Patched (Ptch) receptors are critical negative regulators of Hedgehog signaling, where Ptch1 loss causes basal cell carcinoma and Ptch1;Ptch2 loss disrupts skin and hair follicle development.Adolphe et al. use single molecule fluorescent in situ hybridization to show quantitatively that Ptch receptors create a Hedgehog signaling gradient that may specify hair follicle development.
Both sporadic and inherited BCCs are associated with mutations in the tumor suppressor gene PTCH1, but there is still uncertainty on the role of its homolog PTCH2.
These data indicate that basal cell carcinomas are associated with a functionally distinct population of fibroblast-like cells that overexpress known tumor-specific markers (ptch and ptch2).
In situ hybridization revealed high expression of PTCH2 transcripts in both familial and sporadic basal cell carcinomas in similarity to what has been observed for PTCH1, suggesting a negative regulation of PTCH2 by PTCH1.