GLI1 expression is an important prognostic factor that contributes to the poor prognosis of rhabdomyosarcoma

The GLI1 and MDM2 genes are amplified or exhibit copy number gains in rhabdomyosarcoma (RMS). Here, we used immunohistochemistry to determine the relationships between GLI1 and MDM2 protein expression and several clinicopathological variables of RMS. GLI1 and MDM2-positivity rates were 61.36% and 13.64%, respectively. GLI1 expression correlated with presence of the PAX3-FOXO1 fusion gene (P=0.040) and lymph node metastasis (P=0.034), and a significant association was found between GLI1 expression and overall survival (OS) (P=0.008). However, there was no association between MDM2 expression and any of the clinicopathological parameters or OS. Thus, GLI1 may be a biomarker of poor prognosis in RMS patients, and could itself be a therapeutic target. This contrasts with the apparent lack of clinical importance of MDM2 in RMS pathology, at least in the cohorts we examined.