TERT Expression in Pituitary Adenomas

Transcription

1 Original Article doi: /tjath TERT Exression in Pituitary Adenomas Nuray Can 1, Mehmet ÇELİK 2, Buket Yılmaz BÜLBÜL 2, Necdet SÜT 3, Filiz ÖZYILMAZ 1, Semra AYTÜRK 2, Sibel GÜLDİKEN 2, Nurtaç SARIKAŞ 1, Fulya ÖZ PUYAN 1, Tülin Deniz YALTA 1, Ali Kemal KUTLU 1 Deartment of 1 Pathology, 2 Internal Medicine, Division of Endocrinology and Metabolism, and 3 Biostatistics, Trakya University, Faculty of Medicine, Edİrne, Turkey ABSTRACT Objective: Although ituitary have benign histomorhological features, some of them may resent in an aggressive manner. To redict the behaviour of these tumours, telomerase reverse transcritase (TERT) activity in ituitary has been the subject of a few studies with contradictory results. This study aims to investigate whether immunohistochemical exression of TERT differs in neolastic and nonneolastic ituitary tissues and aims to investigate whether TERT exression is related to clinicoathological features of ituitary. Material and Method: The study included 48 atients who had been diagnosed with ituitary and had clinical follow-us. Nonneolastic ituitary tissues were obtained from autosy secimens (n=20). Immunohistochemistry for TERT antibody was erformed. Both the nuclear and cytolasmic exression of TERT antibody was noted, and total combined TERT staining was evaluated according to nuclear and cytolasmic stainings. Results: TERT exression did not differ between neolastic and nonneolastic ituitary tissues. Neither total (combined nuclear and cytolasmic) TERT nor nuclear TERT exression revealed any statistically significant relationshi with any of the clinicoathological features. Higher cytolasmic TERT exression was observed in with recurrence than without recurrence (=0.035). Conclusion: This study introduces the notion that immunohistochemical exression of TERT does not differ in neolastic and nonneolastic ituitary tissues. Pituitary with cytolasmic immunohistochemical exression of TERT have significantly higher rates of recurrence. Further studies, including combined methods of immunohistochemistry and molecular analyses in larger grous, may reveal alicable results for the clinical significance of TERT in ituitary. Key Words: Pituitary, Telomerase reverse transcritase, Clinicoathological features INTRODUCTION Pituitary are adenohyohyseal tumours with increasing incidence due to the imroving radiological methods and hormone assays for detection (1). The revalence of these tumours is 14.4% in autosy series and 22.5% in radiological studies, with an overall estimated revalence of 16.7% (2). Several clinical outcomes according to tumour size and hormonal activity may occur in these tumours that evolve from a small endocrine gland (1,3). These clinical scenarios may include either local mass effects or systemic effects resulting from endocrine disorders (3). Pituitary can be classified according to size as micro ( 10 mm) or macro (>10 mm) and according to radiological aearance as invasive, noninvasive, or aggressive-invasive (4). The World Health Organization (5) currently classifies ituitary based on the immunohistochemical demonstration of roduced and exressed hormones with clinical reflections. However, the most recent classification of ituitary is based on an immunohistochemical anel consisting of immune rofiling of adenohyohyseal hormones by monoclonal antibodies, cell-secific transcrition factors, and low-molecular-weight keratin (CAM5.2), Ki-67, and 53 (6,7). Although ituitary have benign histomorhological features, some of these tumours may resent in an aggressive manner by invasion of surrounding tissues, recurrences, and resistance to medical theraies (4,8). Thus, the WHO classification defined these tumours as invasive ituitary with increased mitotic activity, a Ki-67 roliferation index of >3%, and extensive 53 immune staining, namely, atyical. To redict the behaviour of these tumours, many studies have been erformed by investigating various markers related to chromosomal alterations, micrornas (mirnas), roliferation markers, oncogenes, tumour suressor genes, angiogenesis, cell adhesion, growth factors, and their recetors (1,4,9-12). Such studies show that none of these markers may redict the behaviour of these tumours alone, (Turk Patoloji Derg 2017, 33: ) Received : Acceted : Corresondence: Nuray CAN Deartment of Pathology, Trakya University, Faculty of Medicine Balcan Camus, Edirne, Turkey nuraycan@ymail.com Phone:

2 but combinations of fibroblast growth factor recetor 4 (FGFR4), matrix metalloroteinases (MMPs), articularly MMP2 and MMP9, Ki-67, 53, ituitary tumour transforming gene (PTTG), and deletions in chromosome 11 seem to have benefits for redicting the aggressiveness of ituitary (1). Moreover, investigations continue into several biomarkers other than the suggested anel mentioned above (13, 14). One of these markers is telomerase reverse transcritase (TERT). Telomerase is a ribonucleic rotein comlex that includes a catalytic subunit TERT (telomerase associated rotein 2) and an RNA comonent (TERC), and it maintains telomere homeostasis and chromosomal integrity (15). Telomeres are located at the end and inner sides of chromosomes, and shortening of these nucleotide sequences in cell divisions induces aotosis or cell senescence. On the other hand, lengthening of the telomeres results in revention of cell relication and thus is assumed to be a art of tumorigenesis, articularly by exression or activation of telomerase (16). TERT exression is suressed in normal adult somatic tissues, but it can be exressed in embryogenic tissues. Reactivation of TERT has been detected in aroximately 90% of human cancers (3,17-20). Thus, TERT activity in ituitary has been the subject of a few studies that showed contradictory results (3,16,21). The resent study aims to investigate mainly two issues. Initially, the authors aim to investigate whether immunohistochemical exression of TERT differs in neolastic and nonneolastic ituitary tissues. Then, the authors will investigate whether TERT exression is related to clinicoathological features of ituitary such as gender, age at the resentation, tumour size, hormonal activity of the tumour, and recurrence. MATERIAL and METHODS Patient Selection The medical reorts of atients who were referred to the Deartment of Pathology were reviewed between August 2007 and August The study rotocol was aroved by the local Ethics Committee of the University Hosital. Patients selected for the study had been diagnosed with ituitary and had clinical follow-us. In all, 78 atients who fulfilled the criteria were included in the study. Patient data regarding age at the time of diagnosis, sex, and data from clinical follow-us (recurrence of disease, re-oeration) were obtained from the records of the Deartment of Clinical Endocrinology and Metabolism Diseases. Also, nonneolastic ituitary tissues were obtained from autosy secimens among those who died from causes other than endocrine diseases (n=20). Haematoxylinand eosin-stained slides (Figure 1A), reticulin stained slides (Figure 1B), and immunohistochemical stainings a B Figure 1: A) Pituitary adenoma surrounded by nonneolastic ituitary tissue (H&E; x200). B) Destruction of reticulin meshwork in ituitary adenoma, note the maintenance of reticulin meshwork in nonneolastic ituitary tissue (Reticulin; x200). 104

3 of adenohyohyseal hormones (growth hormone [GH], rolactin [PRL], adrenocorticotrohic hormone [ACTH], follicle-stimulating hormone [FSH], luteinizing hormone [LH], and thyroid stimulating hormone [TSH]) obtained from araffin-embedded blocks of secimens were reevaluated by one athologist (N.C.) who was blinded to the original athological diagnosis of the slide and to clinical and rognostic data. The araffin-embedded blocks containing aroriate tissues reresenting the of 48 atients were selected for immunohistochemical studies for TERT. The atients whose secimens did not reresent tumour tissue were excluded from the study. Clinicoathological Criteria Tumours were groued according to the reoerative radiological size and the secreted hormone(s) that caused clinical signs. Tumours sized 10 mm were classified as micro, whereas tumours sized >10 mm were classified as macro. Tumours were groued according to the clinical symtoms and dominant immune reaction of secreted hormones as in the following (since adenohyohyseal transcrition factors could not be erformed, the classification was erformed according to the status of adenohyohyseal hormones): - GH roducing/exressing : Somatotroh - PRL roducing/exressing : Lactotroh - FSH-LH roducing/exressing : Gonadotroh - ACTH roducing/exressing : Corticotroh - TSH roducing/exressing : Thyrotroh - GH and PRL roducing/exressing : Mixed somatotroh and lactotroh - Nonroducing : Null cell The clinical features considered in the statistical analysis included age at the time of diagnosis, sex (male or female), tumour size ( 10 mm, >10 mm) and recurrence (absent/ resent). Immunohistochemistry Immunostaining for the TERT antibody was erformed with a fully automated immunohistochemistry and in situ hybridization (IHC/ISH) staining machine (Ventana BenchMark XT, USA). The following rimary antibody at the indicated dilutions was used for TERT immune staining (TERT olyclonal antibody, unconjugated, 1:100; Bioss, USA, Catalogue No. bs-1411r). A single athologist (N.C.) who was blinded to the clinical assessments of each case evaluated the exression in tissues with a Nikon Eclise 80i microscoe. Both nuclear and cytolasmic exression of TERT antibody was noted (22) and scored. Then, a total (combined nuclear and cytolasmic) score was obtained from the sum of cytolasmic and nuclear scores. The scoring schema is resented below. The scoring of cytolasmic TERT exression: - Cytolasmic score 0: Cytolasmic staining in <10% of the tissue (Figure 2A), - Cytolasmic score 1: Mild cytolasmic staining in 10% of the tissue (Figure 2B), - Cytolasmic score 2: Moderate cytolasmic staining in 10% of the tissue (Figure 2C), - Cytolasmic score 3: Significant cytolasmic staining in 10% of the tissue (Figure 2D). The scoring of nuclear TERT exression: - Nuclear score 0: Nuclear staining in <10% of the tissue, - Nuclear score 1: Dot-like nuclear staining in 10% of the tissue (Figure 3A), - Nuclear score 2: Comlete nuclear staining in 10% of the tissue (Figure 3B). Total (combined nuclear and cytolasmic) TERT exression: - Negative for TERT exression: The sum of nuclear and cytolasmic scores <2, - Positive for TERT exression: The sum of nuclear and cytolasmic scores 2 (Figures 3C-3D). Statistical Analysis Statistical analysis was carried out using SPSS v20.0 software (IBM SPSS, Inc., Chicago, IL, USA). Aroriate chi-square tests (Pearson, Yates, or Fisher) were used to comare the total TERT exression with clinicoathological features such as tissue tye, gender, tumour size, hormonal tumour tye, and recurrence. The Mann-Whitney U test and Kruskal-Wallis test were used in the comarisons of numerical data (nuclear/cytolasmic TERT score with tissue tye, gender, tumour size, hormonal tumour tye, and recurrence). A value of <0.05 was considered statistically significant. 105

4 RESULTS Clinicoathological Features of Patients in the Study Grou The clinicoathological features of the atients are summarized in Table I. The median age of the atients was 52.7 years (ranging from 18 to 79 years). Of the 48 atients, 18 (37.5%) were female and 30 (62.5%) were male. Tumour tye according to the hormonal status was somatotroh adenoma in 13 (27.1%), lactotroh adenoma in 8 (16.7%), gonadotroh adenoma in 3 (6.3%), corticotroh adenoma in 5 (10.4%), thyrotroh adenoma in 1 (2.1%), mixed somatotroh and lactotroh adenoma in 9 (18.7%), and null cell adenoma in 9 (18.7%) of the atients. Table I: Clinicoathological features of atients Female Gender Male Hormonal tye Somatotroh adenoma Lactotroh adenoma Gonadotroh adenoma Corticotroh adenoma Thyrotroh adenoma Mixed somatotroh and lactotroh adenoma Null cell adenoma 10 mm Tumor size > 10 mm Recurrence Absent Present A B C D n (%) 18 (37.5) 30 (62.5) 13 (27.1) 8 (16.7) 3 (6.3) 5 (10.4) 1 (2.1) 9 (18.7) 9 (18.7) 8 (16.7) 40 (83.3) 44 (91.7) 4 (8.3) Figure 2: A) Cytolasmic TERT staining in < 10% of the tissue, score 0 (TERT; x40). B) Mild cytolasmic staining, score I (TERT; x40). C) Moderate cytolasmic staining, score II (TERT; x40), D) Significant cytolasmic staining, score III (TERT; x40). 106

5 When the atients were groued according to tumour size, 8 (16.7%) had micro, while the tumour size was larger than 10 mm in 40 (83.3%) of the cases. Among all of the cases, 4 (8.3%) of the tumours recurred after initial surgery, whereas 44 (91.7%) did not. The mean follow-u eriod for the atients was 57.5±31.07 months. All of the atients were alive. Comarisons of TERT Exression in Neolastic and Nonneolastic Pituitary Tissues TERT exression did not significantly differ between neolastic and nonneolastic ituitary tissues. According to these results, TERT exression was resent in 4 (20%) of 20 nonneolastic autosy tissues, whereas it was exressed in 16 (33.3%) of 48 neolastic tissues. Desite the absence of statistical significance, mean ranks of cytolasmic and nuclear TERT exression was higher in neolastic tissues than in nonneolastic autosy tissues (>0.05) (Table II). Comarisons of Total (Combined Nuclear and Cytolasmic) TERT Exression with Clinicoathological Features The results of the comarisons of clinicoathological features with total (combined nuclear and cytolasmic) TERT exression are resented in Table III. TERT exression did not reveal any statistically significant relationshi with any of the clinicoathological features. TERT ositivity was resent in 30.8% (4/13) of somatotroh, in 25.0% (2/8) of lactotroh, in 33.3% (1/3) of gonadotroh, in 40% (2/5) of corticotroh, in none (0/1) of the thyrotroh, in 33.3% (3/9) of mixed somatotroh and lactotroh, and finally, in 44.4% (4/9) of null cell. TERT staining was defined in 50.0% (4/8) of micro, while it was defined as 30.0% (12/40) A B C D Figure 3: A) Dot-like nuclear staining of TERT; score 1 (TERT; x200). B) Comlet nuclear staining of TERT; score 2 (TERT; x400). C) Dot-like nuclear staining (Nuclear score 1) with mild cytolasmic exression (cytolasmic score I) (TERT; x200). D) Moderate cytolasmic exression (cytolasmic score II) (TERT; x400). 107

6 Table II: Comarisons of TERT exression in neolastic and nonneolastic ituitary tissues TERT exression Combined nuclear and cytolasmic Nuclear Cytolasmic Absent n (%) Present n (%) Mean rank Mean rank Tissue tye Nonneolastic 16/20 (80.0) 4/20 (20.0) Neolastic 32/48 (66.7) 16/48 (33.3) Table III: Comarisons of total (combined nuclear and cytolasmic) TERT exression with clinicoathological features TERT exression Total Absent n (%) Present n (%) n Gender Female 12 (66.7) 6 (33.3) 18 Male 20 (66.7) 10 (33.3) Hormonal tye Somatotroh adenoma 9 (69.2) 4 (30.8) 13 Lactotroh adenoma 6 (75.0) 2 (25.0) 8 Gonadotroh adenoma 2 (66.7) 1 (33.3) 3 Corticotroh adenoma 3 (60.0) 2 (40.0) Thyrotroh adenoma 1 (100.0) 0 (0.0) 1 Mixed somatotroh and lactotroh adenoma 6 (66.7) 3 (33.3) 9 Null cell adenoma 5 (55.6) 4 (44.4) 9 Tumor size 10 mm 4 (50.0) 4 (50.0) 8 > 10 mm 28 (70.0) 12 (30.0) Recurrence Absent 31 (70.5) 13 (29.5) 44 Present 1 (25.0) 3 (75.0) of macro. Total TERT exression was observed in 75.0% (3/4) of the atients with recurrence, whereas staining was resent in 29.5% (13/44) of the atients without recurrence. Comarisons of Nuclear TERT Exression with Clinicoathological Features The results of the comarisons of clinicoathological features with nuclear TERT exression are resented in Table IV. Nuclear TERT exression did not reveal any statistically significant relationshi with any of the clinicoathological features. However, mean ranks of nuclear TERT exression were higher in males than in females, in mixed somatotroh and lactotroh, in lactotroh, and in sized >10 mm (>0.05). Comarisons of Cytolasmic TERT Exression with Clinicoathological Features The results of the comarisons of clinicoathological features with cytolasmic TERT exression are resented in Table IV. Cytolasmic TERT exression had a significant relationshi with recurrence (=0.035); namely, higher cytolasmic TERT exression was observed in some with recurrence but not in without recurrence. Cytolasmic TERT exression was observed in 3 of 4 atients who had recurred. Nuclear TERT exression was not observed in any of the atients with recurrence. Two of these 3 atients were male and 1 was female. Tumours were sized >10 mm in 2 of the atients and sized 10 mm in 1 atient. Among these 3 atients, hormonal tye was corticotroh adenoma in 1 of the atients, gonadotroh adenoma in 1, and null cell adenoma in 1. The follow-u eriod ranged between 37 months and 256 months. There was no significant relationshi between cytolasmic TERT exression and clinicoathological features other than recurrence. Although there was no significant relationshi, mean ranks of cytolasmic TERT exression were higher in males than in females, in corticotroh and lactotroh than in other tyes, and in micro than in macro (>0.05). DISCUSSION Pituitary have benign histomorhological features, but some of these tumours may resent in an 108

7 Table IV: Comarisons of nuclear TERT exression and cytolasmic TERT exression with clinicoathological features TERT exression Nuclear Cytolasmic Mean rank Mean rank Gender Female Male Hormonal tye Somatotroh adenoma Lactotroh adenoma Gonadotroh adenoma Not calculated Not calculated Corticotroh adenoma Thyrotroh adenoma Not calculated Not calculated Mixed somatotroh and lactotroh Null cell adenoma Tumor size 10 mm > 10 mm Recurrence Absent Present aggressive manner by local invasion through surrounding tissues, recurrences, and resistance to medical theraies (4,8). Many studies have aimed to discover a significant redictor of an aggressive clinical course in ituitary (1,4,9-12). Telomerase reverse transcritase (TERT), a catalytic subunit of telomerase that includes an RNA comonent (TERC), therewithal maintains the telomere homeostasis and chromosomal integrity (15). Reactivation of TERT has been detected in aroximately 90% of human cancers (3,17-20). This study attemted to investigate whether immunohistochemical exression of TERT differs in neolastic and nonneolastic ituitary tissues and aimed to investigate whether TERT exression is related to clinicoathological features of ituitary. In this context, the results of the resent study can be summarised as follows: i) Total immunohistochemical exression of TERT does not differ in neolastic and nonneolastic ituitary tissues with significance, ii) Total immunohistochemical exression of TERT does not have any relationshi to clinicoathological arameters, and iii) Cytolasmic immune staining with TERT antibody is significantly more common in ituitary with recurrence (=0.035). Telomerase activity in neolastic and in nonneolastic ituitary tissues has been the subject of a few revious studies using various methods of olymerase chain reaction (PCR) (14,21). The mentioned revious studies have reorted that there is no difference in telomerase activity and telomere length between neolastic and nonneolastic ituitary tissues. It has been suggested that this may be elucidated by the low mitotic activity of ituitary (14). In agreement with revious studies, the resent study showed no significant difference in total TERT exression in neolastic and nonneolastic ituitary tissues. Although TERT exression was evaluated by immunohistochemistry targeting only TERT and not TERC in the resent study and the comarisons showed a lack of statistical significance (>0.05), TERT exression rates were higher in neolastic tissues than in nonneolastic tissues. The most accurate state of telomerase activity and telomere length in ituitary tumours/nonneolastic ituitary tissues should be investigated in larger study grous by combined synchronous detection methods. The effects of telomerase activity and telomere lengths on clinicoathological features in ituitary have been evaluated in several studies (3,14,16,21,23-25). Some of these aers have concluded that telomerase activity and telomere length do not have any imact on the clinical course of ituitary based on investigations of telomerase activity and telomere length by various tyes of olymerase chain reactions (14,16,21,25). On the other hand, some of the revious studies have suggested that TERT exression is associated with an aggressive clinical course, articularly recurrences and invasiveness (3,23,24). Harada et al. (24) have reorted telomerase activity by using Southern blotting and reverse transcritase-chain reaction in a ituitary carcinoma evolving in a background of an initially telomerase-negative PRL-roducing benign 109

8 adenoma. Yoshino et al. (23) have reorted telomerase activity via PCR-based telomeric reeat amlification rotocol (TRAP) assay and PCR enzyme-linked immunosorbent assay (ELISA) in 13% of with invasive features. Ortiz-Plata et al. (3) have examined telomerase activity by TERT immunohistochemistry and have reorted that telomerase activity could be a marker for cellular roliferation, angiogenesis and hormonal activity in ituitary. However, the authors did not inform either cellular localisation or the degree of TERT exression in their study. In the resent study, we could not determine any significant relationshi between total TERT exression and clinicoathological features, including resentation age, gender, tumour size, recurrence, and hormonal tye. But, we could observe that cytolasmic staining with TERT olyclonal antibody is significantly related to tumour recurrence, as in the case reorted by Harada et al. (24). Also, total TERT exression was resent in 75% of ituitary with recurrence without any significance. Although the resent study has limitations, including the immunohistochemical evaluation of only the TERT catalytic subunit of telomerase rotein comlex but not TERC or any detections of mutational status, the authors resent the significant increase of recurrence in ituitary with cytolasmic TERT exression. According to the current roosals, a anel of some biomarkers, including PTTG1 and MMPs (MMP1), may redict the aggressive behaviour of ituitary (1). It is said that higher levels of electron transort system (ETS) transcrition factors induce MMP1 exression and cause tumour invasion in ituitary (1). One of the most recent reorts investigating the TERT exression in malignant melanoma has concluded that mutations in TERT romoter create additional binding sites for ETS transcrition factors, articularly ETS1, and finally activates the mitogen-activated rotein kinase (MAPK) athway and cell roliferation (19). PTTG1 is a member of the securin family and is highly exressed in hormonesecreting invasive ituitary (1). Another recent study observing the relationshi between PTTG1 and TERT exressions in human mesenchymal stem cells has reorted that overexression of TERT induces PTTG1 exression, and this interaction between TERT and PTTG1 is mediated by Ku70, which is a heterodimeric rotein involved in maintenance of telomeres, in an increase in the cell cycle, autohagy, and self-renewal (26). Consideration of distinct results of the revious studies and the resent study about telomerase activity and telomere length in ituitary and the recent observations revealing interactions of TERT with PTTG1 and ETS1 may require further studies. Such studies should investigate these interactions in ituitary and may contribute detailed data in the issue of TERT exression as a rognostic redictor in ituitary. In conclusion, the resent study osits that immunohistochemical exression of TERT does not significantly differ in neolastic and nonneolastic ituitary tissues. In addition, ituitary with cytolasmic immunohistochemical exression of TERT have significantly higher rates of recurrence. Further studies, including combined methods of immunohistochemistry and molecular analyses in larger grous, may reveal alicable results for the clinical significance of telomerase activity and telomere length in ituitary. CONFLICT of INTEREST The authors declare no conflict of interest. REFERENCES 1. Mete O, Ezzat S, Asa SL. Biomarkers of aggressive ituitary. J Mol Endocrinol. 2012;49:R Ezzat S, Asa SL, Couldwell WT, Barr CE, Dodge WE, Vance ML, McCutcheon IE. The revalence of ituitary : A systematic review. Cancer. 2004;101: Ortiz-Plata A, Tena Suck ML, Loez-Gomez M, Heras A, Sanchez Garcia A. Study of the telomerase htert fraction, PCNA and CD34 exression on ituitary. Association with clinical and demograhic characteristics. J Neurooncol. 2007;84: Wierinckx A, Auger C, Devauchelle P, Reynaud A, Chevallier P, Jan M, Perrin G, Fevre-Montange M, Rey C, Figarella-Baranger D, Raverot G, Belin MF, Lachuer J, Trouillas J. A diagnostic marker set for invasion, roliferation, and aggressiveness of rolactin ituitary tumors. Endocr Relat Cancer. 2007;14: DeLellis RA. Pathology and genetics of tumours of endocrine organs. Lyon:IARC Press; Mete O, Asa SL. Clinicoathological correlations in ituitary. Brain Pathol. 2012;22: Gomez-Hernandez K, Ezzat S, Asa SL, Mete O. Clinical imlications of accurate subtying of ituitary : Persectives from the treating hysician. Turk Patoloji Derg. 2015;31 Sul 1: Scheithauer BW, Kovacs KT, Laws ER Jr, Randall RV. Pathology of invasive ituitary tumors with secial reference to functional classification. J Neurosurg. 1986;65: Wierinckx A, Raverot G, Nazaret N, Jouanneau E, Auger C, Lachuer J, Trouillas J. Proliferation markers of human ituitary tumors: Contribution of a genome-wide transcritome aroach. Mol Cell Endocrinol. 2010;326:

9 10. Wierinckx A, Roche M, Raverot G, Legras-Lachuer C, Croze S, Nazaret N, Rey C, Auger C, Jouanneau E, Chanson P, Trouillas J, Lachuer J. Integrated genomic rofiling identifies loss of chromosome 11 imacting transcritomic activity in aggressive ituitary PRL tumors. Brain Pathol. 2011;21: Cornelius A, Cortet-Rudelli C, Assaker R, Kerdraon O, Gevaert MH, Prevot V, Lassalle P, Trouillas J, Delehedde M, Maurage CA. Endothelial exression of endocan is strongly associated with tumor rogression in ituitary adenoma. Brain Pathol. 2012;22: Mete O, Hayhurst C, Alahmadi H, Monsalves E, Gucer H, Gentili F, Ezzat S, Asa SL, Zadeh G. The role of mediators of cell invasiveness, motility, and migration in the athogenesis of silent corticotroh. Endocr Pathol. 2013;24: De Martino I, Visone R, Wierinckx A, Palmieri D, Ferraro A, Caabianca P, Chiaetta G, Forzati F, Lombardi G, Colao A, Trouillas J, Fedele M, Fusco A. HMGA roteins u-regulate CCNB2 gene in mouse and human ituitary. Cancer Res. 2009;69: Martins CS, Santana-Lemos BA, Saggioro FP, Neder L, Machado HR, Moreira AC, Calado RT, de Castro M. Telomere length and telomerase exression in ituitary tumors. J Endocrinol Invest. 2015;38: Martinez P, Blasco MA. Telomeric and extra-telomeric roles for telomerase and the telomere-binding roteins. Nat Rev Cancer. 2011;11: Kochling M, Ewelt C, Furtjes G, Peetz-Dienhart S, Koos B, Hasselblatt M, Paulus W, Stummer W, Brokinkel B. htert romoter methylation in ituitary. Brain Tumor Pathol. 2016;33: Xu L, Li S, Stohr BA. The role of telomere biology in cancer. Annu Rev Pathol. 2013;8: Agostini A, Panagooulos I, Andersen HK, Johannesen LE, Davidson B, Troe CG, Heim S, Micci F. HMGA2 exression attern and TERT mutations in tumors of the vulva. Oncol Re. 2015;33: Vallarelli AF, Rachakonda PS, Andre J, Heidenreich B, Riffaud L, Bensussan A, Kumar R, Dumaz N. TERT romoter mutations in melanoma render TERT exression deendent on MAPK athway activation. Oncotarget. 2016;7: Chen C, Han S, Meng L, Li Z, Zhang X, Wu A. TERT romoter mutations lead to high transcritional activity under hyoxia and temozolomide treatment and redict oor rognosis in gliomas. PLoS One. 2014;9:e Martins CS, de Castro M, Calado RT. Absence of TERT romoter mutations in ituitary. J Endocrinol Invest. 2016;39: Kyo S, Masutomi K, Maida Y, Kanaya T, Yatabe N, Nakamura M, Tanaka M, Takarada M, Sugawara I, Murakami S, Taira T, Inoue M. Significance of immunological detection of human telomerase reverse transcritase: Re-evaluation of exression and localization of human telomerase reverse transcritase. Am J Pathol. 2003;163: Yoshino A, Katayama Y, Fukushima T, Watanabe T, Komine C, Yokoyama T, Kusama K, Moro I. Telomerase activity in ituitary : Significance of telomerase exression in redicting ituitary adenoma recurrence. J Neurooncol. 2003;63: Harada K, Arita K, Kurisu K, Tahara H. Telomerase activity and the exression of telomerase comonents in ituitary adenoma with malignant transformation. Surg Neurol. 2000;53: Hiraga S, Ohnishi T, Izumoto S, Miyahara E, Kanemura Y, Matsumura H, Arita N. Telomerase activity and alterations in telomere length in human brain tumors. Cancer Res. 1998;58: Lee HJ, Choi JH, Jung J, Kim JK, Lee SS, Kim GJ. Changes in PTTG1 by human TERT gene exression modulate the selfrenewal of lacenta-derived mesenchymal stem cells. Cell Tissue Res. 2014;357: