SMYD3 is a histonemethylase that di- and tri-methylates histone H3 at lysine 4. SMYD3 is frequently upregulated in human colorectal, liver and breast cancers and its transcriptional activity is involved in the development or progression of these tumors. Published microarray data suggest that SMYD3 positively regulate Sonic hedgehog transcription. The Sonic hedgehog pathway is often deregulated in Rhabdomyosarcomas, one of the most common solid tumors of childhood. We hypothesize that upregulation of SMYD3 plays an important role in the onset of rhabdomyosarcoma, through the abnormal transcriptional activation of the sonic hedgehog pathway. The deregulated activation of the Sonic hedgehog pathway would contribute to the maintenance of Rhabdomyosarcoma cells in a proliferative state and prevent differentiation. Our initial approach will be to evaluate the role of SMYD3 and Sonic hedgehog in the proliferation and invasiveness of rhabdomyosarcoma cells. A further objective of the project will be to define a functional mechanism that accounts for a potential involvement of SMYD3 in Sonic hedgehog transcriptional regulation, employing the chromatin immunoprecipitation technique. Moreover, we will identify SMYD3 target genes by the combination of the chromatin immunoprecipitation technique with massively sequencing technology (ChIp- seq). Successful outcome of this proposal can elucidate the mechanisms underlying the onset of rhabdomyosarcoma and will shed light on the more general dynamics through which SMYD3 impact carcinogenesis.