Long-term outcomes of neuroendoscopic cyst partial resection combined with stereotactic radiotherapy for craniopharyngioma.

PURPOSE: The aim of this study was to evaluate the treatment outcomes of neuroendoscopic cyst partial resection (ECPR) combined with stereotactic radiotherapy (SRT) for cystic craniopharyngiomas. METHODS: In this retrospective study, 22 craniopharyngioma patients undergoing ECPR combined with SRT were included. This combination therapy was indicated for suprasellar cystic craniopharyngiomas in patients whose pituitary function was preserved but would be difficult to preserve in direct surgery. The outcomes of combination therapy, including tumor control and postoperative visual and pituitary functions, were investigated. RESULTS: ECPR was safely performed, and cyst shrinkage was accomplished in all cases. After ECPR, visual function improved in 12 of 13 patients (92%) with visual field disturbance and did not deteriorate in any patients. Pituitary function was preserved in 14 patients (64%) and deteriorated in eight patients (36%) after ECPR. As a complication of ECPR, meningitis occurred because of a wound infection in one patient. In 18 of 22 patients (82%), the tumor was controlled without further treatment 19 - 87 months (median, 33 months) after SRT. Hypopituitarism was an adverse event after SRT in two of the 18 patients who achieved tumor control. Four patients (18%) had enlarged cysts after SRT. Postoperative pituitary function was significantly more likely to deteriorate in cases of extensive detachment from the ventricular wall, and retreatment was significantly more common in cases with hypothalamic extension. CONCLUSION: Although limited to some cases, ECPR combined with SRT is a less invasive and useful therapeutic option for suprasellar cystic craniopharyngiomas. However, its long-term prognosis requires further evaluation.

Effects of the Cortisol Milieu on Tumor-Infiltrating Immune Cells in Corticotroph Tumors.

CONTEXT: Corticotrophs are susceptible to lymphocyte cytotoxicity, as seen in hypophysitis, suggesting that an immunological approach may be a potential strategy for corticotroph-derived tumors. OBJECTIVE: We aimed to clarify whether corticotroph tumors that induce hypercortisolemia (ACTHomas) could be targets for immunotherapy. METHODS: Tumor-infiltrating immune cells were immunohistochemically analyzed. ACTHomas were compared with other pituitary tumors, and further divided into 3 different cortisol-exposed milieus: Naïve (ACTHomas without preoperative treatment), Met (ACTHomas with preoperative metyrapone), and SCA (silent corticotroph adenomas). A 3-dimensional cell culture of resected tumors was used to analyze the effects of immune checkpoint inhibitors. RESULTS: The number of tumor-infiltrating lymphocytes (TILs) was low in ACTHomas. Among these, the number of CD8+ cells was lower in ACTHomas than in both somatotroph and gonadotroph tumors (both P < .01). Then we compared the differences in TILs among Naïve, Met, and SCA. The number of CD4+ cells, but not CD8+ cells, was higher in both Met and SCA than in Naïve. Next, we investigated tumor-associated macrophages, which could negatively affect T cell infiltration. The numbers of CD163+ and CD204+ cells were positively associated with cortisol levels. Moreover, tumor size was positively correlated with the number of CD204+ cells. CONCLUSION: We found the possibility that ACTHomas were immunologically cold in a cortisol-independent manner. In contrast, the tumor infiltration of CD4+ cells and M2-macrophages were associated with the cortisol milieu. Future studies are needed to validate these results and develop effective immunotherapy while considering the cortisol milieu.

Clinical Factors Affecting Daily Dosage of Desmopressin Orally Disintegrating Tablets in Arginine Vasopressin Deficiency.

CONTEXT: Desmopressin orally disintegrating tablets (ODTs) are widely used to treat arginine vasopressin deficiency (AVP-D). However, limited information is available on the dosage regimen; the dosage for each patient is selected based on their response to the initiation dose. OBJECTIVE: To investigate the relationships between clinical characteristics and the daily dose of ODTs and to identify factors that affect ODT dosages. METHODS: This retrospective study included 209 adult patients with AVP-D. Patients were administered ODTs sublingually and instructed to restrict eating and drinking for 30 minutes after taking ODTs using a patient leaflet. ODT dose titration was conducted during hospitalization with close monitoring of urine output, body weight, and serum sodium levels. Multivariable linear regression models were applied to identify clinical factors associated with the daily dose of ODTs at discharge. We also evaluated the dosage at 1 year in 134 patients who were followed up in our hospital. RESULTS: The median daily dose of ODTs at discharge was 90 µg (IQR 60-120 µg). Multivariable linear regression models identified sex, age, and estimated creatinine clearance (eCCr) as significant factors associated with the daily dose of ODTs, with eCCr having the strongest effect. After excluding patients recovering from AVP-D, 71% of those followed up at our hospital took the same daily dose at 1 year after discharge. CONCLUSION: To achieve the safe and stable treatment of AVP-D, the daily dose of ODT needs to be selected based on a patient's sex, age, and eCCr under appropriate sublingual administration by patient education.

Touch imprint cytology is useful for the intraoperative pathological diagnosis of PitNETs' surgical margins.

Touch imprint cytology (TIC) and frozen section (FS) procedures are essential for intraoperative pathological diagnosis (IPD). They are invaluable tools for therapeutic decision-making, helping surgeons avoid under or overtreatment of patients. Pituitary neuroendocrine tumors (PitNETs) are generally small, slow-growing tumors with low-grade malignancy located at the base of the skull where it is impossible to maintain a wide tumor margin. Therefore, transsphenoidal surgery (TSS) should be performed with necessary caution, and with sufficient and minimal resection. Thus, this study aimed to evaluate the diagnostic accuracy of TIC for the diagnosis of PitNET and determine its ability to accurately evaluate the surgical margin compared to the FS procedure. A total of 104 fresh specimens from 28 patients who underwent TSS for PitNETs were examined using TIC and FS. TIC specimens were categorized according to the cell imprinting pattern. All specimens with a large number of neuroendocrine cells diffusely attached to the glass surfaces had PitNET components. Contrarily, no rich or diffuse cell attachments were observed in any non-tumoral endocrine cells. In conclusion, recognizing a pattern of endocrine cell adherence to glass is highly effective in IPD to certify the existence of a PitNET component.

Clinical decision-making based on 11C-methionine PET in recurrent Cushing's disease with equivocal MRI findings.

OBJECTIVE: Diagnosis and accurate localization of recurrent tumors in Cushing's disease (CD) are challenging, especially after multiple transsphenoidal surgeries (TSSs) or radiosurgery. Even experts face difficulties in detecting these recurrent tumors, and a favorable surgical outcome is not guaranteed. In this report, the authors aimed to determine the usefulness of 11C-methionine positron emission tomography (MET-PET) for evaluating patients with recurrent CD with inconclusive magnetic resonance imaging (MRI) lesions and to develop a treatment protocol for these cases. METHODS: In this retrospective study of patients with recurrent CD in the period between April 2018 and December 2022, the authors assessed the usefulness of MET-PET in determining whether equivocal MRI findings were recurrent tumors or postsurgical cavities and deciding further treatment options. All patients had undergone at least one TSS, and most had undergone multiple TSSs and had pathologically confirmed corticotroph tumors with hypercortisolemia. RESULTS: Overall, 15 patients with recurrent CD (10 females and 5 males) were included, all of whom had undergone MET-PET. All patients had been subjected to multiple treatments, including TSSs or radiosurgeries. Their MRI scans demonstrated less-enhanced lesions that were not confirmed as recurrences even with cutting-edge MRI because they could not be distinguished from postsurgical changes with confidence. MET uptake was positive in 8 patients (9 examinations) and negative in 7. Following MET-PET, repeat TSS was performed in 5 patients. Corticotroph tumors were identified in all 5 patients, even though one of them had negative MET uptake. The MET uptake precisely identified a tumor location on the opposite side of the MRI-suspected lesion in 2 patients. Meanwhile, patients with negative uptake and mild hypercortisolism were only observed. Nonsurgical options were also used in other patients: temozolomide (TMZ) was administered in 2 patients owing to a prior history of multiple TSSs and radiosurgery and the drug-resistant nature of the disease. TMZ was highly effective in these patients; their Cushing's symptoms ameliorated, and their adrenocorticotropic hormone and cortisol levels continued to decline. Interestingly, MET uptake disappeared following TMZ treatment. CONCLUSIONS: MET-PET is extremely useful for confirming equivocal lesions on MRI in patients with recurrent CD and for deciding further treatment options. The authors propose a novel protocol based on MET-PET results for treating patients with relapsing CD in whom the recurrent tumors cannot be confirmed with MRI.

Immunohistochemical and ultrastructural review of six cases previously diagnosed as null cell PitNETs.

Pituitary neuroendocrine tumors (PitNETs) lacking lineage affiliation are termed "null cell" PitNETs (NCTs). NCTs are characterized as being immunonegative for pituitary hormones as well as transcription factors. We analyzed the ultrastructure and immunohistochemistry of six hormone-negative and transcription factor (TPIT, PIT1, SF1)-negative PitNETs, with less than 1% immunoreactive cells. Histologically, three cases presented a perivascular pattern and pseudorosettes; the other three showed a solid pattern with oncocytic changes. Electron microscopic examination revealed poorly differentiated tumor cells with sparsely scattered secretory granules and intracellular organelles in all null cell tumors when compared with hormone-positive PitNETs. Two cases harbored a honeycomb Golgi (HG) structure, and three oncocytic tumors showed mitochondrial accumulation. The two HG cases were immunopositive for newly obtained TPIT (CL6251) and showed some adrenocorticotropic hormone-positive cells, while the remaining four were diffusely immunopositive for GATA3, with two SF1-positive cases identified in subsequent immunostaining. Thus, these six cases may be classified as two sparsely granulated corticotroph PitNETs, two gonadotroph PitNETs with SF1 re-staining, and two likely gonadotroph PitNETs with GATA3 immunostaining. No "true NCT" was detected among 1071 PitNETs, demonstrating the importance of precise diagnosis following the most recent criteria to improve therapeutic success.

Marked reduction of proteinuria after removal of a growth hormone-producing pituitary adenoma in a patient with focal segmental glomerulosclerosis: a case report and literature review.

Focal segmental glomerulosclerosis is a rare complication of acromegaly. A 74-year-old man was found to have acromegaly features such as enlargement of the forehead, nose, and hands. Laboratory tests showed a urine protein/creatinine ratio of 3.16 g/gCr and serum creatinine of 1.34 mg/dL. The levels of growth hormone and insulin-like growth factor I were markedly elevated, and the growth hormone level was not suppressed after 75 g oral glucose loading. Magnetic resonance imaging revealed a pituitary tumor with a diameter of 1.2 cm. Renal biopsy confirmed the diagnosis of focal segmental glomerulosclerosis. Transsphenoidal resection of the pituitary tumor led to remission of acromegaly and reduction in proteinuria highlighting the causal link between growth hormone overproduction and proteinuria. Treatment of acromegaly may be effective for acromegaly-associated focal segmental glomerulosclerosis.

Proteogenomic landscape and clinical characterization of GH-producing pituitary adenomas/somatotroph pituitary neuroendocrine tumors.

The clinical characteristics of growth hormone (GH)-producing pituitary adenomas/somatotroph pituitary neuroendocrine tumors (GHomas/somatotroph PitNETs) vary across patients. In this study, we aimed to integrate the genetic alterations, protein expression profiles, transcriptomes, and clinical characteristics of GHomas/somatotroph PitNETs to identify molecules associated with acromegaly characteristics. Targeted capture sequencing and copy number analysis of 36 genes and nontargeted proteomics analysis were performed on fresh-frozen samples from 121 sporadic GHomas/somatotroph PitNETs. Targeted capture sequencing revealed GNAS as the only driver gene, as previously reported. Classification by consensus clustering using both RNA sequencing and proteomics revealed many similarities between the proteome and the transcriptome. Gene ontology analysis was performed for differentially expressed proteins between wild-type and mutant GNAS samples identified by nontargeted proteomics and involved in G protein-coupled receptor (GPCR) pathways. The results suggested that GNAS mutations impact endocrinological features in acromegaly through GPCR pathway induction. ATP2A2 and ARID5B correlated with the GH change rate in the octreotide loading test, and WWC3, SERINC1, and ZFAND3 correlated with the tumor volume change rate after somatostatin analog treatment. These results identified a biological connection between GNAS mutations and the clinical and biochemical characteristics of acromegaly, revealing molecules associated with acromegaly that may affect medical treatment efficacy.

Resection of the Cavernous Sinus Medial Wall Improves Remission Rate in Functioning Pituitary Tumors: Retrospective Analysis of 248 Consecutive Cases.

BACKGROUND: The purpose of transsphenoidal surgery (TSS) for a functioning pituitary tumor (FPT) is to achieve endocrinological remission. The biggest challenge is aggressive tumor resection invading the cavernous sinus (CS). OBJECTIVE: To evaluate the effects of the medial wall of CS (MWCS) resection during FPT surgery. METHODS: Consecutive FPTs were reviewed for CS invasion (CSI) between April 2018 and December 2021. We operated on more than 250 FPTs, including 134 somatotroph tumors, 70 corticotroph tumors, 35 lactotroph tumors, and 9 thyrotroph tumors. RESULTS: The patients were classified into 3 groups based on the relationship between the tumor and the CS: group A (no clear wall invasion), in which MWCS was not removed because of no tumorous direct contact with MWCS (N = 92) and group B (possible wall invasion), where MWCS was removed because we were not confident of MWCS invasion (N = 102). Among these 102 patients, histological tumor invasion was confirmed in 45 of 79 patients (57%) for whom histology findings were available. Tumors invading the CS clearly during surgery were classified into the "clear CS invasion" (group C: N = 55) group. The overall complete remission rate in group B was 94%, which was as high as that in group A (87%). Moreover, we clarified that microscopic invasion of MWCS could not always be predicted from Knosp grading. CONCLUSION: MWCS invasion occurred in 57% of cases confirmed histologically where it was unclear during surgery, and its resection can improve the overall complete remission rate in FPT cases.

Apoplexy in sellar metastasis from papillary thyroid cancer: A case report and literature review.

Background: Pituitary metastasis from papillary thyroid cancer (PTC) is rare and only a few cases have been reported. Case Description: We report the case of a patient who presented with visual dysfunction and panhypopituitarism. Magnetic resonance imaging revealed a pituitary tumor and hydrocephalus. Transsphenoidal surgery had been indicated, but his surgery had been postponed due to COVID-19 pandemic. During that waiting period, he showed pituitary apoplexy with consciousness disturbance, resulting in acute adrenal insufficiency and diabetes insipidus. He was urgently hospitalized and underwent transsphenoidal surgery. Rapid and permanent pathological examinations have confirmed metastasis of PTC to the pituitary. The patient also underwent serial thyroidectomy. He was also suspected to have secondary hydrocephalus and underwent lumboperitoneal shunting after excluding cerebrospinal fluid metastasis. Thereafter, his cognitive dysfunction and performance status improved dramatically. Conclusion: To the best of our knowledge, this is the first patient with PTC who developed pituitary apoplexy secondary to metastasis.

Temozolomide and Capecitabine Treatment for an Aggressive Somatotroph Pituitary Tumor: A Case Report and Literature Review.

Aggressive somatotroph pituitary tumor that causes acromegaly is extremely rare and resists conventional treatments such as multiple surgeries, radiotherapies, and various types of somatostatin analogs. Here, we propose a novel treatment option for these rare cases by discussing our case and reviewing the literature. We experienced an aggressive somatotroph tumor in a 52-year-old woman with acromegaly. Not only could a complete remission of growth hormone (GH) and insulin-like growth factor-1 (IGF-1) not be obtained, but the tumor continued to grow and eventually recurred around the brainstem despite multidisciplinary treatments. We employed immunohistochemistry and a three-dimensional (3D) spheroid ex vivo assay to determine the best treatment option for this case. Although histology showed strong O 6-methylguanine DNA methyltransferase expression and high Ki-67 labeling index (22%), temozolomide (TMZ) combined with capecitabine (CAPTEM) treatment was performed based on the results of the patient-derived 3D spheroid ex vivo assay, which predicted more effective treatment with CAPTEM than with TMZ alone. Consequently, GH and IGF-1 levels were restored to normal range with remarkable tumor shrinkage after CAPTEM treatment. To the best of our knowledge, there have been even very few reports describing successful treatment for such aggressive and refractory somatotroph tumors and this is the first report showing the effectiveness of CAPTEM on refractory somatotroph tumor both ex vivo and in vivo.

Responsiveness to DDAVP in Cushing's disease is associated with USP8 mutations through enhancing AVPR1B promoter activity.

PURPOSE: To clarify the characteristics of Cushing's disease (CD) patients who respond to the desmopressin (DDAVP) test and its underlying mechanisms. METHODS: Forty-seven patients with CD who underwent DDAVP testing were included. Patients were divided into two groups: DDAVP test (+) (adrenocorticotropic hormone [ACTH] levels increased by ≥ 1.5-fold during the DDAVP test) and DDAVP test (-) (ACTH levels increased by < 1.5-fold). AVP receptor expression levels in these tumors were quantified using quantitative RT-PCR and immunohistochemistry. AVP receptor promoter activity was analyzed using a dual-luciferase reporter assay system. RESULTS: Females (96.9%) and USP8 mutants (85.7%) were more prevalent in the DDAVP test (+) than in the DDAVP test (-). Indeed, the ACTH and cortisol responsiveness to DDAVP was greater in USP8 mutation positive tumors than that in USP8 wild type tumors (3.0-fold vs. 1.3-fold, 1.6-fold vs. 1.1-fold, respectively). Responsiveness to DDAVP was correlated with the expression levels of AVPR1B, but not with those of AVPR2. Comparably, Avpr1b promoter activity was enhanced by the overexpression of mutant USP8 compared to the wild type. CONCLUSIONS: We found that the responsiveness of ACTH to DDAVP in CD was greater in tumors with USP8 mutations. The present data suggest that USP8 mutations upregulate the AVPR1B promoter activity. Additionally, we showed that the DDAVP test can predict the presence of USP8 mutations.

An extremely rare case of pituitary functioning gonadotroph microadenoma accompanied by ovarian hyperstimulation syndrome in a woman of reproductive age.

Objective: To report a case of pituitary functioning gonadotroph microadenoma accompanied by ovarian hyperstimulation syndrome (OHSS) in a woman of reproductive age. Design: A case report. Setting: Tertiary care unit of a university hospital. Patients: A 42-year-old parous woman with bilateral ovarian enlargement presumed to be secondary to a functioning gonadotroph pituitary microadenoma. Interventions: Oral contraceptives and endoscopic transsphenoidal surgery for adenoma that initially could not be visualized on a magnetic resonance imaging (MRI) scan. Main Outcome Measures: Medical and radiographic assessment of endogenously induced OHSS and its resolution after treatment. Results: The patient was diagnosed with OHSS secondary to elevations in endogenous levels of follicle-stimulating hormone (FSH). The cranial contrast-enhanced MRI scan did not show any apparent tumor in the pituitary gland. She was, therefore, treated with oral contraceptives, which resulted in a modest resolution of ovarian enlargement; however, this treatment became ineffective 3 years later. A small pituitary adenoma (maximum diameter of 8 mm) was suspected on repeated MRI (2 years after the first MRI). Selective adenomectomy was performed, which resulted in normalization of the ovarian size and resumption of regular menstrual cycles. Conclusions: We report a case of a functional pituitary microadenoma secreting FSH in quantities significant enough to result in OHSS. The excessive FSH production was resistant to medical therapy; however, surgical treatment was ultimately successful.

Studies on anti-rabphilin-3A antibodies in 15 consecutive patients presenting with central diabetes insipidus at a single referral center.

Central diabetes insipidus (CDI) is a rare condition caused by various underlying diseases including inflammatory and autoimmune diseases, and neoplasms. Obtaining an accurate definitive diagnosis of the underlying cause of CDI is difficult. Recently, anti-rabphilin-3A antibodies were demonstrated to be a highly sensitive and specific marker of lymphocytic infundibuloneurohypophysitis (LINH). Here, we report a detailed case series, and evaluated the significance of anti-rabphilin-3A antibodies in differentiating the etiologies of CDI. A prospective analysis was conducted in 15 consecutive patients with CDI from 2013 to 2020 at a single referral center. Anti-rabphilin-3A antibodies were measured and the relationship between antibody positivity and the clinical/histopathological diagnoses was evaluated. Among 15 CDI patients, the positive anti-rabphilin-3A antibodies were found in 4 of 5 LINH cases, 3 of 4 lymphocytic panhypophysitis (LPH) cases, one of 2 sarcoidosis cases, and one intracranial germinoma case, respectively. Two Rathke cleft cyst cases and one craniopharyngioma case were negative. This is the first report of anti-rabphilin-3A antibodies positivity in CDI patients with biopsy-proven LPH. Measurement of anti-rabphilin-3A antibodies may be valuable for differentiating CDI etiologies.

Pasireotide-resistant Refractory Cushing's Disease without Somatostatin Receptor 5 Expression.

Pasireotide, which has a high affinity for somatostatin receptor (SSTR) 5, has attracted attention as a new treatment for refractory Cushing's disease. The patient was a 28-year-old man. He had refractory Cushing's disease and underwent multiple surgeries, radiotherapy, and medication therapy. An examination of the adenoma by immunohistochemistry revealed a low SSTR5 expression. An USP8 mutation was not detected by reverse transcription polymerase chain reaction. Although we administered pasireotide, it was ineffective. While a further investigation is necessary, the analysis of SSTR5 expression may support the prediction of the efficiency of pasireotide for Cushing's disease. We report this case as a useful reference when considering whether or not to use pasireotide for refractory corticotroph adenomas.

Efficacy of temozolomide combined with capecitabine (CAPTEM) on refractory prolactinomas as assessed using an ex vivo 3D spheroid assay.

PURPOSE: Refractory prolactinomas resistant to dopamine agonists (DAs) pose a clinical challenge. Temozolomide (TMZ) is a recommended treatment option, but its effects are difficult to predict, and the alternatives are limited. Recent reports suggested that TMZ combined with capecitabine (CAPTEM) can be effective for the treatment of aggressive pituitary tumors. This study sought to evaluate the effect of TMZ in an ex vivo three-dimensional (3D) spheroid culture assay and determine if this assay could be used to predict the therapeutic effect of CAPTEM in actual refractory prolactinomas. METHODS: Surgically resected tumor tissues from two patients with refractory prolactinoma were cultured as 3D spheroids. The effects of TMZ were assessed based on its suppression of cell viability and reduction of prolactin (PRL) levels. RESULTS: In Case 1, the 3D culture assay showed no effect of TMZ on cell viability or PRL suppression. Clinically, TMZ treatment did not reduce PRL levels (8870→8274 ng/mL) and the tumor progression. However, CAPTEM partially reduced PRL levels (9070→4046 ng/mL) and suppressed the tumor growth. In Case 2, TMZ in the 3D culture assay showed a 50% reduction of cell viability and 40% reduction of PRL levels. Clinically, CAPTEM was highly effective, with a considerable reduction in PRL level (17,500→210 ng/mL), and MRI showed almost no residual tumor. CONCLUSIONS: This is the first report to describe the effects of CAPTEM treatment on refractory prolactinomas. The ex vivo 3D spheroid culture assay reliably predicted TMZ sensitivity and informed the selection between TMZ or CAPTEM treatment for refractory prolactinomas.

Tumor Shrinkage by Metyrapone in Cushing Disease Exhibiting Glucocorticoid-Induced Positive Feedback.

CONTEXT: Paradoxical increases in serum cortisol in the dexamethasone suppression test (DST) have been rarely observed in Cushing disease (CD). Its pathophysiology and prevalence remain unclear. CASE DESCRIPTION: A 62-year-old woman with suspected CD showed paradoxical increases in cortisol after both 1-mg and 8-mg DST (1.95-fold and 2.52-fold, respectively). The initiation of metyrapone paradoxically decreased plasma adrenocorticotropic hormone (ACTH) levels and suppressed cortisol levels. Moreover, the pituitary tumor considerably shrank during metyrapone treatment. EX VIVO EXPERIMENTS: The resected tumor tissue was enzymatically digested, dispersed, and embedded into Matrigel as 3D cultured cells. ACTH levels in the media were measured. In this tumor culture, ACTH levels increased 1.3-fold after dexamethasone treatment (P < 0.01) while control tumor cultures exhibited no increase in ACTH levels, but rather a 20% to 40% suppression (P < 0.05). CLINICAL STUDY: A cross-sectional, retrospective, multicenter study that included 92 patients with CD who underwent both low-dose and high-dose DST from 2014 to 2020 was performed. Eight cases (8.7%) showed an increase in serum cortisol after both low-dose and high-dose DST. CONCLUSION: This is the first report of a patient with glucocorticoid (GC)-driven positive feedback CD who showed both ACTH suppression and tumor shrinkage by metyrapone. Our cohort study revealed that 8.7% of patients with CD patients possibly possess GC-driven positive-feedback systems, thereby suggesting the presence of a new subtype of CD that is different from the majority of CD cases. The mechanisms exhibiting GC positive feedback in CD and the therapeutic approach for these patients remain to be investigated.

Two Distinctive POMC Promoters Modify Gene Expression in Cushing Disease.

CONTEXT: Mechanisms underlying pituitary corticotroph adenoma adrenocorticotropin (ACTH) production are poorly understood, yet circulating ACTH levels closely correlate with adenoma phenotype and clinical outcomes. OBJECTIVE: We characterized the 5' ends of proopiomelanocortin (POMC) gene transcripts, which encode the precursor polypeptide for ACTH, in order to investigate additional regulatory mechanisms of POMC gene transcription and ACTH production. METHODS: We examined 11 normal human pituitary tissues, 32 ACTH-secreting tumors, as well as 6 silent corticotroph adenomas (SCAs) that immunostain for but do not secrete ACTH. RESULTS: We identified a novel regulatory region located near the intron 2/exon 3 junction in the human POMC gene, which functions as a second promoter and an enhancer. In vitro experiments demonstrated that CREB binds the second promoter and regulates its transcriptional activity. The second promoter is highly methylated in SCAs, partially demethylated in normal pituitary tissue, and highly demethylated in pituitary and ectopic ACTH-secreting tumors. In contrast, the first promoter is demethylated in all POMC-expressing cells and is highly demethylated only in pituitary ACTH-secreting tumors harboring the ubiquitin-specific protease 8 (USP8) mutation. Demethylation patterns of the second promoter correlate with clinical phenotypes of Cushing disease. CONCLUSION: We identified a second POMC promoter regulated by methylation status in ACTH-secreting pituitary tumors. Our findings open new avenues for elucidating subcellular regulation of the hypothalamic-pituitary-adrenal axis and suggest the second POMC promoter may be a target for therapeutic intervention to suppress excess ACTH production.