Evidence for lack of enhanced hedgehog target gene expression in common extracutaneous tumors.

Abnormal hedgehog signaling, most commonly caused by loss of PTCH1 inhibitor activity,drives tumorigenesis of basal cell carcinomas (BCCs). To assess whether other tumors also have abnormal hedgehog signaling, we have assayed RNA from common cancers at nine different sites for levels of expression of hedgehog target genes that are up-regulated uniformly in BCCs. We report here that such dysregulation appears not to be common in the types of non-BCC cancers studied, indicating that the molecular pathogenesis of BCCs, like their frequency and behavior, differs markedly from that of most other cancers.