Determination of the proliferation and apoptotic index in adrenocorticotropin-secreting pituitary tumors : comparison between micro- and macroadenomas

Integrative Clinical, Radiological, and Molecular Analysis for Predicting Remission and Recurrence of Cushing Disease

CONTEXT

Adrenocorticotropin (ACTH)-secreting pituitary tumors (ACTHomas) are associated with severe comorbidities and increased mortality. Current treatments mainly focus on remission and prevention of persistent disease and recurrence. However, there are still no useful biomarkers to accurately predict the clinical outcome after surgery, long-term remission, or disease relapse.

OBJECTIVES

This work aimed to identify clinical, biochemical, and molecular markers for predicting long-term clinical outcome and remission in ACTHomas.

METHODS

A retrospective multicenter study was performed with 60 ACTHomas patients diagnosed between 2004 and 2018 with at least 2 years' follow-up. Clinical/biochemical variables were evaluated yearly. Molecular expression profile of the somatostatin/ghrelin/dopamine regulatory systems components and of key pituitary factors and proliferation markers were evaluated in tumor samples after the first surgery.

RESULTS

Clinical variables including tumor size, time until diagnosis/first surgery, serum prolactin, and postsurgery cortisol levels were associated with tumor remission and relapsed disease. The molecular markers analyzed were distinctly expressed in ACTHomas, with some components (ie, SSTR1, CRHR1, and MKI67) showing instructive associations with recurrence and/or remission. Notably, an integrative model including selected clinical variables (tumor size/postsurgery serum cortisol), and molecular markers (SSTR1/CRHR1) can accurately predict the clinical evolution and remission of patients with ACTHomas, generating a receiver operating characteristic curve with an area under the curve of 1 (P < .001).

CONCLUSION

This study demonstrates that the combination of a set of clinical and molecular biomarkers in ACTHomas is able to accurately predict the clinical evolution and remission of patients. Consequently, the postsurgery molecular profile represents a valuable tool for clinical evaluation and follow-up of patients with ACTHomas.

Clinical Study and Systematic Review of Pituitary Microadenomas vs. Macroadenomas in Cushing's Disease: Does Size Matter?

Background: Reports on clinical and biochemical differences between adrenocorticotropic hormone (ACTH)-secreting pituitary microadenomas and macroadenomas are limited and inconsistent. Objective: Compare clinical and biochemical characteristics of patients with corticotroph microadenomas and macroadenomas and assess predictive factors for biochemical response to dynamic testing for Cushing’s disease (CD) in a clinical trial and a systematic review. A second aim was to evaluate differences between macroadenomas with and without cavernous and sphenoid sinus invasion. Methods: Retrospective charts review of patients with CD, treated at Rabin Medical Center between 2000 and 2020 or at Maccabi Healthcare Services in Israel between 2005 and 2017. Clinical and biochemical factors were compared between patients with corticotroph microadenomas and macroadenomas. We have also performed a systematic review of all studies (PRISMA guidelines) comparing corticotroph microadenomas with macroadenomas up to 31 November 2021. Results: The cohort included 105 patients (82 women, 78%; mean age, 41.5 ± 14.5 years), including 80 microadenomas (mean size, 5.2 ± 2.2 mm) and 25 macroadenomas (mean size, 18.0 ± 7.7 mm). Other baseline characteristics were similar between groups. Most common presentation suggestive for hypercortisolemia among patients with both micro- and macroadenomas were weight gain (46.3% vs. 48.0%, p = NS) and Cushingoid features (27.5% vs. 20.0%, p = NS). Mean 24 h urinary free cortisol (5.2 ± 5.4 × ULN vs. 7.8 ± 8.7 × ULN) and serum cortisol following low-dose dexamethasone (372.0 ± 324.5 vs. 487.6 ± 329.8 nmol/L), though higher for macroadenomas, were not significant. Levels of ACTH were greater for macroadenomas (1.9 ± 1.2 × ULN vs. 1.3 ± 0.8 × ULN, respectively, p = 0.01). Rates of recurrent/persistent disease were similar, as were rates of post-operative adrenal insufficiency and duration of post-operative glucocorticoid replacement. Macroadenomas with sphenoid or cavernous sinus invasion were associated with higher ACTH, 24 h free urinary cortisol, and serum cortisol following low-dose dexamethasone, compared with suprasellar or intrasellar macroadenomas. Conclusions: While ACTH-secreting macroadenomas exhibit higher plasma ACTH than microadenomas, there was no association between tumor size with cortisol hypersecretion or clinical features of hypercortisolemia. Though overall rare, increased awareness is needed for patients with CD with tumor extension in the cavernous or sphenoid sinus, which displays increased biochemical burden, highlighting that extent/location of the adenoma may be more important than size per se. Our systematic review, the first on this topic, highlights differences and similarities with our study.

Extended Prophylactic Effect of N-tert-Butyl-α-phenylnitron against Oxidative/Nitrosative Damage Caused by the DNA-Hypomethylating Drug 5-Azacytidine in the Rat Placenta

Antioxidant N-tert-Butyl-α-phenylnitron (PBN) partly protected embryos from the negative effects of a DNA demethylating drug 5-azacytidine during pregnancy. Our aim was to investigate PBN's impact on the placenta. Fischer rat dams were treated on gestation days (GD) 12 and 13 by PBN (40 mg/kg), followed by 5azaC (5 mg/kg) after one hour. Global methylation was assessed by pyrosequencing. Numerical density was calculated from immunohistochemical expression in single cells for proliferating (PCNA), oxidative (oxoguanosine) and nitrosative (nitrotyrosine) activity. Results were compared with the PBN-treated and control rats. PBN-pretreatment significantly increased placental weight at GD15 and GD20, diminished by 5azaC, and diminished apoptosis in GD 20 placentas caused by 5azaC. Oxoguanosine expression in placentas of 5azaC-treated dams was especially high in the placental labyrinth on GD 15, while PBN-pretreatment lowered its expression on GD 15 and GD 20 in both the labyrinth and basal layer. 5azaC enhanced nitrotyrosine level in the labyrinth of both gestational stages, while PBN-pretreatment lowered it. We conclude that PBN exerted its prophylactic activity against DNA hypomethylating agent 5azaC in the placenta through free radical scavenging, especially in the labyrinthine part of the placenta until the last day of pregnancy.

A Nomogram for Preoperatively Predicting the Ki-67 Index of a Pituitary Tumor: A Retrospective Cohort Study

Background

The Ki-67 index is an indicator of proliferation and aggressive behavior in pituitary adenomas (PAs). This study aims to develop and validate a predictive nomogram for forecasting Ki-67 index levels preoperatively in PAs.

Methods

A total of 439 patients with PAs underwent PA resection at the Department of Neurosurgery in Jinling Hospital between January 2018 and October 2020; they were enrolled in this retrospective study and were classified randomly into a training cohort (n = 300) and a validation cohort (n = 139). A range of clinical, radiological, and laboratory characteristics were collected. The Ki-67 index was classified into the low Ki-67 index (<3%) and the high Ki-67 index (≥3%). Least absolute shrinkage and selection operator algorithm and uni- and multivariate logistic regression analyses were applied to identify independent risk factors associated with Ki-67. A nomogram was constructed to visualize these risk factors. The receiver operation characteristic curve and calibration curve were computed to evaluate the predictive performance of the nomogram model.

Results

Age, primary-recurrence subtype, maximum dimension, and prolactin were included in the nomogram model. The areas under the curve (AUCs) of the nomogram model were 0.694 in the training cohort and 0.658 in the validation cohort. A well-fitted calibration curve was also generated for the nomogram model. A subgroup analysis revealed stable predictive performance for the nomogram model. A correlation analysis revealed that age (R = −0.23; p < 0.01), maximum dimension (R = 0.17; p < 0.01), and prolactin (R = 0.16; p < 0.01) were all significantly correlated with the Ki-67 index level.

Conclusions

Age, primary-recurrence subtype, maximum dimension, and prolactin are independent predictors for the Ki-67 index level. The current study provides a novel and feasible nomogram, which can further assist neurosurgeons to develop better, more individualized treatment strategies for patients with PAs by predicting the Ki-67 index level preoperatively.

Etiology-, Sex-, and Tumor Size-Based Differences in Adrenocorticotropin-Dependent Cushing Syndrome

OBJECTIVE

To examine demographic, clinical, and biochemical differences in patients with adrenocorticotropin (ACTH)-dependent Cushing syndrome (CS) based on etiology, sex, and tumor size.

METHODS

This was a single-center study of 211 patients with ACTH-dependent CS followed for 35 years. Patients were stratified into 3 groups based on etiology: Cushing disease (CD)/transsphenoidal surgery, Cushing disease/total bilateral adrenalectomy (CD/TBA), and ectopic ACTH secretion (EAS). Patients were also stratified based on sex and tumor size (nonvisualized, microadenoma, and macroadenoma).

RESULTS

CD was the commonest cause of ACTH-dependent CS (190; 90%). Most patients presented in the third decade (median age, 29 years). Clinical features, cortisol, and ACTH were significantly greater in the EAS group. The CD/TBA group had more nonvisualized tumors (22% vs 8%; P = .000) and smaller tumor size (4 vs 6 mm; P = .001) compared with the CD/transsphenoidal surgery group. There was female predominance in CD (2.06:1) and male predominance in EAS (2:1). Men had shorter duration of symptoms (2 years; P = .014), were younger (23 years; P = .001), had lower body mass index (25.1 kg/m²; P = .000), and had more severe disease (low bone mineral density, hypokalemia). Macroadenomas were frequent (46; 24.2%), and ACTH correlated with tumor size in CD (r = 0.226; P = .005).

CONCLUSION

Our cohort presented at an earlier age than the Western population with a distinct, but slightly lower, female predilection. Patients with CD undergoing TBA had frequent negative imaging. Men had a clinical profile suggesting aggressive disease. Microadenoma and macroadenoma were difficult to distinguish on a clinicobiochemical basis.

Ki67 in endocrine neoplasms: to count or not to count, this is the question! A systematic review from the English language literature

BACKGROUND

Endocrine neoplasms are generally slow-growing tumors that can show hormonal activity and give metastases. In most cases they are benign and clearly malignant forms are easy to diagnose. However, borderline forms may occur and be, for the pathologists, very difficult to classify. In these cases, there is a strong need to identify factors that may aid. Official classification systems for endocrine neoplasms are based on the evaluation of proliferation and, in most cases, they rely on mitotic count. In support, the study of Ki67 is carried out which, however, has not yet been included in any official classification system, except for neuroendocrine neoplasms of the gastro-entero-pancreatic tract.

PURPOSE

The aim of the present study was to investigate the proven or unproven role of Ki67 in endocrine neoplasms, in different districts, in order to bring to light the substantial differences, in terms of proliferation, existing between neoplasms so similar, but at the same time, so different.

METHODS

A thorough search of English language literature was performed, looking for articles concerning Ki67 in five endocrine neoplasms (pituitary adenomas, thyroid neoplasms, adrenocortical neoplasms, pheochromocytomas and paragangliomas).

RESULTS

From 2170, 236 articles were selected and it was seen that the endocrine neoplasm in which Ki67 was most studied was the pituitary, where it still shows a controversial role. In other neoplasms different roles were identified.

CONCLUSION

The pathologist should be aware of the contribution that this proliferative marker can give to the diagnosis and, sometimes, to the therapy selection, for the clinician.

Effects of carnosine on apoptosis, transient receptor potential melastatin 2, and betatrophin in rats exposed to formaldehyde

We investigated the effects of exposure to formaldehyde on transient receptor potential melastatin 2, betatrophin, total oxidant status and total antioxidant status in rat liver and kidney tissues. We also investigated the effects of carnosine on formaldehyde treated animals. We used 28 male rats divided ramdomly into four groups of seven: untreated control group, carnosine treated group, formaldehyde treated group and formaldehyde + carnosine group. The experiment lasted for four weeks. Betatrophin levels in samples were measured uing the enzyme-linked immunosorbent assay, and total oxidant status and total antioxidant status were measured using REL assay diagnostic kits. We detected betatrophin and transient receptor potential melastatin 2 immunoreactivity using immunohistochemistry and assessed apoptosis using terminal deoxynucleotidyl transferase dUTP nick end labeling. The betatrophin and total antioxidant status levels decreased in kidney, liver and plasma following exposure to formaldehyde, while total oxidant status and terminal deoxynucleotidyl transferase dUTP nick end labeling positivity increased. Carnosine supplementation reversed histopathology and biochemical damage caused by formaldehyde. We suggest that carnosine treatment may be useful for protecting persons exposed to formaldehyde.

Cushing's disease due to somatic USP8 mutations: a systematic review and meta-analysis

PURPOSE

Cushing's disease (CD) is a severe illness generally caused by microcorticotropinomas (MICs) and in approximately 7-20% of patients by macrocorticotropinomas (MACs). USP8-mutations have been identified as a major genetic cause of CD (~ 50%). Few studies have reported the distribution between MICs-MACs related to USP8-mutations and their genotype-phenotype correlations. Therefore, we aimed to evaluate USP8-mutations in a cohort of MICs-MACs from a unique center and to perform a systematic review and meta-analysis.

METHODS

DNA-tumor-tissues from 47 corticotropinomas (16 MICs and 31 MACs) were sequenced. Clinical-biochemical data, radiological imaging data and remission/recurrence rates were evaluated. In addition, we performed a meta-analysis of nine published series (n = 630).

RESULTS

We identified four different USP8-mutations previously described, in 11 out of 47 (23.4%) corticotropinomas; 8 out of 11 were MACs. The urinary cortisol levels of our patients with corticotrophin USP8-mutated-alleles were lower than those of patients with wild-type (WT) alleles (p ≤ 0.017). The frequency of USP8-mutated-alleles among the series was approximately 30% with a higher prevalence in female-patients (p < 0.1 × 10^-4). Among the 5 series, the remission rates were higher in patients with USP8-mutated-alleles than in those with the USP8-WT-alleles (p < 0.1 × 10^-4).

CONCLUSION

Our data, as well as the retrospective review of CD series associated with USP8-mutated alleles, show heterogeneous findings among the series. Several drawbacks included the lack of a systematic protocol to evaluate these patients before surgery and follow-up. Further prospective studies using a systematic protocol will provide more consistent information about the influence of the corticotropinomas with USP8-mutated alleles on the phenotype, responses to treatment and outcome of patients with CD.

A Free Radical Scavenger Ameliorates Teratogenic Activity of a DNA Hypomethylating Hematological Therapeutic

The spin-trap free radical scavenger N-tert-butyl-α-phenylnitron (PBN) ameliorated effects of several teratogens involving reactive oxygen species (ROS). We investigated for the first time whether PBN could ameliorate teratogenesis induced by a DNA hypomethylating hematological therapeutic 5-azacytidine (5azaC). At days 12 and 13 of gestation, Fisher rat dams were pretreated by an i.v. injection of PBN (40 mg/kg) and 1 h later by an i.p. injection of 5azaC (5mg/kg). Development was analyzed at gestation day 15 in embryos and day 20 in fetuses. PBN alone did not significantly affect development. PBN pretreatment restored survival of 5azaC-treated dams' embryos to the control level, restored weight of embryos and partially of fetuses, and partially restored crown-rump lengths. PBN pretreatment converted limb adactyly to less severe oligodactyly. PBN pretreatment restored global DNA methylation level in the limb buds to the control level. Cell proliferation in limb buds of all 5azaC-treated dams remained significantly lower than in controls. In the embryonic liver, PBN pretreatment normalized proliferation diminished significantly by 5azaC; whereas in embryonic vertebral cartilage, proliferation of all 5azaC-treated dams was significantly higher than in PBN-treated dams or controls. Apoptotic indices significantly enhanced by 5azaC in liver and cartilage were not influenced by PBN pretreatment. However, PBN significantly diminished ROS or reactive nitrogen species markers nitrotyrosine and 8-hydroxy-2'deoxyguanosine elevated by 5azaC in embryonic tissues, and, therefore, activity of this DNA hypomethylating agent was associated to the activation of free radicals. That pretreatment with PBN enhanced proliferation in the liver and not in immature tissue is interesting for the treatment of 5azaC-induced hepatotoxicity and liver regeneration.

Cushing's disease in older patients: Presentation and outcome

BACKGROUND

To define the symptoms, signs and treatment outcomes in a population of older patients with Cushing's disease (CD).

METHODS

We analysed the clinical presentation and treatment outcomes in 45 CD patients older than 60 years, in comparison with 90 CD patients younger than 60, and a control group of 45 older patients with nonfunctioning pituitary adenomas. We reviewed preoperative clinical characteristics, medical comorbidities, imaging findings and endocrine testing as well as surgical and endocrine outcomes.

RESULTS

Older CD patients had significantly lower body mass index (BMI) (P = 0.031), were more likely to have muscle wasting (P = 0.006) and women were less likely to have hirsutism (P = 0.033). Older patients with CD had more medical comorbidities than younger patients, which correlated with a higher ASA grade (P < 0.001), but the surgical complication rates were similar in both groups. Surgical remission was achieved in 38/45 (84.4%) older patients and 78/90 (86.7%) younger patients (P = NS). Recurrent disease was more frequent in younger patients (19.2%) in comparison with older patients (2.6%, P = 0.019).

CONCLUSIONS

Older patients with CD appear to have a distinct phenotype with a more catabolic picture, including a lower BMI and greater prevalence of muscle wasting. Surgical outcomes are similar without a significant age-related increase in complications.

Atypical pituitary adenoma: a clinicopathologic case series

OBJECTIVE In 2004, the WHO classified atypical pituitary adenoma as a distinct adenoma subtype. However, the clinical significance of this distinction remains undetermined. The authors sought to define patient characteristics, tumor features, and treatment outcomes associated with atypical pituitary adenoma. METHODS The authors reviewed records of patients who underwent resection of pituitary adenoma at the University of California, San Francisco, between 2007 and 2014. Per institutional protocol, adenomas exhibiting mitotic activity underwent evaluation for all 3 markers of atypicality (mitotic index, extensive p53 staining, and MIB-1 index ≥ 3%). Statistical analyses were performed using χ2, Fisher's exact test, t-test, log-rank, and logistic regression. RESULTS Between 2007 and 2014, 701 patients underwent resection for pituitary adenoma. Among these patients, 122 adenomas exhibited mitotic activity and therefore were evaluated for all 3 markers of atypicality, with 36 tumors (5%) proving to be atypical. There were 21 female patients (58%) and 15 male patients (42%) in the atypical cohort, and 313 female patients (47%) and 352 male patients (53%) in the nonatypical cohort (p = 0.231). The mean age of patients in the atypical cohort was 37 years (range 10-65 years), which was significantly lower than the mean age of 49 years (range 10-93 years) for patients in the nonatypical cohort (p < 0.001). The most common presenting symptoms for patients with atypical adenomas were headaches (42%) and visual changes (33%). Atypical adenomas were more likely to be functional (78%) than nonatypical adenomas (42%; p < 0.001). Functional atypical adenomas were significantly larger than functional nonatypical adenomas (mean diameter 2.2 vs 1.4 cm; p = 0.009), as were nonfunctional atypical adenomas compared with nonfunctional nonatypical adenomas (mean diameter 3.3 vs 2.3 cm; p = 0.01). Among the entire adenoma cohort, larger presenting tumor size was associated with cavernous sinus invasion (p < 0.001), and subtotal resection was associated with cavernous sinus invasion (p < 0.001) and larger size (p < 0.001) on binomial multivariate regression. The median time until recurrence was 56 months for atypical adenomas, 129 months for functional nonatypical adenomas, and 204 months for nonfunctional nonatypical adenomas (p < 0.001). Functional atypical adenomas recurred more frequently and significantly earlier than functional nonatypical adenomas (p < 0.001). When accounting for extent of resection, cavernous sinus invasion, size, age, sex, and functional subtype, atypicality remained a significant predictor of earlier recurrence among functional adenomas (p = 0.002). CONCLUSIONS When compared with nonatypical pituitary adenomas, atypical adenomas are more likely to present in younger patients at a larger size, are more often hormonally hypersecretory, and are associated with earlier recurrence. These features lend credence to atypical pituitary adenomas being a distinct clinical entity in addition to a discrete pathological diagnosis.

Ovarian hyperstimulation syndrome due to follicle-stimulating hormone-secreting pituitary adenomas

PURPOSE

Gonadotroph adenomas are pituitary adenomas with inefficient and variable secretory characteristics, that is why they are usually considered as a subgroup of nonfunctioning pituitary adenomas (NFPA) and are recognized only at immunohistochemistry. When gonadotroph adenomas secrete active hormones, they may cause spontaneous ovarian hyperstimulation syndrome (OHSS) in premenopausal women. Aim of our study is to describe three women with OHSS diagnosed before the removal of the adenoma and to calculate the prevalence of OHSS in premenopausal women with a clinical diagnosis of NFPA.

METHODS

We reviewed clinical records of premenopausal women that underwent neurosurgery for NFPA at our centre between 1993 and 2014. OHSS was diagnosed in patients with high levels of FSH, suppressed LH, hyperestrogenism, abdominal symptoms, polymenorrhea, enlarged ovaries with cysts or previous surgery for ovarian cysts.

RESULTS

171 women were included into the study; 62 (36.6%) had a gonadotroph adenoma diagnosed at immunohistochemistry. Two patients were retrospectively diagnosed as having OHSS due to gonadotroph adenoma and three had OHSS diagnosed before neurosurgery. The prevalence of OHSS was 2.9% in the overall group of patients with NFPA and 8.1% among patients with a gonadotroph adenoma detected at immunohistochemistry.

CONCLUSIONS

Frequency of OHSS due to a gonadotroph adenoma is not negligible. Increased awareness of the characteristic clinical and hormonal picture should permit an early detection of this condition in premenopausal women with a pituitary adenoma.

Calpain-1 Expression in Triple-Negative Breast Cancer: A Potential Prognostic Factor Independent of the Proliferative/Apoptotic Index

Triple-negative breast cancer (TNBC) is an aggressive type of breast cancer in which calpain system plays an important role in its cellular processes including apoptosis and proliferation. Although such roles have been assessed in tumor pathogenesis, the correlation of its expression to the proliferating/apoptotic index has not been studied yet. Immunohistochemical staining of calpain-1 was performed on paraffin-embedded tissues to correlate its expression with clinicopathological variables and outcome. The proliferation activity was determined by calculating the percentage of cells expressing the Ki-67 antigen. The apoptotic index was assessed morphologically and biochemically using Haematoxylin & Eosin method and Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay, respectively. Calpain-1 was significantly expressed in TNBC tissues varying from low to high with a significant correlation to lymph node status but not with the other clinicopathological variables, suggesting its role as a prognostic factor. In addition, a positive correlation was found between both apoptotic counts assays (P < 0.001, r = 0.547) as well as with proliferation (P = 0.045). Calpain-1 expression had no significant correlation with either proliferation (P = 0.29) or apoptotic indices (P = 0.071 and P = 0.100). Determining calpain-1 expression may provide relevant prognostic value for TNBC cancer patients.

Proopiomelanocortin, glucocorticoid, and CRH receptor expression in human ACTH-secreting pituitary adenomas

ACTH-secreting pituitary tumors are by definition partially autonomous, i.e., secrete ACTH independent of physiological control. However, only few, small-sized studies on proopiomelanocortin (POMC) and its regulation by corticotropin-releasing hormone (CRH) or glucocorticoids are available. Objective of the present study was to report on constitutive and CRH- and dexamethasone-regulated POMC, CRH (CRH-R1), and glucocorticoid receptor (NR3C1) gene expression in a large series of human corticotrope adenomas. Fifty-three ACTH-secreting adenomas were incubated with 10 nM CRH or 10 nM dexamethasone for 24 h. POMC, CRH-R1, NR3C1, and its alpha and beta isoforms were quantified and medium ACTH measured. Constitutive POMC expression proved extremely variable, with macroadenomas exhibiting higher levels than microadenomas. POMC increased during CRH in most specimens; conversely, changes induced by dexamethasone were varied, ranging from decrease to paradoxical increase. No correlation between POMC and ACTH was detected in any experimental condition. CRH-R1 expression was not linked to the response to CRH while NR3C1 was expressed at greater levels in specimens who failed to inhibit during dexamethasone; glucocorticoid receptor α was the more abundant isoform and subject to down-regulation by dexamethasone. Our results demonstrate a considerable variability in POMC expression among tumors and no correlation between POMC and ACTH, suggesting that POMC peptide processing/transport plays a major role in modulating ACTH secretion. Further, CRH-R1 and NR3C1 expression were not linked to the expected ligand-induced outcome, indicating that receptor signaling rather than abundance determines corticotrope responses. Our findings pave the way to new avenues of research into Cushing's disease pathophysiology.

Negative correlation between tumour size and cortisol/ACTH ratios in patients with Cushing's disease harbouring microadenomas or macroadenomas

PURPOSE

Pituitary macroadenomas (MACs) represent 10-30 % of Cushing's disease (CD) cases. The aim of this study was to report the clinical, laboratorial and imaging features and postsurgical outcomes of microadenoma (MIC) and MAC patients.

METHODS

Retrospective study with 317 CD patients (median 32 years old, range 9-71 years) admitted between 1990 and 2014, 74 (23.3 %) of whom had MAC.

RESULTS

Hirsutism, plethora facial, muscular weakness and muscular atrophy were more frequent in the MIC patients. Nephrolithiasis, osteopenia, hyperprolactinaemia and galactorrhoea were more prevalent in MAC patients. The morning serum cortisol (Fs), nocturnal salivary cortisol (NSC), nocturnal Fs (Fs 2400 h), low- and high-dose dexamethasone suppression test results and CRH and desmopressin test results were similar between the subgroups. MIC patients showed higher urinary cortisol at 24 h (UC), and MAC patients presented higher ACTH levels but lower Fs/ACTH, Fs 2400 h/ACTH, NSC/ACTH and UC/ACTH ratios. There were negative correlations of tumour size with Fs/ACTH, Fs 2400 h/ACTH, NSC/ACTH and UC/ACTH ratios. Overall, the postsurgical remission and recurrence rates were similar between MIC and MAC. However, patients in remission (MIC + MAC) showed smaller tumour diameters and a lower prevalence of invasion and extension on MRI.

CONCLUSIONS

Despite exhibiting higher plasma ACTH levels, CD patients with MAC presented lower cortisol/ACTH ratios than did patients with MIC, with a negative correlation between tumour size and cortisol/ACTH ratios. The overall postsurgical remission and recurrence rates were similar between MIC and MAC patients, with those with larger and/or invasive tumours showing a lower remission rate.

Clinicopathological predictive factors in the early remission of corticotroph pituitary macroadenomas in a tertiary referral centre

OBJECTIVE

Corticotroph macroadenomas are a rare cause of Cushing's disease (CD), but their properties are not well-recognised. The aim of this study was to evaluate the clinical and pathological aspects of corticotroph macroadenomas with particular emphasis on proliferation markers and their associations with the efficacy of surgical treatment.

DESIGN

A prospective cohort study was conducted in a tertiary referral centre in Poland.

METHODS

In total, 59 patients with CD (20 macroadenomas and 39 microadenomas) were included in this study. Hormonal and imaging parameters, histopathological and ultrastructural features of the corticotroph tumours and the early surgical outcomes were evaluated.

RESULTS

ACTH and ACTH/cortisol ratios were higher in macroadenomas (P<0.001 and P=0.002 respectively). Greater tumour volumes were associated with higher Ki-67 and p53 expression (Ptrend=0.009 and Ptrend=0.024 respectively) and the rates of sparsely granulated adenomas (Ptrend=0.036). Immediate postoperative remission and early biochemical remission rates were lower in macroadenomas compared to microadenomas (P<0.001). A logistic regression model showed that the immediate postoperative remission or early biochemical remission depended on tumour volume (P=0.005 and P=0.006 respectively) and invasiveness based on Knosp grades 3 and 4 for macroadenomas and a lack of surgical pseudocapsule for microadenomas (P=0.004 and P=0.007 respectively).

CONCLUSION

Corticotroph macroadenomas differ from the more common microadenomas not only in terms of hormonal and imaging characteristics but also in terms of immunohistochemical and ultrastructural features and proliferation markers. The early effectiveness of surgery depends primarily on tumour volume and invasiveness.

Factors influencing improvement of visual field after trans-sphenoidal resection of pituitary macroadenomas: a retrospective cohort study

AIM

To investigate the influencing factors of visual field improvement after trans-sphenoidal resection of pituitary macroadenomas.

METHODS

This retrospective cohort study included 201 patients (366 eyes) with visual field defect induced by pituitary macroadenomas. All of them were treated with trans-sphenoidal surgery. Ophthalmologic evaluation, best-corrected visual acuity (BCVA), and visual field examination were performed before and 3mo after surgery. BCVA, visual field defect index mean deviation (MD), duration of symptoms, age, sex, and volume of tumors were compared. Expression of vascular endothelial growth factor (VEGF) and Ki-67 of tumor tissue were detected by immunohistochemical technique.

RESULTS

The mean age of patients was 44.23±1.29y. Ninety-three patients were female and 108 were male. The mean tumor volume was 14.36±6.23 cm(3). The mean duration of preoperative symptoms was 11.50±0.88mo. Mean preoperative MD was -17.50±0.82 dB. Mean Preoperative visual acuity was 0.64±0.04. Postoperative visual field improved in 270 (73.77%) eyes, unchanged in 96 (26.23%) eyes. Multivariate logistic regression displayed that the factors independently influencing visual field improvement were young age (OR=1.71, 95%CI: 1.325-2.387, P=0.013), low preoperative MD absolute value (OR=1.277, 95%CI: 1.205-1.355, P<0.001), small volume of tumor (OR=1.458, 95%CI: 1.060-4.289, P<0.001), low expression of VEGF in tumor tissue (OR=1.554, 95%CI: 1.089-2.457, P=0.022), and low expression of Ki-67 in tumor tissue (OR=1.552, 95%CI: 1.161-2.847, P=0.026).

CONCLUSION

After pituitary macroadenomas trans-sphenoidal resection, the independent influencing factors of the visual fields recovery were low preoperative MD absolute value, young age, small volume of tumor, and expression levels of VEGF/ Ki-67.

Clinicopathological correlates of extrasellar growth patterns in pituitary adenomas

We reviewed clinical, imaging and histopathology details of 297 patients who underwent surgery for pituitary adenomas, with an equal distribution of functional and non-functioning tumors, to examine clinicopathological correlates of extrasellar growth. Knosp grades of 3 and 4 on MRI defined cavernous sinus invasion, Hardy grades of C and D defined significant suprasellar/subfrontal extension, and intraoperative evidence of tumor eroding through the clivus or sellar floor defined infrasellar invasion. Disease status at follow-up was known in 246 patients overall, including 35 patients who were evaluated for progression of residual disease on serial imaging. On univariate analysis, we found several statistically significant associations (p < 0.05) including adenoma size with age, sex and tumor protein p53 reactivity; cavernous sinus invasion with size, non-functional status, increased mitotic activity, an elevated MIB-1 proliferation index and p53 reactivity; suprasellar/subfrontal extension with p53 reactivity; and infrasellar invasion with age and tumor size. When adjusting for confounders with logistic regression, several significant associations were evident including adenoma size with male sex and p53 reactivity; cavernous sinus invasion with size and elevated MIB-1 proliferation index; suprasellar/subfrontal extension with p53 reactivity; and infrasellar invasion with adenoma size alone. Patients with early progression of postoperative residual tumor were younger with a non-significant trend towards higher MIB-1 proliferation indices. Individual patterns of extrasellar growth in pituitary adenomas are associated with unique clinical and immunohistochemical profiles. Younger patients with elevated MIB-1 values are probably at high risk for early recurrence of non-functioning tumors. Definitions of atypia must be standardized before more robust assumptions about tumor biology can be established.

An analysis of granulation patterns, MIB-1 proliferation indices and p53 expression in 101 patients with acromegaly

BACKGROUND

Despite the wide spectrum of adenoma behavior in patients with acromegaly, the ability of most pathological markers to predict clinical and radiological behavior remains controversial. The authors sought to comprehensively examine clinical and radiological correlates of growth hormone (GH)-secreting pituitary adenomas with regard to several commonly used immunocytochemical techniques in patients undergoing transsphenoidal surgery for acromegaly.

METHOD

We performed a retrospective review of histopathological findings in 101 surgically resected GH adenomas. Tumors were assessed radiologically for different patterns of extension. Each tumor specimen was subject to immunocytochemical analysis, including assessments of granulation patterns, MIB-1 labeling indices, prolactin cosecretion, p53 expression and mitotic activity. Endocrinological outcome was assessed in 93 patients, with remission defined by the 2010 consensus criteria.

RESULTS

Most tumors were macroadenomas and almost half were invasive. When compared to densely granulated tumors, sparsely granulated adenomas were associated with a younger age at presentation, higher preoperative IGF-1 levels, elevated MIB-1 index and pure GH immunostaining, but did not differ significantly in terms of extrasellar invasion or outcome. Increased mitotic activity and p53 expression were also associated with higher proliferation indices and a younger age at presentation. Mixed GH/prolactin tumors demonstrated significantly higher remission rates, independent of variations in extrasellar growth. MIB-1 indices did not correlate with the preoperative GH/IGF-1 levels, adenoma size or Knosp grade.

CONCLUSION

The pathobiology of acromegaly is complex, and the clinicoradiological significance of subtyping on the basis of the markers employed in this study is debatable. Further investigation of newer molecular markers is warranted.

Different levels of various glucocorticoid-regulated genes in corticotroph adenomas

Recently, correlations between corticotroph tumor dedifferentiation and both E-cadherin immunostaining and reduced mRNA expression of the E-cadherin gene (CDH1) have been demonstrated. The purpose of this study was to explore whether tumor dedifferentiation correlated with glucocorticoid resistance and whether the resistance was associated with both positively and negatively regulated genes. Tumor material from 20 patients with verified Cushing's disease or Nelson's syndrome operated on at Rikshospitalet, Oslo. Reverse transcription polymerase chain reaction analysis of genes such as E-cadherin (CDH1), proopiomelanocortin (POMC), glucocorticoid-induced leucine zipper (GILZ), and thioredoxin-interacting protein (TXNIP) was performed. The correlations between the expression of the GILZ, TXNIP, and POMC genes in different stages of corticotroph adenomas, the E-cadherin mRNA expression and staining pattern, and the preoperative 24-h cortisol excretion were examined. The GILZ and TXNIP expression levels were positively correlated to the CDH1 expression and were highest in microadenomas and in tumors with a high membranous E-cadherin reactivity. In contrast, the POMC expression was not significantly different between the groups. This divergence between the genes that were positively and negatively regulated by glucocorticoids could not be supported by other gene expression analyses. No correlations to urinary cortisol were found. The expression of the glucocorticoid-responsive genes POMC, GILZ, and TXNIP in corticotroph adenomas showed a remarkable variation. The pattern and variability of glucocorticoid resistance in corticotroph adenomas seem to correlate with a loss of the epithelial phenotype associated with corticotroph tumor dedifferentiation.

Apoptosis in adhesions and the adhesion-tendon gliding interface: relationship to adhesion-tendon gliding mechanics

PURPOSE

Adhesion formation is closely related to tendon-gliding function. We aimed to investigate apoptosis (programmed cell death) in adhesions and tendons and study its relationship to the mechanics of adhesions and healing tendons.

METHODS

The flexor digitorum profundus tendons of 30 long toes in 15 chickens were completely transected and repaired surgically. At postoperative weeks 4, 6, and 8, tendon-gliding excursions were tested and adhesion scores were recorded. Tendons and surrounding adhesions were then harvested for analysis of apoptosis using in situ terminal deoxynucleotidyl transferase dUTP (deoxyuridine triphosphate) nick end labeling assay. Three-dimensional image reconstruction was used to provide an overall view of cellular distribution in tendons and adhesions. Finally, we analyzed the correlation between the apoptotic index measured at the adhesions and the gliding excursions. Ten uninjured tendons served as normal controls.

RESULTS

Apoptosis was found to be a dominant cellular event in the adhesion tissues at both the adhesion-tendon gliding interface and the adhesion core. The apoptotic index in the adhesions was generally above 20% to 50%. The apoptotic index was significantly higher in the adhesions than in the junction region of the cut tendon ends at weeks 4, 6, and 8. A higher apoptotic index in the adhesions significantly correlated to lower tendon excursions at week 6.

CONCLUSIONS

Apoptosis in adhesions and at the adhesion-tendon interface is a prominent event in the tendon-healing process. The tendons exhibiting a lower tendon-gliding amplitude, meaning more severe adhesions, tended to have a greater apoptotic index in their adhesions during a certain period of the tendon-remodeling process.

CLINICAL RELEVANCE

Apoptosis in the adhesions and at the adhesion-tendon interface may contribute remarkably to the fate of adhesions and the restoration of the tendon gliding surface, which may be closely related to the tendon function.

Cellular apoptosis and proliferation in the middle and late intrasynovial tendon healing periods

PURPOSE

Cellular apoptosis might be an important molecular event in the middle or late healing periods of intrasynovial tendons, but this has not been studied. We aimed to investigate cellular apoptosis and corresponding cellular proliferation in the middle and late healing stages of intrasynovial tendons.

METHODS

The flexor digitorum profundus tendons of 48 long toes (24 chickens) were completely transected within the sheath region and were repaired surgically. At days 28, 42, 56, and 84 after surgery, tendons were harvested and sectioned. In situ terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay was performed to detect apoptotic cells. The sections were stained immunofluorescently with antibodies to proliferating cell nuclear antigen to assess proliferation and to Bcl-2 (an anti-apoptotic protein). Positively stained tenocytes were counted, and their distributional differences were verified in 3-dimensional images.

RESULTS

The repaired intrasynovial tendons exhibited generally greater apoptosis in the surface region than in the core. The differences were more remarkable in the extended region than in the junction region of the cut tendon. At the core of the junction site, apoptosis of tenocytes was pronounced at all time points, but it was less severe at the core of the extended region. The proliferating cell nuclear antigen-positive and Bcl-2-positive tenocytes decreased significantly and continually at days 28, 42, and 56, respectively; these tenocytes were at a minimum at days 56 and 84.

CONCLUSIONS

Apoptotic changes of tenocytes are most marked in the surface region and in the junction region of the healing tendon in the middle and late healing stages. Apoptosis in the core is less dramatic compared to that in the surface in the extended tendon regions. Cellular proliferation declines drastically and is minimal at days 56 and 84.

CLINICAL RELEVANCE

Tenocyte apoptosis in the middle and late stages might be an important event contributing to intrasynovial tendon remodeling, which affects the healing strength and formation of adhesions.

Reduced levels of E-cadherin correlate with progression of corticotroph pituitary tumours

OBJECTIVES

Loss of E-cadherin is an important marker of epithelial tumour progression. The aims of this study were to explore whether E-cadherin expression and localization correlate to corticotroph tumour progression, relate the expression of the E-cadherin gene (CDH1) to immunohistochemical E-cadherin staining pattern, and study whether the E-cadherin levels were correlated to methylation status of the CDH1 promoter region.

DESIGN

Immunohistochemical analyses of E-cadherin protein were performed, as was RT-qPCR of the CDH1 and the POMC genes. Methylation pattern of the promoter region of CDH1 was measured using pyrosequencing of bisulfite-treated DNA.

PATIENTS

Forty-five patients operated at a tertiary referral centre in Oslo, Norway. Adenoma tissue sections and RNA samples from patients with verified Cushing's disease or Nelson's syndrome were collected.

MEASUREMENTS

Expression of E-cadherin mRNA and protein in pituitary corticotroph adenomas and average percentage of methylated cytosines in a cytosine-phosphate-guanosine island of the CDH1 promoter.

RESULTS

Correlations were observed between tumour progression and both nuclear expression of E-cadherin and reduced CDH1 mRNA. The E-cadherin expression was not determined by the methylation pattern of the CDH1 promoter.

CONCLUSIONS

Corticotroph tumour progression was associated with reduced expression of the epithelial marker E-cadherin.

Ki-67 and minichromosome maintenance-7 (MCM7) expression in canine pituitary corticotroph adenomas

Pituitary-dependent hyperadrenocorticism (PDH) caused by pituitary corticotroph adenoma is a common endocrine disorder in dogs. The ratio between pituitary height and the area of the brain (P/B) has been used to evaluate the pituitary size. A P/B ratio > 0.31 indicates an enlarged pituitary, whereas a P/B ratio ≤ 0.31 indicates a nonenlarged pituitary. The aim of this study was to investigate the expression of proliferation markers Ki-67 and minichromosome maintenance-7 (MCM7) in canine corticotroph adenomas in enlarged and in nonenlarged pituitaries and to evaluate their relation with the size of canine pituitary corticotroph adenomas. Ki-67 and MCM7 expression in ACTH-positive tumor cells was determined by dual-labeling immunohistochemistry in resected corticotroph adenomas from 15 dogs with PDH. The mean ± SD Ki-67 labeling index (LI) was 0.55% ± 0.59% in corticotroph adenomas with nonenlarged pituitaries and 1.6% ± 0.6% in adenomas with enlarged pituitaries. The MCM7 LI in corticotroph adenomas with nonenlarged pituitaries and in adenomas with enlarged pituitaries was 2.9% ± 2.2% and 10.9% ± 3.7%, respectively. The Ki-67 LI and MCM7 LI were significantly greater in the adenomas with enlarged pituitaries than in the adenomas with nonenlarged pituitaries (P < 0.01 and P < 0.01, respectively). The MCM7 LI was significantly greater than the Ki-67 LI in adenomas (P < 0.01). The Ki-67 LI was positively correlated with the MCM7 LI (r = 0.820, P < 0.01), and the P/B ratio was positively correlated with the Ki-67 LI (r = 0.560, P = 0.03) and the MCM7 LI (r = 0.854, P < 0.01). In conclusion, canine corticotroph adenomas in enlarged pituitaries show greater proliferation potential than do adenomas in nonenlarged pituitaries. MCM7 expression was significantly greater than Ki-67 expression in canine pituitary corticotroph adenomas. Thus, MCM7 may be superior to Ki-67 as a proliferation marker in pituitary tumors.

Biomarkers of pituitary neoplasms: a review (Part II)

Several new markers have shown a capacity to predict the clinicopathological behavior of pituitary neoplasms; these markers have shown potential to correlate with tumor subtype and size and patient age and sex. These various markers are involved in a host of cellular functions, including cell-cycle progression, cell proliferation, apoptosis, cell adhesion, and tumor vascularity. In this companion article to our first review of Ki-67 as a marker of pituitary adenomas, we present and analyze the literature regarding matrix metalloproteinases and their inhibitors (tissue inhibitor metalloproteinases), vascular endothelial growth factor, fibroblast growth factor and its receptor, apoptotic markers and p53, as well as cyclooxygenase-2, galectin-3, and pituitary tumor transforming gene. Some of these markers, such as fibroblast growth factor and fibroblast growth factor receptor and matrix metalloproteinases, show particular promise in their ability to identify pituitary tumors that behave in an aggressive manner. We suggest the need for uniform design and application of methods and standardized criteria for the interpretation of results. A uniform approach will establish clinicopathological utility of emerging markers.

Salvage therapy with temozolomide in patients with aggressive or metastatic pituitary adenomas: experience in six cases

OBJECTIVE

The prognosis of either pituitary carcinoma or aggressive pituitary adenoma resistant to standard therapies is poor. We assessed the efficacy of treatment with temozolomide, an oral second-generation alkylating agent, in a consecutive series of six patients with aggressive pituitary adenomas.

DESIGN

This was a 1-year prospective study of temozolomide therapy in six consecutive patients with pituitary carcinoma (one case) or atypical pituitary adenoma (five cases) resistant to standard therapies. There were three males and three females. Age at enrollment ranged between 52 and 64 years. Temozolomide was given orally at a dose of 150-200 mg/m(2) per day for 5 days every 4 weeks for a maximum of 12 cycles.

METHODS

Response assessment was based on measurable change in tumor size, as assessed on magnetic resonance imaging, and hormone levels. Response was defined as reduction of at least 50% of tumor size and hormone levels.

RESULTS

Four patients completed the 12 cycles of temozolomide treatment, as planned. Two patients stopped the drug after 3 and 6 months respectively because of the progression of disease. Two patients responded to temozolomide, while the remaining two patients had stable disease. Immunohistochemistry for O(6)-methylguanine-DNA methyltransferase (MGMT) in tumor sample showed a partial association with treatment response.

CONCLUSIONS

Temozolomide treatment has a wide range of efficacy in patients with pituitary carcinoma or locally aggressive pituitary adenoma. Positive staining for MGMT seems likely to predict a lower chance of response.

Possible relevance between prohormone convertase 2 expression and tumor growth in human adrenocorticotropin-producing pituitary adenoma

CONTEXT

Methods for preoperative diagnosis of prohormone convertase 2 (PC2)-positive ACTH-producing pituitary adenomas (APPAs) have not been established. Also, their characteristics are not evident.

OBJECTIVE

This study was designed to understand the meaning of plasma alphaMSH levels and the role of cell proliferation-signaling molecules in PC2-positive APPAs.

PATIENTS AND MAIN OUTCOME MEASURES

Nineteen human APPAs (four males and 15 females) were examined for the expression of PC2, phosphorylated ERK1/2, phosphorylated Akt1/2/3 (p-Akt) and receptor tyrosine kinases. alphaMSH was measured in extracted plasma from 17 APPA patients and 30 healthy volunteers.

RESULTS

Nine adenomas (47.4%) were immunopositive for PC2 and were large and invasive in nature. In all normal controls and eight PC2-negative cases, plasma alphaMSH was undetectable, whereas in four PC2-positive cases, it was detected at abnormally higher levels. Eight adenomas (42.1%) were immunopositive for both PC2 and p-Akt, and seven others (36.8%) were immunonegative for both, suggesting significant coexpression of PC2 and p-Akt in tumors. Quantitative RT-PCR revealed that PC2 expression is associated with phosphorylation of Akt but not with its gene expression. Most APPAs expressed receptor tyrosine kinases, but membrane-bound receptors could not be identified.

CONCLUSIONS

Our study suggests that PC2 expression and Akt phosphorylation are related at the molecular level, resulting in a change in cell cycle and an increase in pituitary adenoma size. An elevation of plasma alphaMSH could conjecture the activation of the phosphatidylinositol 3/Akt cascade in PC2-positive APPAs and may become a valuable clinical marker of tumor growth in Cushing's disease.

Labeling index in pituitary adenomas evaluated by means of MIB-1: is there a prognostic role? A critical review

OBJECTIVE

The present article presents an overview of the literature, and analyses the methods and the primary questions related to assessment of proliferation index using the Ki-67/MIB-1 labeling index in pituitary adenomas. Although atypical adenomas are characterized by their atypical morphological features by an elevated mitotic index, a Ki-67 (MIB-1) labeling index greater than 3% and extensive nuclear staining for p53, use of the proliferation index (LI) of pituitary adenomas in assessing the degree of tumor aggressiveness is a controversial topic in the literature, and there are disparate results involving many studies.

METHODS

A review of literature was carried out to correlate the role of Ki-67 LI and its correlation with clinical findings, tumor size, invasiveness, recurrence, adenoma subtype, adenoma doubling time, and pituitary carcinomas is addressed.

RESULTS

The prognosis cannot be predicted on the basis of the Ki-67 LI alone. Although there is no direct relation between Ki-67 LI and some of these variables and controversial data were found regarding some topics, our review justify the use of Ki-67 in the analysis of pituitary adenomas as an additional information for clinical decision.

CONCLUSION

Although assessment of proliferative may be helpful in predicting subsequent tumor recurrence or invasiveness, there are many other important and as yet unidentified factors pituitary tumors. It is clear that further research is needed to clarify these molecular mechanisms to predict those with a potentially poor clinical outcome.

Expression of Ki-67, PCNA, and p27kip1 in canine pituitary corticotroph adenomas

Pituitary-dependent hypercortisolism (PDH), which is caused by adrenocorticotropic hormone (ACTH)-secreting pituitary adenomas, is a common endocrinopathy in dogs. Dogs with non-enlarged pituitaries harboring a microadenoma have a better prognosis than those with enlarged pituitaries. The aim of this study was to investigate the expression of the proliferation markers Ki-67 and proliferating cell nuclear antigen (PCNA) and the cell-cycle inhibitor p27kip1 in corticotroph adenomas in enlarged and non-enlarged pituitaries. The expression of Ki-67, PCNA, and p27kip1 was analyzed by immunohistochemical staining of 17 pituitary adenoma samples harvested during pituitary surgery in dogs with PDH. The labeling index was calculated by counting the number of immunopositive cells per 1,000 cells. The mean (+/- standard deviation) labeling index for Ki-67 was 8.4%+/-14.2% for the group with enlarged pituitaries, and 8.8%+/-5.5% for the group with non-enlarged pituitaries; that for PCNA was 35.5%+/-12.2% and 37.0%+/-15.5%; and that for p27kip1 was 29.3%+/-22.6% and 42.5%+/-27.9%, respectively. No significant differences in Ki-67, PCNA, and p27kip1 labeling indices were found between enlarged and non-enlarged pituitaries. However, a trend toward significance was observed when comparing the expression of p27kip1 in enlarged pituitaries versus normal pituitary tissue. It is concluded that Ki-67 and PCNA are not useful as proliferative markers for studying the pathobiology of pituitary corticotroph adenomas in dogs.

Inhibitory effect of prepro-thyrotrophin-releasing hormone (178-199) on adrenocorticotrophic hormone secretion by human corticotroph tumours

Prepro-thyrotrophin-releasing hormone (TRH) (178-199), a 22-amino acid cleavage product of the TRH prohormone, has been postulated to act as an adrenocorticotrophin hormone (ACTH)-release inhibitor. Indeed, although in vitro evidence indicates that this peptide may inhibit basal and stimulated ACTH secretion in rodent anterior pituitary primary cultures and cell lines, not all studies concur and no study has as yet evaluated the effect of this peptide in Cushing's disease. The present study aimed to test the effect of preproTRH(178-199) in human tumoural corticotrophs. Twenty-four human ACTH-secreting pituitary tumours (13 macroadenomas, 11 microadenomas) were collected during surgery and incubated with 10 or 100 nm preproTRH(178-199). ACTH secretion was assessed after 4 and 24 h of incubation by immunometric assay and expressed relative to levels observed in control, unchallenged wells (= 100%). Parallel experiments were performed in rat anterior pituitary primary cultures. A clear inhibition of ACTH secretion at 4 and 24 h was observed in 12 specimens (for 10 nm ppTRH: 70 +/- 4% control at 4 h and 83 +/- 5% control at 24 h; for 100 nm ppTRH: 70 +/- 4% control at 4 h and 85 +/- 5% control at 24 h), whereas a mild and short-lasting stimulatory effect was observed in three tumours and no changes in ACTH secretion in the remaining nine tumoural specimens. The inhibitory effect of preproTRH(178-199) was more evident in macroadenomas and significantly correlated with sensitivity to dexamethasone inhibition. Significant inhibition of ACTH secretion by preproTRH(178-199) in rat pituitary cultures was observed after 24 h of incubation. The present study conducted in a large series of human corticotroph tumours shows that preproTRH(178-199) inhibits tumoural ACTH secretion in a sizable proportion of specimens, in close relation to the size of the tumour and its sensitivity to glucocorticoid negative feedback. This appears a promising avenue of research and further studies are warranted to explore the full scope of preproTRH(178-199) as a regulator of ACTH secretion.

Determination of cell proliferation using Mcm2 antigen and evaluation of apoptosis and TGF-beta1 expression in GH-secreting or clinically nonfunctioning pituitary adenomas

Pituitary adenomas (PA) occasionally show aggressive behavior, with invasion of the surrounding tissues. The identification of markers able to recognize aggressive PA in early stages remains a challenge. We aimed to determine the expression of a new cell proliferation marker, Mcm2, and the presence of apoptosis in PA, and to evaluate the association of clinicopathological features with the apoptotic and proliferative indices. Additionally, the TGF-beta1 expression, an inducer of apoptosis, was determined. The proliferative index was determined in GH-secreting or clinically nonfunctioning PA using immunohistochemical (IH) methods for Mcm2 and Ki-67 antigens. The apoptosis was assessed by the TUNEL method and the TGF-beta1 expression by IH. A significant positive correlation was found between log Mcm2 index and log Ki-67 index (p < 0.001). Mcm2 and Ki-67 detected a similar number of proliferating cells. Mcm2 index showed a significant association with tumor extension (p = 0.02), but not with tumor invasion. Apoptosis was detected in 17% of the adenomas, with a maximum apoptotic index of 0.77%. Immunoreactivity to TGF-beta1 was observed in 77% of the adenomas, showing an association with tumor extension. We concluded that, in this sample, Mcm2 was similar to Ki-67 in the identification of the proliferating cells and that apoptosis was rare.

Follicular apoptosis in the mussel (Mytella strigata) as potential indicator of environmental stress in coastal ecosystems

Follicular apoptosis in the tropical mussel Mytella strigata was assessed in three coastal lagoons located in the southern Gulf of California, Mexico. Mussels were collected from three coastal lagoons associated with different scenarios of anthropogenic stress during one year. The gonad of each mussel was dissected, weighed, and sampled for histology and apoptosis analysis by TUNEL labeling. Two apoptotic indices were used: the apoptotic index of cells (AIC) based on the number of follicular cells in apoptosis in one thousand cells counted per gonad, and the apoptotic index of follicles (AIF) based on the number of follicular cells per follicle per gonad. Both indices showed high association with each other for all developmental stages, although AIF seemed to better discriminate among sites. Higher AIF and AIC were observed at the Urias Estuary (1.6 and 1.5 respectively) ranked as highly polluted, followed by Ensenada del Pabellon (0.82 and 0.95 respectively), ranked as moderately polluted, and the Teacapan Estuary (0.57 and 0.76 respectively) ranked as slightly polluted. Our data indicate that the apoptotic index in tropical mussels could be a useful indicator of environmental stress in coastal ecosystems; however, the ecological relevance of follicular apoptosis in polluted environments needs further investigation.

Molecular events of cellular apoptosis and proliferation in the early tendon healing period

PURPOSE

Cellular proliferation is accompanied by cellular apoptosis. In the healing digital flexor tendon, molecular events concerning cellular apoptosis have not been investigated. This study aimed to investigate the relationship between cellular apoptosis and proliferation in early tendon healing.

METHODS

The flexor digitorum profundus tendons of 50 long toes in 25 chickens were transected and were repaired surgically. On postoperative days 3, 7, 14, 21, and 28, we subjected tendons to in situ terminal deoxynucleotide transferase dUTP nick end labeling (TUNEL) assay to detect apoptotic cells, immunofluorescence staining with antibodies to proliferating cell nuclear antigen to assess proliferation, and Bcl-2, an anti-apoptotic protein, to assess responses suppressive to apoptosis. The positively labeled tenocytes were counted microscopically and compared statistically. We also stained sections with hematoxylin and eosin to observe their healing status. An additional 12 tendons (6 chickens) served as day 0 controls.

RESULTS

Compared with tendons at day 0, the healing tendons had notably greater cellularity in both epitenon and endotenon areas. The total number of cells and number of TUNEL-positive cells peaked at day 3. At days 7 to 21, the number of proliferating cell nuclear antigen-positive cells peaked. At days 7 and 14, the cells positively stained with Bcl-2 peaked. At days 14 to 28, the total number of cells and TUNEL-positive cells decreased significantly compared with those at days 3 and 7, yet the numbers remained greater than those on day 0.

CONCLUSIONS

Apoptosis in the healing tendons peaks at day 3, followed about 10 days later by the peak proliferation period. Because Bcl-2 serves to inhibit apoptosis, a later increase in Bcl-2-positive cells indicates that tendon apoptosis is inhibited. These findings indicate that tenocyte apoptosis is accelerated within several days after injury, followed by increases in cellular proliferation and activation of molecular events to inhibit apoptosis in 2 to 4 weeks.

Ki-67 in pituitary neoplasms: a review--part I

KI-67, A MARKER of cellular proliferation, has been studied extensively in pituitary neoplasia. It is of relevance to various clinicopathological parameters, including tumor subtype, size, invasiveness, and recurrence, as well as patient age and sex. Generally, pituitary tumors behaving aggressively have increased Ki-67 labeling indices. Nonetheless, there is considerable overlap in Ki-67 labeling between noninvasive and invasive adenomas as well as between adenomas and pituitary carcinomas. Not only is there no general agreement regarding the relationship of Ki-67 labeling index and tumor invasiveness, but the same is also true of the association with pituitary tumor size, growth fraction, and recurrence. Whereas a number of studies found conclusive associations of Ki-67 labeling indices with aggressive behavior, size, and/or adenoma subtype, others fail to do so. It is evident that discrepant data regarding tumor behavior in part has its basis in nonuniform study criteria. For example, different investigators use varying criteria of tumor invasion and recurrence. Herein, we review the literature relating Ki-67 expression and various other clinicopathological parameters and conclude that uniform definitions and methods, as well as new markers, are key to improved treatment of pituitary tumors.

Clinical aspects and therapeutic outcome in thyrotropin-secreting pituitary adenomas: a single center experience

BACKGROUND AND AIM

The management of pituitary adenomas secreting TSH has evolved considerably over the last decades.We report the clinical features, management, and outcome of a large monocentric series.

MATERIAL AND METHODS

A monocentric retrospective cohort of 26 patients admitted to our Department of Endocrinology between 1983 and 2007, followed for a period up to 204 months. The diagnosis of TSH-secreting adenoma was based on clinical and biochemical findings of central hyperthyroidism. Evaluation of basal and dynamic pituitary function, magnetic resonance imaging or computerized tomography scan were performed in all patients. Twenty-two patients, of whom 15 pre-treated by somatostatin analogs (SSA), underwent trans-sphenoidal surgery and were regularly re-evaluated.

RESULTS

The number of cases increased over the years. Age at diagnosis, micro- to macroadenoma ratio, and mean estimated latency between first symptoms and diagnosis did not appreciably change over time. Latency was significantly shorter in macroadenomas. Following surgery, 55% of patients obtained remission (success rate of 40 and 67% in macro- and microadenomas, respectively). SSA pre-treatment led to an apparent although not statistically- significant increase in success rate in micro- but not in macroadenomas.

CONCLUSIONS

In a monocentric group of 26 TSH-secreting adenomas the high ratio between micro- and macroadenomas remained stable over time with a significantly shorter diagnosis latency in macroadenomas. A more precocious recognition of the tumors and possibly the use of presurgical SSA allowed a high remission rate. A varied combination of neurosurgery, SSA, radiotherapy, and thyroid ablation led to the control of the disease in all the patients studied.

A comparative study by age and gender of the pituitary adenoma and ACTH and alpha-MSH secretion in dogs with pituitary-dependent hyperadrenocorticism

Pituitary-dependent hyperadrenocorticism (PDH) is frequent in dogs. Little is known about its presentation in different age groups and its characteristics. Dividing the population under study (n=107) into three age groups we observed that 11.2% were young, 51.4% adults and 37.4% aged. Using magnetic resonance, pituitary tumours were intra-sellar (IS) in 30.8% and extra-sellar (ES) in 62.6% and the pars intermedia (PI) was affected in 6.5%. ES are predominant in females and IS in males (p<0.0001). In the adult-aged population, the ES and PI are predominant, while in the young, the IS predominate (p<0.0001). ACTH concentration was greater in the ES vs. IS (p<0.05). alpha-MSH did not present significant differences according to tumour size, showing a negative correlation (r=-0.47; p<0.01) vs. ACTH. Differences in adenoma size according to gender and their age-related frequency of apparition could be because of different origins of the corticotrophinoma.

Anti-proliferation Effect of Polypeptide Extracted from Scorpion Venom on Human Prostate Cancer Cells in vitro

BACKGROUND

Prostate cancer is a major cause of cancer-related death in men. Therefore there has been considerable interest to explore neoadjuvant therapy. Polypeptide extracted from scorpion venom (PESV), originally obtained from the East-Asian scorpion Buthus martensi Karsch (BmK), is being studied for both prevention and treatment of various human malignancies including prostate cancer.

METHODS

The present study was to investigate the effect of PESV on cell proliferation, cell cycle, and apoptosis in human androgen-independent prostate cancer cells DU-145 in vitro.

RESULTS

PESV treatment on these cells resulted in a significantly dose-dependent growth inhibition with a G1 phase arrest at 40μg/mL after 48h treatment. PESV treatment strongly induced expression of p27 (Kip1), but resulted in a decrease in cyclin E, one of cyclins involved in G1 progression. In other studies, PESV treatment also induced high apoptosis index (AI), confirmed by TdTmediated dUTP-biotin nick-end labeling (TUNEL) assay. Further, the apoptosis induction by PESV (40μg/mL) in DU145 cells was associated with an increase of pro-apoptotic protein Bax.

CONCLUSIONS

These results suggest that PESV modulates the expression of cell cycle-related and apoptosis-related proteins and induces growth inhibition and apoptosis of DU145 cells, providing a strong rationale for future studies to evaluate prevention or/and intervention strategies for PESV in pre-clinical prostate cancer models.

KEYWORDS

Prostate cancer, PESV, cell proliferation, cell cycle, apoptosis.

Early results of surgery in patients with nonfunctioning pituitary adenoma and analysis of the risk of tumor recurrence

OBJECT

Nonfunctioning pituitary adenomas (NFPAs) are benign tumors of the pituitary gland that typically cause visual and/or hormonal dysfunction. Surgery is the treatment of choice, but patients remain at risk for tumor recurrence for several years afterwards. The authors evaluate the early results of surgery and the long-term risk of tumor recurrence in patients with NFPAs.

METHODS

Between 1990 and 2005, 491 previously untreated patients with NFPA underwent surgery at the Università Vita-Salute. Determinations of recurrence or growth of the residual tumor tissue during the follow-up period were based on neuroradiological criteria.

RESULTS

Residual tumor after surgery was detected in 173 patients (36.4%). Multivariate analysis showed that invasion of the cavernous sinus, maximum tumor diameter, and absence of tumor apoplexy were associated with an unfavorable surgical outcome. At least 2 sets of follow-up neuroimaging studies were obtained in 436 patients (median follow-up 53 months). Tumors recurred in 83 patients (19.0%). When tumor removal appeared complete, younger age at surgery was associated with a risk of tumor recurrence. In patients with incomplete tumor removal, adjunctive postoperative radiotherapy had a marked protective effect against growth of residual tumor.

CONCLUSIONS

Complete surgical removal of NFPAs can be safely achieved in > 50% of cases. Visual symptoms and, less frequently, pituitary function may improve after surgery. However, tumor can recur in patients after apparently complete surgical removal. In patients with incomplete tumor removal, radiation therapy is the most effective adjuvant therapy for preventing residual tumor growth.

ACTH and alpha-subunit are co-expressed in rare human pituitary corticotroph cell adenomas proposed to originate from ACTH-committed early pituitary progenitor cells

The functional differentiation of pituitary cells and adenomas follows the combination of transcription factors and co-factors in three cell lineages [growth hormone-prolactin-thyroid-stimulating hormone lineage, adrenocorticotrophic hormone (ACTH)/pro-opiomelanocortin (POMC) lineage, and follicular stimulating hormone (FSH)/luteinizing hormone (LH) lineage], which include Pit-1, GATA-2, SF-1, NeuroD1/beta2, Tpit, ERalpha, and others. Only rarely are hormones from different lineages co-expressed in the same adenoma cells. Most corticotroph cell adenomas belonging to the ACTH/POMC lineage are mono-hormonal. In our study of 89 corticotroph cell adenomas, 5 cases expressed both ACTH and alpha-subunit; these adenomas did not express any other anterior pituitary hormones or subunits. To clarify the mechanism involved, we studied the transcription factors that regulate pituitary cell differentiation. NeuroD1 and T-pit, markers of the ACTH/POMC lineage, and SF-1 and DAX-1, related to the LH/FSH cell lineage were expressed in all cases. GATA2, a synergistic factor in the gonadotroph cell lineage with SF-1, was also expressed in three of five cases. As ACTH and alpha-subunit are the earliest hormones to appear during development, we speculate that these particular adenomas are derived from committed ACTH progenitor cells. The molecular process governing functional differentiation of these adenomas requires further investigation.

The characteristics of incidental pituitary microadenomas in 120 Korean forensic autopsy cases

To investigate the characteristics of incidental pituitary microadenomas, we examined 120 pituitary glands from Korean forensic autopsy cases, from which eight tumors were identified (incidence 6.7%). The average age of the affected subjects was 50 yr (range: 33-96 yr) with a female predominance. The maximum diameters of the tumors ranged from 0.4 to 5.4 mm (mean: 2.8 mm). Immunohistochemical analysis of pituitary hormones revealed three growth hormone-secreting adenomas, one prolactin-producing adenoma, one gonadotropin-producing adenoma, one plurihormonal adenoma, and two null cell adenomas. MIB-1 staining for Ki-67 antigen showed no positive expression. The microvessel density (MVD) of the pituitary microadenomas ranged from 2.3 to 11.6% (mean: 5.3%) and was significantly lower than that of nonneoplastic pituitary glands (11.9-20.1%, mean: 14.8%). Our study provides reference data on incidental pituitary microadenomas in the Korean population.

Presurgical treatment with somatostatin analogs in patients with acromegaly: effects on the remission and complication rates

Object

The question of whether preoperative therapy with somatostatin analogs can improve surgical outcome in acromegaly has not been definitively answered. In this paper, the authors report the effects of preoperative treatment with somatostatin analogs in a large sample of patients with acromegaly.

Methods

Between 1990 and 2003, 399 consecutive patients with acromegaly underwent surgery at the Istituto Scientifico San Raffaele. Thirty-three patients who had previously undergone surgery or radiation treatment, 48 patients treated with somatostatin analogs for fewer than 3 months, and patients who had stopped therapy for too long a time before surgery were excluded from the study. One hundred forty-three patients who had received somatostatin analogs prior to surgery (Group 1) were randomly matched to 143 patients who had never been treated with somatostatin analogs (Group 2). Matching criteria were tumor size and invasiveness into the cavernous sinus. Before surgery, Group 1 patients showed reduction of growth hormone levels to less than 50% of baseline in 64% of cases, but insulin-like growth factor–I was normalized in only 19.5%. Surgical remission occurred in 81 Group 1 patients (56.6%) and in 91 Group 2 patients (63.6%; p = 0.28). No significant difference in the remission rate was observed when cases were analyzed according to tumor size or invasiveness. Logistic regression analysis confirmed that pretreatment with somatostatin analogs was not associated with surgical outcome. Surgical morbidity was mild and similar in Group 1 and Group 2 patients (7 and 5.6%, respectively; p = 0.81). Surgical remission and complication rates in patients with acromegaly who received treatment with somatostatin analogs prior to surgery were not significantly different from those of matched patients who did not receive these agents.

Conclusions

At present, the routine use of presurgical therapy with somatostatin analogs for patients with acromegaly cannot be recommended.

Effect of protracted treatment with rosiglitazone, a PPARgamma agonist, in patients with Cushing's disease

OBJECTIVE

Cushing's disease, hypercortisolism due to a pituitary ACTH-secreting tumour, is a highly morbid illness as yet without effective medical therapy. Recent studies have demonstrated that peroxisome proliferator-activated receptor gamma (PPARgamma) agonists effectively suppress ACTH secretion in a murine tumoral corticotroph cell line, but the few studies conducted so far in patients with ACTH-secreting pituitary adenomas have yielded variable results.

DESIGN

Ten patients with Cushing's disease were treated with 4-16 mg rosiglitazone p.o. daily for 1-8 months (median 3 months) and plasma ACTH and cortisol, urinary free cortisol (UFC), as well as parameters of insulin sensitivity, were recorded. An acute challenge with 8 mg rosiglitazone for 2 days preceded long-term rosiglitazone administration.

RESULTS

The acute challenge with rosiglitazone did not significantly modify plasma ACTH and cortisol levels. During protracted treatment with rosiglitazone, four patients showed a persistent reduction in UFC levels (up to 24% of pretreatment values), achieving normalization in three. In the others, UFC as well as plasma ACTH and cortisol decrements were inscribed within wide, random oscillations indicating that disease activity was substantially unchanged. Insulin sensitivity was ameliorated in most patients, without relation to ACTH or cortisol secretion. Untoward effects, such as weight gain, oedema and worsening of ecchymoses, were reported in several patients.

CONCLUSIONS

Although effective in a subset of patients, protracted rosiglitazone administration did not consistently restrain ACTH and cortisol secretion in patients with Cushing's disease. Further investigations are needed to fully define the therapeutic potential of PPARgamma agonists in this disorder.

Relevance of high Ki-67 in pituitary adenomas

Pituitary adenomas are heterogeneous in growth rate, invasiveness, and recurrence. To understand the biological behavior of the individual adenoma more fully, cell proliferation markers such as monoclonal antibodies targeted against the Ki-67 antigen have been applied. The Ki-67 antigen is a protein related to cell proliferation and is expressed in cell nuclei throughout the entire cell cycle. The authors report the case of an extremely rapidly growing pituitary adenoma with cavernous sinus invasion. The lesion, which displayed a high Ki-67 labeling index (LI; 22%), was found in a 54-year-old woman who presented with diplopia and headaches. The patient underwent three transsphenoidal operations in less than 6 months and, ultimately, was treated with fractionated intensity-modulated radiation therapy. The relationships between high Ki-67 LIs and tumor recurrence, invasiveness, and growth velocity in pituitary adenomas are reviewed.

Results of Transsphenoidal Surgery in a Large Series of Patients with Pituitary Adenoma

OBJECTIVE:

To report the efficacy and safety of microsurgical transsphenoidal surgery in a series of previously untreated patients with pituitary adenoma.

METHODS:

One thousand one hundred forty consecutive patients undergoing transsphenoidal resection of a pituitary adenoma at our department from January 1990 through December 2002 were included in our study. Postoperative results were classified uniformly during the period of the study. Patients were considered in remission of disease when strict hormonal and radiological criteria of cure were met.

RESULTS:

The most frequent tumor type was clinically nonfunctioning adenoma (NFPA) (33.2%), followed by growth hormone-secreting adenoma (28.1%), adrenocorticotropin-secreting adenoma (23.0%), prolactin-secreting adenoma (13.2%), and last, thyrotropin-secreting adenoma (2.5%). The patient population was 59.7% female and 40.3% male. Mean age was 43.0 ± 0.4 years. There were 788 macroadenomas (69.1%), and in 233 patients (20.4%), the tumor invaded one or both cavernous sinuses. The overall rate of early surgical success was achieved in 504 (66.1%) of the 762 patients with a hormone-active adenoma. Surgical outcome was better in patients with microadenomas than in patients with macroadenomas (78.9% and 55.5%, respectively), whereas tumors invading the cavernous sinus had a poorer outcome (7.4%). In patients with NFPA, no residual adenoma was present in 234 patients (64.8%). Normalization of visual defects occurred in 117 (40.5%) of the 289 patients with visual disturbances and improved in another 148 patients (51.2%). Three patients (0.3%) died as a consequence of surgery.

CONCLUSION:

Transsphenoidal surgery is an effective and safe treatment for most patients with pituitary adenoma and could be considered the first-choice therapy in all cases except for prolactinomas responsive to dopamine agonists. Other treatment methods, such as radiotherapy, stereotactic radiosurgery, and medical therapy, play an important role in patients not cured by surgery.

Species-specific urokinase receptor ligands reduce glioma growth and increase survival primarily by an antiangiogenesis mechanism

Species-specific urokinase receptor (uPAR) ligands with improved pharmacokinetics were generated by site-specific mutagenesis and amino-terminal pegylation. These molecules were used to probe the role of uPAR in brain tumor progression and angiogenesis. The ligands blocked endothelial cell tube formation in Matrigel in a species-specific manner and reduced both baseline and uPA amino-terminal fragment-stimulated cell migration on vitronectin gradients. Treatment of U87MG gliomas implanted orthotopically in mice with single species-specific or combination uPAR ligands resulted in significant decreases in tumor size, which translated to increases in survival time, and which were most significant when the murine-specific ligand was included. Further analysis of tumors showed that the reduced sizes were correlated with a decrease in tumor cell proliferation and mean vessel density and an increase in tumor cell apoptosis. In addition, a large increase in collagen deposition was observed in the treated groups. Statistical analysis showed that the combination therapy demonstrated a clear synergy as compared to the individual agent treatments. These results suggest that the major role of the uPAR system in brain tumor progression is in the stromal compartment and particularly in neovascularization, a hallmark of invasive brain tumors.

Correlation between clinical characteristics and proliferative activity in patients with craniopharyngioma

OBJECTIVES

The aim of the study was to correlate the Ki-67 and cyclin A labelling index (LI) with clinical characteristics and risk of recurrence of craniopharyngiomas.

METHODS

47 consecutive patients were studied, 21 female and 26 male, aged 34.3 (2.8) years. Immunohistochemical analysis was performed on paraffin wax embedded material using monoclonal antibodies directed against the proliferation associated nuclear antigen Ki-67 and cyclin A.

RESULTS

The median Ki-67 LI was 8.6% (interquartile range, 4.4%-14.0%). Ki-67 LI was significantly higher in tumours with a heavy inflammatory reaction and diabetes insipidus at presentation, whereas other clinical and histological features were not associated with the proliferation index. There was a strong linear correlation between Ki-67 LI and cyclin A LI (r = 0.77; p<0.0001); therefore, cyclin A LI showed the same clinical and histological relations described for Ki-67 LI. Recurrence of craniopharyngioma occurred in 13 of 46 patients (28.3%). The median Ki-67 LI in the 13 recurrent craniopharyngiomas (9.0%) was not significantly different from that of non-recurring tumours (7.9%). Cyclin A LI was also not associated with the risk of relapse.

CONCLUSIONS

This study confirms the great variability of proliferative activity in craniopharyngiomas. Ki-67 and cyclin A LIs were associated with the presence of a heavy inflammatory reaction and diabetes insipidus, but did not correlate with the long term risk of tumour regrowth.

Molecular defects in the pathogenesis of pituitary tumours

The majority of pituitary adenomas are trophically stable and change relatively little in size over many years. A comparatively small proportion behave more aggressively and come to clinical attention through inappropriate hormone secretion or adverse effects on surrounding structures. True malignant behaviour with metastatic spread is very atypical. Pituitary adenomas that come to surgery are predominantly monoclonal in origin and roughly half are aneuploid, indicating either ongoing genetic instability or transition through a period of genetic instability at some time during their development. Few are associated with the classical mechanisms of tumour formation but it is generally believed that the majority harbour quantitative if not qualitative differences in molecular composition compared to the normal pituitary. Despite their prevalence and the ready availability of biopsy material, at the present time, the precise molecular pathogenesis of the majority of pituitary adenomas remains unclear. This review summarizes current thinking.

Correlation of bcl-2 and bax with apoptosis in human pituitary adenomas

Bcl-2 oncogene and Bax gene play an important role in regulating apoptosis. In the present study, the expression of bcl-2 and bax was investigated and correlated with apoptosis in a series of 81 pituitary adenomas. Bcl-2 and bax proteins were localized by immunohistochemistry and the histoscore (HSC) was assessed by multiplying the immunohistostaining grade (1 to 4) by the staining intensity grade (1 to 3). According to bcl-2/bax HSC the tumors were separated in group A when > or = 1 and group B when < 1. The apoptotic labeling index (ALI) was accessed by the in situ end-labeling (ISEL) technique. Bcl-2 protein was equally detected in functioning and nonfunctioning adenomas with statistically significant higher HSC in nonfunctioning tumors (P < 0.03). Bax protein was immunopositive in the substantial majority of adenomas with significantly higher HSC in functioning as compared to nonfunctioning adenomas (P < 0.0009). The ALI was significantly higher in functioning adenomas as compared to nonfunctioning adenomas (P < 0.04). In addition, ALI was significantly higher in group B than in group A (P < 0.004) and it was correlated with bax HSC (P < 0.004). Finally, the group B of bcl-2/bax significantly predominated in nonfunctioning tumors (P < 0.0009) and in microadenomas (P = 0.05), as compared with functioning adenomas and macroadenomas respectively. In conclusion, our findings suggest that bcl-2 and bax molecules play a role in the regulation of apoptotic mechanisms in pituitary adenomas.

Effects of octreotide treatment on the proliferation and apoptotic index of GH-secreting pituitary adenomas

To investigate the effects of octreotide administration on the growth rate of GH-secreting pituitary adenomas, we measured both the Ki-67 labeling index (LI) and the apoptotic index in tumor specimens from octreotide-treated or matched untreated acromegalic patients. Thirty-nine patients who received octreotide until the day of or the day before surgery and 39 untreated patients matched for sex, age, tumor size, extension, and invasiveness were studied. Immunocytochemical analysis was performed on paraffin-embedded material using a monoclonal antibody (MIB-1) directed against a proliferation-associated nuclear antigen, Ki-67, to measure the growth fraction. Apoptosis was assessed by the terminal deoxynucleotidyl transferase-mediated deoxy-UTP nick endlabeling method, using a monoclonal antibody recognizing areas of DNA fragmentation. The Ki-67 LI and apoptosis were counted on separate slides in at least 1000 evaluable cells. Octreotide-treated patients showed a lower Ki-67 LI (1.8 +/- 0.3%) than untreated controls (3.8 +/- 0.7%; P < 0.02). Overall, the mean Ki-67 LI of treated patients was 53% lower than that in untreated patients. The antiproliferative effect of octreotide occurred independently of tumor extension and invasiveness. Octreotide-treated and untreated patients showed similar apoptotic indexes (0.6 +/- 0.2% and 0.8 +/- 0.3%, respectively). There was a positive correlation between the Ki-67 LI and the apoptotic index (r = 0.29; P < 0.03). Our study demonstrates that acromegalic patients receiving chronic octreotide treatment have a lower value of the proliferation marker Ki-67, but no significant difference in the apoptotic index compared with matched untreated patients. The antiproliferative effect of octreotide on GH-secreting adenomas should imply a lower risk of tumor growth during long-term chronic treatment with the drug.