs). However, the mechanism involved in hyperprolactinemia in NFPA is not fully illustrated. The current study aims to investigate predictors for hyperprolactinemia in NFPA via analyzing relevant clinical features. Thus, in this study, a cohort of 214 cases with integrated medical records was retrospectively analyzed concerning clinical, pathological, and endocrinological studies before and after surgery.Hyperprolactinemia happened in 93 cases (43.5%). Women (adjust odds ratio [OR] = 3.093; P < .01), age of patients (adjust OR = 0.951; P < .01), and serum free tetraiodothyronine (FT4) level (adjust OR = 0.882; P = .02) were independent predictors for developing preoperative hyperprolactinemia. Tumor size and hypopituitarism had no impact on hyperprolactinemia. During a median follow-up of 43.5 (range, 22-80) months, 83.9% patients with preoperative hyperprolactinemia experienced prolactin (PRL) normalization. Preoperative PRL level (adjusted OR = 1.741, P = .03) was the exclusive predictor for PRL normalization after adjusting for tumor volume, preoperative serum FT4 concentration, and postoperative residual. The PRL normalization rate of patients with lower PRL level (<2.35-fold upper limit of normal range) was 95.2% and decreased to 65.5% for patients with higher PRL level.In conclusion, our results suggest existence of potentially alternative mechanisms underlying hyperprolactinemia in NFPAs, like the discrepancy of sex and age and the negative feedback of FT4. Preoperative PRL is a predictor for postoperative PRL normalization, which is of clinically relevant for postoperative management of NFPAs.

Autophagy and Pituitary Adenoma

Pituitary adenomas (PAs) are common, benign intracranial tumors that are usually effectively controlled with surgery, pharmacotherapy or radiotherapy. Some PAs against which conventional treatment is ineffective are great clinical challenges at present. Autophagy is a widespread physiological process in cells. Through autophagy, cells can degrade damaged or redundant proteins and organelles and achieve the recycling of intracellular substances to maintain the homeostasis of the intracellular environment. An increasing number of studies have demonstrated the importance of autophagy in tumor therapy. Both radiotherapy and chemotherapy can induce autophagy, which plays different roles in the course of therapy. In recent years, there has been growing interest in the role of autophagy during the treatment of PAs. This chapter reviews the recent progress of research on autophagy in PA and the autophagic mechanisms in the treatment of PA.

Inhibiting MAPK14 showed anti-prolactinoma effect

BACKGROUND

The specific underlying pathogenesis of prolactinoma has not been clarified yet, to the best of our knowledge. p38 mitogen-activated protein kinase (MAPK) signaling including p38α MAPK (MAPK14), p38β (MAPK11), p38γ (MAPK12) and p38δ (MAPK13) is associated with the development and progression of several types of cancer.

METHODS

Immunofluorescence analysis was performed on the prolactin (PRL) and MAPK14 expressions of pituitary gland in C57BL/6 mice and human prolactinoma specimen. In the present study, the role of MAPK14 in prolactinoma was determined using estradiol-induced mice and dopamine D2 receptor knockout (DRD2^-/-) mice models in C57BL/6 wild-type (WT), MAPK14^-/- and DRD2^-/-MAPK14^+/- mice. GH3 cells were transfected with different sets of MAPK14 small interfering RNA, which to study MAPK14 and PRL expression in GH3 cells.

RESULTS

Immunofluorescence analysis showed that PRL and MAPK14 expression were colocalized and increased in the pituitary gland of mice and human prolactinoma specimen compared with the control specimen. It was shown that PRL and MAPK14 expression was colocalized and increased significantly in the pituitary gland of estradiol-injected prolactinoma mice compared with the control mice. Knockout of MAPK14 significantly inhibited tumor overgrowth, and PRL expression was decreased in estradiol-induced mice. Furthermore, MAPK14 knockout of DRD2^-/-MAPK14^+/- mice significantly reduced the overgrowth of pituitary gland and PRL production and secretion compared with DRD2^-/- mice. MAPK14 knockout using siRNA inhibited PRL production in GH3 cells.

CONCLUSION

These results suggest that MAPK14 serves a promoting role in the formation of prolactinoma, and highlights the potential of MAPK14 as a potential therapeutic target in the treatment of prolactinoma.

The KBTBD6/7-DRD2 axis regulates pituitary adenoma sensitivity to dopamine agonist treatment

Pituitary adenoma (PA) is one of the most common intracranial tumors, and approximately 40% of all PAs are prolactinomas. Dopamine agonists (DAs), such as cabergoline (CAB), have been successfully used in the treatment of prolactinomas. The expression of dopamine type 2 receptor (DRD2) determines the therapeutic effect of DAs, but the molecular mechanisms of DRD2 regulation are not fully understood. In this study, we first demonstrated that DRD2 underwent proteasome-mediated degradation. We further employed the yeast two-hybrid system and identified kelch repeat and BTB (POZ) domain containing 7 (KBTBD7), a substrate adaptor for the CUL3-RING ubiquitin (Ub) ligase complex, as a DRD2-interacting protein. KBTBD6/7 directly interacted with, and ubiquitinated DRD2 at five ubiquitination sites (K221, K226, K241, K251, and K258). CAB, a high-affinity DRD2 agonist, induced DRD2 internalization, and cytoplasmic DRD2 was degraded via ubiquitination under the control of KBTBD6/7, the activity of which attenuated CAB-mediated inhibition of the AKT/mTOR pathway. KBTBD7 knockout (KO) mice were generated using the CRISPR-Cas9 technique, in which the static level of DRD2 protein was elevated in the pituitary gland, thalamus, and heart, compared to that of WT mice. Consistently, the expression of KBTBD6/7 was negatively correlated with that of DRD2 in human pituitary tumors. Moreover, KBTBD7 was highly expressed in dopamine-resistant prolactinomas, but at low levels in dopamine-sensitive prolactinomas. Knockdown of KBTBD6/7 sensitized MMQ cells and primary pituitary tumor cells to CAB treatment. Conversely, KBTBD7 overexpression increased CAB resistance of estrogen-induced in situ rat prolactinoma model. Together, our findings have uncovered the novel mechanism of DRD2 protein degradation and shown that the KBTBD6/7-DRD2 axis regulates PA sensitivity to DA treatment. KBTBD6/7 may thus become a promising therapeutic target for pituitary tumors.

Artesunate exerts anti-prolactinoma activity by inhibiting mitochondrial metabolism and inducing apoptosis

BACKGROUND

Prolactinoma is the most common hormone-secreting pituitary adenoma. Dopamine receptor agonists (DAs) are effective in reducing prolactin levels and tumor mass, but some prolactinoma patients are resistant to DAs. Treating patients with DA-resistant prolactinoma is challenging. In this study, we examined the anti-prolactinoma effect of artesunate (ART), a potential new treatment option for prolactinoma, and its mechanism of action.

METHODS

Cell Counting Kit-8 (CCK8) and flow cytometry were used to detect the effect of ART on the proliferation, cycle, and apoptosis of rat pituitary adenoma cell line MMQ. The subcellular localization of ART was observed using confocal fluorescence microscopy. The JC-1 mitochondrial membrane potential (MMP) detection and Seahorse assays were used to detect the effect of ART on mitochondrial function. Real-time quantitative polymerase chain reaction (RT-qPCR) and Western blot analysis were used to detect the effect of ART on the expression of prolactin (PRL) and apoptosis-related proteins. A mouse xenograft model of prolactinoma was used to detect the inhibitory effect of ART on MMQ in vivo.

RESULTS

ART specifically inhibited MMQ proliferation and PRL synthesis, induced G0/G1 phase arrest and apoptosis in vitro. ART accumulated in the mitochondria of MMQ cells, inhibiting mitochondrial respiratory function and mediating apoptosis through the mitochondrial pathway. ART also inhibited proliferation and activated the apoptosis of MMQ cells in vivo.

CONCLUSIONS

ART has a strong inhibitory effect on prolactinoma both in vitro and in vivo, and its effects rely on high MMP to inhibit mitochondrial metabolism and induce apoptosis. Our results provide evidence for ART as a candidate drug for the treatment of prolactinoma.

Decrease of Proliferative Potential and Vascular Density of Giant Prolactinoma in Patients Treated with Cabergoline

Introduction:

Currently, cabergoline therapy is the main treatment for prolactinomas. The use of the drug in most cases leads to regression of the tumor, normalization of prolactin (PRL) levels, and restoration of gonadotropic function. The mechanism of its action in tumor cells “in vivo” tracked in dynamics in the same human tumor is of considerable interest.

Materials and Methods:

A 30-year-old male was admitted to N.N. Burdenko National Medical Research Center of Neurosurgery. An magnetic resonance imaging (MRI) revealed a giant pituitary adenoma. The level of PRL was more than 5000 mU/l (30-360) (serum dilution was not used to determine PRL). Transcranial microsurgical removal of the tumor was performed. He was treated by cabergoline after surgery. Endoscopic transsphenoidal approach was repeated with subtotal removal of the rest of the tumor. Morphological and immunohistochemical studies of the tumor were done.

Results:

A morphological study revealed PRL-positive tumor with a Ki-67 LI of 8% with a distinctive expression of D2R, CD31, and CD34 markers. Control MRI in 3 months after surgery revealed remnants of a tumor of endoinfrasellar localization, the tumor remainders were found in endoinfrasellar localization. The tumor retained pronounced immunopositivity to PRL and D2R and a decrease in the Ki-67 to 2% and in the expression of CD31 and CD34. Subsequent therapy with cabergoline resulted in persistent normoprolactinemia, restoration of androgenic function, and absence of tumor recurrence during the 10-year follow-up period.

Conclusions:

Cabergoline is an effective treatment for prolactinoma, which leads to tumor regression. One of its mechanisms is the reduction of the proliferative index and tumor angiogenesis.

Evolution of macroprolactinomas during pregnancy: A cohort study of 85 pregnancies

OBJECTIVE

Pregnancy in patients with macroprolactinomas has been associated with a higher risk of pituitary tumour growth. However, the incidence and risk factors remain unclear. We aimed to evaluate the evolution of macroprolactinomas during pregnancy and to identify potential risk factors.

DESIGN, PATIENTS AND MEASUREMENTS

This is a two-centre, retrospective, observational study. All patients with macroprolactinomas, treated with a dopamine receptor agonist (DA), and who had at least one pregnancy were included.

RESULTS

There were a total of 85 viable pregnancies in 46 patients with macroprolactinomas. At diagnosis, mean size of pituitary adenomas was 17.9 ± 8.2 mm (10-43 mm) and mean plasma prolactin level was 1012.2 ± 1606.1 µg/L (60-7804 µg/L). Tumour growth-related symptoms were identified 12 times in 9 patients (19.6%) including 3 cases of apoplexy. Restarting, changing and/or increasing DA treatment was effective in 10 cases. Emergency surgery had to be performed twice (due to pituitary apoplexy). Patients with tumour progression tended to present with larger tumours after initial treatment and before pregnancy (9.9 vs 5.9 mm; P = .0504 and 11.5 vs 7.3 mm; P = .0671, respectively), whereas adenoma size at diagnosis did not seem to be a significant factor. The obstetrical outcomes were comparable to the general population.

CONCLUSIONS

Symptomatic growth of macroprolactinoma during pregnancy occurred in 19.6% of medically treated patients. This risk seems higher for patients with poor initial tumour response to the DA treatment. Tumour progression is generally well controlled with medical treatment during pregnancy.

Endoscopic Transsphenoidal Surgery of Microprolactinomas: A Reappraisal of Cure Rate Based on Radiological Criteria

BACKGROUND

Current standard treatment of microprolactinomas is dopamine agonist therapy. As this drug treatment is lifelong in up to 80% of cases, many patients consult pituitary surgeons regarding a surgical alternative.

OBJECTIVE

To identify prognostic criteria for surgical remission, we reviewed outcomes of our series of microprolactinomas treated with endoscopic transsphenoidal surgery, with a special emphasis on magnetic resonance adenoma delineation and position.

METHODS

Our study cohort comprises a single center series of 60 patients operated for histopathologically verified magnetic resonance imaging unequivocally identifiable endosellar microprolactinoma between 2003 and 2017. In 31 patients the adenoma was enclosed by pituitary gland (group ENC), in 29 patients the adenoma was located lateral to the gland adherent to the medial cavernous sinus wall (group LAT).

RESULTS

After a mean follow-up of 37 mo (range 4-143 mo), remission rate was significantly higher in adenomas enclosed by pituitary gland (group ENC) than adenomas located lateral to the gland (group LAT), with 87% vs 45%, P = .01. Intraoperatively, 4 patients showed signs of invasiveness. Preoperative prolactin levels did not differ between the groups (mean 155 and 187 ng/ml in group ENC and LAT, respectively).A binary logistic regression model revealed that only the radiological criteria applied showed a significant correlation (P = .003) with endocrine remission.

CONCLUSION

According to our results, remission rate is significantly higher in microprolactinomas enclosed by the pituitary gland. However, the decision for surgery should take into account surgeons experience and possibility of complications.

Treatment of Pituitary and Other Tumours with Cabergoline: New Mechanisms and Potential Broader Applications

Cabergoline is a dopamine agonist that has been used as the first-line treatment option for prolactin-secreting pituitary adenomas for several decades. It not only suppresses hormone production from these prolactinomas, but also causes tumour shrinkage. Recent studies revealed some novel mechanisms by which cabergoline suppresses tumour cell proliferation and induces cell death. In this article, we review the most recent findings in cabergoline studies, focusing on its anti-tumour function. These studies suggest the potential broader clinical use of cabergoline in the treatment of other tumours such as breast cancer, pancreatic neuroendocrine tumours, and lung cancer.

Statins Directly Regulate Pituitary Cell Function and Exert Antitumor Effects in Pituitary Tumors

INTRODUCTION

Pituitary neuroendocrine tumors (PitNETs), the most abundant of all intracranial tumors, entail severe comorbidities. First-line therapy is transsphenoidal surgery, but subsequent pharmacological therapy is often required. Unfortunately, many patients are/become unresponsive to available drugs (somatostatin analogues [SSAs]/dopamine agonists), underscoring the need for new therapies. Statins are well-known drugs commonly prescribed to treat hyperlipidemia/cardiovascular diseases, but can convey additional beneficial effects, including antitumor actions. The direct effects of statins on normal human pituitary or PitNETs are poorly known. Thus, we aimed to explore the direct effects of statins, especially simvastatin, on key functional parameters in normal and tumoral pituitary cells, and to evaluate the combined effects of simvastatin with metformin (MF) or SSAs.

METHODS

Effects of statins in cell proliferation/viability, hormone secretion, and signaling pathways were evaluated in normal pituitary cells from a primate model (Papio anubis), tumor cells from corticotropinomas, somatotropinomas, nonfunctioning pituitary tumors, and PitNET cell-lines (AtT20/GH3-cells).

RESULTS

All statins decreased AtT20-cell proliferation, simvastatin showing stronger effects. Indeed, simvastatin reduced cell viability and/or hormone secretion in all PitNETs subtypes and cell-lines, and ACTH/GH/PRL/FSH/LH secretion (but not expression), in primate cell cultures, by modulating MAPK/PI3K/mTOR pathways and expression of key receptors (GH-releasing hormone-receptor/ghrelin-R/Kiss1-R) regulating pituitary function. Addition of MF or SSAs did not enhance simvastatin antitumor effects.

CONCLUSION

Our data reveal direct antitumor effects of simvastatin on PitNET-cells, paving the way to explore these compounds as a possible tool to treat PitNETs.

MiR-137's Tumor Suppression on Prolactinomas by Targeting MITF and Modulating Wnt Signaling Pathway

CONTEXT

Prolactinomas are the most common functional pituitary adenomas; the aggressive tumors still present challenge to clinicians. Aberrant expression of miRNAs has been functionally associated with prolactinomas.

OBJECTIVE

Here we explored the role of miR-137 on the proliferation, invasion, and apoptosis of prolactinomas and its possible mechanism.

RESULTS

Low expression of miR-137 was correlated with the invasive behavior of human prolactinomas and predicted high recurrence. MiR-137 inhibited cell proliferation, invasion, and survivals of MMQ and GH3 cells and reduced tumor volume in F344 rat prolactinomas. The luciferase reporter assay confirmed that microphthalmia-associated transcription factor (MITF) was the direct target of miR-137. In addition, miR-137 mimics could inhibit MITF expression in vivo and in vitro. Upregulation of MITF expression promoted cell proliferation, invasion, and survivals and reversed the antitumor effect of miR-137 in vivo and in vitro. Furthermore, miR-137 could also upregulate wnt-inhibitory factor-1 and inhibit nuclear translocation of β-catenin. Upregulation of wnt-inhibitory factor-1 with decitabine can enhance the inhibition on cell proliferation of miR-137. A glycogen synthase kinase-3 inhibitor, SB 216763, promoted cell proliferation by upregulation of total/cytoplasmic/nuclear β-catenin and reversed tumor suppression of miR-137 mimics.

CONCLUSIONS

Our data suggest that miR-137 possesses a tumor invasive suppressor function with a prognostic value in prolactinomas by targeting MITF and modulating Wnt-β-catenin signaling pathway.

Exosome-Transmitted lncRNA H19 Inhibits the Growth of Pituitary Adenoma

CONTEXT

Our previous study demonstrated that the expression of long noncoding RNA (lncRNA) H19 was frequently downregulated in human primary pituitary adenomas and negatively correlated with tumor progression. However, the role of exosomal lncRNA H19 in the inhibition of pituitary tumor growth remains unclear.

OBJECTIVE

To investigate whether exosomal H19 could be transported across the cell membrane to exert its inhibitory effect on pituitary tumor growth.

DESIGN

Empty lentivirus GH3 cells with or without H19 overexpression were used to establish a xenograft model. Isolated exosomes were identified by transmission electron microscopy, nanoparticle tracking, and Western blotting. The expression levels of serum exosomal H19 from 200 healthy subjects and 206 patients with various subtypes of pituitary tumors were detected by ultracentrifugation and quantitative real-time PCR.

RESULTS

The growth of distal tumor cells was inhibited by transferring exosomal H19, which could be transported through cell membrane and exert its inhibitory effect. Cabergoline increased H19 expression and played a synergic therapeutic effect with exosomal H19. Exosomal H19 inhibited phosphorylation of the mTORC1 substrate 4E-BP1. Of note, the expression level of exosomal H19 in the patients with all subtypes of pituitary tumors was significantly lower than that in the healthy subjects. The change of plasma exosomal H19 level may be correlated with the prognosis or drug response of the patients.

CONCLUSION

Exosomal H19 inhibits the growth of distal pituitary tumors through inhibiting 4E-BP1 phosphorylation. Plasma exosomal H19 may serve as an important biomarker for predicting medical responses of patients with prolactinomas.

Identification of chlorprothixene as a potential drug that induces apoptosis and autophagic cell death in acute myeloid leukemia cells

Although acute myeloid leukemia (AML) is a highly heterogeneous malignance, the common molecular mechanisms shared by different AML subtypes play critical roles in AML development. It is possible to identify new drugs that are effective for various AML subtypes based on the common molecular mechanisms. Therefore, we developed a hypothesis-driven bioinformatic drug screening framework by integrating multiple omics data. In this study, we identified that chlorprothixene, a dopamine receptor antagonist, could effectively inhibit growth of AML cells from different subtypes. RNA-seq analysis suggested that chlorprothixene perturbed a series of crucial biological processes such as cell cycle, apoptosis, and autophagy in AML cells. Further investigations indicated that chlorprothixene could induce both apoptosis and autophagy in AML cells, and apoptosis and autophagy could act as partners to induce cell death cooperatively. Remarkably, chlorprothixene was found to inhibit tumor growth and induce in situ leukemic cell apoptosis in the murine xenograft model. Furthermore, chlorprothixene treatment could reduce the level of oncofusion proteins PML-RARα and AML1-ETO, thus elevate the expression of apoptosis-related genes, and lead to AML cell death. Our results provided new insights for drug repositioning of AML therapy and confirmed that chlorprothixene might be a potential candidate for treatment of different subtypes of AML by reducing expression of oncofusion proteins. DATABASE: RNA-seq data are available in GEO database under the accession number GSE124316.

Ubenimex induces apoptotic and autophagic cell death in rat GH3 and MMQ cells through the ROS/ERK pathway

Purpose

Ubenimex, an aminopeptidase N (APN) inhibitor, is widely known for its use as an adjunct therapy for cancer therapy. However, in recent studies, it has also conferred antitumour effects in many cancers, but its anticancer mechanism is largely unknown. This study aims to investigate the specific anticancer activities and mechanisms of ubenimex in GH3 and MMQ cells.

Materials and methods

In this study, we investigated the anticancer effects of ubenimex in GH3 and MMQ cells. Cell viability and cell death were assessed by the Cell Counting Kit-8 kit (CCK-8) and a LIVE/DEAD cell imaging kit. Apoptosis and intracellular reactive oxygen species (ROS) generation were assessed by flow cytometry and fluorescence microscopy. Autophagosome formation was detected by transmission electron microscopy, and autophagic flux was measured with mRFP-GFP-LC3 adenoviral transfection. The protein expression level was detected by Western blotting.

Results

The results revealed that treatment with ubenimex induced apoptotic and autophagic cell death in GH3 and MMQ cells, which resulted in decreased viability, an increased proportion of apoptotic cells, and autophagosome formation. Further experiments showed that ubenimex induced ROS generation and activated the ROS/ERK pathway. The ROS scavenger NAC could attenuate ubenimex-induced apoptosis and autophagy.

Conclusion

Our studies revealed that ubenimex exerted anticancer effects by inducing apoptotic and autophagic cell death in GH3 and MMQ cells, rendering it a possible effective adjunctive therapy for pituitary treatment.

Chemometric Expertise Of Clinical Monitoring Data Of Prolactinoma Patients

The present investigation indicates hidden relationships between the several clinical parameters usually monitored on prolactinoma patients using non-hierarchical cluster analysis. The major goal of the chemometric data mining is to offer a possible mode of optimization of the monitoring procedure by selecting a reduced number of health status indicators. The intelligent data analysis reveals the formation of three patterns of prolactinoma patients each one of them described by a set of clinical parameters. Thus, better strategies for considering patients with this diagnosis could be developed and clinically applied.

Clinical management of difficult to treat macroprolactinomas

INTRODUCTION

Prolactinomas represent the most common pituitary adenomas encountered in the clinic. While a majority of these tumors will be successfully treated by dopamine agonist (DA) such as cabergoline, their management becomes problematic since a resistance to DA can occur and/or if the tumor displays features of aggressiveness, two conditions that are closely related.

AREAS COVERED

Epidemiology and medical treatment of prolactinomas; resistance to DA and molecular basis of DA-resistance; therapeutical alternatives in case of DA-resistant Prolactinomas and therapies in development; summarizing conclusions.

EXPERT OPINION

The management of DA-resistant prolactinomas requires a multidisciplinary approach by an expert team. Along with discussions about surgery with or without gamma knife radiosurgery, genetic screening for multiple endocrine neoplasia type 1 (MEN1) syndrome is actively discussed in a case-by-case approach. In case of surgery, a careful analysis of the tumor sample can provide information about its aggressivity potential according to recent criteria. Ultimately, temozolomide can be indicated if the tumor is rapidly growing and/or threatening for the patient.

Bromocriptine and cabergoline induce cell death in prolactinoma cells via the ERK/EGR1 and AKT/mTOR pathway respectively

The treatment of hyperprolactinemia is based on the use of dopamine agonists, mainly bromocriptine (BRC) and cabergoline (CAB). They reduce tumour size effectively and restore gonadal function. However, there is a difference in drug sensitivity between CAB and BRC in patients with prolactinoma, although the underlying mechanisms are still unknown. Thus, we investigated whether there are differences in tumour sensitivity to CAB and BRC and their possible differential mechanisms in two prolactinoma cell lines. In our study, we found that GH3 cells are more sensitive to BRC and that MMQ cells are more sensitive to CAB. Moreover, BRC and CAB elicited cell death via different pathways; BRC induced prolactinoma cell death mainly through the apoptosis pathway, and CAB induced pituitary prolactinoma cell death mainly via the autophagic cell death pathway. Using gene microarray analysis, we found that BRC induces the apoptosis of prolactinoma cells through the ERK/EGR1 signalling pathway, whereas CAB induces autophagic death by inhibiting the AKT/mTOR signalling pathway. Our study showed the difference in tumour sensitivity and differential mechanisms in BRC- and CAB-treated prolactinoma cells, which provides a theoretical basis for the accurate treatment of prolactinoma.

Calcified Prolactinoma of the Pituitary Gland: Illustrative Case Reports Highlighting Medical versus Surgical Intervention

The presence of calcification is uncommon in pituitary adenomas, and often lends support to other diagnoses including craniopharyngioma. The majority of calcified pituitary adenomas are prolactin-secreting tumors. We report two patients with calcified macroprolactinomas, one that was treated medically with a biochemical response and partial tumor response, and one that was treated successfully via an endoscopic endonasal transsphenoidal approach. Suspected calcified prolactinomas can be initially managed medically as per standard treatment for typical prolactinomas; however, the presence of diffuse calcification may hinder tumor shrinkage. Tumors that are refractory to medical treatment can be safely managed with surgery.

Epidemiology and Management Challenges in Prolactinomas

Clinically relevant pituitary adenomas are present in about 1 per 1,000 of the general population and prolactinomas are by far the most common clinical subtype of pituitary adenomas. Usually prolactinomas affect premenopausal women and present with typical symptoms of menstrual disturbance and/or galactorrhea. They are generally managed with dopamine agonists to restore fertility and to control symptoms and tumor size. In a subset of prolactinomas, however, management remains challenging. Studies in recent years have identified the factors related to dopamine agonist resistance, such as male sex, genetic features, and aggressive tumor behavior. Certain other patient groups represent particular challenges for management, such as pediatric patients and pregnant women. Treatment with dopamine agonists is usually safe and effective, and adverse effects such as clinically relevant cardiac valvular complications and impulse control disorders may occur in isolated instances. A number of important disease characteristics of prolactinomas remain to be explained, such as the difference in sex prevalence before and after menopause, the higher prevalence of macroadenomas in older males, and the biochemical mechanisms of resistance to dopaminergic agonists.

Cabergoline for the treatment of bromocriptine-resistant invasive giant prolactinomas

PURPOSE

Few studies have specifically focused on the effect of cabergoline on invasive giant prolactinomas (IGPs) resistant to bromocriptine. This study aims to evaluate whether cabergoline could be used as an effective therapy for patients with bromocriptine-resistant IGPs.

METHODS

This retrospective study included 15 patients with bromocriptine-resistant IGPs who received treatment at our department during 2007-2015. Cabergoline was administered in all 15 patients, with the dose adjusted depending on the prolactin response of each patient. Parameters for outcome assessment included prolactin level, pituitary function, tumor size, improvement of the clinical symptoms, visual field defects, drug tolerance, and disease recurrence.

RESULTS

Cabergoline was effective for the treatment of the patients with bromocriptine -resistant IGPs as represented by normalization of the prolactin level in 12/15 patients; improvement or normalization of the pituitary function in 4/5 patients with hypopituitarism; significant reduction in tumor size in 14/15 patients; and relief of the clinical symptoms in 11/15 patients. All 15 patients showed good tolerance to cabergoline. In addition, no recurrence was observed during the mean follow-up period of 63.47 (range 30-145) months.

CONCLUSIONS

Data of this retrospective study demonstrate that cabergoline is an excellent option for the treatment of patients with bromocriptine-resistant IGPs.

Is receptor profiling useful for predicting pituitary therapy?

Medical treatment of pituitary tumours may present important challenges in the presence of resistance to first line therapy. In this setting, the availability of specific markers of responsiveness/resistance could be helpful to provide tailored patients' treatment. Pituitary receptor profiling has emerged as a potentially useful tool for predicting the response to specific pituitary-directed medical therapy, mainly somatostatin analogues and dopamine agonists. However, its utility is not always straightforward. In fact, agonist-receptor coupling to the consequent biological response is complex and sometimes jeopardizes the understanding of the molecular basis of pharmacological resistance. Defective expression of pituitary receptors, genetic alterations, truncated variants, impaired signal transduction or involvement of other proteins, such as cytoskeleton proteins or the Aryl hydrocarbon receptor interacting protein amongst others, have been linked to differential tumour phenotype or treatment responsiveness with conflicting results, keeping the debate on the utility of pituitary receptor profiling open. Why does this occur? How can we overcome the difficulties? Is there a true role for pituitary receptor profiling in the near future? All authors of this debate article agree on the need of prospective studies using standardized methods in order to assess the efficacy of receptor profiling as a reliable clinical predictive factor.