Do glucagonomas always produce glucagon?

Area of Science:

• Endocrinology
• Oncology
• Molecular Biology

Background:

• Pancreatic islet α-cell tumors overexpressing proglucagon typically cause glucagonoma syndrome.
• Paraneoplastic phenomena from enteric proglucagon peptide overexpression are less recognized, causing gastrointestinal dysfunction and hyperinsulinaemic hypoglycemia.
• Clinical diversity of glucagon-expressing tumors stems from differential post-translational processing of proglucagon.

Purpose of the Study:

• To review the clinical presentation of proglucagon-expressing tumors.
• To correlate presentations with physiological actions of proglucagon-derived peptides.
• To highlight biochemical characterization for improved diagnosis and management.

Main Methods:

• Review of clinical and biochemical literature on proglucagon-expressing tumors.
• Analysis of proglucagon processing patterns in islet α-cells versus enteroendocrine L-cells.
• Correlation of secreted peptide repertoire with clinical manifestations.

Main Results:

• Proglucagon tumors are biochemically subtyped by secretion of glucagon or GLP-1, GLP-2, glicentin, and oxyntomodulin.
• Tumor processing patterns reflect either islet α-cell or enteroendocrine L-cell proglucagon processing.
• Diverse clinical manifestations are linked to specific peptide repertoires.

Conclusions:

• Understanding the peptide repertoire from proglucagon tumors is crucial for explaining diverse clinical presentations.
• Biochemical characterization of secreted peptides offers novel diagnostic and management avenues.
• Further research into proglucagon processing and its clinical impact is warranted.