Differential expression of the Notch1 receptor, and its ligands Dll1, Dll3 and Dll4 in distinct human pituitary adenoma subtypes.

Pituitary adenoma (PA) is a common type of benign tumor of the pituitary gland that is characterized by specific signs and symptoms, primarily associated with hypersecretion of pituitary glycoprotein hormones (thyroid-stimulating, growth and adrenocorticotrophic hormones, and prolactin). Surgery is the first-line treatment, although postoperative residual tissues/cells and subsequent recurrence remain notable complications. Gene therapy is an effective approach for treatment, as previous studies have demonstrated that the Notch signaling pathway participates in the pathogenesis of PA. The focus of the present study was on the associations between the expression of the Notch1 receptor and its ligands δ-like canonical Notch ligand (Dll) 1, Dll3 and Dll4 in patients with PA. Using reverse transcription-quantitative polymerase chain reaction and western blot analyses, to the best of our knowledge, this is the first study to provide a description of the differential expression of the Notch1 receptor and its ligands Dll1, Dll3, and Dll4 in various types of human PA at the mRNA and protein levels. The results of the present study demonstrated that Notch1 protein expression was positively correlated with Dll4 protein expression, but negatively correlated with Dll3 protein expression, indicating synergistic effects between the Notch1 receptor and Dll4 ligand. Furthermore, the Dll3 ligand may be an inhibitor of the Notch1 receptor, indicating an antagonistic association between Notch1 and the Dll3 ligand. These results have identified a potential target for the treatment of patients with PA.