Biomarkers of pituitary neoplasms: a review (Part II)

XIST in Brain Cancer

Long non-coding RNAs (lncRNAs) make up the majority of the human genome. They are a group of small RNA molecules that do not code for any proteins but play a primary role in regulating a variety of physiological and pathological processes. X-inactive specific transcript (XIST), one of the first lncRNAs to be discovered, is chiefly responsible for X chromosome inactivation: an evolutionary process of dosage compensation between the sex chromosomes of males and females. Recent studies show that XIST plays a pathophysiological role in the development and prognosis of brain tumors, a heterogeneous group of neoplasms that cause significant morbidity and mortality. In this review, we explore recent advancements in the role of XIST in migration, proliferation, angiogenesis, chemoresistance, and evasion of apoptosis in different types of brain tumors, with particular emphasis on gliomas.

Association of PTTG1 expression with invasiveness of non-functioning pituitary adenomas

Background

Pituitary tumor transforming gene 1 (PTTG1), paired-like homeodomain 2 (PITX2), and galectin-3 have been widely studied as predictive biomarkers for various tumors and are involved in tumorigenesis and tumor progression. We evaluated the usefulness of PTTG1, PITX2, and galectin-3 as predictive biomarkers for invasive non-functioning pituitary adenomas (NFPAs) by determining the relationship between the expressions of these three proteins and the invasiveness of the NFPAs. We also investigated whether PTTG1, E-cadherin, and Ki-67, which are known to be related to each other, show a correlation with NFPA features.

Methods

A retrospective study was conducted on 87 patients with NPFAs who underwent surgical removal. The NFPAs were classified into three groups based on magnetic resonance imaging findings of suprasellar extension and cavernous sinus invasion. Immunohistochemical staining for PTTG1, PITX2, galectin-3, E-cadherin, and Ki-67 was performed on tissue microarrays.

Results

PTTG1 expression showed a statistically significant correlation with the invasiveness of NFPAs, whereas PITX2 and galectin-3 did not have a relationship with the invasiveness of NFPAs. Moreover, there was no association among PTTG1, E-cadherin, and Ki-67 expression.

Conclusion

PTTG1 has the potential to serve as a predictive biomarker for invasive NFPA. Furthermore, this study may serve as a reference for the development of PTTG1-targeted therapeutic agents.

[Use of chemotherapy in the treatment of aggresive pituitary adenomas]

AIM

To clarify the concept of 'aggressive pituitary adenoma' using analysis of the current concepts, as well as to determine the optimal treatment algorithm for this disease and the place of chemotherapy in this treatment. Pituitary adenomas comprise from 10 to 15% of intracranial neoplasms. Despite the fact that pituitary adenomas are benign neoplasms, in 25-55% of cases they demonstrate invasive growth, growing into the surrounding structures (sphenoid sinus, cavernous sinus, etc.). Due to the lack of a standard definition of aggressive pituitary adenomas (due to the lack of clear criteria for this disease), there are no studies in the literature reporting optimal treatment for this group of patients, except for several publications describing the use of Temozolomide as palliative therapy.

LncRNA XIST depletion prevents cancer progression in invasive pituitary neuroendocrine tumor by inhibiting bFGF via upregulation of microRNA-424-5p

Background

Long noncoding RNAs (lncRNAs) are vital mediators in human cancers including pituitary neuroendocrine tumor (PitNET) and could function as competing endogenous RNAs (ceRNAs) of microRNAs (miRNAs). The main objective of this study is to identify effect of lncRNA X-inactive specific transcript (XIST) and microRNA-424-5p (miR-424-5p) on PitNET.

Methods

Microarray analysis was employed to identify the PitNET-related differentially expressed lncRNAs. PitNET tissues, including both invasive and non-invasive subtypes in parallel with normal pituitary tissues were collected for the determination of the expression of XIST, miR-424-5p and basic fibroblast growth factor (bFGF) and the interaction among them. Subsequently, the expression of XIST, miR-424-5p and bFGF in PitNET cells was altered to elucidate their biological significance in the aspects of proliferation, migration, invasion, and the apoptosis.

Results

Both XIST and bFGF exhibited high expression, but miR-424-5p had a low expression in invasive PitNET tissues as compared to non-invasive PitNET normal pituitary tissues. Additionally, XIST competitively bound to miR-424-5p to elevate the expression of bFGF. Furthermore, depleted XIST or bFGF, or elevated miR-424-5p was revealed to suppress the proliferation, migration, invasion, and promote cell cycle arrest and apoptosis of invasive PitNET cells. miR-424-5p repressed the proliferation, migration, invasion of invasive PitNET cells by targeting bFGF.

Conclusion

In conclusion, the fundamental findings of the present study suggested that the functional suppression of XIST downregulated bFGF to inhibit the development of PitNET by increasing miR-424-5p expression, proposing XIST as a novel therapeutic target for PitNET.

Increased expression of aromatase cytochrome P450 enzyme is associated with prolactinoma invasiveness in post-menopausal women

Objectives

To investigate the expression levels of aromatase cytochrome P450 enzyme (P450AROM) and related molecules—estrogen receptor-beta (ER-β), Ki-67, and p53—in prolactinoma tumor tissue from pre- and post-menopausal women, and to determine the associations of tumor invasiveness with expression levels of these genes.

Methods

This study recruited 90 patients with prolactinoma who underwent adenoidectomy between 2012 and 2017. Information was collected regarding clinical characteristics, hormones, laboratory tests, and magnetic resonance imaging-assessed tumor invasiveness. Expression levels of P450AROM, ER-β, Ki-67, and p53 were examined by immunohistochemistry in prolactinoma tissues.

Results

Increased P450AROM expression was found in invasive prolactinoma tissues in post-menopausal women, compared with its expression in non-invasive prolactinoma tissues. ER-β level was significantly higher in patients resistant to treatment with bromocriptine, a dopamine agonist. However, there were no differences in rate of resistance to treatment (8.2% vs. 3.4%) or expression levels of P450AROM, Ki-67, p53, and ER-β between pre- and post-menopausal patients.

Conclusions

Our results demonstrated that increased P450AROM expression in prolactinoma of post-menopausal women was positively associated with invasiveness. Moreover, ER-β level was higher in both pre- and post-menopausal patients who were resistant to dopamine agonist treatment.

Immunohistochemical Study of NR2C2, BTG2, TBX19, and CDK2 Expression in 31 Paired Primary/Recurrent Nonfunctioning Pituitary Adenomas

This study investigated potential markers for predicting nonfunctioning pituitary adenoma (NFPA) invasion and recurrence by high-throughput tissue microarray analyses. We retrospectively studied two groups of patients: 60 nonrecurrent NFPA cases that included noninvasion and invasion subtypes and 43 recurrent cases that included primary NFPA. A total of 31 paired patient samples were evaluated (12 patients with one surgery and 31 who had undergone two operations, with both tumors analyzed). Expressions of nuclear receptor subfamily 2 group C member 2 (NR2C2), B cell translocation gene 2, T-box-19 (TBX19), and cyclin-dependent kinase 2 (CDK2) in surgically resected specimens were assessed by immunohistochemistry. The relationships between marker expression and clinical characteristics including age, sex, tumor volume, and follow-up time were analyzed. Tumor volume and invasion as well as follow-up time were significantly associated with invasion and recurrence (P < 0.01). Of the 60 nonrecurrent samples, 15/41 and 13/19 showed high NR2C2 expression in the noninvasion and invasion groups, respectively (χ ² =5.287, P = 0.021). NR2C2 was also overexpressed in 43 primary recurrent cases (χ ² =5.433, P = 0.02), whereas CDK2 (χ ² = 11.242, P = 0.001) and TBX19 (χ ² = 4.875, P = 0.027) were downregulated. In the 31 paired samples, NR2C2 was more highly expressed in the recurrent as compared to the primary tumor. High NR2C2 expression was associated with NFPA invasion, recurrence, and progression, while TBX19 and CDK2 were associated with NFPA recurrence.

[Morphofunctional features of non-functioning pituitary adenomas]

Non-functioning pituitary adenomas (NFPAs) account for about 30% of all pituitary tumors. NFPAs are characterized by the lack of secretory potential or its weak expression insufficient for determination of the blood level of adenohypophyseal tropic hormones and for development of a specific clinical picture. Morphologically, NFPAs are a heterogeneous group of tumors, the classification of which was previously based only on immunoreactivity for pituitary tropic hormones. The WHO revised its Classification of Tumors of Endocrine Organs (4th edition) in 2017. The main changes relate to adenohypophysial-cell lineage for the designation of adenomas into subtypes. The introduction of transcription factor antibodies has become a fundamentally new approach to the classification of NFPAs, which is necessary to recognize less differentiated tumor types. This paper provides information on the new histopathological classification of pituitary adenomas, on the theories of silent adenomas, and on the proliferative and prognostic markers of NFPAs.

Refractory pituitary adenoma: a novel classification for pituitary tumors

Pituitary adenomas are classified as typical or atypical, invasive or noninvasive, and aggressive or nonaggressive based on pathological features, radiological findings, and clinical behavior. Only pituitary tumors with cerebrospinal and/or systemic metastasis are considered malignant carcinomas. However, some pituitary adenomas with high Ki-67 indexes exhibit aggressive behaviors, such as rapid growth, early and frequent recurrence, and resistance to conventional treatment, even in the absence of metastasis. Novel terminology is needed to define these tumors. Here, we propose the use of the term “refractory pituitary adenoma” to define malignant pituitary tumors exhibiting 1) a high Ki-67 index and rapid growth, 2) early and high frequency of recurrence, 3) resistance to conventional treatments and/or salvage treatment with temozolomide (TMZ), 4) poor prognosis, 5) and a lack of cerebrospinal or systemic metastases. To illustrate the utility of this refractory pituitary adenoma classification and the difficulty in managing disease in these patients, we examined twelve clinical cases. Correctly identifying refractory pituitary adenomas is crucial for improving patient prognoses. Early identification might encourage the early use of aggressive therapeutic strategies to prevent or delay recurrence.

Criteria for the definition of Pituitary Tumor Centers of Excellence (PTCOE): A Pituitary Society Statement

INTRODUCTION

With the goal of generate uniform criteria among centers dealing with pituitary tumors and to enhance patient care, the Pituitary Society decided to generate criteria for developing Pituitary Tumors Centers of Excellence (PTCOE).

METHODS

To develop that task, a group of ten experts served as a Task Force and through two years of iterative work an initial draft was elaborated. This draft was discussed, modified and finally approved by the Board of Directors of the Pituitary Society. Such document was presented and debated at a specific session of the Congress of the Pituitary Society, Orlando 2017, and suggestions were incorporated. Finally the document was distributed to a large group of global experts that introduced further modifications with final endorsement.

RESULTS

After five years of iterative work a document with the ideal criteria for a PTCOE is presented.

CONCLUSIONS

Acknowledging that very few centers in the world, if any, likely fulfill the requirements here presented, the document may be a tool to guide improvements of care delivery to patients with pituitary disorders. All these criteria must be accommodated to the regulations and organization of Health of a given country.

Alpha subunit in clinically non-functioning pituitary adenomas: An immunohistochemical study

Pituitary adenomas may be classified as either functioning or non-functioning, depending on whether excess hormone secretion can be clinically identified. Of the six hormones produced in the anterior pituitary, TSH, FSH and LH are known as glycoproteins and contain two subunits (α and β). While α-subunit is identical within all of them, each β-subunit is unique and biologically specific. Independently, the α- and β-subunits are inactive and only induce a hormonal response when they are non-covalently associated. Studies have shown that in certain cases, pituitary adenomas may abnormally secrete only α-subunit, detectable in the serum or through immunohistochemical analysis. In the present study, we examined α-subunit immunoexpression in surgically removed non-functioning pituitary adenomas and analyzed its prognostic value. Results showed that expression of α-subunit in clinically non-functioning pituitary adenomas is not a rare occurrence. While there were no age/gender differences between tumors that expressed α-subunit and those that did not, α-subunit immunonegative adenomas presented with suprasellar extension more frequently and had an Ki67 proliferation greater than 3%. The use of immunohistochemical techniques to determine the presence of α-subunit may provide information on tumor cell proliferation and biologic behavior. To fully understand the role of α-subunit in pituitary adenomas more work is needed.

Selective molecular biomarkers to predict biologic behavior in pituitary tumors

To date, several cell proliferation markers, apoptosis, vascular markers, oncogenes, tumor suppressor genes, cell cycle mediators, microRNA (miRNAs), and long noncoding RNAs (lncRNAs) have been identified to be involved in the tumorigenesis, migration, proliferation and invasiveness of pituitary adenomas. There are still no reliable morphologic markers predictive of pituitary adenoma recurrence. Recent scientific research introduced new techniques to enable us to attain new information on the genesis and biologic behavior of pituitary adenomas. Areas covered: This review covers selected, compelling and cumulative information in regards to TACSTD family (EpCAM, TROP2), neuropilin (NRP-1), oncogene-induced senescence (OIS), fascins (FSCN1), invasion-associated genes (CLDN7, CNTNAP2, ITGA6, JAM3, PTPRC and CTNNA1) EZH2, and ENC1 genes and endocan. Expert commentary: Ongoing research provides clinicians, surgeons and researchers with new information not only on diverse pathways in tumorigenesis but also on the clinical aggressive behavior of pituitary adenomas. Newly developed molecular techniques, bioinformatics and new pharmaceutical drug options are helpful tools to widen the perspectives in our understanding of the complex nature of pituitary tumorigenesis. The discovery of new molecular biomarkers can only be accomplished by continuing to investigate pituitary embryogenesis, histogenesis and tumorigenesis.

Biomarkers of pituitary carcinomas

Pituitary carcinoma is a rare tumor originating from adenohypophyseal cells. Currently, diverse pathogenetic mechanisms, i.e. de novo versus malignant transformation from pituitary adenoma, remain obscure and require further investigation. During the last two decades, scientific research added new horizons not only in regards to general tumor concepts but also in next generation biomarker armamentarium that sheds light on alternate pathways in carcinogenesis. Areas covered: In this review, the impact of apoptotic and proliferative markers, angiogenesis, telomerase activity, H-ras, HIF-1, HER-2/neu, Rb gene, and microRNAs in pathogenetic mechanisms of pituitary carcinomas were revised. Expert commentary: It is becoming increasingly important for the need of standardization of new biomarkers but also for better comprehension of the diverse pathways in tumorigenesis. This can only be accomplished by tapping into the continuously expanding spectrum of new biomarkers.

Nonfunctioning giant pituitary adenomas: Invasiveness and recurrence

BACKGROUND

We report our surgical series of 35 patients with giant nonfunctioning pituitary adenomas (GNFPA). We analyzed the rule of Ki-67 antigen expression in predicting recurrence.

METHODS

Thirty-five patients were operated between 2000 and 2010. Suprassellar extension of the tumors were classified according to Hardy and Mohr based on magnetic resonance (MR) studies. Pituitary endocrine function and MR scans were assessed preoperatively and at 1, 6, and 12 months postoperatively. Immunohistochemical studies were based in regard to the expression of the proliferative Ki-67 index and the hormonal receptor for luteinizing hormone, follicle stimulating hormone, growth hormone, thyroid stimulating hormone, adrenocorticotropic hormone, and prolactin. Tumors specimens were obtained from 35 patients with GNFPA. Endoscopic transsphenoidal surgery was the approach of choice.

RESULTS

Thirty-five patients were submitted to 49 surgeries, 44 (89.8%) were transsphenoidal and 5 (10.2%) were transcranial. The most frequent preoperative complaints were visual acuity impairment and visual field defect in 25 (71.2%) and 23 (65.7%) cases, respectively. Improvement of visual acuitiy and visual field deficit after surgery was seen in 20 (80%) and 17 (73.9%) patients, respectively. Endocrinological deficits were encountered in 20 patients (57.1%). After surgery, 18 patients (51.4%) required hormonal replacement. Three patients had visual symptoms related to pituitary apoplexy and recovered after surgery. The Ki-67 labeling index (LI) ranged from <1% to 4.8%. The rate of recurrence in tumors with Ki-67 <3% was 7.7% (2 patients), Ki-67 >3% was present in 5 patients and the recurrence committed 3 patients.

CONCLUSION

In our series, regardless the improvement of visual function and compressing symptoms, 5 patients with expression of Ki-67 LI more than 3% experienced a recurrence.

Lhx4 deficiency: increased cyclin-dependent kinase inhibitor expression and pituitary hypoplasia

Defects in the Lhx4, Lhx3, and Pitx2 genes can cause combined pituitary hormone deficiency and pituitary hypoplasia in both humans and mice. Not much is known about the mechanism underlying hypoplasia in these mutants beyond generally increased cell death and poorly maintained proliferation. We identified both common and unique abnormalities in developmental regulation of key cell cycle regulator gene expression in each of these three mutants. All three mutants exhibit reduced expression of the proliferative marker Ki67 and the transitional marker p57. We discovered that expression of the cyclin-dependent kinase inhibitor 1a (Cdkn1a or p21) is expanded dorsally in the pituitary primordium of both Lhx3 and Lhx4 mutants. Uniquely, Lhx4 mutants exhibit reduced cyclin D1 expression and have auxiliary pouch-like structures. We show evidence for indirect and direct effects of LHX4 on p21 expression in αT3-1 pituitary cells. In summary, Lhx4 is necessary for efficient pituitary progenitor cell proliferation and restriction of p21 expression.

Invasive, atypical and aggressive pituitary adenomas and carcinomas

Aggressive pituitary adenomas have a high risk of recurrence, a lack of therapeutic response, and resistance to conventional treatment. So far, no satisfactory biomarkers are available for predicting their behavior. Some specific pituitary adenoma histotypes are more prone to follow an aggressive behavior. Pituitary carcinomas are rare and show cerebrospinal and/or systemic metastasis. They have worse prognosis than aggressive adenomas, and radiation is of limited use in their treatment.

Aggressive pituitary tumors

Pituitary adenomas are common intracranial tumors that are mainly considered as benign. Rarely, these tumors can exhibit an aggressive behavior, characterized by gross invasion of the surrounding tissues, resistance to conventional treatment leading to early and frequent recurrences. Even more rarely, pituitary tumors can give rise to cerebrospinal or systemic metastases qualifying as pituitary carcinomas according to the latest WHO definition. In the same classification, a subset of tumors with relatively distinct histopathological features was identified and defined as atypical adenomas designated to follow a more aggressive clinical course. This classification, although clinically useful, does not provide an accurate correlation between histopathological findings and the clinical behavior of these tumors, neither is it adequate to convey the precise features of 'aggressive' tumors. Thus, 'aggressive' pituitary adenomas need to be properly defined with clinical, radiological, histological and molecular markers in order to identify patients at increased risk of early recurrence or subsequent tumor progression. At present, no single marker or classification system of pituitary tumor aggressiveness exists, and clinically useful information in the literature is insufficient to guide diagnostic and therapeutic decisions. Treatment of patients with aggressive pituitary tumors is challenging since conventional treatments often fail, necessitating multiple surgical procedures with additional radiotherapy. Although traditional chemotherapy applied in other neuroendocrine tumors has not been shown to be efficacious, newer agents, particularly temozolomide, have shown promising results and are currently used despite the lack of data from a randomized prospective trial. Molecular targeted therapies such as mTOR and epidermal growth factor inhibitors have also been applied and might prove to be useful in the management of these patients. In the present review, we provide information regarding the epidemiology and clinical, histopathological and molecular features of aggressive pituitary tumors using recent employed definitions. In addition, we review currently employed therapeutic means providing a therapeutic algorithm and highlight the need to identify more specific disease-related and prognostic markers and the necessity for central registration of these tumors.

Aggressive pituitary adenomas--diagnosis and emerging treatments

The WHO categorizes pituitary tumours as typical adenomas, atypical adenomas and pituitary carcinomas, with typical adenomas constituting the major class. However, the WHO classification does not provide an accurate correlation between histopathological findings and clinical behaviour. Tumours lacking typical histological features are classified as atypical, but not all are clinically atypical or exhibit aggressive behaviour. Pituitary carcinomas, by definition, have craniospinal or systemic metastases, although not all display classical cytological features of malignancy. Aggressive pituitary adenomas, defined from a clinical perspective, have earlier and more frequent recurrences and can be resistant to conventional treatments. Specific biomarkers have not yet been identified that can distinguish between clinically aggressive and nonaggressive pituitary adenomas, although the antigen Ki-67 proliferation index might be of value. This Review highlights the need to develop new biomarkers to facilitate the early detection of clinically aggressive pituitary adenomas and discusses emerging markers that hold promise for their identification. Defining aggressiveness is of crucial importance for improving the management of patients by enhancing prognostic predictions and effectiveness of treatment. New drugs, such as temozolomide, have potential use in the management of these patients; anti-VEGF therapy, mTOR and tyrosine kinase inhibitors are also potentially useful in managing selected patients.

Identification of a subtype-specific ENC1 gene related to invasiveness in human pituitary null cell adenoma and oncocytomas

Non-functioning pituitary adenomas (NFPAs) may be locally invasive. Surgery is a treatment option, but unlike the case for functional pituitary adenomas, there are almost no drug treatments available for NFPAs. Markers of invasiveness are needed to guide therapeutic decision-making and identify potential adjuvant drugs. Owing to the highly heterogeneous nature of NFPAs, little is known regarding the subtype-specific gene expression profiles associated with invasiveness. To identify important biomarkers of invasiveness, we selected 23 null cell adenomas and 20 oncocytomas. These tumors were classified as invasive or non-invasive adenomas based on magnetic resonance imaging, pathology slides and surgical findings. Firstly, we observed that there were significant differences in expression between invasive (n = 3) and non-invasive (n = 4) adenomas by gene expression microarray. A total of 1,188 genes were differentially expressed in the invasive and non-invasive adenomas. Among these 1,188 genes, 578 were upregulated and 610 were downregulated in invasive adenomas. Secondly, the expression of ENC1, which displayed the significant alterations, was further confirmed by qRT-PCR and Western blot analysis in all 43 tumor samples and three normal pituitary glands. Low levels of ENC1 were found in tumor samples, while high levels were detected in normal pituitary glands. Interestingly, the ENC1 expression level was low in invasive null cell adenomas compared with non-invasive adenomas, but this relationship was not observed in invasive oncocytomas. Immunohistochemistry also demonstrated that the staining of ENC1 was different between invasive and non-invasive null cell adenomas. In addition, bioinformatics studies, including gene ontology and protein interaction analyses, were also performed to better understand the critical role of ENC1 in the development and progression of null cell adenomas and oncocytomas. Consequently, ENC1 may be an important biomarker for null cell adenomas and oncocytomas, and it is specific to invasive null cell adenomas.

Pituitary carcinoma with endolymphatic sac metastasis

Pituitary carcinoma is characterized by the presence of a metastatic lesion(s) in a location non-contiguous with the original pituitary tumor. The mechanism(s) of malignant transformation are not known. A 15 year-old male was diagnosed in 1982 with a pituitary macroadenoma and acromegaly (random GH 67 ng/ml and no suppression by oral glucose). His prolactin was normal between 18 and 23 ng/ml. Transcranial resection in July 1983 was followed by radiation therapy. The tumor was immunopositive for GH and prolactin. The proliferation MIB-1 index was 0-1%. With aqueous Octreotide 100 mcg 4× daily both GH and IGF-1 became normal. The patient was lost to follow-up and was treated by his local physician. In 2001, his IGF-1 level was 1271 ng/ml, and his random GH was 1.8-2.4 ng/ml by ILMA despite progressive increase in the dose of Sandostatin LAR to 140 mg/month in divided doses. Prolactin remained normal or minimally increased between 15 and 25 ng/ml. In 2009 he was diagnosed with the tumor in the location of left endolymphatic sac. Histological examination showed low grade pituitary carcinoma strongly immunopositive for prolactin but negative for GH. MIB-1 antibody labeled 0-5% cells. In 2012 endoscopic resection of the pituitary tumor remnant was attempted. Immunohistochemical stains were strongly immunopositive for both prolactin and GH, similar to his original pituitary tumor. The MIB-1 proliferation index was low from 0 to 1%. To our knowledge this is the first case of pituitary carcinoma in the endolymphatic sac region. The dichotomy between the cell population of the pituitary lesion (GH/prolactin producing) and the metastasis (purely prolactin-producing) may suggest that the metastatic pituitary lesion derived from a clone distinct from the original one.

Nonfunctioning pituitary adenomas: association of Ki-67 and HMGA-1 labeling indices with residual tumor growth

BACKGROUND

The postoperative biological behavior of nonfunctioning pituitary adenomas (NFPAs) is variable. Some residual NFPAs are stable long-term, others grow, and some recur despite complete removal. The usual histological markers of tumor aggressiveness are often similar between recurring, regrowing, and stable tumors, and therefore are not reliable as prognostic parameters. In this study, the clinical utility of proliferation indices (labeling index, Li) based on immunohistochemistry targeted at antigens Ki-67 and High-mobility group A1 (HMGA-1) for prediction of NFPA prognosis was investigated.

METHODS

Fifty patients with NFPAs were investigated. In each patient, Ki-67 and HMGA-1 Li were evaluated. Based on postoperative magnetic resonance images, patients were classified as tumor-free (18 patients), or harboring a residual tumor (32 patients). The latter group was further subdivided into groups with stable tumor remnants (11 patients) or progressive tumor remnants (21 patients).

RESULTS

The median follow-up period was 8 years. No significant relationship between HMGA-1 Li and residual tumor growth was found. Growing residual tumors showed a trend towards higher Ki-67 Li compared with stable ones (p = 0.104). All tumor remnants with Ki-67 Li above 2.2% were growing. The relationship between residual tumor growth and Ki-67 Li exceeding the cutoff value of 2.2% was significant (p = 0.01 in univariate, p = 0.044 in multivariate analysis).

CONCLUSIONS

The prognostic significance of the HMGA-1 antigen was not confirmed. In contrast, the Ki-67 Li provides useful and valuable information for the postoperative management of NFPAs. In residual adenomas with a Ki-67 Li above 2.2%, regrowth should be expected, and these tumors may require shorter intervals of follow-up magnetic resonance imaging (MRI) and/or early adjuvant therapy. Future larger studies are needed to confirm the results of this study.

Pituitary carcinoma in situ

OBJECTIVE

Pituitary carcinomas are extremely rare tumors associated with poor prognosis despite surgery, radiation, and chemotherapy. The hallmark of diagnosis implies subarachnoid, brain, or systemic tumor spread.

METHODS

We report a case of rapid transformation of atypical nonfunctioning pituitary adenoma to a carcinoma.

RESULTS

A 64-year-old woman presented with sudden onset of ophthalmoplegia. Magnetic resonance imaging (MRI) scan showed a pituitary macroadenoma (2.2 x 2.1 cm) with invasion of the right cavernous sinus. Biochemical data was consistent with a nonfunctioning pituitary adenoma. Pathology showed a pituitary adenoma with negative immunohistochemistry for pituitary hormones. The patient returned a month later with weakness, lethargy, and a dilated nonreactive right pupil. MRI showed an invasive large mass (5 x 4.7 cm). After an emergent second transsphenoidal surgery, histopathologic examination revealed a widely infiltrative neoplasm invading the overlying mucosa and showing a high mitotic activity and necrosis and a very high Ki-67 (MIB-1) proliferation index (80%). MIB-1 retrospectively performed on the first specimen was also elevated (30%). Soon after the second surgery, MRI showed a 7.9 x 8.0 cm mass that metastasized to dura mater and extended into the right orbit, right middle cranial fossa, nasopharynx, clivus, posterior fossa, and along the right tentorium cerebelli, resulting in significant compression of the brainstem.

CONCLUSION

Development of a pituitary carcinoma from an adenoma is an exceptional occurrence and predictors of such course are currently lacking. A very high Ki-67 proliferation index should raise concern of a pituitary carcinoma in situ or premetastatic carcinoma.

Therapeutic implications of accurate classification of pituitary adenomas

Recent data suggest that 1 of 5 individuals in the general population is affected with a pituitary adenoma. Many of these neoplasms are clinically non-functioning adenomas that may be small and clinically undetected or may present as mass lesions; others are hormonally active and cause significant morbidity due to the metabolic effects of hormone excess (e.g., acromegaly and cushing's disease). In either case, they can grow and invade adjacent anatomic structures. Tumors with similar clinical features are morphologically heterogenous and detailed comprehensive classification of pituitary adenomas is important to predict specific clinical behaviors and genetic changes that serve as targets for therapy. We provide a practical approach to clinical diagnosis and highlight the pitfalls in the classification of these common neoplasms.

The role of mediators of cell invasiveness, motility, and migration in the pathogenesis of silent corticotroph adenomas

Silent corticotroph adenomas (SCAs) represent a distinct subset of clinically non-functioning pituitary adenomas. There are two variants of SCA; type I are densely granulated basophilic tumors and type II are sparsely granulated and chromophobic tumors. SCAs are known to be aggressive than the more common non-functioning gonadotroph adenomas (NFGAs). Cell-matrix interactions play an important role in the pathogenesis of pituitary adenomas. In this study, we compared 19 SCAs and 50 NFGAs with known fibroblast growth factor receptor-4 (FGFR4) status using semi-quantitative immunohistochemistry to localize β1-integrin, osteopontin, and matrix metalloproteinase-1 (MMP-1) as cytoplasmic, membranous, or mixed cytoplasmic-membranous staining to achieve scores of 1-4. Staining for β1-integrin was significantly higher in SCAs (100 %, score 3.3) than in NFGAs (96 %; score 2.6) (p = 0.0482); there was no statistical difference within subgroups of SCA (type II score 3.4; type I score 2.8) (p = 0.2663). Osteopontin immunoreactivity was also higher in SCAs (100 %, score 3.7) than in NFGAs (42 %, score 0.8) (p = 0.0001); there was no statistical difference within subgroups of SCA (type II score 3.6; type I score 3.9) (p = 0.2787). In contrast, MMP-1 immunoreactivity was lower in SCAs (89 %; score 2.5) than in NFGAs (98 %; score 3.6) (p = 0.0005); there was no statistical difference within subgroups of SCA (type II score 2.7; type I score 2.0) (p = 0.30704). The MMP-1 results correlated with FGFR4 expression (NFGA 96 %, type II SCA 71 %, type I SCA 40 %). Our data indicate that the biological aggressivity of SCAs compared with NFGA may be due to high osteopontin expression; in contrast, high MMP-1 is characteristic of NFGAs that also express more FGFR4. Further investigations are warranted to clarify the underlying regulatory mechanisms of these markers. The high osteopontin or FGFR4/MMP-1 expression levels in SCAs and NFGAs, respectively, indicate the potential for therapeutic strategies targeting osteopontin or FGFR4/MMP-1 for inoperable tumors of these types.

Characterization of MENX-associated pituitary tumours

AIMS

The aim of this study is to evaluate the pathological features, serum hormone levels and ex vivo cultures of pituitary adenomas that occur in rats affected by MENX syndrome. MENX is multiple endocrine neoplasia syndrome caused by a germline mutation in the cell cycle inhibitor p27. Characterization of MENX adenomas is a prerequisite to exploit this animal model for molecular and translational studies of pituitary adenomas.

METHODS

We investigated MENX pituitary adenomas with immunohistochemistry, double immunofluorescence, electron microscopy, reverse transcription polymerase chain reaction (RT-PCR), measurement of serum hormone levels and ex vivo cultures.

RESULTS

Adenomas in MENX rats belong to the gonadotroph lineage. They start from 4 months of age as multiple neoplastic nodules and progress to become large lesions that efface the gland. Adenomas are composed of chromophobic cells predominantly expressing the glycoprotein alpha-subunit (αGSU). They show mitotic activity and high Ki67 labelling. A few neoplastic cells co-express gonadotropins and the transcription factor steroidogenic factor 1, together with growth hormone or prolactin and Pit-1, suggesting that they are not fully committed to one cell lineage. Ex vivo cultures show features similar to the primary tumour.

CONCLUSIONS

Our results suggest that p27 function is critical to regulate gonadotroph cells growth. The MENX syndrome represents a unique model to elucidate the physiological and molecular mechanisms mediating the pathogenesis of gonadotroph adenomas.

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.

Angiogenic markers: molecular targets for personalized medicine in pituitary adenoma

AIM

Pituitary adenomas are typically slow-growing and histologically benign tumors that can occasionally behave in a malignant-like manner, invading adjacent structures or recurring after treatment. Using protein analysis methods and multiplex xMAP assays, we aimed to find out if these particular types of tumors express angiogenic markers VEGF and basic FGF (bFGF), which are associated with tumor growth and invasiveness, and quantify them in order to establish their usefulness as biomarkers.

MATERIALS & METHODS

We have analysed the expression of angiogenic markers VEGF and bFGF in serum and tissue specimens from 66 pituitary adenomas (43 invasive and 23 noninvasive). For serum analysis, we used xMAP and ELISA, and for tissue analysis, we performed histopathology and immunohistochemistry.

RESULTS & CONCLUSION

We measured the serum angiogenic factors in pituitary adenomas. The quantification methods revealed significant differences between pituitary adenoma patients and controls, for both VEGF (212.4 vs 112.5 pg/ml in controls) and bFGF (mean value of 12.6 vs 10.8 pg/ml in controls), and also differentiated between invasive and noninvasive adenomas (p < 0.05). The tissue expression of VEGF and bFGF strongly correlated with their serum level increase. Our findings can be further developed into methods for selection of patients suitable for personalized, antiangiogenic therapy.

Pituitary gland development and disease: from stem cell to hormone production

Many aspects of pituitary development have become better understood in the past two decades. The signaling pathways regulating pituitary growth and shape have emerged, and the balancing interactions between the pathways are now appreciated. Markers for multipotent progenitor cells are being identified, and signature transcription factors have been discovered for most hormone-producing cell types. We now realize that pulsatile hormone secretion involves a 3D integration of cellular networks. About a dozen genes are known to cause pituitary hypoplasia when mutated due to their essential roles in pituitary development. Similarly, a few genes are known that predispose to familial endocrine neoplasia, and several genes mutated in sporadic pituitary adenomas are documented. In the next decade, we anticipate gleaning a deeper appreciation of these processes at the molecular level, insight into the development of the hypophyseal portal blood system, and evolution of better therapeutics for congenital and acquired hormone deficiencies and for common craniopharyngiomas and pituitary adenomas.

Radiologic presentation of pituitary adenoma

PURPOSE

This case report aims to educate the importance of ordering radiographic studies when suspicion arises: visual field defects and optic nerve appearance may lead to the discovery of otherwise asymptomatic central nervous system disease.

CASE REPORT

We describe a patient who was previously diagnosed and successfully treated for a pituitary adenoma but who presents with worsening visual acuity and visual field defects.

CONCLUSIONS

Pituitary tumors are the most common of all tumors arising from the sellar and parasellar region. Owing to the high prevalence and proximity of these tumors to the optic nerve, chiasm, and tract, it is especially important to incorporate an appropriate history, examination, and radiographic workup in patients with suspicious visual field or optic nerve appearances. It is also critical to have anatomic and physiologic familiarity with the sellar and parasellar region. This case report explores the clinical presentation, test results, anatomy and physiology, interdisciplinary co-management, and current and future treatments of pituitary adenomas.

Biomarkers of aggressive pituitary adenomas

Pituitary adenomas exhibit a wide range of behaviors. The prediction of aggressive or malignant behavior in pituitary adenomas remains challenging; however, the utility of biomarkers is rapidly evolving. In this review, we discuss potential biomarkers as they relate to aggressive behavior in pituitary adenomas. While detailed histological subtyping remains the best independent predictor of aggressive behavior in the majority of cases, evidence suggests that the additional analyses of FGFR4, MMP, PTTG, Ki-67, p53, and deletions in chromosome 11 may contribute to decisions concerning management of aggressive pituitary adenomas.

Pituitary Centers of Excellence

Pituitary tumors and associated neuroendocrine disorders pose significant challenges in diagnostic and therapeutic management. Optimal care of the “pituitary patient” is best provided in a multidisciplinary collaborative environment that includes not only experienced pituitary practitioners in neurosurgery and endocrinology, but also in otorhinolaryngological surgery, radiation oncology, medical oncology, neuro-ophthalmology, diagnostic and interventional neuroradiology, and neuropathology. We provide the background and rationale for recognizing pituitary centers of excellence and suggest a voluntary verification process, similar to that used by the American College of Surgeons for Trauma Center verification. We propose that pituitary centers of excellence should fulfill 3 key missions: (1) provide comprehensive care and support to patients with pituitary disorders; (2) provide residency training, fellowship training, and/or continuing medical education in the management of pituitary and neuroendocrine disease; and (3) contribute to research in pituitary disorders. As this is a preliminary proposal, we recognize several issues that warrant further consideration including center and surgeon practice volume as well as oversight of the verification process.

Adrenocorticotropic hormone-producing pituitary carcinoma with intracranial metastases

BACKGROUND

Pituitary carcinomas are rare and challenging clinical entities. Because of the paucity of cases, there is limited information in the literature on how best to diagnose and treat pituitary carcinomas.

METHODS

We review the literature and describe a woman who presented with an adrenocorticotropic hormone (ACTH)-secreting pituitary macroadenoma that later evolved into a carcinoma with intracranial metastases.

RESULTS

A 39-year-old woman presented at age 27 with classic findings of Cushing's syndrome and a pituitary macroadenoma. Her initial treatment was transsphenoidal surgery, during which we confirmed an ACTH-secreting pituitary neoplasm. For 5 years, she was asymptomatic before her first recurrence. During the next 6 years, she underwent four transsphenoidal surgeries and two craniotomies. After each surgery, there was some reduction in the size of the macroadenoma but the residual tumor mass would rapidly enlarge. Immunochemical staining was positive for ACTH, and a stain for Ki-67 antigen showed a high mitotic index. Eleven years after her initial presentation, magnetic resonance imaging revealed bilateral hippocampal and tempero-occipital masses. The patient's health continued to deteriorate, largely from complications of severe hypercortisolemia, and she died from sepsis. At postmortem, the hippocampus and tempero-occipital lobe masses proved to be a pituitary tumor with positive ACTH staining.

CONCLUSIONS

Pituitary carcinomas are rare, may present many years after diagnosis of a primary pituitary adenoma, and should be suspected in patients with persistent or recurrent disease. Reliable histopathologic ways to distinguish between carcinoma and adenoma are difficult because the features of hypercellularity, nuclear pleomorphism, and mitotic figures are not always helpful.