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

Comparative analysis of intraoperative and imaging features of invasive growth in pituitary adenomas

BACKGROUND

Most pituitary adenomas (PAs), also termed pituitary neuroendocrine tumors, are benign in nature and can be treated effectively by surgical resection, medical treatment, and in special cases by radiotherapy. However, invasive growth can be an important feature of a more aggressive behavior and adverse prognosis. The extension of PAs into the cavernous sinus can be categorized according to the Knosp criteria on magnetic resonance imaging (MRI). Comparative analyses of MRI features and intraoperative findings of invasive growth regarding different clinical factors are still scarce.

MATERIALS AND METHODS

We performed a retrospective single-center analysis of 764 PAs that were surgically treated between October 2004 and April 2018. Invasive growth was assessed according to the surgical reports and preoperative MRI (Knosp criteria). Clinical data, such as patient age at diagnosis and gender, histopathological adenoma type, and extent of resection, were collected.

RESULTS

Invasive features on MRI were seen in 24.4% (Knosp grades 3A-4, 186/764) of the cases. Intraoperatively, invasion was present in 42.4% (324/764). Complete resection was achieved in 80.0% of adenomas and subtotal resection, in 20.1%. By multivariate analysis, invasion according to intraoperative findings was associated with the sparsely granulated corticotroph (SGCA, P = .0026) and sparsely granulated somatotroph (SGSA, P = .0103) adenoma type as well as age (P = .0287). Radiographic invasion according to Knosp grades 3A-4 correlated with age (P = .0098), SGCAs (P = .0005), SGSAs (P = .0351), and gonadotroph adenomas (P = .0478). Both criteria of invasion correlated with subtotal resection (P = .0001, respectively).

CONCLUSIONS

Both intraoperative and radiographic signs of invasive growth are high-risk lesions for incomplete extent of resection and occur more frequently in older patients. A particularly high prevalence of invasion can be found in the SGCA and SGSA types. Cavernous sinus invasion is also more common in gonadotroph adenomas. Usage of the Knosp classification is a valuable preoperative estimation tool.

Construction of an M2 macrophage-related prognostic model in hepatocellular carcinoma

Background

M2 macrophages play a crucial role in promoting tumor angiogenesis and proliferation, as well as contributing to chemotherapy resistance and metastasis. However, their specific role in the tumor progression of hepatocellular carcinoma (HCC) and their impact on the clinical prognosis remain to be further elucidated.

Materials and methods

M2 macrophage-related genes were screened using CIBERSORT and weighted gene co-expression network analysis (WGCNA), while subtype identification was performed using unsupervised clustering. Prognostic models were constructed using univariate analysis/least absolute shrinkage selector operator (LASSO) Cox regression. In addition, Gene Ontology (GO)/Kyoto Encyclopedia of Genes and Genomes (KEGG), gene set enrichment analysis (GSEA), gene set variation analysis (GSVA), and mutation analysis were used for further analysis. The relationship between the risk score and tumor mutation burden (TMB), microsatellite instability (MSI), the efficacy of transcatheter arterial chemoembolization (TACE), immunotype, and the molecular subtypes were also investigated. Moreover, the potential role of the risk score was explored using the ESTIMATE and TIDE (tumor immune dysfunction and exclusion) algorithms and stemness indices, such as the mRNA expression-based stemness index (mRNAsi) and the DNA methylation-based index (mDNAsi). In addition, the R package "pRRophetic" was used to examine the correlation between the risk score and the chemotherapeutic response. Finally, the role of TMCC1 in HepG2 cells was investigated using various techniques, including Western blotting, RT-PCR and Transwell and wound healing assays.

Results

This study identified 158 M2 macrophage-related genes enriched in small molecule catabolic processes and fatty acid metabolic processes in HCC. Two M2 macrophage-related subtypes were found and a four-gene prognostic model was developed, revealing a positive correlation between the risk score and advanced stage/grade. The high-risk group exhibited higher proliferation and invasion capacity, MSI, and degree of stemness. The risk score was identified as a promising prognostic marker for TACE response, and the high-risk subgroup showed higher sensitivity to chemotherapeutic drugs (e.g., sorafenib, doxorubicin, cisplatin, and mitomycin) and immune checkpoint inhibitor (ICI) treatments. The expression levels of four genes related to the macrophage-related risk score were investigated, with SLC2A2 and ECM2 showing low expression and SLC16A11 and TMCC1 exhibiting high expression in HCC. In vitro experiments showed that TMCC1 may enhance the migration ability of HepG2 cells by activating the Wnt signaling pathway.

Conclusion

We identified 158 HCC-related M2 macrophage genes and constructed an M2 macrophage-related prognostic model. This study advances the understanding of the role of M2 macrophages in HCC and proposes new prognostic markers and therapeutic targets.

Predictive Value of Blood Markers in Nonfunctional Pituitary Adenomas using Artificial Neural Network

Background

Nonfunctioning pituitary adenomas (NFPAs) are the most common pituitary tumors and although they do not secrete hormones, they can have systemic effects. These tumors affect the function of other organs in the body by exerting pressure on the pituitary gland. There are differences between biomarkers NFPAs compared to healthy people. This study was conducted to show blood marker changes in adenomas compared to healthy people.

Materials and Methods

This article compared the blood markers of NFPAs with healthy individuals retrospectively. The difference between blood markers in the two groups was statistically investigated where the predictive value of blood markers in the differentiation of the two groups was determined. An artificial neural network was also designed using the blood markers with its accuracy and predictive value determined.

Results

A total of 96 NFPAs (nonfunctional pituitary adenoma) and 96 healthy individuals were evaluated. There was statistically a significant difference and positive correlation in platelet to lymphocyte ratio, neutrophil to lymphocyte ratio, and derived neutrophil to lymphocyte ratio between NFPAs and healthy individuals. There was a significant and negative correlation between red blood cell (RBC), lymphocyte, and monocyte between the two groups. RBC as an independent factor was associated with NFPAs. In this study, the artificial neural network was able to differentiate between NFPTs cases and healthy individuals with an accuracy of 81.2%.

Conclusion

There are differences between blood markers in NFPAs relative to healthy people and the artificial neural network can accurately differentiate between them.

Nkx3-1 and Fech genes might be switch genes involved in pituitary non-functioning adenoma invasiveness

Non-functioning pituitary adenomas (NFPAs) are typical pituitary macroadenomas in adults associated with increased mortality and morbidity. Although pituitary adenomas are commonly considered slow-growing benign brain tumors, numerous of them possess an invasive nature. Such tumors destroy sella turcica and invade the adjacent tissues such as the cavernous sinus and sphenoid sinus. In these cases, the most critical obstacle for complete surgical removal is the high risk of damaging adjacent vital structures. Therefore, the development of novel therapeutic strategies for either early diagnosis through biomarkers or medical therapies to reduce the recurrence rate of NFPAs is imperative. Identification of gene interactions has paved the way for decoding complex molecular mechanisms, including disease-related pathways, and identifying the most momentous genes involved in a specific disease. Currently, our knowledge of the invasion of the pituitary adenoma at the molecular level is not sufficient. The current study aimed to identify critical biomarkers and biological pathways associated with invasiveness in the NFPAs using a three-way interaction model for the first time. In the current study, the Liquid association method was applied to capture the statistically significant triplets involved in NFPAs invasiveness. Subsequently, Random Forest analysis was applied to select the most important switch genes. Finally, gene set enrichment (GSE) and gene regulatory network (GRN) analyses were applied to trace the biological relevance of the statistically significant triplets. The results of this study suggest that "mRNA processing" and "spindle organization" biological processes are important in NFAPs invasiveness. Specifically, our results suggest Nkx3-1 and Fech as two switch genes in NFAPs invasiveness that may be potential biomarkers or target genes in this pathology.

Ectodermal‑neural cortex 1 affects the biological function of lung cancer through the MAPK pathway

Ectodermal-neural cortex 1 (ENC1), a highly expressed protein in lung cancer tissues, was identified from the Cancer Genome Atlas (TCGA) database. The objective of the present study was to examine the effects of ENC1 on the biological functions of lung cancer cells. For this purpose, the expression of ENC1 was examined by RT-qPCR to compare mRNA expression levels between 28 lung cancer tissue samples and para-cancerous tissue samples. The association between ENC1 expression and clinicopathological features was evaluated between the 2 tissue types. Using RT-qPCR and western blot analysis, the expression of ENC1 was investigated in a normal lung cell line (16HBE) and 2 lung cancer cell lines (A549 and H1299). The effect of siRNA targeting ENC1 (si-ENC1) on the proliferation of A549 and H1299 cells was detected by CCK-8 assay at the indicated time points. Transwell assay was used to measure the migration and invasion of A549 and H1299 cells following transfection with siRNA targeting ENC1 (si-ENC1). The expression levels of several proteins related to migration and invasion were examined by western blot analysis. A mouse model of subcutaneous tumor xenotransplantation was established in nude mice to examine the effects of ENC1 downregulation on cancer cells. The results revealed that the expression of ENC1 in lung cancer tissues and lung cancer cells was significantly higher than that in para-cancerous tissues and non-cancer lung cells, respectively. The knockdown of ENC1 in the A549 and H1299 cells using si-ENC1 significantly decreased cell proliferation, migration and invasion compared with the untransfected cells. The knockdown of ENC1 significantly downregulated the levels of matrix metalloproteinase (MMP)2, MMP9, N-cadherin, p-c-Jun N-terminal kinase (JNK), p-extracellular signal-regulated kinase (ERK) and p-p38. The levels of E-cadherin were upregulated. In the mouse lung tumor model, reduced levels of ENC1 inhibited the growth of lung tumors. On the whole, the present study demonstrates that ENC1 is involved in the proliferation, migration and invasion of lung cancer cells, and may thus be an effective diagnostic target for certain cancers. The inhibition or reduction of ENC1 activity may represent a breakthrough in the treatment of lung cancer.

Ectodermal-neural cortex 1 as a novel biomarker predicts poor prognosis and induces metastasis in breast cancer by promoting Wnt/β-catenin pathway

Breast cancer, as the most common malignancy, is the second leading cause of cancer‐related death in women. One of the kelch family member ENC1 is involved in various pathophysiologic processes. But the role of ENC1 in breast cancer has not been investigated. The present study value the feature, clinical significance and the molecular mechanisms of ENC1 in breast cancer. The expression and prognosis value of ENC1 expression among breast cancer and normal breast tissue were investigated in The Cancer Genome Atlas database and human samples. ENC1 was knockdown to explore its function in various breast cancer cell lines. Western blot was performed to explore the potential molecular mechanisms. We observed that ENC1 was overexpressed in breast cancer tissues. ENC1 overexpression was associated with high metastasis and predicted a poor prognosis in patients with breast cancer. ENC1 Knockdown inhibits the growth, clone formation, migration and invasion of breast cancer cells. Mechanism analysis revealed ENC1 was strong associated with the metastasis by modulating β‐catenin pathway. Our study emphasizes that ENC1 is a potential prognostic and metastasis‐related marker of breast cancer, and may function as a possible therapeutic target against breast cancer.

Demethylation Status of Somatic DNA Extracted From Pituitary Neuroendocrine Tumors Indicates Proliferative Behavior

BACKGROUND

Cytosine intermediaries 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC), epigenetic hallmarks, have never been investigated in pituitary neuroendocrine tumors (PitNET).

OBJECTIVE

To examine methylation-demethylation status of global deoxyribonucleic acid (DNA) in PitNET tissues and to assess its correlation with clinical and biological parameters.

MATERIALS AND METHODS

Altogether, 57 PitNET and 25 corresponding plasma samples were collected. 5mC and 5hmC were investigated using liquid chromatography-tandem mass spectrometry. Expression of DNA methyltransferase 1 (DNMT1); tet methylcytosine dioxygenase 1 through 3 (TET1-3); and ubiquitin-like, containing PHD and RING finger domains 1 and 2 (UHRF1-2) were measured by reverse transcription-polymerase chain reaction. Levels of 5hmC and UHRF1-2 were explored by immunohistochemistry. Effect of demethylating agent decitabine was tested on pituitary cell lines.

RESULTS

5hmC/5mC ratio was higher in less differentiated PitNET samples. A negative correlation between Ki-67 proliferation index and 5hmC, 5hmC to 5mC ratio were revealed. Higher 5mC was observed in SF-1 + gonadotroph adenomas with a higher Ki-67 index. Expressions of TET2 and TET3 were significantly higher in adenomas with higher proliferation rate. UHRF1 showed gradually increased expression in higher proliferative adenoma samples, and a significant positive correlation was detected between UHRF2 expression and 5hmC level. Decitabine treatment significantly decreased 5mC and increased 5hmC levels in both cell lines, accompanied with decreased cell viability and proliferation.

CONCLUSION

The demethylation process negatively correlated with proliferation rate and the ratio of 5hmC to 5mC was higher in less differentiated adenomas. Therefore, epigenetic markers can be potential biomarkers for PitNET behavior. Altering the epigenome in adenoma cells by decitabine decreased proliferation, suggesting that this treatment might be a novel medical treatment for PitNET.

Genetic and Epigenetic Causes of Pituitary Adenomas

Pituitary adenomas (PAs) can be classified as non-secreting adenomas, somatotroph adenomas, corticotroph adenomas, lactotroph adenomas, and thyrotroph adenomas. Substantial advances have been made in our knowledge of the pathobiology of PAs. To obtain a comprehensive understanding of the molecular biological characteristics of different types of PAs, we reviewed the important advances that have been made involving genetic and epigenetic variation, comprising genetic mutations, chromosome number variations, DNA methylation, microRNA regulation, and transcription factor regulation. Classical tumor predisposition syndromes include multiple endocrine neoplasia type 1 (MEN1) and type 4 (MEN4) syndromes, Carney complex, and X-LAG syndromes. PAs have also been described in association with succinate dehydrogenase-related familial PA, neurofibromatosis type 1, and von Hippel-Lindau, DICER1, and Lynch syndromes. Patients with aryl hydrocarbon receptor-interacting protein (AIP) mutations often present with pituitary gigantism, either in familial or sporadic adenomas. In contrast, guanine nucleotide-binding protein G(s) subunit alpha (GNAS) and G protein-coupled receptor 101 (GPR101) mutations can lead to excess growth hormone. Moreover, the deubiquitinase gene USP8, USP48, and BRAF mutations are associated with adrenocorticotropic hormone production. In this review, we describe the genetic and epigenetic landscape of PAs and summarize novel insights into the regulation of pituitary tumorigenesis.

Low expression of ENC1 predicts a favorable prognosis in patients with ovarian cancer

Ectodermal-neural cortex 1 (ENC1) belongs to a member of the kelch family of genes. It is an actin-binding protein and plays a pivotal role in neuronal and adipocyte differentiation. Here, we found that lower expression of ENC1 in the ovarian cancer patients was associated with favorable prognosis. In addition, ENC1 was heterogeneously expressed in various ovarian cancer cells. The messenger RNA and protein expression levels of ENC1 in HO-8910PM and NIH:OVCAR-3 cells were obviously higher than that in the other types of ovarian cancer cells. Knockdown of ENC1 in HO-8910PM or NIH:OVCAR-3 cells could significantly increase the reactive oxygen species levels, resulting in inhibition of in vitro proliferation, migration, and invasion. Our findings suggest that decreasing expression of ENC1 may be a new approach that can be used for ovarian cancer treatment.

Prognostic factors of regrowth in nonfunctioning pituitary tumors

Surgery is the treatment of choice for nonfunctioning pituitary tumors (NFPTs). Postoperative tumor regrowth during follow-up is present in about half of the patients with invasive NFPTs with residual tumor but occurs also in 15% of patient without residue. Therapeutic strategies should consider this risk of recurrence and the potential side effects associated with therapeutic options. Identification of prognostic markers is mandatory to help clinicians to predict the risk of recurrence and to choose the best strategy between conservative follow-up, second surgery, postoperative adjuvant radiation therapy, and medical treatment (dopamine agonists, somatostatin analogs). Recent advances in pathological classification may be the first step for identification of NFPTs with a high risk of recurrence.

Non-invasive radiomics approach potentially predicts non-functioning pituitary adenomas subtypes before surgery

PURPOSE

To make individualised preoperative prediction of non-functioning pituitary adenoma (NFPAs) subtypes between null cell adenomas (NCAs) and other subtypes using a radiomics approach.

METHODS

We enrolled 112 patients (training set: n = 75; test set: n = 37) with complete T1-weighted magnetic resonance imaging (MRI) and contrast-enhanced T1-weighted MRI (CE-T1). A total of 1482 quantitative imaging features were extracted from T1 and CE-T1 images. Support vector machine trained a predictive model that was validated using a receiver operating characteristics (ROC) analysis on an independent test set. Moreover, a nomogram was constructed incorporating clinical characteristics and the radiomics signature for individual prediction.

RESULTS

T1 image features yielded area under the curve (AUC) values of 0.8314 and 0.8042 for the training and test sets, respectively, while CE-T1 image features provided no additional contribution to the predictive model. The nomogram incorporating sex and the T1 radiomics signature yielded good calibration in the training and test sets (concordance index (CI) = 0.854 and 0.857, respectively).

CONCLUSION

This study focused on the preoperative prediction of NFPA subtypes between NCAs and others using a radiomics approach. The developed model yielded good performance, indicating that radiomics had good potential for the preoperative diagnosis of NFPAs.

KEY POINTS

• MRI may help in the pre-operative diagnosis of NFPAs subtypes • Retrospective study showed T1-weighted MRI more useful than CE-T1 in NCAs diagnosis • Treatment decision making becomes more individualised • Radiomics approach had potential for classification of NFPAs.

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.

Integrative proteomics and transcriptomics revealed that activation of the IL-6R/JAK2/STAT3/MMP9 signaling pathway is correlated with invasion of pituitary null cell adenomas

Non-functioning pituitary adenomas (NFPAs) are a highly heterogeneous group, but few studies have explored the invasion mechanism of specific subtypes of NFPAs. The objective of this study was to investigate the differential molecular expression patterns and the critical biological signaling pathways involved in the invasion of pituitary null cell adenomas (PNCAs) through integrative proteomics and transcriptomics. A total of 1160 genes and 283 proteins were found to be differentially expressed in invasive and non-invasive PNCAs. The differentially expressed molecules related to invasion were enriched in 15 canonical signaling pathways, 15 clusters of diseases or biological functions and 5 upstream molecules. Among them, the majority of the differentially expressed molecules were found to be involved in transport of molecule, migration of cells and cell movement. Notably, IL-6 was a significantly activated upstream regulator, and the IL6R/JAK2/STAT3 cascade was found to play a critical role in acute phase response signaling, which was the most significant canonical signaling pathway. Furthermore, we validated the overexpression of IL-6R, JAK2, STAT3, p-STAT3 and MMP9 in invasive PNCAs. Our data suggest that overactivation of the IL-6R/JAK2/STAT3/MMP9 pathway is critical for the invasion of PNCAs.

Current biomarkers of invasive sporadic pituitary adenomas

Though pituitary adenomas (PA) are considered benign, some of them exhibit invasive behaviors such as recurrence and low rate of total surgical resection. Reliable prognostic biomarkers for invasive PA are highly desired; however they remain to be identified. In this review, we summarize the current controversial findings of biomarkers for invasive sporadic PA, and we discuss the possible reasons for the controversies.

Expression of AGR2 in pituitary adenomas and its association with tumor aggressiveness

The aim of the present study was to study the expression of anterior gradient 2 (AGR2) to determine its clinical significance in pituitary adenoma (PA), and to evaluate the potential effect of AGR2 on the diagnosis, therapy or prognosis of PA. Immunohistochemistry was performed to detect the expression of AGR2 in 117 PA tissue samples. Western blotting was performed to confirm the expression profile of AGR2 in different subtypes of PAs. The data showed that in 117 different histological subtypes of PA, 51.3% exhibited AGR2-positive expression. Although AGR2 expression occurred more frequently in PAs secreting growth hormone (GH; 62.5%), adrenocorticotropic hormone (ACTH; 80.0%) and follicle-stimulating hormone (FSH; 75.0%),the positive expression rate of AGR2 showed no statistically significant differences between PA subtypes (P>0.05). The association between AGR2 expression and clinical parameters was analyzed using a χ² test, or Fisher's exact probability test when appropriate. The result showed that the aggressiveness of PA was significantly associated with AGR2 expression, and that in the majority of aggressive PAs, AGR2 was negative (P<0.001). In conclusion, the current study detected the expression of AGR2 in different subtypes of PAs for the first time. The data indicated that GH-, ACTH- and FSH-secreting PAs present marginally more frequently with AGR2 expression, howeverm the association was not significant (P>0.05). AGR2 may be a target for the study of PA aggressiveness, and a potential index for the diagnosis or prognosis of PAs.

Post-surgical management of non-functioning pituitary adenoma

Post-surgical surveillance of non-functioning pituitary adenoma (NFPA) is based on magnetic resonance imaging (MRI) at 3 or 6 months then 1 year. When there is no adenomatous residue, annual surveillance is recommended for 5 years and then at 7, 10 and 15 years. In case of residue or doubtful MRI, prolonged annual surveillance monitors any progression. Reintervention is indicated if complete residue resection is feasible, or for symptomatic optic pathway compression, to create a safety margin between the tumor and the optic pathways ahead of complementary radiation therapy (RT), or in case of post-RT progression. In case of residue, unless the tumor displays elevated growth potential, it is usually recommended to postpone RT until progression is manifest, as efficacy is comparable whether treatment is immediate or postponed. The efficacy of the various RT techniques in terms of tumor volume control is likewise comparable. RT-induced hypopituitarism is frequent, whatever the technique. The choice thus depends basically on residue characteristics: size, delineation, and proximity to neighboring radiation-sensitive structures. Reduced rates of vascular complications and secondary brain tumor can be hoped for with one-dose or hypofractionated stereotactic RT, but there has been insufficient follow-up to provide evidence. Somatostatin analogs and dopaminergic agonists have yet to demonstrate sufficient efficacy. Temozolomide is an option in aggressive NFPA resistant to surgery and RT.

Overexpression of the cell adhesion molecule claudin-9 is associated with invasion in pituitary oncocytomas

Pituitary oncocytoma is a subtype of nonfunctioning pituitary adenomas with the potential to be locally invasive. Currently, surgery is the most effective treatment, whereas functional pituitary adenomas can be treated by drugs. We analyzed the invasiveness of pituitary oncocytomas to identify biomarkers that may be useful for guiding future therapeutic decision making. To identify important biomarkers of pituitary oncocytomas, 20 oncocytomas that were negative for hormone-specific immunostaining were confirmed by anti-mitochondria antibody immunostaining and electron microscopy. Our clinical phenotype data showed a prominent male predilection (85%). These tumors were classified as invasive or noninvasive based on preoperative magnetic resonance imaging, intraoperative records, and pathology slide. We observed significantly different expression profiles between pituitary oncocytomas (n = 3) and normal pituitary glands (n = 3). A total of 1937 genes were differentially expressed between the pituitary oncocytomas and normal pituitary glands. Among these 1937 genes, 954 were up-regulated and 983 were down-regulated in pituitary oncocytomas. The most significantly altered gene, claudin-9 (CLDN9), was further confirmed by quantitative real-time polymerase chain reaction, Western blot, and immunohistochemical staining in 10 invasive pituitary oncocytoma samples and 10 noninvasive pituitary oncocytoma samples. High levels of CLDN9 were found in the pituitary oncocytomas, whereas low levels were detected in normal pituitary glands. In addition, the CLDN9 expression level was higher in invasive oncocytomas compared with noninvasive oncocytomas. Bioinformatics Gene Ontology analysis was performed to better understand the critical role of CLDN9 in the development and progression of oncocytomas. Consequently, CLDN9 may be an important biomarker for invasive pituitary oncocytomas.