Sonic hedgehog inhibition reduces in vitro tumorigenesis and alters expression of Gli1-target genes in a desmoplastic medulloblastoma cell line

Medulloblastoma is one of the most frequent and aggressive tumors of childhood. The Sonic hedgehog (Shh) pathway, related to human development, is altered in most medulloblastomas: genes like Ptch, Smo, or Sufu suffer mutations in 15% to 25% of these tumors. We tested Shh inhibition in the Daoy medulloblastoma cell line by two methods: a molecular one, direct Gli1 siRNA inhibition; and a pharmacological inhibition of Smo, upstream of Gli1, by cyclopamine. Afterwards, a comparison of cellular and molecular responses was done. In general, we proved that cell viability, cell migration and cell colony formation decreased after Shh inhibition, which might confer a less tumorigenic status to Daoy cells. Moreover, we assessed the expression of different Gli1 target genes and other genes and found that Shh shows a crosstalk with oncogenes and tumor suppressor genes that have been described in numerous tumors. All these experiments give an overview of the Shh pathway in medulloblastoma, together with the demonstration of the efficacy of cyclopamine and Gli1 siRNA Shh inhibition in vitro