Endothelin-2 is upregulated in basal cell carcinoma under control of Hedgehog signaling pathway

Vasoactive peptide endothelins are a group of small peptides with diverse paracrine/autocrine actions and are reported to be involved in the pathogenesis of many human malignancies. Basal cell carcinoma (BCC) is a common malignant skin tumor that frequently has aberrant activation of the Hedgehog (HH) signaling pathway. We show here that endothelin-2 (ET-2) is overexpressed in BCC under the control of HH signaling. By real-time quantitative RT-PCR analysis, significant expression of ET-2 mRNA was observed in 19 of 20 cases (95%) compared to normal skin. In addition, inhibition of the HH signaling pathway in a mouse BCC cell line downregulated endogenous ET-2, and activation of HH signaling in mouse embryonic fibroblast upregulated endogenous ET-2. Moreover, the 3′ promoter region of ET-2 gene contains the GLI-binding site and a 0.8 kb downstream fragment containing GLI-binding sites activates transcription in a reporter assay. These data indicate that ET-2 is a direct target gene of HH signaling in BCC.