Naoko Inoshita

High incidence of low O6-methylguanine DNA methyltransferase expression in invasive macroadenomas of Cushing's disease

CONTEXT Crookes cell adenoma (CCA), characterized by massive Crookes hyaline change in corticotroph adenoma, causes a rare subtype of Cushings disease. In contrast to ordinary corticotroph adenomas, CCAs are generally aggressive and present as invasive macroadenomas, which are refractory to both surgery and radiotherapy and have a high-recurrence rate. Moreover, some patients with CCA present with distant or craniospinal metastases. Currently, there are no effective standard therapies for CCA. OBJECTIVE We report a patient with Crookes cell carcinoma who presented with local invasion and liver metastases, which was refractory to conventional therapeutic modalities including transsphenoidal surgery, radiosurgery, medications, and hepatic transcatheter arterial embolization. After all these treatments failed, the patient had monthly temozolomide administrations, resulting in gradual clinical improvement and biochemical data that were consistent with tumor shrinkage. In glioblastoma, low O(6)-methylguanine DNA methyltransferase (MGMT) expression is associated with epigenetic gene silencing and predicts a better response to temozolomide. METHODS We thus investigated MGMT expression, immunohistochemically, in seven CCAs (five invasive macroadenomas and two invasive microadenomas) and 17 ordinary-type adenomas (OTAs; three noninvasive macroadenomas, 12 noninvasive microadenomas, and two invasive microadenomas) from patients with Cushings disease. RESULTS In seven CCAs, all five invasive macroadenomas exhibited low MGMT expression, defined as <5% nuclear MGMT staining. In 17 OTAs, only one adenoma showed low MGMT expression. CONCLUSION In Cushings disease, invasive macroadenomas including CCA usually have low-MGMT expression. Temozolomide thus may be a new therapeutic option for invasive macroadenomas such as CCA particularly when conventional treatments are ineffective.

Surgical outcome in 90 patients with craniopharyngioma: an evaluation of transsphenoidal surgery.

OBJECTIVE To analyze surgical outcomes in 90 patients with craniopharyngioma treated by standard transsphenoidal surgery (TSS) or extended transsphenoidal surgery (eTSS). METHODS From 1990-2008, 90 patients (64 adults and 26 children) underwent TSS for craniopharyngioma (34 subdiaphragmatic and 56 supradiaphragmatic). TSS was performed as the initial surgery in 62 patients and as the second procedure in 28 patients. RESULTS Total tumor removal was achieved in 70 (77.8%) patients, subtotal removal was achieved in 17 (18.9%), and partial removal was achieved in 3 (3.3%). Total removal was more often accomplished in initial surgery (56 of 62 [90.3%]) than second surgery (14 of 28 [50.0%]). Postoperative deterioration of anterior pituitary hormones developed in 31 of 47 (66.0%) patients with preoperative normal function or partial anterior pituitary loss. New-onset postoperative diabetes insipidus (DI) developed in 35 of 67 (52.2%) patients. Of 61 patients with preoperative visual loss, 55 (90.2%) noted some degree of visual improvement after surgery. The early postoperative mortality rate was 2.2% (2 of 90 patients). Cerebrospinal fluid (CSF) leakage occurred in 11 patients (12.2%), and 5 patients required surgical repair of the leak. Tumor recurrence was observed in seven (7.8%) patients during a mean follow-up period of 4.6 years. CONCLUSIONS Most craniopharyngiomas including the supradiaphragmatic type can be removed safely by TSS with a good outcome, although endocrine function frequently worsens after surgery. Dural fascia graft is a very effective technique to prevent CSF leaks, especially after eTSS.

The USP8 mutational status may predict drug susceptibility in corticotroph adenomas of Cushing's disease

CONTEXT Somatic mutations in the ubiquitin-specific peptidase USP8 gene were recently detected in one- to two-third(s) of corticotroph adenomas of Cushings disease (CD). These mutations may lead to the deubiquitination of EGFR, thereby increasing EGFR signaling, which has been implicated in ACTH hypersecretion. OBJECTIVE Our objective was to determine the impact of USP8 mutations on the clinicopathological features of CD. SUBJECTS AND METHODS USP8 mutations as well as clinicopathological characteristics were examined in 60 corticotroph adenomas including 15 Crookes cell adenomas (CCAs), a rare histological variant presenting with generally aggressive behavior, using qRT-PCR and/or immunohistochemistry. RESULTS USP8 mutations were exclusively detected in women, except for one case, with a prevalence of 42.2% in non-CCA and 13.3% in CCA (overall 35%). Clinically well-behaved presentations including microadenoma and curative resection were more common in mutated cases. The expression of EGFR was not associated with the mutation status. In contrast, mutated tumors expressed significantly higher levels of POMC, SSTR5, and MGMT. CONCLUSIONS Microadenomas that strongly express POMC were common among mutated tumors, which may lead to the mechanisms by which very small adenomas secrete excess ACTH to present overt CD. While USP8 mutations were less likely to enhance tumorous ACTH hypersecretion via EGFR-mediated activation, the presence of USP8 mutations may predict favorable responses to the somatostatin analog pasireotide, which exhibits high affinity for SSTR5. In contrast, non-mutated aggressive tumors such as CCA may respond better to the alkylating agent temozolomide because of their significantly weak expression of MGMT.

Surgical management and outcomes in patients with Cushing disease with negative pituitary magnetic resonance imaging.

OBJECTIVE To analyze our experience with transsphenoidal surgery (TSS) in patients with Cushing disease (CD) with no visible adenoma on magnetic resonance imaging (MRI). METHODS Between January 1988 and October 2010, 183 patients with CD underwent TSS at Toranomon Hospital. We retrospectively analyzed data in 18 patients without visible adenomas on MRI and compared them with 106 patients with microadenomas. RESULTS Of 106 patients with MRI-visible microadenomas, postoperative remission was achieved in 104 patients (98.1%) and recurrence of CD was observed in 4 patients (3.8%) during a mean follow-up of 5.2 years. Of the 18 patients with negative MRI, postoperative remission was achieved in 0 of the 3 patients with negative inferior petrosal sinus sampling (IPSS), in 50% of those with positive IPSS (7 of 14 patients), and in 1 patient with inconclusive IPSS. No disease recurrence has been observed during a mean follow-up of 3.3 years in the 8 patients with remission, and no tumor has emerged on MRI in 10 patients with failed surgery during a mean follow-up of 4.2 years. No major perioperative complications, including hypopituitarism, occurred in this series. CONCLUSIONS When the pituitary origin of adrenocorticotropic hormone secretion is established by IPSS in patients with normal MRI findings, we recommend TSS as the first-line treatment for CD, although chance of surgical cure (50% in this series) is lower than that of MRI-visible microadenomas. In contrast, other therapeutic options must be considered in patients with negative MRI and IPSS findings.

Clinicopathological characteristics and therapeutic outcomes in thyrotropin-secreting pituitary adenomas: a single-center study of 90 cases

OBJECT The aim of this study was to analyze clinicopathological characteristics and treatment outcomes in a large single-center clinical series of cases of thyrotropin (TSH)-secreting pituitary adenomas. METHODS The authors retrospectively reviewed clinical, pathological, and treatment characteristics of 90 consecutive cases of TSH-secreting pituitary adenomas treated with transsphenoidal surgery between December 1991 and May 2013. The patient group included 47 females and 43 males (median age 42 years, range 11-74 years). RESULTS Sixteen tumors (18%) were microadenomas and 74 (82%) were macroadenomas. Microadenomas were significantly more frequent in the more recent half of our case series (12 of 45 cases) (p = 0.0274). Cavernous sinus invasion was confirmed in 21 patients (23%). In 67 cases (74%), the tumors were firm elastic or hard in consistency. Acromegaly and hyperprolactinemia were observed, respectively, in 14 (16%) and 11 (12%) of the 90 cases. Euthyroidism was achieved in 40 (83%) of 48 patients and tumor shrinkage was found in 24 (55%) of 44 patients following preoperative somatostatin analog treatment. Conventional transsphenoidal surgery, extended transsphenoidal surgery, and a simultaneous combined supra- and infrasellar approach were performed in 85, 2, and 3 patients, respectively. Total removal with endocrinological remission was achieved in 76 (84%) of 90 patients, including all 16 (100%) patients with microadenomas, 60 (81%) of the 74 with macroadenomas, and 8 (38%) of the 21 with cavernous sinus invasion. None of these 76 patients experienced tumor recurrence during a median follow-up period of 2.8 years. Stratifying by Knosp grade, total removal with endocrinological remission was achieved in 34 of 36 patients with Knosp Grade 0 tumors, all 24 of those with Grade 1 tumors, 12 of the 14 with Grade 2 tumors, 6 of the 8 with Grade 3 tumors, and none of the 8 with Grade 4 tumors. Cavernous sinus invasion and tumor size were significant independent predictors of surgical outcome. Immunoreactivity for growth hormone, prolactin, or both hormones was present in 32, 9, and 24 patients, respectively. The Ki-67 labeling index was less than 3% in 71 (97%) of 73 tumors for which it was obtained and 3% or more in 2. Postsurgery pituitary dysfunction was found in 15 patients (17%) and delayed hyponatremia was seen in 9. CONCLUSIONS TSH-secreting adenomas, particularly those in the microadenoma stage, have increased in frequency over the past 5 years. The high surgical success rate achieved in this series is due to relatively early diagnosis and relatively small tumor size. In addition, the surgical strategies used, such as extracapsular removal of hard or solid adenomas, aggressive resction of tumors with cavernous sinus invasion, or extended transsphenoidal surgery or a simultaneous combined approach for large/giant multilobulated adenomas, also may improve remission rate with a minimal incidence of complications.

Clinicopathological Features of Growth Hormone-Producing Pituitary Adenomas in 242 Acromegaly Patients: Classification according to Hormone Production and Cytokeratin Distribution

The aim of this study was to clarify the relationship between the histological features of GH-producing adenomas surgically resected at the Toranomon Hospital and the clinical features of the patients. Histological examinations, including immunohistochemistry for anterior pituitary hormones and cytokeratin (CK), were performed on 242 consecutively excised GH-producing pituitary adenomas. Immunohistochemistry showed 45% of the adenomas to be monohormonal and 55% to be plurihormonal, producing GH-PRL (77%), GH-TSH (13%), and GH-PRL-TSH (10%). One-fourth of the monohormonal GH adenomas had a dot-like pattern of CK immunoreactivity in the majority of the tumor cells (>80%); they were significantly more common in female or younger patients and usually tended to be larger and more invasive than monohormonal GH adenomas with perinuclear CK. Interestingly, CK-immunonegative adenomas were found in only 5% of the patients; they also showed a tendency to be larger, suggesting that they are a distinct type of GH adenoma with clinically aggressive features. Serum hormone levels correlated well with tumor size only in GH-producing adenomas with a perinuclear pattern of CK immunoreactivity. Each histological subtype of adenoma, classified according to the pattern of CK immunoreactivity, was associated with distinct clinical characteristics. This information is useful for understanding the pathophysiology of acromegaly-causing GH-producing adenomas.

Resistance to dopamine agonists in prolactinoma is correlated with reduction of dopamine D2 receptor long isoform mRNA levels.

OBJECTIVE Dopamine agonists normalize prolactin (PRL) levels and reduce tumour size in responsive prolactinoma. However, several cases have shown resistance to dopamine agonists upon initial treatment. Infrequently, prolactinoma initially responds, but then becomes refractory to prolonged treatment (secondary resistance). We investigated the possible mechanisms of resistance to dopamine agonists. SUBJECTS AND METHODS Twelve cases of prolactinoma were surgically resected and classified according to the responsiveness of PRL levels and tumour size to dopamine agonists: good responders (n = 5), poor responders (n = 5), or secondary resistance (n = 2). We examined the expression of dopamine D(2) receptor (D(2)R) isoform (short: D(2)S and long: D(2)L) mRNA and protein. We investigated DNA methylation patterns in the promoter region of the DRD2 gene. RESULTS The predominant D(2)R isoform expressed in prolactinoma was D(2)L. Levels of D(2)L mRNA were significantly lower in secondary resistance and poor responders than in good responders. Expression of D(2)R protein was variable among cases. Almost no CpG sites of the DRD2 gene promoter region were methylated. CONCLUSION Resistance of prolactinoma to dopamine agonists is correlated with a reduction in D(2)L isoform mRNA levels. Silencing of the DRD2 gene by methylation in the promoter region is unlikely to play a role in dopamine agonist resistance in prolactinoma.

Histopathological alterations of the parathyroid glands in haemodialysis patients with secondary hyperparathyroidism refractory to cinacalcet hydrochloride

Background Cinacalcet treatment for secondary hyperparathyroidism (SHPT) has demonstrated parathyroid size regression and morphological changes, such as cystic degeneration and hypovascularisation, on ultrasonography.; However, there have been very few reports regarding the histopathological alterations of hyperplastic parathyroid glands in patients with SHPT after administration of cinacalcet. The aim of this study was to elucidate the effects of cinacalcet for histopathological alterations on the parathyroid glands. Methods A total of 92 hyperplastic parathyroid glands were obtained from 24 dialysis patients with severe SHPT who underwent total parathyroidectomy and were enrolled in this study. Patients were divided into those treated with and without cinacalcet (cinacalcet group and conventional group, respectively; both n=12). The areas of oxyphil cells, cystic degeneration, haemorrhagic changes and haemosiderin deposition were assessed semiquantitatively. Results Total maximal parathyroid gland weight and maximal-to-minimal parathyroid gland weight ratio were significantly higher in the cinacalcet group compared with the conventional group (1798.7±1658.3 mg vs 764.2±471.1 mg, p=0.018, 15.8±13.9 vs p=0.047, 6.6±4.2, respectively). Significant increases were observed in oxyphil cell area (61.7%±17.1% vs 36.7%±15.6%, p=0.001) and haemosiderosis score (1.50±1.24 vs 0.42±0.51, p=0.029) in the former rather than the latter group. Conclusions These results suggest that cinacalcet may induce specific qualitative alterations of hyperplastic parathyroid glands in patients with severe SHPT.

Upregulation of CDKN2A and suppression of cyclin D1 gene expressions in ACTH-secreting pituitary adenomas

OBJECTIVE Cushings disease (CD) is usually caused by ACTH-secreting pituitary microadenomas, while silent corticotroph adenomas (SCA) are macroadenomas without Cushingoid features. However, the molecular mechanism(s) underlying their different tumor growth remains unknown. The aim of the current study was to evaluate and compare the gene expression profile of cell cycle regulators and cell growth-related transcription factors in CD, SCA, and non-functioning adenomas (NFA). DESIGN AND METHODS Tumor tissue specimens resected from 43 pituitary tumors were studied: CD (n=10), SCA (n=11), and NFA (n=22). The absolute transcript numbers of the following genes were quantified with real-time quantitative PCR assays: CDKN2A (or p16(INK4a)), cyclin family (A1, B1, D1, and E1), E2F1, RB1, BUB1, BUBR1, ETS1, and ETS2. Protein expressions of p16 and cyclin D1 were semi-quantitatively evaluated by immunohistochemical study. RESULTS AND CONCLUSION CDKN2A gene expression was about fourfold greater in CD than in SCA and NFA. The gene expressions of cyclins D1, E1, and B1, but not of A1, in CD were significantly suppressed than those in NFA. Cyclin D1 gene expression positively correlated with cyclins B1 and E1. The gene expressions of E2F1, RB1, BUB1, BUBR1, ETS1, and ETS2 did not differ between each group. Positive immunostaining for p16 and negative immunostaining for cyclin D1 were more frequent in CD than in NFA; there were positive correlations between mRNA and protein expressions of p16 and cyclin D1. Thus, it is suggested that upregulated CDKN2A with the concomitant downregulated cyclin gene family is partly involved in the small size of ACTH-secreting adenoma.

Cinacalcet upregulates calcium-sensing receptors of parathyroid glands in hemodialysis patients.

Background: Cinacalcet hydrochloride (cinacalcet), a calcimimetic, has been shown to upregulate calcium-sensing receptor (CaSR) expression in parathyroid glands of rats with chronic renal insufficiency. However, the effect of cinacalcet on the reduced CaSR expression in human parathyroid glands remains to be elucidated. Methods: Four normal parathyroid glands and 71 hyperplastic parathyroid glands from 18 hemodialysis patients with refractory secondary hyperparathyroidism (SHPT) treated with (n = 10; cinacalcet group) or without (n = 8; conventional group) cinacalcet were examined immunohistochemically with a specific antibody against CaSR. The expression level of CaSR was analyzed semiquantitatively. Results: Compared with normal glands, the immunohistochemical expression of CaSR was decreased significantly in both the cinacalcet and conventional groups. In the cinacalcet group, the expression of CaSR was increased significantly compared with that in the conventional group (1.83 ± 0.14 vs. 0.87 ± 0.15, p < 0.001), even though the proportion of patients using vitamin D sterols and the mean administered dose of calcitriol equivalents were not significantly different between the two groups. The expression of CaSR was significantly decreased in the larger glands (>500 mg) compared with that in the smaller glands (<500 mg) in both groups; furthermore, it was markedly decreased in areas of nodular hyperplasia compared with diffuse hyperplasia in the cinacalcet group. Conclusions: Our results indicate that cinacalcet upregulates the depressed expression of CaSR in hemodialysis patients with SHPT, and that insufficient expression of CaSR, especially in larger glands with advanced nodular hyperplasia, underlies the pathogenesis of SHPT in patients who are resistant to cinacalcet.