Plexiform neurofibromas express the transcription factor Gli1.

Background: Plexiform neurofibromas occur commonly in individuals with neurofibromatosis type 1 (NF1) and consist of neurofibromatous change in multiple nerve fascicles. Previously, we had observed that both plexiform neurofibromas and normal cutaneous nerves expressed Hedgehogs (Hhs), which are intercellular signaling molecules and regulate growth and patterning during embryonic development, and their receptors. In the present study, we examined the expression of Gli1, a transcription factor which mediates Hh signaling to investigate the activation of Hh signaling in plexiform neurofibromas and normal cutaneous nerves.

Methods: An antihuman Gli1 antibody was used with a standard immunoperoxidase technique to determine Gli1 expression in 5 specimens of plexiform neurofibromas and 5 specimens of normal cutaneous nerves.

Results: Our results showed Gli1 expression in S-100-positive tumor cells within the involved nerve fascicles in plexiform neurofibromas but not in control normal skins.

Conclusions: Our findings indicate that the Hh signaling pathway is activated in plexiform neurofibromas.