Immunohistochemical Expression of Sonic hedgehog and Snail in Oral Epithelial Dysplasia and Squamous Cell Carcinoma

Abstract

Summary The hedgehog (Hh) signaling pathway is an important pathway for regulation of cell differentiation and organ formation during embryonic development, as well as the maintenance of adult stem cells. Three members of this family are known in mammals, Shh is the most potent of these ligands and is the most widely expressed in the adult tissues. Activation of the Hh signaling is initiated by binding of any of the three ligands: Shh, Dhh and Ihh, to PTCH, which acts as a negative regulator for SMO. Binding between any of the ligands and PTCH results in derepression of SMO, thereby activating a cascade that leads to the translocation of the active form of the transcription factor GLI to the nucleus. Nuclear GLI activates expression of a variety of target genes.