Notch system is differentially expressed and activated in pituitary adenomas of distinct histotype, tumor cell lines and normal pituitaries

Abstract

Pituitary adenomas are among the most frequent intracranial neoplasms and treatment depends on tumor subtype and clinical features. Unfortunately, non responder cases occur, then new molecular targets are needed.Notch system component expression and activation data are scarce in pituitary tumorigenesis, we therefore aimed to characterize Notch system in pituitary tumors of different histotype. In human pituitary adenomas we showed NOTCH1-4 receptors, JAGGED1 ligand and HES1 target gene expression with positive correlations between NOTCH1,2,4 and HES1, and NOTCH3 and JAGGED1 denoting Notch system activation in a subset of tumors. Importantly, NOTCH3 positive cells were higher in corticotropinomas and somatotropinomas compared to non functioning adenomas. In accordance, Notch activation was evidenced in AtT20 tumor corticotropes, with higher levels of NOTCH1-3 active domains, Jagged1 and Hes1 compared to normal pituitary.In the prolactinoma cell lines GH3 and MMQ, in vivo GH3 tumors and normal glands, Notch system activation was lower than in corticotropes. In MMQ cells only the NOTCH2 active domain was increased, whereas NOTCH1 active domain was higher in GH3 tumors. High levels of Jagged1 and Dll1 were found solely in GH3 cells, and Hes1, Hey1 and Hey2 were expressed in a model dependent pattern.Prolactinomas harbored by lacDrd2KO mice expressed high levels of NOTCH1 active domain and reduced Hes1.We show a differential expression of Notch system components in tumoral and normal pituitaries and specific Notch system involvement depending on adenoma histotype, with higher activation in corticotropinomas. These data suggest that targeting Notch pathway may benefit non responder pituitary adenomas.

Inhibition of Notch signaling attenuates pituitary adenoma growth in Nude mice

“…Xenotransplant tissue or GH3 cells cultured in vitro were processed for recovery of total RNA using TRIzol reagent (Invitrogen). Reverse transcription was performed as previously described (Perrone et al 2017).…”

“…We recently found that all four Notch receptors are expressed in the pituitary gland and also demonstrated enhanced gene expression of the Notch ligands Jag1 and Dll1, and the target gene Hey1, as well as activated Notch2 intracellular domain N2ICD in the somatolactotrope cell line GH3 compared to normal rat pituitaries (Perrone et al 2017). Furthermore, in prolactinomas harbored by lacDrd2KO female mice an activated Notch signaling pathway was found (Perrone et al 2017). Therefore, in the present study, we undertook a functional approach to evaluate Notch participation in pituitary adenoma growth.…”

The Stem Cell Connection of Pituitary Tumors

“…The NOTCH pathway can be either activated or suppressed depending on pituitary tumor histotype ( 46 ). For instance, NOTCH3 and JAG1 expression was found upregulated in NFPA in comparison to normal human pituitary tissue ( 47 – 49 ).…”

Experimental Evidence and Clinical Implications of Pituitary Adenoma Stem Cells

“…Interestingly, CD133 and dopamine D2 receptor (D2R) expression, analyzed by FACS, segregate in different subpopulations (93). In another series of human PAs, NOTCH 1-4 receptor subtypes, and their ligand JAGGED1 were detected by RT-PCR, suggesting the presence of a constitutive autocrine/paracrine NOTCH system activation in a subset of tumor cells (94). In this study, NOTCH3 immunohistochemistry showed that NFPAs, prolactinomas, GHomas, and ACTH-secreting PAs (ACTHomas) express the protein in the cytoplasm and membrane of tumor cells.…”