Supplementary Material for: A New Generation Somatostatin-Dopamine Analogue Exerts Potent Antitumoral Actions on Pituitary Neuroendocrine Tumor Cells

<b><i>Background:</i></b> Pituitary neuroendocrine tumors (PitNETs) represent approximately 15% of all intracranial tumors and usually are associated with severe comorbidities. Unfortunately, a relevant number of patients do not respond to currently available pharmacological treatments, that is, somatostatin analogs (SSAs) or dopamine-agonists (DA). Thus, novel, chimeric somatostatin/dopamine compounds (dopastatins) that could improve medical treatment of PitNETs have been designed. <b><i>Objective:</i></b> This study aims to determine the direct therapeutic effects of a new-generation dopastatin, BIM-065, on primary cell cultures from different PitNETs subtypes. <b><i>Methods:</i></b> Thirty-one PitNET-derived cell cultures (9 corticotropinomas, 9 somatotropinomas, 11 nonfunctioning pituitary adenomas [NFPAs], and 2 prolactinomas), were treated with BIM-065, and key functional endpoints were assessed (cell viability, apoptosis, hormone secretion, expression levels of key genes, free cytosolic [Ca²⁺]_i dynamics, etc.). AtT-20 cell line was used to evaluate signaling pathways in response to BIM-065. <b><i>Results:</i></b> This chimeric compound decreased cell viability in all corticotropinomas and somatotropinomas tested, but not in NFPAs. BIM-065 reduced ACTH, GH, chromogranin-A and PRL secretion, and increased apoptosis in corticotropinomas, somatotropinomas, and NFPAs. These effects were possibly mediated through modulation of pivotal signaling cascades like [Ca²⁺]_i kinetic and Akt- or ERK1/2-phosphorylation. <b><i>Conclusions:</i></b> Our results unveil a robust antitumoral effect in vitro of the novel chimeric compound BIM-065 on the main PitNET subtypes, inform on the mechanisms involved, and suggest that BIM-065 could be an efficacious therapeutic option to be considered in the treatment of PitNETs.