EXPRESSION OF ITPR ISOFORMS IN SECRETING PITUITARY TUMOR CELLS

GILDA FLORENCIA MEZGER; FACUNDO GARCIA BARBERÁ; NATACHA ZLOCOWSKI; JUAN DE BATISTA ; LAURA CECENARRO ; VERONICA ANDREOLI ; LILIANA SOSA ; JUAN PABLO PETITI

Mar del Plata

Congreso; REUNIÓN CONJUNTA SAIC SAB AAFE AACYTAL 2023; 2023

SOCIEDAD ARGENTINA DE INVESTIGACIÓN CLÍNICA (SAIC), SOCIEDAD ARGENTINA DE BIOLOGÍA (SAB), ASOCIACIÓN ARGENTINA DE FARMACOLOGÍA EXPERIMENTAL (AAFE), AACYTAL

Large-scale chromosomal alterations and mutations in Ca2+ signaling genes, which are involved in regulating hormone secretion and cell proliferation, have been detected in hyper-secreting pituitary neuroendocrine tumors (PitNET). Inositol 1,4,5 trisphosphate receptors (ITPR1-3) are a family of endoplasmic reticulum Ca2+ channels essential for the control of intracellular Ca2+ levels in different mammalian cell type, but its role in the behavior of pituitary tumors has not been full described. The objective of the study was to analyze the gene expression and subcelluar localization of ITPR1-3 in pituitary tumor cells with linage PIT1(GH- and PRL-secreting). We used primary cultures from patients with somatoroph, silent somatotroph and lactotroph tumors from Hospital Privado Universitario of Córdoba, Argentina, and GH3 cell line that secret GH and PRL. This project was approved by the Ethics Committee (RepisN° HP 4-342). The RNAm expression levels were calculated by quantitative re al-time PCR analysis and the GAPDH gene was used as a reference gene. The ΔΔCT method was used for relative quantification. The subcellular localization of ITPRs was analyzed by immunofluorescence. In all PitNETs and also in the GH3 cell line we observed a very strong expression in ITPR3, followed by ITPR1 with no expression in ITPR2. In somatotroph cells the fluorescence of ITPR1-3 was strongly and widely distributed within the cell with a higher intensity in the nucleus and plasma membrane, while in silent somatotroph cells the immunostaining was principally in the perinuclear region and absent from the cell nucleus. These results suggest that ITPR3 may be the isoform more linked with the Ca2+ release, and consequently modulate the hormone secretion in GH and PRL tumor cells. In addition, the subcellular localization of ITPRs could indicate that PitNETs possess mechanisms able to produce selective increases of Ca2+ in different compartment according functional necessity.