AUTHOR=Herrera-Martínez Yiraldine , Contreras González María José , Pedraza-Arévalo Sergio , Guerrero Martínez Maria del Carmen , Rodrigo Martínez Ángela , González Menchen Alberto , Blanco Molina Maria Angeles , Gálvez-Moreno Maria Angeles , Moreno-Vega Alberto L. , Luque Raúl M. , Herrera-Martínez Aura D. 

TITLE=Calcitriol-Mediated Hypercalcemia, Somatostatin Receptors Expression and 25-Hydroxyvitamin D3-1α- Hydroxylase in GIST Tumors

JOURNAL=Frontiers in Endocrinology

VOLUME=12

YEAR=2022

URL=https://www.frontiersin.org/journals/endocrinology/articles/10.3389/fendo.2021.812385

DOI=10.3389/fendo.2021.812385

ISSN=1664-2392

ABSTRACT=<p>Hypercalcemia is a common complication in cancer patients Mainly caused by Parathyroid hormone-related protein (PTHrP) secretion and metastasis. Calcitriol secretion is a rare source of hypercalcemia in solid tumors, especially in gastrointestinal stromal tumors (GIST). We present a case report of a female patient with a 23 cm gastric GIST that expressed somatostatin-receptors and presented with severe hypercalcemia due to calcitriol secretion. Calcium control was achieved with medical treatment before the use of targeted-directed therapies. Surgery was performed and allowed complete tumor resection. Two years later, patient remains free of disease. Molecular analysis revealed the mRNA expression of 25-hydroxyvitamin D<sub>3</sub>-1-hydroxylase (1αOHase) and vitamin-D receptors in the tumor cells, confirming the calcitriol-mediated mechanism. Furthermore, the expression of the endotoxin recognition factors CD14 and TLR4 suggests an inflammatory mediated mechanism. Finally, the expression of somatostatin-receptors, especially <italic>SST2</italic> might have been related with clinical evolution and prognosis in this patient.</p>