High levels of tyrosine phosphorylated proto-ret in sporadic phenochromocytomas

• Published in: Cancer research (Chicago, Ill.) Vol. 60; no. 5; pp. 1365 - 1370
• Main Authors: Le Hir, H, Colucci-D'Amato, L G, Charlet-Berguerand, N, Plouin, P F, Bertagna, X, de Franciscis, V, Thermes, C
• Format: Journal Article
• Language: English
• Published: United States 01.03.2000
• Subjects: Adrenal Gland Neoplasms - genetics; Adrenal Gland Neoplasms - metabolism; Drosophila Proteins; Gene Expression Regulation, Neoplastic; Glial Cell Line-Derived Neurotrophic Factor; Glial Cell Line-Derived Neurotrophic Factor Receptors; Humans; Nerve Growth Factors; Nerve Tissue Proteins - biosynthesis; Nerve Tissue Proteins - genetics; Pheochromocytoma - genetics; Pheochromocytoma - metabolism; Phosphorylation; Proto-Oncogene Proteins - biosynthesis; Proto-Oncogene Proteins - genetics; Proto-Oncogene Proteins - metabolism; Proto-Oncogene Proteins c-ret; Receptor Protein-Tyrosine Kinases - biosynthesis; Receptor Protein-Tyrosine Kinases - genetics; Receptor Protein-Tyrosine Kinases - metabolism; Signal Transduction; Tyrosine
• ISSN: 0008-5472

Pheochromocytomas are tumors originating from chromaffin cells, the large majority of which are sporadic neoplasms. The genetic and molecular events determining their tumorigenesis continue to remain unknown. On the other hand, RET germ-line mutations cause the inheritance of familial tumors in multiple endocrine neoplasia (MEN)-2 diseases, which account for a minority of pheochromocytomas. We investigated the expression of the RET gene in 14 sporadic tumors harboring no activating mutations. A subset of highly RET-expressing tumors (50%) could be distinguished. They showed RET transcript, protein amounts as well as Ret-associated phosphotyrosine levels similar to those measured in MEN-2A-associated pheochromocytomas. We also determined the GDNF and GDNF family receptor alpha (GFRalpha)-1 transcript levels in tumors and in normal tissues. Whereas the GFRalpha-1 transcripts were detected at similar levels in normal tissues and in tumors, GDNF was frequently found expressed in sporadic tumors at levels several times higher than in controls. These results led us to propose the existence of an autocrine or paracrine loop leading to chronic stimulation of the Ret signaling pathway, which could participate in the pathogenesis of a number of sporadic pheochromocytomas.