RT-PCR analysis of corticotroph-associated genes expression in carcinoid tumours in the ectopic-ACTH syndrome

Paraneoplastic isolated adrenocorticotropic hormone deficiency revealed after immune checkpoint inhibitors therapy: new insights into anti-corticotroph antibody

Introduction

A recently discovered facet of paraneoplastic adrenocorticotropic hormone (ACTH) deficiency exists in two forms: a paraneoplastic spontaneous isolated ACTH deficiency (IAD) and an immune checkpoint inhibitor (ICI)-related hypophysitis. Autoantibodies against corticotrophs, such as circulating anti-proopiomelanocortin (POMC) antibodies are considered disease markers. However, the number of identified cases was limited, implying that the characteristics of these autoantibodies are not fully understood.

Methods

We investigate circulating autoimmune autoantibodies in detail through a novel case of IAD that developed as a paraneoplastic autoimmune ACTH deficiency.

Results

The patient developed IAD after 25 weeks of ICI therapy for metastasis of large-cell neuroendocrine carcinoma at 69 years of age. Ectopic ACTH expression and infiltration of CD3+, CD4+, CD8+, and CD20+ lymphocytes were observed in the tumor tissues and circulating anti-POMC antibodies were detected specifically in the patient's serum. Moreover, detailed analyses of immunofluorescence staining using patient serum revealed that the recognition site of the autoantibody was ACTH25-39, which had not been identified in previous cases of paraneoplastic autoimmune ACTH deficiency.

Conclusion

This case involved a combination of paraneoplastic spontaneously acquired IAD and ICI-related hypophysitis occupying the middle ground. Moreover, our study reveals new aspects of anti-POMC antibodies in patients with paraneoplastic ACTH deficiency. This report expands our understanding of the immunological landscape and provides new insights for the identification of antibodies associated with paraneoplastic autoimmune ACTH deficiency.

Paediatric and adolescent ectopic Cushing's syndrome: systematic review

OBJECTIVE

The data on clinical, biochemical, radiological characteristics, and outcomes in paediatric ectopic adrenocorticotropic hormone syndrome (EAS) are limited owing to rarity of the condition. We report three new cases and perform a systematic review of paediatric EAS.

DESIGN AND METHOD

Case records of paediatric and adolescent EAS patient's ≤20 years presenting at our centre between 1997 and 2021 were retrospectively reviewed, and a systematic review of the literature published between January 1970 and December 2022 was performed.

RESULTS

A total of 161 patients including 3 new patients from our centre were identified. Bronchial neuroendocrine tumours (NET) (28.5%), thymic NET (22.9%), primitive cell-derived tumours (18.6%), and gastro-entero-pancreatic-NET (13.7%) were the common causes. Primitive cell-derived tumours were the most common in the first decade (24/45, 53.4%) and were the largest (82 [60-100] mm), whereas bronchial NETs predominated during the second decade (42/116, 36.2%) and were the smallest (15 [10-25] mm). Computed tomography localized 92.9% (118/127) of paediatric EAS patients. Immediate postoperative remission was attained in 77.9% (88/113) patients, whereas 30.4% (24/79) relapsed over a median (IQR) period of 13 (8-36) months. Over a median (IQR) follow-up of 2 (0.6-4.6) years, 31.4% of patients died. The median survival was higher in bronchial NET than in other tumour groups. Distant metastasis and tumour size were independent negative predictors of survival.

CONCLUSIONS

Aetiological profile of paediatric and adolescent EAS is distinct from that of adults. Bronchial NETs have the best long-term survival, whereas distant metastasis and tumour size predict poor survival.

Biochemical testing to differentiate Cushing's disease from ectopic ACTH syndrome

The differential diagnosis of ACTH-dependent Cushing's syndrome is often a diagnostic challenge that has been debated in numerous studies. In this short article, we will discuss the performance and main drawbacks of the biochemical tests used for this diagnosis.

The novel concept of "Onco-Immuno-Endocrinology" led to the discovery of new clinical entity "paraneoplastic autoimmune hypophysitis"

Recent advances in tumor immunology have enabled to develop immune checkpoint inhibitors and to save many patients with advanced cancer. Various endocrine diseases are caused by autoimmune mechanisms; it is important to understand that many endocrine organs are targeted by autoimmunity. In addition, some of malignant tumors ectopically produce hormones and lead to a clinically relevant ectopic hormone syndrome as an endocrine paraneoplastic syndrome. Thus, interplay between oncology, immunology, and endocrinology is important. We have defined a new clinical entity "paraneoplastic autoimmune hypophysitis" as "hypophysitis associated with autoimmunity against pituitary antigens caused by an ectopic expression of these antigens in the tumor and resulting in a breakdown of immune tolerance". To understand the pathophysiology of paraneoplastic autoimmune hypophysitis requires a fusion of the fields of oncology, immunology, and endocrinology; therefore, I propose a new concept of Onco-Immuno-Endocrinology.

Paraneoplastic autoimmune hypophysitis: An emerging concept

Pituitary autoimmunity is one of the principal causes of hypopituitarism. Additionally, hypophysitis is one of the immune-related adverse events associated with immunotherapy. Recent case-oriented research has revealed a novel type of autoimmune hypophysitis, anti-PIT-1 hypophysitis, related to isolated adrenocorticotropic hormone (ACTH) deficiency and immune checkpoint inhibitor-related hypophysitis, as a form of paraneoplastic syndrome. Under these conditions, the ectopic expression of pituitary antigens present in tumors evokes a breakdown of immune tolerance, resulting in the production of autoantibodies and autoreactive cytotoxic T cells that specifically harm pituitary cells. Consequently, an innovative clinical entity of paraneoplastic autoimmune hypophysitis has been purported. This novel concept and its underlying mechanisms provide clues for understanding the pathogenesis of autoimmune pituitary diseases and can be applied to other autoimmune diseases. This review discusses the etiology of paraneoplastic autoimmune hypophysitis and its future.

Consensus statement by the French Society of Endocrinology (SFE) and French Society of Pediatric Endocrinology & Diabetology (SFEDP) on diagnosis of Cushing's syndrome

Cushing's syndrome is defined by prolonged exposure to glucocorticoids, leading to excess morbidity and mortality. Diagnosis of this rare pathology is difficult due to the low specificity of the clinical signs, the variable severity of the clinical presentation, and the difficulties of interpretation associated with the diagnostic methods. The present consensus paper by 38 experts of the French Society of Endocrinology and the French Society of Pediatric Endocrinology and Diabetology aimed firstly to detail the circumstances suggesting diagnosis and the biologic diagnosis tools and their interpretation for positive diagnosis and for etiologic diagnosis according to ACTH-independent and -dependent mechanisms. Secondly, situations making diagnosis complex (pregnancy, intense hypercortisolism, fluctuating Cushing's syndrome, pediatric forms and genetically determined forms) were detailed. Lastly, methods of surveillance and diagnosis of recurrence were dealt with in the final section.

Consensus on diagnosis and management of Cushing's disease: a guideline update

Cushing's disease requires accurate diagnosis, careful treatment selection, and long-term management to optimise patient outcomes. The Pituitary Society convened a consensus workshop comprising more than 50 academic researchers and clinical experts to discuss the application of recent evidence to clinical practice. In advance of the virtual meeting, data from 2015 to present about screening and diagnosis; surgery, medical, and radiation therapy; and disease-related and treatment-related complications of Cushing's disease summarised in recorded lectures were reviewed by all participants. During the meeting, concise summaries of the recorded lectures were presented, followed by small group breakout discussions. Consensus opinions from each group were collated into a draft document, which was reviewed and approved by all participants. Recommendations regarding use of laboratory tests, imaging, and treatment options are presented, along with algorithms for diagnosis of Cushing's syndrome and management of Cushing's disease. Topics considered most important to address in future research are also identified.

Autoimmune Pituitary Disease: New Concepts With Clinical Implications

Some endocrine disorders, including hypophysitis and isolated adrenocorticotropic hormone (ACTH) deficiency, are caused by an autoimmune response to endocrine organs. Although the pathogenesis of some autoimmune endocrine diseases has been elucidated, it remains obscure for most. Anti-PIT-1 hypophysitis (anti-PIT-1 antibody syndrome) is a newly described pituitary autoimmune disease characterized by acquired and specific growth hormone (GH), prolactin (PRL), and thyroid-stimulating hormone (TSH) deficiencies. This disorder is associated with a thymoma or neoplasm that ectopically expresses pituitary-specific transcription factor 1 (PIT-1) protein. Circulating anti-PIT-1 antibody is a disease marker, and PIT-1-reactive cytotoxic T cells (CTLs) play a pivotal role in disease development. In addition, isolated ACTH deficiency appears to be caused by autoimmunity to corticotrophs; however, the pathogenesis remains unclear. A recently described case of isolated ACTH deficiency with large cell neuroendocrine carcinoma (LCNEC) showed ectopically expressed proopiomelanocortin (POMC), and circulating anti-POMC antibody and POMC-reactive CTLs were also detected. As CTL infiltrations around corticotrophs were also observed, isolated ACTH deficiency may be associated at least in part with a paraneoplastic syndrome. Although several underlying mechanisms for pituitary autoimmunity have been proposed, these observations highlight the importance of paraneoplastic syndrome as a cause of pituitary autoimmune disease. In this review, we focus on the pathophysiology and connection of anti-PIT-1 hypophysitis and isolated ACTH deficiency and discuss the state-of-art knowledge for understanding pituitary autoimmunity.

Molecular analysis and literature-based hypothesis of an immunonegative prostate small cell carcinoma causing ectopic ACTH syndrome

Ectopic ACTH syndrome (EAS) due to a prostate small cell carcinoma (SCC) is very rare with only 26 cases reported to date and has a poor prognosis. We here describe another case of this disorder that was clinically typical based on prior reports as it showed hypercortisolemia and severe hypokalemia with multiple metastasis. However, our current case of prostate SCC causing EAS is the first to display negative immunostaining for ACTH despite detectable POMC mRNA expression in the primary lesion. ACTH immunonegativity is thought to be associated with a more aggressive disease course and a poorer prognosis although there are few studies of the underlying mechanisms. We explored two possibilities for this finding in our current patient: aberrant POMC processing prevented immunodetection with an anti-ACTH antibody; and the ACTH content per cell was below the threshold for immunodetection due to its rapid secretion or low synthesis. The aberrant processing theory was thought to be less likely because of immunonegative findings even using anti-POMC/ACTH antibodies. As the plasma ACTH levels in our patient were comparable with those reported for previous immunopositive prostate EAS cases, we speculated that the depletion of ACTH may be caused not only by rapid secretion but also by low production levels as a sign of de-differentiation. De-differentiation may therefore explain the mechanism underlying the negative correlation between immunoreactivity for ACTH in EAS and disease aggressiveness. We believe that our present findings will be of use in future prospective studies aimed at confirming the mechanism of immunonegativity.

Recommendations of the Neuroendocrinology Department of the Brazilian Society of Endocrinology and Metabolism for the diagnosis of Cushing's disease in Brazil

Although it is a rare condition, the accurate diagnosis and treatment of Cushing's disease is important due to its higher morbidity and mortality compared to the general population, which is attributed to cardiovascular diseases, diabetes mellitus and infections. Screening for hypercortisolism is recommended for patients who present multiple and progressive clinical signs and symptoms, especially those who are considered to be more specific to Cushing's syndrome, abnormal findings relative to age (e.g., spinal osteoporosis and high blood pressure in young patients), weight gain associated with reduced growth rate in the pediatric population and for those with adrenal incidentalomas. Routine screening is not recommended for other groups of patients, such as those with obesity or diabetes mellitus. Magnetic resonance imaging (MRI) of the pituitary, the corticotropin-releasing hormone (CRH) test and the high-dose dexamethasone suppression test are the main tests for the differential diagnosis of ACTH-dependent Cushing's syndrome. Bilateral and simultaneous petrosal sinus sampling is the gold standard method and is performed when the triad of initial tests is inconclusive, doubtful or conflicting. The aim of this article is to provide information on the early detection and establishment of a proper diagnosis of Cushing's disease, recommending follow-up of these patients at experienced referral centers. Arch Endocrinol Metab. 2016;60(3):267-86.

[Cushing syndrome: Physiopathology, etiology and principles of therapy]

The most frequent cause of Cushing's syndrome is iatrogenic, as Cushing's syndrome is the unavoidable consequence of long-term glucocorticoid treatment using more than 7.5 mg prednisone per day. The most frequent cause of endogenous Cushing's syndrome is Cushing's disease (CD), which is an ACTH dependent hypercortisolism linked to a pituitary corticotroph adenoma. This adenoma is often very small, its diagnosis may require bilateral inferior petrosal sinus sampling and the first line treatment of CD is transsphenoidal surgery by an expert neurosurgeon. The second line treatments include drugs that can act either on the pituitary adenoma or on adrenal steroidogenesis, pituitary radiotherapy or bilateral adrenalectomy. Ectopic ACTH dependent Cushing's syndrome is linked either to poorly differentiated endocrine tumors with a very poor prognosis, such as small cell lung cancer, or to well differentiated endocrine tumors, such as bronchial carcinoid tumors, which have a good prognosis when treated by surgery, but may be very difficult to localize. Adrenal Cushing's syndromes, which are independent of pituitary ACTH secretion, include adrenal cortex carcinoma, which requires abdominal surgery with extended adrenalectomy by an expert surgeon, adrenal adenoma which is treated by laparoscopic unilateral adrenalectomy and bilateral macronodular hyperplasia, whose surgical treatment may require unilateral or bilateral adrenalectomy. Treatment of Cushing's syndrome generally leads to spectacular clinical results, which must not hide the fact that the reversibility of some signs is actually incomplete. This underlines the need for a timely multidisciplinary management of the patients by an expert team.

Differential gene expression profiles of POMC-related enzymes, transcription factors and receptors between non-pituitary and pituitary ACTH-secreting tumors

The differential gene expression of proopiomelanocortin (POMC)-related processing enzymes, transcription factors, and receptors responsible for ACTH secretion between non-pituitary and pituitary ACTH-secreting tumors remains obscure. This study was attempted to determine the gene expression profiles of transcription factors (Tpit, NeuroD1 and IKZF1), proprotein convertase (PC) 1/3 and PC2, and several key receptors linked to ACTH secretion, including corticotrophin releasing hormone receptor (CRHR1), vasopressin receptor 1b (V1bR), somatostatin receptor (SSTR) subtype-2, -5 and dopamine receptor type 2 (D2R) in non-pituitary and pituitary ACTH-secreting tumors. Surgical tissue specimens from carcinoid tumors causing ectopic ACTH syndrome (EAS: n=4) and pituitary tumors causing Cushing's disease (CD: n=13), were subjected to real-time RT-PCR for measurements of each mRNA levels. POMC and CRHR1 mRNA levels in CD were far greater than those in EAS, whereas IKZF1, PC2, SSTR-2 and -5 mRNA levels in EAS were significantly greater than those in CD. NeuroD1, Tpit, PC1/3, V1bR and D2R mRNA levels were comparable between EAS and CD. In conclusion, differential gene expression profiles revealed more abundant mRNA expression in EAS than in CD of 1) IKZF1 with its potential implication of cell differentiation and hormone secretion, 2) PC2 with its possible enhanced processing activity of mature ACTH, and 3) SSTR-2 and -5 with their potential therapeutic application of more selective agonists in EAS patients.

The multiple endocrine neoplasia type 1 (MEN1) tumor suppressor regulates peroxisome proliferator-activated receptor gamma-dependent adipocyte differentiation

Menin, the product of the MEN1 (multiple endocrine neoplasia type 1) tumor suppressor gene, is involved in activation of gene transcription as part of an MLL1 (mixed-lineage leukemia 1)/MLL2 (KMT2A/B)-containing protein complex which harbors methyltransferase activity for lysine 4 of histone H3 (H3K4). As MEN1 patients frequently develop lipomas and peroxisome proliferator-activated receptor gamma (PPARgamma) is expressed in several MEN1-related tumor types, we investigated regulation of PPARgamma activity by menin. We found that menin is required for adipocyte differentiation of murine 3T3-L1 cells and PPARgamma-expressing mouse embryonic fibroblasts. Menin augments PPARgamma target gene expression through recruitment of H3K4 methyltransferase activity. Menin interacts directly with the activation function 2 transcription activation domain of PPARgamma in a ligand-independent fashion. Ligand-dependent coactivation, however, is dependent on the LXXLL motif of menin and the intact helix 12 of PPARgamma. We propose that menin is an important factor in PPARgamma-mediated adipogenesis and that loss of PPARgamma function may contribute to lipoma development in MEN1 patients.

Expression of pituitary homeobox 1 gene in human gastric carcinogenesis and its clinicopathological significance

AIM: To investigate the effect of pituitary homeobox 1 (PITX1) expression in cases of human gastric cancer on cancer differentiation and progression, and carcinogenesis.

METHODS: Using polyclonal PITX1 antibodies, we studied the expression of PITX1 in normal gastric mucosa, atypical hyperplasia, intestinal metaplasia, and cancer tissue samples from 83 gastric cancer patients by immunohistochemistry. Moreover, semi-reverse transcription polymerase chain reaction (semi-RT-PCR) was performed to detect the mRNA level of PITX1 in three gastric cancer cell lines and a normal gastric epithelial cell line. Subsequently, somatic mutations of the PITX1 gene in 71 gastric cancer patients were analyzed by a combination of denaturing high performance liquid chromatography (DHPLC) and DNA sequencing.

RESULTS: Immunohistochemistry showed that PITX1 was strongly or moderately expressed in the parietal cells of normal gastric mucosa (100%), while 55 (66.3%) out of 83 samples of gastric cancers showed decreased PITX1 expression. Moreover, PITX1 expression was reduced in 20 out of 28 cases (71.5%) of intestinal metaplasia, but in only 1 out of 9 cases (11%) of atypical hyperplasia. More importantly, PITX1 expression was significantly associated with the differentiation, position and invasion depth of gastric cancers (r = -0.316, P < 0.01; r = 0.213, P < 0.05; r = -0.259, P < 0.05, respectively). Similarly, levels of PITX1 mRNA were significantly decreased in 2 gastric cancer cell lines, BGC-823 and SGC-7901, compared with the normal gastric epithelial cell line GES-1 (0.306 ± 0.060 vs 0.722 ± 0.102, P < 0.05; 0.356 ± 0.081 vs 0.722 ± 0.102, P < 0.05, respectively). Nevertheless, no somatic mutation of PITX1 gene was found in 71 samples of gastric cancer by DHPLC analysis followed by sequencing.

CONCLUSION: Down-regulation of PITX1 may be a frequent molecular event in gastric carcinogenesis. Aberrant levels of PITX1 expression may be closely correlated with the progression and differentiation of gastric cancer.

Peroxisome proliferator-activated receptor gamma in the human pituitary gland: expression and splicing pattern in adenomas versus normal pituitary

Pituitary adenomas are slow-growing tumours arising within the pituitary gland. If secreting, they give rise to well-known syndromes such as Cushing's disease or acromegaly; when hormonally inactive, they come to clinical attention often with local mass effects or pituitary deficiency. Peroxisome proliferator-activated receptor gamma (PPARgamma), a nuclear hormone receptor with a key role in fat and glucose metabolism, but also involved in several neoplasia, has recently been detected in pituitary adenomas. In the present study, we evaluated the occurrence and splicing profile of PPARgamma in 43 cases of pituitary adenoma of different subtypes and compared it to 12 normal pituitary glands. By real-time polymerase chain reaction, PPARgamma was expressed as much in adrenocorticotrophic hormone (ACTH)-secreting and ACTH-silent adenomas as in controls, with a moderate underexpression in somatotrophinomas and prolactinomas and overexpression in 54% of nonfunctioning pituitary adenomas (NFPA). There was no apparent qualitative change in the splicing profile of pathological pituitary glands, nor was the presence of specific isoforms with dominant negative effects against PPARgamma detected. Western blotting revealed similar expression levels in the different subgroups of pituitary adenomas and normal glands. Immunohistochemistry confirmed PPARgamma expression in approximately one-half of analysed samples. The intra- and intergroup differences observed in pituitary adenomas may represent new elements in the process of understanding the different clinical responses of Cushing's and Nelson patients to PPARgamma-ligand treatment. Moreover, the higher level of PPARgamma expression detected in the NFPA subgroup may suggest its possible role as a molecular target in these pituitary adenomas, paving the way for investigations on the effectiveness of treatment with thiazolidinediones in such patients.

Decreased PITX1 homeobox gene expression in human lung cancer

The PITX1 (pituitary homeobox 1) gene has essential roles in human development and has been considered a tumor suppressor in various cancers. However, in lung cancer the role of PITX1 remains to be elucidated. In this study, we analyzed the expression of PITX1 at both mRNA and protein levels in human lung cancer. The reduced PITX1 expression was found in cancer cell lines test compared to normal human bronchial epithelia cells (HEBC) and small airway epithelia cells (SAEC) by Northern blot analysis and RT-PCR as well as Western blot analysis. In primary lung tissues, PITX1 mRNA was found to be downregulated in the majority of tumors compared with normal lung tissues. An association between the lack of PITX1 mRNA expression and higher tumor grade was observed. A tissue microarray containing 135 primary lung carcinomas was analyzed by immunohistochemistry. Eighty-four cases (62%) exhibited no expression of PITX1 and the lower expression of PITX1 was significantly linked to higher tumor stages. Additionally, PITX1 was found to be upregulated in lung cancer cell lines H2228 and H526 after they were exposed to a differentiation modifying agent 5-bromodeoxyuridine (BrdU). Since homeobox genes are known to transcriptionally regulate key cellular processes and associated with differentiation and carcinogenesis, we suggest that PITX1 might be linked to lung cancer development and progression.