Overexpression of the insulin-like growth factor I receptor in human pheochromocytomas.

In order to determine the role of the IGF-I receptor (IGF-IR) in human pheochromocytomas we have compared the expression of the IGF-IR in normal tissues and in pheochromocytomas with regard to the IGF-IR mRNA levels and ligand binding. By semiquantitative reverse transcription polymerase chain reaction (RT-PCR), the mRNA of the IGF-IR could be detected in all samples of normal adrenomedullary cells (n=13) and pheochromocytomas (n=16). However, pheochromocytomas exhibited 2.8-fold higher mean IGF-IR mRNA levels than normal adrenomedullary cells (2.8±0.5×105 molecules/μg RNA vs 7.8±1.2×105 molecules/μg RNA; P < 0.001). This overexpression of the IGF-IR in pheochromocytomas could be confirm…