We aimed at the evaluation of MEG3 and GADD45γ expression in sporadic functioning and clinically non-functioning human pituitary adenomas, morphologically characterized by immunohistochemistry analysis and their association with clinical features. Thirty eight patients who had undergone hypophysectomy at São José Hospital of Irmandade Santa Casa de Misericórdia in Porto Alegre, Brazil, were included in this study. We evaluated tumor-type specific MEG3 and GADD45γ expression by qRT-PCR in the pituitary adenomas, and its association with clinical features, as age, gender and tumor size, obtained from medical records. The patients consisted of 21 males and 17 females and the mean age was 47 ± 14 (mean ± SD), ranging from 18 to 73 years-old. Of these 14 were clinically non-functioning, 10 GH-secreting, 9 PRL-secreting, and 5 ACTH-secreting pituitary adenomas. All samples were macroadenomas, except four ACTH-secreting tumors, which were microadenomas. In summary, MEG3 and GADD45γ expression was significantly lost in most clinically non-functioning adenomas (78 and 92%, respectively). Other assessed pituitary tumor phenotypes expressed both genes at significantly different levels, and, in some cases, with overexpression. There was no significant association between gene expression and the analyzed clinical features. Our results confirm the previous report, which indicated that MEG3 and GADD45γ expression is lost in the majority of human pituitary tumors, mainly in clinically-nonfunctioning adenomas. Functioning tumors had differences of relative expression levels. The two groups of tumors are probably genetically different and may have a different natural history.

Estrogen has been shown to play an important role in pituitary tumor pathogenesis. In humans, this biosynthesis is mediated by aromatase, an enzyme that converts androgens to estrogens. Just a few studies about aromatase expression in human pituitary gland, both in normal and pathological ones, are found in the literature. This study aimed to assess aromatase enzyme expression in human pituitary adenomas and associate it with gender, tumor size and tumor subtype. We conducted a cross-sectional study, reviewed clinical data and surgical specimens of consecutive 65 patients (35 women and 30 men) with anatomopathologic diagnosis of pituitary adenoma who underwent adenomectomy at a neurosurgical referral center in southern Brazil. Immunohistochemistry was performed to assess aromatase expression and define tumor subtype, and quantitative reverse transcription-polymerase chain reaction (qRT-PCR) to estimate aromatase gene expression. Mean patient age was 45.6 (±13.3) years (range, 18 to 73 years), 86.2% of our samples were macroadenomas while 13.8% were classified as microadenomas. Based on clinical and immunohistochemical data, 23 (35.4%) patients had non-functioning adenomas, 19 (29.2%) had somatotroph adenomas (acromegaly), 12 (18.5%) had lactotroph adenomas (hyperprolactinemic syndrome), and 11 (16.9%) had corticotroph adenomas (Cushing's disease). Immunohistochemical analysis was performed in 59 cases, and 58 (98.3%) showed no aromatase expression. Quantification by qRT-PCR was performed in 43 samples, and 36 (83.7%) revealed no gene expression. Among tumor specimens examined by both techniques (37 cases), 30 showed no gene or protein expression (concordance index, 0.81). It is possible to mention that aromatase expression was lost in most pituitary adenomas, regardless of gender, tumor subtype, or tumor size.

Despite recent advances in molecular genetics, the pituitary adenoma initiation, development, progress, and the molecular basis of their unique features are still poorly understood. In this sense, it is proposed that stem cell could be involved in pituitary adenoma tumorigenesis. It is suggested that TP63 has important functions in stem cells, and it may have interplay of TP63 and Notch and its ligand Jagged in this process. This study aimed to evaluate the distinct expression of TP63 isoforms (TAp63 and ΔNp63), as well as its correlation with Notch3 receptor and its ligand Jagged1 in human pituitary adenomas at the messenger RNA (mRNA) level. We included 77 pituitary adenoma tumor samples from patients who underwent surgical resection. The expression levels of TP63 isoforms (TAp63 and ΔNp63) and Notch3 and its ligand Jagged1 were evaluated by qRT-PCR using isoform-specific primers. We also evaluated proliferation index immunohistochemically using KI-67 antibody. The expression levels were associated with clinical outcomes, as age, gender, tumor size, and tumor subtype. In summary, we found that mRNA expression of both TP63 isoforms decreased in pituitary adenomas compared with normal pituitary control. On the other hand, there was an increase of relative Notch3 and Jagged1 mRNA expression in the majority of examined samples. The mRNA expression of three genes evaluated was correlated and statistically significantly. There was no significant association between gene expression and the analyzed clinical data. The current study has provided the first time evidence that Tap63 and ΔNp63 isoforms are underexpressed in most pituitary adenomas. These results are correlated with Notch3 and its ligand Jagged1 overexpression, corroborating previous studies pointing its antagonistic interactions.

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