[Acidophil stem cell pituitary neuroendocrine tumors/adenoma: a clinicopathological analysis of five cases]

Objective: To investigate the clinicopathological characteristics of acidophil stem cell pituitary neuroendocrine tumors (PitNET)/adenoma. Methods: Five cases of acidophil stem cell PitNET/adenoma were diagnosed between May 2022 and July 2023 at the Second Hospital of Hebei Medical University, Shijiazhuang, China. The clinicopathological features of the tumor were analyzed by using histology, immunohistochemistry, and electron microscopy. The relevant literature was reviewed. Results: There were 1 male and 4 females, aged from 23 to 69 years. Patient 3 was 55 years old at the time of diagnosis and first surgery, and relapsed 5 years later. The patients' median age was 32 years. Patients 1 and 5 showed elevated blood prolactin, with various degrees of hormonal symptoms except Patient 3, who showed only tumor compression symptoms. Imaging studies showed that all cases involved the sellar floor. The tumors of Patients 1, 2 and 5 were closely related to the cavernous sinus segment of the internal carotid artery. The tumors exhibited a diffuse growth pattern with chromophobic to slightly acidophilic cytoplasm. A few of tumor cells showed chromophobic cytoplasm. The nucleoli were conspicuous. Intranuclear inclusion bodies and variably-sized clear vacuoles were observed occasionally. Under electron microscope, marked mitochondrial abnormalities were observed, including increased mitochondria number, expanded hypertrophy, and absence of mitochondrial ridge fracture. Some mitochondrial matrices were dense, while some were vacuolated. Conclusions: Acidophil stem cell PitNET/adenoma is a rare type of pituitary adenomas/PitNETs. It often has a more clinically aggressive manner with immature cells, diffuse expression of PIT1, prolactin, and varying degrees of growth hormone expression. Because of the obvious diversity of their clinical hormone status and hormone immune expression, the diagnosis of this type tumor is still a challenge.

The improvement of postoperative blood pressure and associated factors in patients with hormone-negative adrenal adenoma and hypertension

OBJECTIVE

To investigate the effect of adrenal surgery on blood pressure (BP) improvements in patients with hormone-negative adrenal adenoma (HNA) concomitant with hypertension and analyze associated prognostic factors.

METHODS

We retrospectively reviewed the clinical data of patients with HNA and hypertension and patients with aldosterone-producing adenoma (APA) and hypertension who underwent adrenal surgery at our center between 2019 and 2022. Hypertension outcomes were evaluated in all patients and subjects were divided into three groups according to follow-up BP and the administration of anti-hypertensive agents: a clinical curation group, an improvement group, and a no-improvement group. Logistic regression analysis was performed to predict factors associated with clinical curation in patients with HNA post-surgery.

RESULTS

Of the 182 patients with HNA, clinical curation was achieved in 58 patients (31.9%), improvement in 72 (39.5%), and no improvement in 52 (28.6%). The clinical curation, improvement and no improvement rates in patients with APA were 64.8% (n = 118), 15.9% (n = 29), and 19.2% (n = 35). Multivariate logistic regression analysis indicated that a duration of hypertension ≤6 years and a plasma aldosterone level >160 pg/ml were both independent factors for the clinical curation of hypertension in patients with HNA after adrenal surgery.

CONCLUSION

Adrenal surgery can cure or improve hypertension in most patients with HNA, especially in a short duration of hypertension and high plasma levels of aldosterone.

Multiple-matrix metabolomics analysis for the distinct detection of colorectal cancer and adenoma

OBJECTIVES

Although colorectal cancer (CRC) is the leading cause of cancer-related morbidity and mortality, current diagnostic tests for early-stage CRC and colorectal adenoma (CRA) are suboptimal. Therefore, there is an urgent need to explore less invasive screening procedures for CRC and CRA diagnosis.

METHODS

Untargeted gas chromatography-mass spectrometry (GC-MS) metabolic profiling approach was applied to identify candidate metabolites. We performed metabolomics profiling on plasma samples from 412 subjects including 200 CRC patients, 160 CRA patients and 52 normal controls (NC). Among these patients, 45 CRC patients, 152 CRA patients and 50 normal controls had their fecal samples tested simultaneously.

RESULTS

Differential metabolites were screened in the adenoma-carcinoma sequence. Three diagnostic models were further developed to identify cancer group, cancer stage, and cancer microsatellite status using those significant metabolites. The three-metabolite-only classifiers used to distinguish the cancer group always keeps the area under the receiver operating characteristic curve (AUC) greater than 0.7. The AUC performance of the classifiers applied to discriminate CRC stage is generally greater than 0.8, and the classifiers used to distinguish microsatellite status of CRC is greater than 0.9.

CONCLUSION

This finding highlights potential early-driver metabolites in CRA and early-stage CRC. We also find potential metabolic markers for discriminating the microsatellite state of CRC. Our study and diagnostic model have potential applications for non-invasive CRC and CRA detection.

Double somatic mutations in CTNNB1 and GNA11 in an aldosterone-producing adenoma

Double somatic mutations in CTNNB1 and GNA11/Q have recently been identified in a small subset of aldosterone-producing adenomas (APAs). As a possible pathogenesis of APA due to these mutations, an association with pregnancy, menopause, or puberty has been proposed. However, because of its rarity, characteristics of APA with these mutations have not been well characterized. A 46-year-old Japanese woman presented with hypertension and hypokalemia. She had two pregnancies in the past but had no history of pregnancy-induced hypertension. She had regular menstrual cycle at presentation and was diagnosed as having primary aldosteronism after endocrinologic examinations. Computed tomography revealed a 2 cm right adrenal mass. Adrenal venous sampling demonstrated excess aldosterone production from the right adrenal gland. She underwent right laparoscopic adrenalectomy. The resected right adrenal tumor was histologically diagnosed as adrenocortical adenoma and subsequent immunohistochemistry (IHC) revealed diffuse immunoreactivity of aldosterone synthase (CYP11B2) and visinin like 1, a marker of the zona glomerulosa (ZG), whereas 11β-hydroxylase, a steroidogenic enzyme for cortisol biosynthesis, was mostly negative. CYP11B2 IHC-guided targeted next-generation sequencing identified somatic CTNNB1 (p.D32Y) and GNA11 (p.Q209H) mutations. Immunofluorescence staining of the tumor also revealed the presence of activated β-catenin, consistent with features of the normal ZG. The expression patterns of steroidogenic enzymes and related proteins indicated ZG features of the tumor cells. PA was clinically and biochemically cured after surgery. In conclusion, our study indicated that CTNNB1 and GNA11-mutated APA has characteristics of the ZG. The disease could occur in adults with no clear association with pregnancy or menopause.

Expression of Periostin in Benign Salivary Gland Tumors

Parotid tumors present a wide range of histological features, from benign to malignant. Periostin, an extracellular matrix protein specifically expressed in the periosteum and periodontal ligament, is isolated from osteoblast cell lines. It regulates fibrosis and collagen deposition and plays an important role in myocardial repair after myocardial infarction. It is also known to be involved in otorhinolaryngological-diseases. This study included 36 patients [38 specimens; 16 men and 20 women, mean age 59.2 (range 26-82) years] who underwent parotid tumor resection at the Division of Otorhinolaryngology, Tohoku Medical and Pharmaceutical University, between April 2017 and March 2022 and were clinically and pathologically diagnosed as having benign parotid tumors. Formalin-fixed, paraffin-embedded sections from the surgical specimens were autoclaved and immunostained with anti-periostin antibodies to evaluate the expression and distribution of periostin. Histologically, the tumors were diagnosed as pleomorphic adenomas in 15 cases (15 specimens), Warthin's tumors in 13 cases (15 specimens), basal cell adenomas in 2 cases (2 specimens), oncocytomas in 4 cases (4 specimens), and myoepitheliomas in 2 cases (2 specimens). An increased expression of periostin was found in 32 of 38 samples (84.2%) in the stroma of benign parotid tumors. Four distinct patterns of periostin expression were observed in benign parotid gland tumors: negative, superficial, infiltrative, and diffuse. Statistically significant differences were found between periostin expression patterns and histological classification of the tumors. Our results suggest that periostin may be involved in the pathogenesis of benign parotid tumors and could serve as a new biomarker for these tumors.

The Impact of Cancer-Associated Fibroblasts on the Biology and Progression of Colorectal Carcinomas

(1) Colorectal cancer (CRC) is a leading cause of cancer-related deaths globally. Cancer-associated fibroblasts (CAFs) are major components of CRC's tumour microenvironment (TME), but their biological background and interplay with the TME remain poorly understood. This study investigates CAF biology and its impact on CRC progression. (2) The cohort comprises 155 cases, including CRC, with diverse localizations, adenomas, inflammations, and controls. Digital gene expression analysis examines genes associated with signalling pathways (MAPK, PI3K/Akt, TGF-β, WNT, p53), while next-generation sequencing (NGS) determines CRC mutational profiles. Immunohistochemical FAP scoring assesses CAF density and activity. (3) FAP expression is found in 81 of 150 samples, prevalent in CRC (98.4%), adenomas (27.5%), and inflammatory disease (38.9%). Several key genes show significant associations with FAP-positive fibroblasts. Gene set enrichment analysis (GSEA) highlights PI3K and MAPK pathway enrichment alongside the activation of immune response pathways like natural killer (NK)-cell-mediated cytotoxicity via CAFs. (4) The findings suggest an interplay between CAFs and cancer cells, influencing growth, invasiveness, angiogenesis, and immunogenicity. Notably, TGF-β, CDKs, and the Wnt pathway are affected. In conclusion, CAFs play a significant role in CRC and impact the TME throughout development.

Analysis of Diffusion-Weighted and T2-Weighted Imaging in the Prediction of Distinct Granulation Patterns of Somatotroph Adenomas

OBJECTIVE

The heterogeneity of the somatotroph adenomas, especially for sparsely granulated (SG) and densely granulated (DG) subtypes, has attracted great attention in identifying their imaging biomarker. The purpose of the current study was to compare the diagnostic performance of diffusion-weighted and T2-weighted magnetic resonance imaging (MRI) sequences for preoperatively distinguishing the granulation patterns of somatotroph adenomas.

METHODS

Thirty-two patients with a clinical diagnosis of somatotroph adenomas from October 2018 to March 2023 were included in this study. Coronal diffusion-weighted imaging (DWI) and T2-weighted MRI sequence data were collected from 3.0T MRI and compared between SG and DG groups. The immunohistochemistry was used to confirm the electron microscopy pathologic subtypes and Ki67 expression levels of somatotroph adenomas postoperatively.

RESULTS

Patients in the SG group had significantly higher signal intensity (SI) ratio of DWI (rDWI) (P < 0.001), lower SI ratio of apparent diffusion coefficient (rADC) (P < 0.001), and higher SI ratio of T2-weighted imaging (P = 0.011). The combined diagnosis index of rDWI and rADC had the highest diagnostic efficiency in predicting SG adenomas (sensitivity, 93.3%; specificity, 88.2%; P < 0.001). The rDWI and rADC values had positive and negative correlations with the Ki67 index and tumor maximum diameter, respectively. Lower rADC×103 was an independent predictor for SG adenomas.

CONCLUSIONS

Our results indicated that compared with previously used T2-weighted imaging, the DWI sequence, especially the combined diagnosis index of rDWI and rADC, could more efficiently distinguish the granulation patterns of somatotroph adenomas preoperatively.

Increased circulating regulatory T cells and decreased follicular T helper cells are associated with colorectal carcinogenesis

Objective

Colorectal cancer (CRC) is the third most prevalent cancer worldwide and is associated with high morbidity and mortality rates. Colorectal carcinogenesis occurs via the conventional adenoma-to-carcinoma and serrated pathways. Conventional T helper (Th) and innate lymphoid cells (ILCs) play vital roles in maintaining intestinal homeostasis. However, the contribution of these two major lymphoid cell populations and their associated cytokines to CRC development is unclear. Therefore, we aimed to analyze peripheral lymphocyte profiles during colorectal carcinogenesis.

Methods

We collected 86 blood samples concurrently, and pathologists confirmed the presence of various pathological conditions (i.e., HPs, adenoma, and carcinoma) using hematoxylin and eosin staining. Ten healthy donors were recruited as healthy controls (HCs) from the physical examination center. We performed flow cytometry on peripheral blood mononuclear cells collected from patients with various pathological conditions and the HCs, and cytokines (interleukin-2, interleukin-4, interleukin-5, interleukin-13, interleukin-17A, interleukin-17F, interleukin-22, interferon-γ, and tumor necrosis factor-α) were quantified. We also analyzed the published single-cell RNA sequence data derived from tissue samples from different stages of colorectal carcinogenesis.

Results

The cytokine response in peripheral CD4+ T cells was upregulated during the carcinoma process. The frequency of peripheral regulatory T cells (Tregs) increased in the adenoma and carcinoma stages. While the T follicular helper (Tfh) cell proportion was downregulated in the adenoma and carcinoma processes. Thus, Th cell subsets, especially Tregs and Tfh cells, were involved in colonic diseases. Moreover, the immunological profile characteristics in the HPs were clarified.

Conclusion

We comprehensively analyzed circulating ILCs and adaptive T-cell lymphocyte subtypes in colorectal carcinoma progression. Our results show the immunological profile characteristics and support the involvement of Th subsets, especially Treg and Tfh cell populations, in colonic diseases. These findings significantly enhance our understanding of the immune mechanisms underlying CRC and its precancerous lesions. Further investigation of the Treg and Tfh cells' function in colorectal disease development will provide potential therapeutic targets for monitoring and preventing CRC development.

A novel somatostatin receptor ligand for human ACTH - and GH -secreting pituitary adenomas

OBJECTIVE

Somatostatin receptor ligands have come to play a pivotal role in the treatment of both ACTH- and GH-secreting pituitary adenomas. Clinical efficacy averages 30-50%, thus a considerable number of patients with Cushing's disease or acromegaly remain unresponsive to this therapeutic approach. HTL0030310 is a new somatostatin receptor ligand selective for subtype 5 over subtype 2, thus with a different receptor profile compared to clinical somatostatin receptor ligands.

DESIGN

Assessment of the effect of HTL0030310 on hormone secretion in human ACTH- and GH-secreting pituitary adenomas in vitro.

METHODS

Primary cultures from 3 ACTH-secreting and 5 GH-secreting pituitary adenomas were treated with 1, 10 and 100 nM HTL0030310 alone or with 10 nM CRH or GHRH, respectively. Parallel incubations with 10 nM pasireotide were also carried out. ACTH and GH secretion were assessed after 4 and 24 hour incubation; SSTR2, SSTR3, SSTR5, GH and POMC expression were evaluated after 24 hours.

RESULTS

HTL0030310 reduced unchallenged ACTH and POMC levels up to 50% in 2 ACTH-secreting adenomas and blunted CRH-stimulated ACTH/POMC by 20-70% in all 3 specimens. A reduction in spontaneous GH secretion was observed in 4 GH-secreting adenomas and in 2 specimens during GHRH co-incubation. SSTRs expression was detected in all specimens.

CONCLUSIONS

This first study on a novel somatostatin receptor 5-preferring ligand indicates that HTL0030310 can inhibit hormonal secretion in human ACTH- and GH-secreting pituitary adenomas. These findings suggest a potential new avenue for somatostatin ligands in the treatment of Cushing's disease and acromegaly.

Determination of dimethylated nucleosides in serum from colorectal cancer patients by hydrophilic interaction liquid chromatography-tandem mass spectrometry

RNA modifications play a crucial regulatory role in a variety of biological processes and are closely related to numerous diseases, including cancer. The diversity of metabolites in serum makes it a favored biofluid for biomarkers discovery. In this work, a robust and accurate hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC-MS/MS) approach was established for simultaneous determination of dimethylated nucleosides in human serum. Using the established method, we were able to accurately quantify the concentrations of N6-2'-O-dimethyladenosine (m6Am), N2,N2-dimethylguanosine (m2,2G), and 5,2'-O-dimethyluridine (m5Um) in serum samples from 53 healthy controls, 57 advanced colorectal adenoma patients, and 39 colorectal cancer (CRC) patients. The results showed that, compared with healthy controls and advanced colorectal adenoma patients, the concentrations of m6Am and m2,2G were increased in CRC patients, while the concentration of m5Um was decreased in CRC patients. These results indicate that these three dimethylated nucleosides could be potential biomarkers for early detection of colorectal cancer. Interestingly, the level of m5Um was gradually decreased from healthy controls to advanced colorectal adenoma patients to CRC patients, indicating m5Um could also be used to evaluate the level of malignancy of colorectal tumor. In addition, this study will contribute to the investigation on the regulatory mechanisms of RNA dimethylation in the onset and development of colorectal cancer.

Dickkopf 1 is expressed in normal fibroblasts during early stages of colorectal tumorigenesis

BACKGROUND AND PURPOSE

Colorectal cancer progression from adenoma to cancer is a time-intensive process; however, the interaction between normal fibroblasts (NFs) with early colorectal tumors, such as adenomas, remains unclear. Here, we analyzed the response of the microenvironment during early tumorigenesis using co-cultures of organoids and NFs.

MATERIALS AND METHODS

Colon normal epithelium, adenoma, cancer organoid, and NFs were established and co-cultured using Transwell inserts. Microarray analysis of NFs was performed to identify factors expressed early in tumor growth. Immunostaining of clinical specimens was performed to localize the identified factor. Functional analysis was performed using HCT116 cells. Serum DKK1 levels were measured in patients with colorectal cancer and adenoma.

RESULTS

Colorectal organoid-NF co-culture resulted in increased organoid diameter and cell viability in normal epithelial and adenomatous organoids but not in cancer organoids. Microarray analysis of NFs revealed 18 genes with increased expression when co-cultured with adenoma and cancer organoids. Immunohistochemical staining revealed DKK1 expression in the tumor stroma from early tumor growth. DKK1 stimulation reduced HCT116 cell proliferation, while DKK1 silencing by siRNA transfection increased cell proliferation. Serum DKK1 level was significantly higher in patients with advanced cancer and adenoma than in controls. Serum DKK1 level revealed area-under-the-curve values of 0.78 and 0.64 for cancer and adenoma, respectively.

CONCLUSION

These findings contribute valuable insights into the early stages of colorectal tumorigenesis and suggest DKK1 as a tumor suppressor. Additionally, serum DKK1 levels could serve as a biomarker to identify both cancer and adenoma, offering diagnostic possibilities for early-stage colon tumors. The present study has a few limitations. We considered using DKK1 as a candidate gene for gene transfer to organoids and NFs; however, it was difficult due to technical problems and the slow growth rate of NFs. Therefore, we used cancer cell lines instead. In addition, immunostaining and ELISA were based on the short-term collection at a single institution, and further accumulation of such data is desirable. As described above, most previous reports were related to advanced cancers, but in this study, new findings were obtained by conducting experiments on endoscopically curable early-stage tumors, such as adenomas.

Clinical characteristics and therapeutic outcomes of acromegalic patients with giant growth hormone-secreting pituitary adenomas: a single-center study of 67 cases

PURPOSE

Acromegalic patients with giant growth hormone-secreting pituitary adenomas (GHPAs) (≥ 40 mm) are relatively rare, and their clinical characteristics and treatment outcome data are limited. This study aims to analyze the clinical practice experience of giant GHPAs.

METHODS

Sixty-seven acromegalic patients with giant GHPAs and 67 patients with macro GHPAs (10-39 mm), matched for age and gender from the same hospital during the same period, were retrospectively recruited. The clinical characteristics, treatment, and outcomes were analyzed.

RESULTS

Enlargement of the extremities and facial features were the most common symptoms in most patients (92.5%). Compared with the macroadenoma group, more frequent visual impairment (86.6% vs. 25.4%, P < 0.001) and gonadal axis dysfunction (49.3% vs. 34.3%, P = 0.008), higher preoperative fasting GH, nadir GH after OGTT and IGF-1 levels, and a higher proportion of extrasellar tumor invasion were seen in the giant adenoma group. As the adenoma size increases, the total resection rate decreases, and postoperative complications and multimodal treatment strategies increase significantly. Fasting and nadir GH levels remained higher at 1 week postoperatively, and there were more surgical complications and cases of anterior hypopituitarism in the giant group. After a median follow-up of 36 months, 12 patients (36.4%) in the giant GHPA group and 17 (36.2%) in the macro GHPA group achieved biochemical remission. Other factors such as age of onset, age of diagnosis, delayed diagnosis time, metabolic complications, p53 positive rate, and Ki-67 index showed no significant difference between the two groups.

CONCLUSIONS

With aggressive multimodal therapy, the biochemical remission rate of acromegalic patients with giant GHPAs is comparable to that of patients with macro adenoma. However, postoperative complications and hypopituitarism need to be closely monitored.

Primary aldosteronism: molecular medicine meets public health

Primary aldosteronism is the most common single cause of hypertension and is potentially curable when only one adrenal gland is the culprit. The importance of primary aldosteronism to public health derives from its high prevalence but huge under-diagnosis (estimated to be <1% of all affected individuals), despite the consequences of poor blood pressure control by conventional therapy and enhanced cardiovascular risk. This state of affairs is attributable to the fact that the tools used for diagnosis or treatment are still those that originated in the 1970-1990s. Conversely, molecular discoveries have transformed our understanding of adrenal physiology and pathology. Many molecules and processes associated with constant adrenocortical renewal and interzonal metamorphosis also feature in aldosterone-producing adenomas and aldosterone-producing micronodules. The adrenal gland has one of the most significant rates of non-silent somatic mutations, with frequent selection of those driving autonomous aldosterone production, and distinct clinical presentations and outcomes for most genotypes. The disappearance of aldosterone synthesis and cells from most of the adult human zona glomerulosa is the likely driver of the mutational success that causes aldosterone-producing adenomas, but insights into the pathways that lead to constitutive aldosterone production and cell survival may open up opportunities for novel therapies.

Low frequency of AIP mutations in patients with young-onset sporadic pituitary macroadenomas

PURPOSE

Mutations in the aryl hydrocarbon receptor interacting protein (AIP) gene cause familial isolated pituitary adenomas (FIPA). AIP mutations have also been found in patients with apparently sporadic pituitary adenomas, particularly in young patients with large adenomas. The aim of this study was to determine the frequency of AIP germline mutations in patients with young-onset sporadic pituitary macroadenomas.

METHODS

The AIP gene was sequenced in 218 Portuguese patients with sporadic pituitary macroadenomas diagnosed before the age of 40 years.

RESULTS

Heterozygous rare sequence variants in AIP were identified in 18 (8.3%) patients. However, only four (1.8%) patients had pathogenic or likely pathogenic variants. These consisted of two already known mutations (p.Arg81* and p.Leu115Trpfs*41) and two novel mutations (p.Glu246*, p.Ser53Thrfs*36). All four patients had GH-secreting adenomas diagnosed between the ages of 14 and 25 years. The frequency of AIP pathogenic or likely pathogenic variants in patients under the age of 30 and 18 years was 3.4% and 5.0%, respectively.

CONCLUSION

The frequency of AIP mutations in this cohort was lower than in other studies. Previous reports may have overestimated the contribution of AIP mutations due to the inclusion of genetic variants of uncertain significance. The identification of novel AIP mutations expands the known spectrum of genetic causes of pituitary adenomas and may help understand the role of AIP mutations in the molecular mechanisms underlying pituitary tumorigenesis.

Regulation of long noncoding RNAs in the pathogenesis and clinical implications of pituitary adenomas

BACKGROUND

Pituitary adenoma (PA) is a type of tumor that develops in the sella turcica and is one of the most frequent intracranial tumors. It belongs to a type of adenoma derived from a single clone of cells in the pituitary gland. PA ranks third among all intracranial tumors, following only gliomas and meningioma. The average prevalence rate is approximately 15% at autopsy and 22.5% at radiological examinations.

OBJECTIVE AND SIGNIFICANCE

Most PAs are benign and non-invasive adenomas that can be removed surgically or controlled with medication. However, approximately 35% of them show invasion into nearby anatomical structures and cannot be completely resected. 0.1%~0.2% of PA cases eventually develop into pituitary carcinomas. Additionally, PA may cause severe morbidity due to mass effects and the disorder of pituitary hormone secretion. Therefore, there is an urgent need to clarify the pathological mechanism of PA, improve the accuracy of diagnosis, and develop targeted therapies.

RESEARCH STATUS

Although current knowledge about the pathogenesis of PA remains limited, epigenetic modulation of PA has been increasingly implicated. Long non-coding RNAs (lncRNAs) are known to regulate gene expression post-transcriptionally and exert substantial roles in the initiation, progression, or suppression of various tumors. Accumulating evidence has shown close relationships between lncRNA dysregulation and PA development.

CONCLUSIONS

This review highlights recent progress in the study of lncRNAs in PA pathogenesis and their potential as diagnostic/prognostic biomarkers or therapeutic targets for PA patients.

Neuromedin B receptor as a potential therapeutic target for corticotroph adenomas

PURPOSE

Cushing's disease (CD) results from autonomous adrenocorticotropic hormone (ACTH) secretion by corticotroph adenomas, leading to excessive cortisol production, ultimately affecting morbidity and mortality. Pasireotide is the only FDA approved tumor directed treatment for CD, but it is effective in only about 25% of patients, and is associated with a high rate of hyperglycemia. Neuromedin B (NMB), a member of the bombesin-like peptide family, regulates endocrine secretion and cell proliferation. Here, we assessed NMB and NMB receptor (NMBR) expression in human corticotroph adenomas and the effects of NMBR antagonist PD168368 on murine and human corticotroph tumors.

METHODS

To investigate NMB and NMBR expression, real-time qPCR and immunostaining on human pathological specimens of corticotroph, non-functional and somatotroph adenomas were performed. The effects of PD168368 on hormone secretion and cell proliferation were studied in vitro, in vivo and in seven patient-derived corticotroph adenoma cells. NMB and NMBR were expressed in higher extent in human corticotroph adenomas compared with non-functional or somatotroph adenomas.

RESULTS

In murine AtT-20 cells, PD168368 reduced proopiomelanocortin (Pomc) mRNA/protein expression and ACTH secretion as well as cell proliferation. In mice with tumor xenografts, tumor growth, ACTH and corticosterone were downregulated by PD168368. In patient-derived adenoma cells, PD168368 reduced POMC mRNA expression in four out of seven cases and ACTH secretion in two out of five cases. A PD168368-mediated cyclin E suppression was also identified in AtT-20 and patient-derived cells.

CONCLUSION

NMBR antagonist represents a potential treatment for CD and its effect may be mediated by cyclin E suppression.

DNA Methylation Pattern in Somatotroph Pituitary Neuroendocrine Tumors

INTRODUCTION

Growth hormone secretion by sporadic somatotroph neuroendocrine pituitary tumors (PitNETs) is a major cause of acromegaly. These tumors are relatively heterogenous in terms of histopathological and molecular features. Our previous transcriptomic profiling of somatotroph tumors revealed three distinct molecular subtypes. This study aimed to investigate the difference in DNA methylation patterns in subtypes of somatotroph PitNETs and its role in distinctive gene expression.

METHODS

Genome-wide DNA methylation was investigated in 48 somatotroph PitNETs with EPIC microarrays. Gene expression was assessed with RNAseq. Bisulfite pyrosequencing and qRT-PCR were used for verifying the results of DNA methylation and gene expression.

RESULTS

Clustering tumor samples based on methylation data reflected the transcriptome-related classification. Subtype 1 tumors are densely granulated without GNAS mutation, characterized by high expression of NR5A1 (SF-1) and GIPR. The expression of both genes is correlated with specific methylation of the gene body and promoter. This subtype has a lower methylation level of 5' gene regions and CpG islands than the remaining tumors. Subtype 2 PitNETs are densely granulated and frequently GNAS-mutated, while those in subtype 3 are mainly sparsely granulated. Methylation/expression analysis indicates that ∼50% genes located in differentially methylated regions are those differentially expressed between tumor subtypes. Correlation analysis revealed DNA methylation-controlled genes, including CDKN1B, CCND2, EBF3, CDH4, CDH12, MGMT, STAT5A, PLXND1, PTPRE, and MMP16, and genes encoding ion channels and semaphorins.

CONCLUSION

DNA methylation profiling confirmed the existence of three molecular subtypes of somatotroph PitNETs. High expression of NR5A1 and GIPR in subtype 1 tumors is correlated with specific methylation of both genes.

Pathology of Crooke Cells in the Human Pituitaries: A Timely Review

Crooke cell change was first found in the regressed and suppressed corticotroph (adrenocorticotropic hormone-producing) cells, and now is known to occur in pituitary tumors. The tumor cells of this type can be recognized by morphology with immunohistochemistry, and are well known to predict aggressive behavior such as invasion and rare metastases. This is one of the representative neuroendocrine tumors in the pituitary which is now considered to have malignant potential as proposed in the pancreas and gastrointestinal tracts. It is important to emphasize the pituitary tumor pathology such as Crooke cell change for prognostication and appropriate therapies. This review article describes the evolution from the Crooke cells to Crooke cell tumors which is timely along with the Fifth WHO classification 2022 published online.

SELENOP modifies sporadic colorectal carcinogenesis and WNT signaling activity through LRP5/6 interactions

Although selenium deficiency correlates with colorectal cancer (CRC) risk, the roles of the selenium-rich antioxidant selenoprotein P (SELENOP) in CRC remain unclear. In this study, we defined SELENOP's contributions to sporadic CRC. In human single-cell cRNA-Seq (scRNA-Seq) data sets, we discovered that SELENOP expression rose as normal colon stem cells transformed into adenomas that progressed into carcinomas. We next examined the effects of Selenop KO in a mouse adenoma model that involved conditional, intestinal epithelium-specific deletion of the tumor suppressor adenomatous polyposis coli (Apc) and found that Selenop KO decreased colon tumor incidence and size. We mechanistically interrogated SELENOP-driven phenotypes in tumor organoids as well as in CRC and noncancer cell lines. Selenop-KO tumor organoids demonstrated defects in organoid formation and decreases in WNT target gene expression, which could be reversed by SELENOP restoration. Moreover, SELENOP increased canonical WNT signaling activity in noncancer and CRC cell lines. In defining the mechanism of action of SELENOP, we mapped protein-protein interactions between SELENOP and the WNT coreceptors low-density lipoprotein receptor-related proteins 5 and 6 (LRP5/6). Last, we confirmed that SELENOP-LRP5/6 interactions contributed to the effects of SELENOP on WNT activity. Overall, our results position SELENOP as a modulator of the WNT signaling pathway in sporadic CRC.

Primary Aldosteronism: Spatial Multiomics Mapping of Genotype-Dependent Heterogeneity and Tumor Expansion of Aldosterone-Producing Adenomas

BACKGROUND

Primary aldosteronism is frequently caused by an adrenocortical aldosterone-producing adenoma (APA) carrying a somatic mutation that drives aldosterone overproduction. APAs with a mutation in KCNJ5 (APA-KCNJ5MUT) are characterized by heterogeneous CYP11B2 (aldosterone synthase) expression, a particular cellular composition and larger tumor diameter than those with wild-type KCNJ5 (APA-KCNJ5WT). We exploited these differences to decipher the roles of transcriptome and metabolome reprogramming in tumor pathogenesis.

METHODS

Consecutive adrenal cryosections (7 APAs and 7 paired adjacent adrenal cortex) were analyzed by spatial transcriptomics (10x Genomics platform) and metabolomics (in situ matrix-assisted laser desorption/ionization mass spectrometry imaging) co-integrated with CYP11B2 immunohistochemistry.

RESULTS

We identified intratumoral transcriptional heterogeneity that delineated functionally distinct biological pathways. Common transcriptomic signatures were established across all APA specimens which encompassed 2 distinct transcriptional profiles in CYP11B2-immunopositive regions (CYP11B2-type 1 or 2). The CYP11B2-type 1 signature was characterized by zona glomerulosa gene markers and was detected in both APA-KCNJ5MUT and APA-KCNJ5WT. The CYP11B2-type 2 signature displayed markers of the zona fasciculata or reticularis and predominated in APA-KCNJ5MUT. Metabolites that promote oxidative stress and cell death accumulated in APA-KCNJ5WT. In contrast, antioxidant metabolites were abundant in APA-KCNJ5MUT. Finally, APA-like cell subpopulations-negative for CYP11B2 gene expression-were identified in adrenocortical tissue adjacent to APAs suggesting the existence of tumor precursor states.

CONCLUSIONS

Our findings provide insight into intra- and intertumoral transcriptional heterogeneity and support a role for prooxidant versus antioxidant systems in APA pathogenesis highlighting genotype-dependent capacities for tumor expansion.

Molecular Imaging of Pituitary Tumors

Tumors of the pituitary gland, although mostly benign adenomas, are a cause of significant morbidity and even excess mortality due to local compressive effects (eg visual loss, hypopituitarism) and unregulated hormone secretion (eg acromegaly or Cushing Disease). Surgery, radiotherapy, and medical management (sometimes in combination) may be needed to mitigate the effects of tumor expansion and endocrine dysfunction. Magnetic resonance imaging (MRI) plays a central role in treatment planning for most patients. However, it does not always reliably identify the site(s) of primary or recurrent disease, especially where post-treatment remodeling results in indeterminate anatomical appearances. In these contexts, molecular imaging is a potential game-changer, allowing precise localization of sites of active disease and enabling safe and effective targeted intervention when patients would otherwise be consigned to expensive life-long medication. For pituitary and parasellar imaging, PET is the preferred modality due to its superior spatial resolution and sensitivity compared with SPECT, and an array of PET radioligands have been studied in different pituitary adenoma (PA) subtypes. While 18F-fluorodeoxyglucose (18F-FDG) is widely available, significant heterogeneity in tumoral uptake has limited its use. Instead, ligands targeting specific molecular pathways relevant to PA biology (eg somatostatin or dopamine receptor expression, amino acid uptake) are increasingly preferred and are beginning to find application in routine clinical practice. In addition, novel approaches to distinguish adenomatous tissue from normal gland (eg through comparison of images obtained with different radiotracers) and increase confidence that a suspected abnormal focus is indeed pathological (eg through subtraction imaging) have been proposed. It is likely therefore that molecular imaging will continue to find increasing application in the management of pituitary tumors just as it already does in other endocrine disorders.

Survivin: A Potential Marker of Resistance to Somatostatin Receptor Ligands

CONTEXT

Invasive and somatostatin receptor ligand (SRL)-resistant pituitary tumors represent a challenge in the clinical practice of endocrinologists. Efforts have been made to elucidate reliable makers for both. Survivin and eukaryotic translation initiation factor-binding protein 1 (4EBP1) are upregulated in several cancers and involved in apoptosis and cell proliferation.

OBJECTIVE

We explored the role of these markers in somatotropinomas.

METHODS

Immunostains for survivin and 4EBP1, and also for somatostatin receptor type 2 (SSTR2), Ki-67, and cytokeratin 18, were analyzed in tissue microarrays containing 52 somatotropinoma samples. Tumor invasiveness was evaluated in all samples while drug resistance was evaluated in 34 patients who received SRL treatment. All these parameters were correlated with first-generation SRL (fg-SRL) responsiveness and tumor invasiveness.

RESULTS

Low survivin expression (P = 0.04), hyperintense signal on T2 weighted image (T2WI) (P = 0.01), younger age (P = 0.01), sparsely granular adenomas (SGA) (P = 0.04), high postoperative growth hormone (GH) and insulin-like growth factor-1 (IGF-1) levels (P = 0.049 and P < 0.001, respectively), and large postoperative tumor size (P = 0.02) were associated with resistance to fg-SRL. Low survivin and SSTR2 expression and high 4EBP1 expression were associated with SGA (P = 0.04, P = 0.01, and P = 0.001, respectively). Younger age (P = 0.03), large tumor pre- and postoperative (P = 0.04 and P = 0.006, respectively), low SSTR2 expression (P = 0.03), and high baseline GH and IGF-1 (P = 0.01 and P = 0.02, respectively) were associated with tumor invasiveness. However, survivin, 4EBP1, Ki-67, and granulation patterns were not associated with tumor invasion.

CONCLUSION

This study suggests that low survivin expression is predictive of resistance to fg-SRL in somatotropinomas, but not of tumor invasiveness.

Lipidomic Profiling of Colorectal Lesions for Real-Time Tissue Recognition and Risk-Stratification Using Rapid Evaporative Ionization Mass Spectrometry

OBJECTIVE

Rapid evaporative ionization mass spectrometry (REIMS) is a metabolomic technique analyzing tissue metabolites, which can be applied intraoperatively in real-time. The objective of this study was to profile the lipid composition of colorectal tissues using REIMS, assessing its accuracy for real-time tissue recognition and risk-stratification.

SUMMARY BACKGROUND DATA

Metabolic dysregulation is a hallmark feature of carcinogenesis; however, it remains unknown if this can be leveraged for real-time clinical applications in colorectal disease.

METHODS

Patients undergoing colorectal resection were included, with carcinoma, adenoma and paired-normal mucosa sampled. Ex vivo analysis with REIMS was conducted using monopolar diathermy, with the aerosol aspirated into a Xevo G2S QToF mass spectrometer. Negatively charged ions over 600 to 1000 m/z were used for univariate and multivariate functions including linear discriminant analysis.

RESULTS

A total of 161 patients were included, generating 1013 spectra. Unique lipidomic profiles exist for each tissue type, with REIMS differentiating samples of carcinoma, adenoma, and normal mucosa with 93.1% accuracy and 96.1% negative predictive value for carcinoma. Neoplasia (carcinoma or adenoma) could be predicted with 96.0% accuracy and 91.8% negative predictive value. Adenomas can be risk-stratified by grade of dysplasia with 93.5% accuracy, but not histological subtype. The structure of 61 lipid metabolites was identified, revealing that during colorectal carcinogenesis there is progressive increase in relative abundance of phosphatidylglycerols, sphingomyelins, and mono-unsaturated fatty acid-containing phospholipids.

CONCLUSIONS

The colorectal lipidome can be sampled by REIMS and leveraged for accurate real-time tissue recognition, in addition to riskstratification of colorectal adenomas. Unique lipidomic features associated with carcinogenesis are described.

SATB2 as a Marker of the Proximal Nephron: Expression in Nephrogenic Adenoma and Correlation With Other Renal Tubular Markers

Nephrogenic adenoma (NA) is an infrequent reactive urothelial lesion. The expression of immunohistochemical renal tubular markers has been reported in NA, although a proximal or distal nephron phenotype has not been established. Special AT-rich sequence-binding protein 2 (SATB2) is a marker of a colorectal origin of adenocarcinomas, occasionally reported in renal samples. We have analyzed SATB2 expression in NA, with correlation with other tubular markers, as well as in the normal kidney. Fifty cases of NA were immunostained with PAX8, SATB2, proximal nephron markers [CD10, renal cell carcinoma (RCC) marker, alpha-methylacyl-CoA racemase (AMACR), and CD15], and distal markers (Ksp cadherin, cytokeratin 7, E-cadherin (E-cad), and cytokeratin 19). Ten normal kidney sections were stained with a double method combining SATB2 plus CD10, RCC marker, AMACR, Ksp cadherin, cytokeratin 7, or E-cad. All NA were immunoreactive for PAX8 and 57% for SATB2. Every case was positive for proximal and distal nephron markers: 100% for cytokeratins 7 and 19, 84.1% E-cad +, 81.6% AMACR +, 68.9% Ksp cadherin +, 63% CD15 +, 53.3% CD10 +, and 28.6 % RCC +. In the normal kidney, SATB2 was detected in the straight part of the proximal tubules and the thin descending loops of Henle. NA shows a multiphenotypic pattern with coexpression of both proximal and distal nephron markers, and constant expression of PAX8, cytokeratins 7 and 19. SATB2 is often positive in NA, which should be kept in mind to avoid a possible misdiagnosis of intestinal adenocarcinoma. SATB2 is a marker of the normal proximal nephron.

Quantitative proteomics identified a novel invasion biomarker associated with EMT in pituitary adenomas

BACKGROUND

Complete resection of invasive pituitary adenoma is usually difficult, resulting in a high recurrence rate. Therefore, it is needed to find potential diagnostic markers and therapeutic targets for invasive pituitary adenoma.

METHODS

We collected samples from patients with invasive and non-invasive pituitary adenomas from Beijing Tiantan Hospital for protein extraction and quantitative analysis. We identified differential proteins (DEPs) by differential analysis of the two groups. The intersection of differential proteins related to invasion and epithelial-mesenchymal transition (EMT) in the GeneCards database was identified as EMT-DEPs. The protein network of EMT-DEPs was analyzed using the STRING database and Cytoscape software, and the hub EMT-DEPs were obtained by the MCC algorithm of the cytoHubba plugin. Correlation analysis was used to obtain the interpairing proteins among EMT-DEPs, and core EMT-DEPs were identified based on the number of paired proteins. The Venn program was used to identify the intersection of hub EMT-DEPs and core EMT-DEPs as key EMT-DEPs. Finally, a series of analyses plus experiments were used to verify the correlation of the target protein with invasion and EMT in pituitary adenoma.

RESULTS

Quantitative comparison of proteins between invasive and non-invasive pituitary adenomas indicated 833 differential proteins. The overlaps of EMT-related proteins and differential proteins consisted of 46 EMT-DEPs. There were 6 intersections between the hub EMT-DEPs and core EMT-DEPs. Using quantitative protein data and GSE169498 chip, we found that solute carrier family 2 member 1 (SLC2A1) was our target protein. SLC2A1 was significantly correlated with the invasiveness of pituitary adenoma, and the ROC curve was satisfactory. The functions and pathways of SLC2A1 and paired protein enrichment were closely linked to the EMT. Consistently, SLC2A1 expression was significantly and positively correlated with the expression of classical markers of EMT. The final experiment revealed that SLC2A1 was significantly upregulated in invasive pituitary adenoma.

CONCLUSION

SLC2A1 is significantly upregulated in invasive pituitary adenoma with satisfactory predictive value. It may regulate EMT. It may be a potential diagnostic marker for invasive pituitary adenoma.

The expression of glucocorticoid and mineralocorticoid receptors in pituitary tumors causing Cushing's disease and silent corticotroph tumors

OBJECTIVE

Pituitary neuroendocrine corticotroph tumors commonly cause Cushing's disease (CD) that results from increased adrenocorticotropic hormone (ACTH) secretion by the pituitary tumor and consequent increase of cortisol levels in blood. However, in some patients, corticotroph tumors remain clinically non-functioning. Cortisol secretion is regulated by the hypothalamic-pituitary-adrenal axis and includes a negative feedback between cortisol and ACTH secretion. Glucocorticoids reduce ACTH level both by hypothalamic regulation and acting on corticotrophs via glucocorticoid (GR) and mineralocorticoid (MR) receptors. The aim of the study was to determine the role of GR and MR expression at mRNA and protein levels in both functioning and silent corticotroph tumors.

METHODS

Ninety-five patients were enrolled, including 70 with CD and 25 with silent corticotroph tumors. Gene expression levels of NR3C1 and NR3C2 coding for GR and MR, respectively, were determined with qRT-PCR in the two tumor types. GR and MR protein abundance was assessed with immunohistochemistry.

RESULTS

Both GR and MR were expressed in corticotroph tumors. Correlation between NR3C1 and NR3C2 expression levels was observed. NR3C1 expression was higher in silent than in functioning tumors. In CD patients NR3C1 and NR3C2 levels were negatively correlated with morning plasma ACTH levels and tumor size. Higher NR3C2 was confirmed in patients with remission after surgery and in densely granulated tumors. Expression of both genes and GR protein was higher in USP8-mutated tumors. Similar relationship between USP8 mutations and expression levels were observed in analysis of silent tumors that also revealed a negative correlation between GR and tumor size and higher NR3C1 expression in densely granulated tumors.

CONCLUSIONS

Although the associations between gene/protein expression and patients clinical features are not strong, they consistently show an evident trend in which higher receptor expression corresponds to more favorable clinical characteristics.

Molecular characterization of epithelial-mesenchymal transition and medical treatment related-genes in non-functioning pituitary neuroendocrine tumors

INTRODUCTION

Different medical therapies have been developed for pituitary adenomas. However, Non-Functioning Pituitary Neuroendocrine Tumors (NF-PitNET) have shown little response to them. Furthermore, epithelial-mesenchymal transition (EMT) has been linked to resistance to medical treatment in a significant number of tumors, including pituitary adenomas.

METHODS

We aimed to evaluate the expression of EMT-related markers in 72 NF-PitNET and 16 non-tumoral pituitaries. To further explore the potential usefulness of medical treatment for NF-PitNET we assessed the expression of somatostatin receptors and dopamine-associated genes.

RESULTS

We found that SNAI1, SNAI2, Vimentin, KLK10, PEBP1, Ki-67 and SSTR2 were associated with invasive NF-PitNET. Furthermore, we found that the EMT phenomenon was more common in NF-PitNET than in GH-secreting pituitary tumors. Interestingly, PEBP1 was overexpressed in recurrent NF-PitNET, and could predict growth recurrence with 100% sensitivity but only 43% specificity. In parallel with previously reported studies, SSTR3 is highly expressed in our NF-PitNET cohort. However, SSTR3 expression is highly heterogeneous among the different histological variants of NF-PitNET with very low levels in silent corticotroph adenomas.

CONCLUSION

NF-PitNET showed an enhanced EMT phenomenon. SSTR3 targeting could be a good therapeutic candidate in NF-PitNET except for silent corticotroph adenomas, which express very low levels of this receptor. In addition, PEBP1 could be an informative biomarker of tumor regrowth, useful for predictive medicine in NF-PitNET.

Molecular targets in acromegaly

Molecular therapeutic targets in growth hormone (GH)-secreting adenomas range from well-characterized surface receptors that recognize approved drugs, to surface and intracellular markers that are potential candidates for new drug development. Currently available medical therapies for patients with acromegaly bind to somatostatin receptors, GH receptor, or dopamine receptors, and lead to attainment of disease control in most patients. The degree of control is variable: however, correlates with both disease aggressiveness and tumor factors that predict treatment response including somatostatin receptor subtype expression, granulation pattern, kinases and their receptors, and other markers of proliferation. A better understanding of the mechanisms underlying these molecular markers and their relationship to outcomes holds promise for expanding treatment options as well as a more personalized approach to treating patients with acromegaly.

The use of mass spectrometry in a proteome-centered multiomics study of human pituitary adenomas

A pituitary adenoma (PA) is a common intracranial neoplasm, and is a complex, chronic, and whole-body disease with multicausing factors, multiprocesses, and multiconsequences. It is very difficult to clarify molecular mechanism and treat PAs from the single-factor strategy model. The rapid development of multiomics and systems biology changed the paradigms from a traditional single-factor strategy to a multiparameter systematic strategy for effective management of PAs. A series of molecular alterations at the genome, transcriptome, proteome, peptidome, metabolome, and radiome levels are involved in pituitary tumorigenesis, and mutually associate into a complex molecular network system. Also, the center of multiomics is moving from structural genomics to phenomics, including proteomics and metabolomics in the medical sciences. Mass spectrometry (MS) has been extensively used in phenomics studies of human PAs to clarify molecular mechanisms, and to discover biomarkers and therapeutic targets/drugs. MS-based proteomics and proteoform studies play central roles in the multiomics strategy of PAs. This article reviews the status of multiomics, multiomics-based molecular pathway networks, molecular pathway network-based pattern biomarkers and therapeutic targets/drugs, and future perspectives for personalized, predeictive, and preventive (3P) medicine in PAs.

Bioinformatics Analysis of RNA-seq Data Reveals Genes Related to Cancer Stem Cells in Colorectal Cancerogenesis

Cancer stem cells (CSC) play one of the crucial roles in the pathogenesis of various cancers, including colorectal cancer (CRC). Although great efforts have been made regarding our understanding of the cancerogenesis of CRC, CSC involvement in CRC development is still poorly understood. Using bioinformatics and RNA-seq data of normal mucosa, colorectal adenoma, and carcinoma (n = 106) from GEO and TCGA, we identified candidate CSC genes and analyzed pathway enrichment analysis (PEI) and protein–protein interaction analysis (PPI). Identified CSC-related genes were validated using qPCR and tissue samples from 47 patients with adenoma, adenoma with early carcinoma, and carcinoma without and with lymph node metastasis and were compared to normal mucosa. Six CSC-related genes were identified: ANLN, CDK1, ECT2, PDGFD, TNC, and TNXB. ANLN, CDK1, ECT2, and TNC were differentially expressed between adenoma and adenoma with early carcinoma. TNC was differentially expressed in CRC without lymph node metastases whereas ANLN, CDK1, and PDGFD were differentially expressed in CRC with lymph node metastases compared to normal mucosa. ANLN and PDGFD were differentially expressed between carcinoma without and with lymph node metastasis. Our study identified and validated CSC-related genes that might be involved in early stages of CRC development (ANLN, CDK1, ECT2, TNC) and in development of metastasis (ANLN, PDGFD).

The Integrated Stress Response Is Tumorigenic and Constitutes a Therapeutic Liability in Somatotroph Adenomas

Somatotroph adenomas are the leading cause of acromegaly, with the nearly sparsely granulated somatotroph subtype belonging to high-risk adenomas, and they are less responsive to medical treatment. The integrated stress response (ISR) is an essential stress-support pathway increasingly recognized as a determinant of tumorigenesis. In this study, we identified the characteristic profiling of the integrated stress response in translocation and translation initiation factor activity in somatotroph adenomas, normal pituitary, or other adenoma subtypes through proteomics. Immunohistochemistry exhibited the differential significance and the priority of eukaryotic translation initiation factor 2β (EIF2β) in somatotroph adenomas compared with gonadotroph and corticotroph adenomas. Differentially expressed genes based on the level of EIF2β in somatotroph adenomas were revealed. MetaSape pathways showed that EIF2β was involved in regulating growth and cell activation, immune system, and extracellular matrix organization processes. The correlation analysis showed Spearman correlation coefficients of r = 0.611 (p < 0.001) for EIF2β and eukaryotic translation initiation factor 2 alpha kinase 1 (HRI), r = 0.765 (p < 0.001) for eukaryotic translation initiation factor 2 alpha kinase 2 (PKR), r = 0.813 (p < 0.001) for eukaryotic translation initiation factor 2 alpha kinase 3 (PERK), r = 0.728 (p < 0.001) for GCN2, and r = 0.732 (p < 0.001) for signal transducer and activator of transcription 3 (STAT3). Furthermore, the invasive potential in patients with a high EIF2β was greater than that in patients with a low EIF2β (7/10 vs. 4/18, p = 0.038), with a lower immune-cell infiltration probability (p < 0.05). The ESTIMATE algorithm showed that the levels of activation of the EIF2 pathway were negatively correlated with the immune score in somatotroph adenomas (p < 0.001). In in vitro experiments, the knockdown of EIF2β changed the phenotype of somatotroph adenomas, including cell proliferation, migration, and the secretion ability of growth hormone/insulin-like growth factor-1. In this study, we demonstrate that the ISR is pivotal in somatotroph adenomas and provide a rationale for implementing ISR-based regimens in future treatment strategies.

Pituitary Adenoma Incidence, Management Trends, and Long-term Outcomes: A 30-Year Population-Based Analysis

OBJECTIVE

To perform a population-based study of pituitary adenoma epidemiology, including longitudinal trends in disease incidence, treatment patterns, and outcomes.

PATIENTS AND METHODS

In this study of incident pituitary adenomas in Olmsted County, Minnesota, from January 1, 1989, through December 31, 2019, we identified 785 patients who underwent primary screening, 435 of whom were confirmed as harboring incident pituitary adenomas and were included. Primary outcomes of interest included demographic characteristics, presenting features, and disease outcomes (tumor control, biochemical control, and complications).

RESULTS

Among our 435 study patients, 438 unique pituitary adenomas were diagnosed at a median patient age of 39 years (interquartile range [IQR], 27 to 58 years). Adenomas were incidentally identified in 164 of the 438 tumors (37%). Common symptomatic presentations included hyperprolactinemia (188 of 438 [43%]) and visual field deficit (47 of 438 [11%]). Laboratory tests confirmed pituitary hormone hypersecretion in 238 of the 435 patients (55%), which was symptomatic in 222. The median tumor diameter was 8 mm (IQR, 5 to 17 mm). Primary management strategies were observation (156 of 438 tumors [36%]), medication (162 of 438 tumors [37%]), and transsphenoidal resection (120 of 438 tumors [27%]). Tumor and biochemical control were achieved in 398 (95%) and 216 (91%) secreting tumors, respectively. New posttreatment pituitary or visual deficits were noted in 43 (11%) and 8 (2%); apoplexy occurred in 28 (6%). Median clinical follow-up was 98 months (IQR, 47 to 189 months). Standardized incidence rates were 3.77 to 16.87 per 100,000 population, demonstrating linear expansion over time (R2=0.67). The mean overall standardized incidence rate was 10.1 per 100,000 population; final point prevalence was 175.1 per 100,000 population.

CONCLUSION

Pituitary adenoma is a highly incident disease, with prolactin-secreting and incidental lesions representing the majority of tumors. Incidence rates and asymptomatic detection appear to be increasing over time. Presenting symptoms and treatment pathways are variable; however, most patients achieve favorable outcomes with observation or a single treatment modality.

Effects of tubastatin A on adrenocorticotropic hormone synthesis and proliferation of AtT-20 corticotroph tumor cells

Cushing's disease is an endocrine disorder characterized by hypercortisolism, mainly caused by autonomous production of ACTH from pituitary adenomas. Autonomous ACTH secretion results in excess cortisol production from the adrenal glands, and corticotroph adenoma cells disrupt the normal cortisol feedback mechanism. Pan-histone deacetylase (HDAC) inhibitors inhibit cell proliferation and ACTH production in AtT-20 corticotroph tumor cells. A selective HDAC6 inhibitor has been known to exert antitumor effects and reduce adverse effects related to the inhibition of other HDACs. The current study demonstrated that the potent and selective HDAC6 inhibitor tubastatin A has inhibitory effects on proopiomelanocortin (Pomc) and pituitary tumor-transforming gene 1 (Pttg1) mRNA expression, involved in cell proliferation. The phosphorylated Akt/Akt protein levels were increased after treatment with tubastatin A. Therefore, the proliferation of corticotroph cells may be regulated through the Akt-Pttg1 pathway. Dexamethasone treatment also decreased the Pomc mRNA level. Combined tubastatin A and dexamethasone treatment showed additive effects on the Pomc mRNA level. Thus, tubastatin A may have applications in the treatment of Cushing's disease.

Update on the Genetics of Primary Aldosteronism and Aldosterone-Producing Adenomas

PURPOSE OF THE REVIEW

Primary aldosteronism (PA) is the leading cause of secondary hypertension, accounting for over 10% of patients with high blood pressure. It is characterized by autonomous production of aldosterone from the adrenal glands leading to low-renin levels. The two most common forms arise from bilateral adrenocortical hyperplasia (BAH) and aldosterone-producing adenoma (APA). We discuss recent discoveries in the genetics of PA.

RECENT FINDINGS

Most APAs harbor variants in the KCNJ5, CACNA1D, ATP1A1, ATP2B3, and CTNNB1 genes. With the exception of β-catenin (CTNNB1), all other causative genes encode ion channels; pathogenic variants found in PA lead to altered ion transportation, cell membrane depolarization, and consequently aldosterone overproduction. Some of these genes are found mutated in the germline state (CYP11B2, CLCN2, KCNJ5, CACNA1H, and CACNA1D), leading then to familial hyperaldosteronism, and often BAH rather than single APAs. Several genetic defects in the germline or somatic state have been identified in PA. Understanding how these molecular abnormalities lead to excess aldosterone contributes significantly to the elucidation of the pathophysiology of low-renin hypertension. It may also lead to new and more effective therapies for this disease acting at the molecular level.

Digital quantification of somatostatin receptor subtype 2a immunostaining: a validation study

OBJECTIVE

The aim of this study was to develop an open-source and reproducible digital quantitative analysis (DIA) of somatostatin receptor subtype 2a (SST2) staining in formalin-fixed paraffin-embedded tissues of pancreatic neuroendocrine tumors (panNETs) and growth hormone (GH)-secreting pituitary adenomas (GHomas).

DESIGN

SST2 immunostaining of 18 panNETs and 39 GHomas was assessed using a novel DIA protocol and compared with a widely used semi-quantitative immunoreactivity score (IRS).

METHODS

The DIA software calculates the staining intensity/area and the percentage of positive cells (%PC). Four representative images were selected for each sample by two independent selectors (S1 and S2), with the analysis performed by two independent analyzers (A1 and A2). Agreement between observers was calculated using the concordance correlation coefficient (CCC).

RESULTS

In panNETs, the CCC ranged 0.935-0.977 for intensity/area and 0.942-0.983 for %PC. In GHomas, the CCC ranged 0.963-0.997 for intensity/area and 0.979-0.990 for %PC. In both panNETs and GHomas, the DIA staining intensity was strongly correlated with the IRS (Spearman rho: 0.916-0.969, P < 0.001), as well as the DIA %PC with the IRS %PC (Spearman rh: 0.826-0.881, P < 0.001). In GHomas, the biochemical response to somatostatin receptor ligands correlated with SST2 expression, evaluated both as DIA intensity/area (Spearman rho: -0.448 to -0.527, P = 0.007-0.004) and DIA %PC (Spearman rho: -0.558 to -0.644, P ≤ 0.001).

CONCLUSIONS

The DIA has an excellent inter-observer agreement and showed a strong correlation with the widely used semi-quantitative IRS. The DIA protocol is an open-source, highly reproducible tool and provides a reliable quantitative evaluation of SST2 immunohistochemistry.

A systematic review of molecular alterations in invasive non-functioning pituitary adenoma

PURPOSE

Invasive non-functional pituitary adenomas (NFPAs) constitute 35% of NFPAs. Despite a relatively large body of molecular investigations on the invasiveness of NFPA, the underlying molecular mechanisms of invasiveness are yet to be determined. Herein, we aimed to provide an overview of gene/microRNA(miRNAs) expression alterations in invasive NFPA.

METHODS

This article describes a systematic literature review of articles published up to March 23, 2021, on the transcriptional alterations of invasive NFPA. Five digital libraries were searched, and 42 articles in total fulfilled the eligibility criteria. Pathway enrichment was conducted, and protein interactions among the identified deregulated genes were inferred.

RESULTS

In total 133 gene/protein transcriptional alterations, comprising 87 increased and 46 decreased expressions, were detected in a collective number of 1001 invasive compared with 1007 non-invasive patients with NFPA. Deregulation of CDH1, PTTG1, CCNB1, SNAI1, SLUG, EZR, and PRKACB, which are associated with epidermal-mesenchymal transition (EMT), was identified. Moreover, six members of the angiogenesis pathway, i.e., VEGFA, FLT1, CCND1, CTNNB1, MYC(c-MYC), and PTTG1, were detected. SLC2A1, FLT1, and VEGFA were also recognized in the hypoxia pathway. Physical interactions of CTNNB1 with FLT1, CCND1, and EZR as well as its indirect interactions with VEGFA, MYC, CCNB1, and PCNA indicate the tight interplay between EMT, angiogenesis, and hypoxia pathways in invasive NFPAs. In addition, Hippo, JAK-STAT, MAPK, Wnt, PI3K-Akt, Ras, TGF-b, VEGF, and ErbB were identified as interwoven signaling pathways.

CONCLUSION

In conclusion, invasive NFPA shares very common deregulated signaling pathways with invasive cancers. A large amount of heterogeneity in the reported deregulations in different studies necessitates the validation of the expressional changes of the suggested biomarkers in a large number of patients with invasive NFPA.

Pituitary adenomas evade apoptosis via noxa deregulation in Cushing's disease

Sporadic pituitary adenomas occur in over 10% of the population. Hormone-secreting adenomas, including those causing Cushing’s disease (CD), cause severe morbidity and early mortality. Mechanistic studies of CD are hindered by a lack of in vitro models and control normal human pituitary glands. Here, we surgically annotate adenomas and adjacent normal glands in 25 of 34 patients. Using single-cell RNA sequencing (RNA-seq) analysis of 27594 cells, we identify CD adenoma transcriptomic signatures compared with adjacent normal cells, with validation by bulk RNA-seq, DNA methylation, qRT-PCR, and immunohistochemistry. CD adenoma cells include a subpopulation of proliferating, terminally differentiated corticotrophs. In CD adenomas, we find recurrent promoter hypomethylation and transcriptional upregulation of PMAIP1 (encoding pro-apoptotic BH3-only bcl-2 protein noxa) but paradoxical noxa downregulation. Using primary CD adenoma cell cultures and a corticotroph-enriched mouse cell line, we find that selective proteasomal inhibition with bortezomib stabilizes noxa and induces apoptosis, indicating its utility as an anti-tumor agent.

Asuzu et al. perform single-cell transcriptomic profiling in Cushing’s disease (CD) adenomas and find overexpression and DNA hypomethylation of PMAIP1, which encodes the pro-apoptotic protein noxa. Noxa is degraded by the proteasome. Proteasomal inhibition rescues noxa and induces apoptosis in CD.

Characterization of Aldosterone-producing Cell Cluster (APCC) at Single-cell Resolution

CONTEXT

The adrenal cortex consists of zona glomerulosa (ZG), fasciculata (ZF), and reticularis. Aldosterone-producing cell clusters (APCCs) that strongly express aldosterone synthase (CYP11B2) are frequently found in adult adrenals and harbor somatic mutations that are also detected in aldosterone-producing adenomas (APAs). Primary aldosteronism is mainly caused by APAs or idiopathic hyperaldosteronism (IHA). We presume that APCCs are causing IHA and are precursors of APAs. However, the gene expression characteristics and especially the development of APCCs are not well understood.

OBJECTIVE

This study aimed to analyze the transcriptome of APCCs at single-cell resolution and infer the developmental trajectory.

METHODS

Single-cell RNA sequencing (scRNA-seq) of 2 adult adrenals was performed.

RESULTS

Immunohistochemical analyses confirmed the 2 adrenals had APCCs. scRNA-seq data of 2928 adrenal cells were obtained and 1765 adrenocortical cells were identified based on unsupervised clustering and the marker gene expression. The adrenocortical cells were divided into 6 clusters, of which 3 clusters (923 cells) were composed of APCC/ZG cells. By further subclustering, the APCC/ZG cells were divided into 3 clusters (clusters C1, C2, and C3), we finally identified APCC cluster (C3) and ZG cluster (C1). Cluster C2 seemed to be ZG-to-ZF transitional cells. RNA velocity analysis inferred the developmental direction from cluster ZG-cluster-C1 to APCC-cluster-C3. The scRNA-seq additionally revealed that many CYP11B2-positive cells were positive for CYP11B1 and/or CYP17A1, which were essential for cortisol but not for aldosterone production.

CONCLUSIONS

Our results revealed the gene expression characteristics of APCC at single-cell resolution and show that some ZG cells remodel to APCC.

MicroRNA in Acromegaly: Involvement in the Pathogenesis and in the Response to First-Generation Somatostatin Receptor Ligands

Acromegaly is a chronic and systemic disease due to excessive growth hormone and insulin-like growth factor type I caused, in the vast majority of cases, by a GH-secreting pituitary adenoma. About 40% of these tumors have somatic mutations in the stimulatory G protein alpha-subunit 1 gene. The pathogenesis of the remaining tumors, however, is still not fully comprehended. Surgery is the first-line therapy for these tumors, and first-generation somatostatin receptor ligands (fg-SRL) are the most prescribed medications in patients who are not cured by surgery. MicroRNAs are small, non-coding RNAs that control the translation of many mRNAs, and are involved in the post-transcriptional regulation of gene expression. Differentially expressed miRNAs can explain differences in the pathogenesis of acromegaly and tumor resistance. In this review, we focus on the most validated miRNAs, which are mainly involved in acromegaly’s tumorigenesis and fg-SRL resistance, as well as in circulating miRNAs in acromegaly.

Association of DNA methylation with steroidogenic enzymes in Cushing's adenoma

DNA methylation and demethylation regulate the transcription of genes. DNA methylation-associated gene expression of adrenal steroidogenic enzymes may regulate cortisol production in cortisol-producing adenoma (CPA). We aimed to determine the DNA methylation levels of all genes encoding steroidogenic enzymes involved in CPA. Additionally, the aims were to clarify the DNA methylation-associated gene expression and evaluate the difference of CPA genotype from others using DNA methylation data. Twenty-five adrenal CPA and six nonfunctioning adrenocortical adenoma (NFA) samples were analyzed. RNA sequencing and DNA methylation array were performed. The methylation levels at 118 methylation sites of the genes were investigated, and their methylation and mRNA levels were subsequently integrated. Among all the steroidogenic enzyme genes studied, CYP17A1 gene was mainly found to be hypomethylated in CPA compared to that in NFA, and the Benjamini-Hochberg procedure demonstrated that methylation levels at two sites in the CYP17A1 gene body were statistically significant. PRKACA mutant CPAs predominantly exhibited hypomethylation of CYP17A1 gene compared with the GNAS mutant CPAs. Inverse associations between CYP17A1 methylation in three regions of the gene body and its mRNA levels were observed in the NFAs and CPAs. In applying clustering analysis using CYP17A1 methylation and mRNA levels, CPAs with PRKACA mutation were differentiated from NFAs and CPAs with a GNAS mutation. We demonstrated that CPAs exhibited hypomethylation of the CYP17A1 gene body in CPA, especially in the PRKACA mutant CPAs. Methylation of CYP17A1 gene may influence its transcription levels.

Aberrant Nuclear Translocation of E2F1 and Its Association in Cushing's Disease

Nonsurgical medical treatments are often performed for Cushing's disease due to high recurrence rates. However, current medical treatment that targets corticotroph adenomas are limited. To develop a treatment that specifically targets corticotrophs in Cushing's disease, it is necessary to identify corticotroph lineage-specific proteins, which are involved in the Cushing's tumor phenotype. We have previously reported that the expression of E2F transcription factor 1 (E2F1), one of the cell cycle regulatory proteins, was increased in corticotrophs in Cushing's disease model mice and was involved in the regulation of POMC gene expression. Phosphorylation of Ser337 of E2F1 (pS337-E2F1) facilitates its binding to the POMC promoter, which was suggested to contribute to elevated POMC expression in corticotrophs. Here, we report that E2F1 expression is specific to the corticotroph lineage in normal human pituitaries and that the E2F1 protein is localized in the cytosol in normal corticotrophs. We show that pS337-E2F1 is localized in the nucleus specifically in Cushing's tumors, while it is localized in the perinuclear cytoplasm in the normal pituitary. This observation demonstrates that pS337 is a marker for Cushing's tumors and suggests that phosphorylation of E2F1 may be a target for developing a novel pharmacological treatment for tumorigenesis and hormone dysregulation of Cushing's disease.

Gene expression profiles in parathyroid adenoma and normal parathyroid tissue

A parathyroid adenoma comprises 80-85% as a cause of primary hyperparathyroidism. The clonal origin of most parathyroid adenomas suggests a defect at the level of the gene controlling growth of the parathyroid cell or the expression of parathyroid hormone (PTH). Two genes, MEN1 and CCND1, a tumor suppressor and a proto-oncogene respectively, have been solidly established as primary tumorigenic drivers in parathyroid adenomas. As well, germline and somatic mutation of other genes involved in cell cycle regulation or PTH regulation have been discovered in parathyroid adenomas. Moreover, comparative genomic studies between parathyroid adenomas and normal parathyroid tissues have suggested more complex genetic landscape. Microarray analysis have revealed differential expression profiles of genes involved in cell cycle regulation, growth factors, apoptotic pathway, or PTH synthesis or regulation pathway such as CASR, GCM2 and KL (Klotho). Furthermore, recent next-generation sequencing analysis reconfirmed previous finding or revealed novel finding, suggesting signal peptidase complex subunit (SPCS2), ribosomal proteins (RPL23, RPL26, RPN1, RPS25), the endoplasmic reticulum membrane (SEC11C, SEC11A, SEC61G), Klotho, cyclin D1, β-catenin, VDR, CaSR and GCM2 may be important factors contributing to the parathyroid adenoma.

Phenotype-genotype correlation in aldosterone-producing adenomas characterized by intracellular cholesterol metabolism

Aldosterone-producing adenoma (APA) is histologically composed of clear and compact tumor cells. KCNJ5- mutated APAs were reported to be associated with higher plasma aldosterone concentration and more abundant clear tumor cells containing lipid droplets than non-KCNJ5- mutated APAs. However, the association among cholesterol uptake and/or synthesis, cellular morphology and genotypes has remained unknown. Therefore, in order to explore these differences, 52 APA cases (KCNJ5 mt: n = 33, non-KCNJ5 mt: n = 19; ATP1A1: n = 3, ATP2B3: n = 3, CACNA1D: n = 5, CTNNB1: n = 1, tumors without any mutation above: n = 7), zona glomerulosa (ZG) tissue adjacent to APA and 10 non-pathological adrenal glands (NAs) were examined for quantitative histopathological analysis of tumor morphology and immunohistochemical analysis of cholesterol receptors (SR-B1, LDL-R), cholesterol metabolic enzymes (ACAT1, ACAT2, HSL, DHCR24, StAR), and the enzymes required for steroid synthesis (CYP11A1, CYP17A, 3βHSD, CYP11B1, CYP11B2). Gas chromatography-mass spectrometry (GC-MS) analysis was further performed to profile cholesterol precursors and metabolites in 21 APA cases (KCNJ5 mt: n = 16, non-KCNJ5 mt: n = 5) and 14 adrenal cortex of adjacent adrenal tissues. Results demonstrated that both SR-B1 and DHCR24 were significantly lower in the ZG than in fasciculata or reticularis of NAs but LDL-R was not significantly different among them in immunohistochemical analysis. SR-B1 and DHCR24 were both significantly higher in APAs than in ZG tissue adjacent to APA. In GC-MS analysis, most cholesterol precursors and metabolites, except for lanosterol, and their metabolic ratios (= concentration of cholesterol/ precursor) were higher in APAs than in the adjacent adrenal cortex tissue. LDL-R, ACAT1/2, HSL, DHCR24 were all significantly lower in clear than in compact tumor cells of APA. LDL-R was significantly lower and cholesterol/lanosterol ratio was significantly higher in KCNJ5- mutated than non-KCNJ5- mutated APAs. We demonstrated SR-B1 mediated selective uptake of cholesterol ester and de novo cholesterol synthesis were both enhanced in APAs. In addition, cholesterol uptake and metabolism were different between clear and compact tumor cells. KCNJ5- mutated APAs were predominantly composed of clear tumor cells containing abundant cholesteryl ester but less activated LDL-R mediated uptake and increased de novo synthesis. Those findings above indicated their more pronounced functional deviation from the normal ZG cells in terms of their steroidogenic and intracellular cholesterol metabolism.

Immunohistochemical Profile of Parathyroid Tumours: A Comprehensive Review

Immunohistochemistry remains an indispensable tool in diagnostic surgical pathology. In parathyroid tumours, it has four main applications: to detect (1) loss of parafibromin; (2) other manifestations of an aberrant immunophenotype hinting towards carcinoma; (3) histogenesis of a neck mass and (4) pathogenetic events, including features of tumour microenvironment and immune landscape. Parafibromin stain is mandatory to identify the new entity of parafibromin-deficient parathyroid neoplasm, defined in the WHO classification (2022). Loss of parafibromin indicates a greater probability of malignant course and should trigger the search for inherited or somatic CDC73 mutations. Aberrant immunophenotype is characterised by a set of markers that are lost (parafibromin), down-regulated (e.g., APC protein, p27 protein, calcium-sensing receptor) or up-regulated (e.g., proliferation activity by Ki-67 exceeding 5%) in parathyroid carcinoma compared to benign parathyroid disease. Aberrant immunophenotype is not the final proof of malignancy but should prompt the search for the definitive criteria for carcinoma. Histogenetic studies can be necessary for differential diagnosis between thyroid vs. parathyroid origin of cervical or intrathyroidal mass; detection of parathyroid hormone (PTH), chromogranin A, TTF-1, calcitonin or CD56 can be helpful. Finally, immunohistochemistry is useful in pathogenetic studies due to its ability to highlight both the presence and the tissue location of certain proteins. The main markers and challenges (technological variations, heterogeneity) are discussed here in the light of the current WHO classification (2022) of parathyroid tumours.

Machine learning as a clinical decision support tool for patients with acromegaly

OBJECTIVE

To develop machine learning (ML) models that predict postoperative remission, remission at last visit, and resistance to somatostatin receptor ligands (SRL) in patients with acromegaly and to determine the clinical features associated with the prognosis.

METHODS

We studied outcomes using the area under the receiver operating characteristics (AUROC) values, which were reported as the performance metric. To determine the importance of each feature and easy interpretation, Shapley Additive explanations (SHAP) values, which help explain the outputs of ML models, are used.

RESULTS

One-hundred fifty-two patients with acromegaly were included in the final analysis. The mean AUROC values resulting from 100 independent replications were 0.728 for postoperative 3 months remission status classification, 0.879 for remission at last visit classification, and 0.753 for SRL resistance status classification. Extreme gradient boosting model demonstrated that preoperative growth hormone (GH) level, age at operation, and preoperative tumor size were the most important predictors for early remission; resistance to SRL and preoperative tumor size represented the most important predictors of remission at last visit, and postoperative 3-month insulin-like growth factor 1 (IGF1) and GH levels (random and nadir) together with the sparsely granulated somatotroph adenoma subtype served as the most important predictors of SRL resistance.

CONCLUSIONS

ML models may serve as valuable tools in the prediction of remission and SRL resistance.

The microenvironment of pituitary adenomas: biological, clinical and therapeutical implications

The microenvironment of pituitary adenomas (PAs) includes a range of non-tumoral cells, such as immune and stromal cells, as well as cell signaling molecules such as cytokines, chemokines and growth factors, which surround pituitary tumor cells and may modulate tumor initiation, progression, invasion, angiogenesis and other tumorigenic processes. The microenvironment of PAs has been actively investigated over the last years, with several immune and stromal cell populations, as well as different cytokines, chemokines and growth factors being recently characterized in PAs. Moreover, key microenvironment-related genes as well as immune-related molecules and pathways have been investigated, with immune check point regulators emerging as promising targets for immunotherapy. Understanding the microenvironment of PAs will contribute to a deeper knowledge of the complex biology of PAs, as well as will provide developments in terms of diagnosis, clinical management and ultimately treatment of patients with aggressive and/or refractory PAs.

The p300 Inhibitor A-485 Exerts Antitumor Activity in Growth Hormone Pituitary Adenoma

CONTEXT

Growth hormone pituitary adenoma (GHPA), a major subtype of pituitary adenoma (PA), can lead to progressive somatic disfigurement, multiple complications, and even increased mortality. The efficacy of current treatments is limited; thus, a novel pharmacological treatment is urgently needed. As a histone acetyltransferase (HAT) coactivator, p300 can regulate the transcription of several genes that are crucial for PA tumorigenesis and progression. However, the role of p300 and its catalytic inhibitor in GHPA is still unclear.

OBJECTIVE

We aimed to identify the expression of p300 in GHPA and in normal pituitary glands.

METHODS

The expression of p300 was detected in GHPA and normal pituitary tissues. Genetic knockdown was performed by siRNA. The efficacy of the p300 inhibitor A-485 in the cell cycle, proliferation, apoptosis, and hormone secretion was investigated by flow cytometry, ELISAs, Western blotting, and qRT-PCR. RNA sequencing, bioinformatic analysis, and subsequent validation experiments were performed to reveal the potential biological mechanism of A-485.

RESULTS

High expression of p300 was found in GHPA tissues compared with normal pituitary tissues. Knockdown of p300 inhibited cell proliferation and clone formation. Treatment with A-485 suppressed cell growth and inhibited the secretion of GH in vitro and in vivo. Further mechanistic studies showed that A-485 could downregulate the expression or activity of several oncogenes, such as genes in the Pttg1, c-Myc, cAMP and PI3K/AKT/mTOR signaling pathways, which are crucial for PA tumorigenesis and progression.

CONCLUSION

Our findings demonstrate that inhibition of HAT p300 by its selective inhibitor A-485 is a promising therapy for GHPA.

Quantitative Ubiquitinomics Revealed Abnormal Ubiquitinated ATP7A Involved in Down-Regulation of ACTH in Silent Corticotroph Adenomas

Ubiquitination is reported to be a critical biological event on ACTH secretion in corticotroph adenomas. However, the effect of ubiquitylation on ACTH secretion in silent corticotroph adenomas (SCAs) remains unclear. The aim of our study was to explore the mechanism of decreased secretion of ACTH in SCAs with ubiquitinomics. The differently expressed ubiquitinated proteins between SCAs and functioning corticotroph adenomas (FCAs) were identified by 4D label-free mass spectrometer, followed by bioinformatics analysis. The function of the candidate ubiquitinated protein ATP7A (K333) was validated in AtT20 cells. A total of 111 ubiquitinated sites corresponding to 94 ubiquitinated proteins were typically different between SCAs and FCAs. Among all the ubiquitinated sites, 102 showed decreased ubiquitination in SCAs, which mapped to 85 ubiquitinated proteins. Pathway enrichment analysis revealed that ubiquitinated proteins were mainly enriched in vesicle pathway and protein secretion pathway. ATP7A (K333) was one of the proteins enriched in vesicle pathway and protein secretion pathway with decreased ubiquitination level in SCAs. In vitro assay indicated that both ATP7A siRNA and omeprazole (ATP7A protein inhibitor) increased the secretion of ACTH in AtT20 cell supernatant compared to control groups (p<0.05). These results indicated that ATP7A might be related to the abnormal expression of ACTH in SCAs and potential for the treatment of SCAs.

Impact of RSUME Actions on Biomolecular Modifications in Physio-Pathological Processes

The small RWD domain-containing protein called RSUME or RWDD3 was cloned from pituitary tumor cells with increasing tumorigenic and angiogenic proficiency. RSUME expression is induced under hypoxia or heat shock and is upregulated, at several pathophysiological stages, in tissues like pituitary, kidney, heart, pancreas, or adrenal gland. To date, several factors with essential roles in endocrine-related cancer appear to be modulated by RWDD3. RSUME regulates, through its post-translational (PTM) modification, pituitary tumor transforming gene (PTTG) protein stability in pituitary tumors. Interestingly, in these tumors, another PTM, the regulation of EGFR levels by USP8, plays a pathogenic role. Furthermore, RSUME suppresses ubiquitin conjugation to hypoxia-inducible factor (HIF) by blocking VHL E3-ubiquitin ligase activity, contributing to the development of von Hippel-Lindau disease. RSUME enhances protein SUMOylation of specific targets involved in inflammation such as IkB and the glucocorticoid receptor. For many of its actions, RSUME associates with regulatory proteins of ubiquitin and SUMO cascades, such as the E2-SUMO conjugase Ubc9 or the E3 ubiquitin ligase VHL. New evidence about RSUME involvement in inflammatory and hypoxic conditions, such as cardiac tissue response to ischemia and neuropathic pain, and its role in several developmental processes, is discussed as well. Given the modulation of PTMs by RSUME in neuroendocrine tumors, we focus on its interactors and its mode of action. Insights into functional implications and molecular mechanisms of RSUME action on biomolecular modifications of key factors of pituitary adenomas and renal cell carcinoma provide renewed information about new targets to treat these pathologies.