IL-18 expression in clinical human pituitary adenoma

BACKGROUND: IL-18 is known as an interferon-inducing factor that belongs to the IL-1 family, and is synthesized as an inactive precursor protein. OBJECTIVE: The present study aims to investigate the expression of IL-18, IL-18R, R and IL-18 binding protein (BP) mRNA in various types of human pituitary tumors, such as adrenocorticotropic hormone (ACTH), growth hormone (GH), prolactin (PRL), thyroid stimulating hormone (TSH)-producing adenomas and non-function adenomas. METHODS: Pituitary adenoma tissues were obtained during the surgery of 41 patients: nine patients had ACTH-producing pituitary adenomas, nine patients had GH-producing pituitary adenomas, five patients had TSH-producing pituitary adenomas, seven patients had PRL-producing pituitary adenomas, and 11 patients had non-functioning adenomas. The mRNA expression levels of IL-18, IL-18BP, IL-18R and IL-18R were quantified using real-time quantitative PCR. RESULTS: The mRNA expression of IL-18 was significantly higher in ACTH-, GH- and PRL-producing adenomas, when compared to non-function tumors. Similarly, a significantly higher mRNA expression of IL-18BP and IL-18R was observed in ACTH-, GH- and PRL-producing adenomas, when compared with non-functional adenomas. In contrast, no upregulation of IL-18R mRNA was observed in any of the pituitary adenomas. CONCLUSIONS: The mRNA levels of IL-18, IL-18BP and IL-18R are significantly elevated in clinical pituitary tumors, such as ACTH-, GH- and PRL-producing adenomas, when compared to non-functional adenomas. These present results suggest the possibility that IL-18 may be involved in the pathogenesis of pituitary adenoma.

SAT-300 Evading Death: Noxa in Cushing’s Disease Pituitary Adenomas

Introduction: Recurrence of Cushing’s disease (CD) caused by benign pituitary microadenomas are challenging clinical problems. Mechanisms underlying adenoma formation and recurrence remain unknown. PMAIP1 gene codes for Noxa, a Bcl-2 homology 3 (BH3) pro-apoptotic protein frequently downregulated in malignant human tumors.1-6 The role of dysregulated apoptosis remains largely unknown in benign tumors and in CD. We hypothesized that altered expression of Noxa protein is a pro-survival adaptation employed by CD adenomas. Methods: Syngeneic human pituitary adenoma and adjacent normal gland pairs (n=2), and an additional CD adenoma were analyzed with RNAseq. 10 CD, 1 growth hormone (GH) and 1 non-functioning adenoma (NFPA) underwent immunohistochemical (IHC) analysis for Noxa expression, which was graded by a neuropathologist as 0=none, 1=light, 2=medium, 3=strong. Staining grade represents relative protein expression. Results: Compared to adjacent normal pituitary tissue, we found that adenomas (n = 3) had a 3.76 fold increase in PMAIP1 mRNA. However, there was attenuated Noxa IHC staining in adenomas compared to normal pituitary in 8 of 10 CD patients (2:3, respectively), but similar staining in 2 of 10 CD patients (2:2 and 2-3:2-3). In GH and NFPA, we found similar patterns of Noxa suppression in the adenomas compared to the normal gland. Conclusion: Despite elevated PMAIP1 (Noxa) gene expression in adenomas compared to adjacent normal gland in CD, protein expression was reduced in adenomas. This downregulation of Noxa protein expression may contribute to reduced apoptosis of tumor cells. These findings suggest that CD adenomas gain pro-survival advantage by downregulating Noxa protein at post-transcriptional or post-translational level. References 1. Escobar, D. et al. Cell Death Dis.6, 1-14 (2015).2. Brinkmann, K. et al. Cell Rep.3, 881-891 (2013).3. Liu, Y. L. et al. Oncotarget5, 11237-11251 (2014).4. Dengler, M. A. et al. Cell Death Dis.5, 1-10 (2014).5. Liang, L. et al. J. Oral Pathol. Med.48, 52-59 (2019).6. Tahir, S. K. et al. Cancer Res.67, 1176-1183 (2007).

Pituitary adenoma in aged rats. A case report

The prevalence of neoplastic disease in the rat is well defined, because this species has been routinely used for decades in large-scale carcinogenic, aging and toxicological studies. Stock and strain-specific differences in the prevalence of some types of tumors are well documented. Pituitary adenoma is a neoplastic lesion which can be observed in older or aged rats of both sexes. In addition to sex, strain, diet, genetic factor, breeding history and accommodation may also play a role. Pituitary adenoma can also affect hamster, guinea pig and mice. The aim of this article is to report an incidence of pituitary adenomas, which was observed in a rat breeding colony of the Center for Experimental Surgery of the Biomedical Research Foundation of the Academy of Athens. During the clinical examination five female Wistar rats, at the age of 18 to 24 months old, expressed anorexia, weight loss, ataxia and bilateral blindness. At necropsy, the pituitary gland was enlarged with lobulations, often dark red to brown and hemorrhagic in appearance. In some cases there was a marked compression of the overlying mesencephalon. Histological examination with haematoxylin-eosin were observed cords and nests of glandular cells bound by strands of connective tissue, with an abundant capillary network. On immunohistochemical examination were observed strong positive reaction of synaptophysin. Findings were similar to pituitary adenoma. Pituitary adenoma is a serious non-reversible disease leading to the death of the animal. Laboratory animals with pituitary adenomas can be used as models in research of human pituitary adenoma.