GIPR in GH-PitNETs: molecular and functional insights.

Area of Science:

• Endocrinology and Molecular Biology
• Pituitary Neuroendocrine Tumors (PitNETs)

Background:

• Acromegaly, caused by GH-secreting PitNETs, often shows resistance to somatostatin receptor ligands (SRLs).
• Glucose-dependent insulinotropic polypeptide receptor (GIPR) overexpression is linked to tumor heterogeneity and specific clinical features in GH-PitNETs.

Purpose of the Study:

• To investigate the functional role of GIPR in somatotroph cells.
• To explore the impact of GIPR activation on signaling pathways, hormone secretion, and cellular behavior in GH-PitNET models.

Main Methods:

• Generation of stable human GIPR-expressing GH3 cells (GH3hGIPR) and comparison with control cells.
• Functional assays measuring cAMP/PKA, MAPK/ERK signaling, hormone secretion (GH, prolactin), and intracellular calcium.
• Transcriptomic analysis to identify differential gene expression patterns.

Main Results:

• GIPR activation induced cAMP/PKA and MAPK/ERK signaling, enhanced GH and prolactin secretion, and increased calcium oscillations.
• Transcriptomic analysis revealed altered gene expression related to cell motility, neuronal development, and extracellular matrix remodeling.
• GIPR overexpression did not affect cell proliferation or viability.

Conclusions:

• GIPR signaling plays a significant role in somatotroph cell function, influencing hormone secretion and cellular pathways.
• GIPR may impact therapeutic responses in acromegaly, but its direct role in tumorigenesis requires further investigation.
• Findings highlight GIPR as a potential factor in GH-PitNET heterogeneity and SRL sensitivity.