PURPOSE: Neuroblastoma (NBL) is a tumor from neural crest cells, and is the most frequent solid tumor in children. Midkine (MK) is a pleiotropin analogon, which is frequently expressed in neuronal and epithelial tumors and is a marker for a poor clinical outcome. The aims of this study were to assess MK expression in NBL and investigate the correlation with clinical outcome. METHODS: Fifty-six specimens of NBL were stained for MK on a tissue microarray by immunohistochemistry (IHC). Fresh frozen tumor tissues were used for RNA isolation, and RT-PCR analysis for MK-mRNA expression was performed. Survival data, risk factors and disease stages were correlated with MK status assessed by IHC and RT-PCR analysis. RESULTS: MK-mRNA expression was found in the majority of the tumor tissues (75%), whereas MK protein could be detected only in 46% of the NBL by IHC. No correlation of MK status with survival, risk factors or disease stage was observed. CONCLUSION: A majority of NBL express MK-mRNA, whereas not all MK mRNA positive tumors showed also a positive MK IHC staining. The high expression of MK-mRNA expression might present a promising target for new adenovirus-based gene therapeutic approaches for the treatment of NBL.
