RIP-Chip analysis of Musashi (Msi1) in the U251, a human glioma cell line

Musashi1 (Msi1) is a highly conserved RNA binding protein that is required during the development of the nervous system. Msi1 has a role in neural stem cells, controlling the balance between self-renewal and differentiation. Msi1 has also been implicated in cancer, being highly expressed in multiple tumor types. In this study, we analyzed Msi1 expression in a large cohort of medulloblastoma samples and showed that Msi1 is highly expressed in tumor tissue compared to normal cerebellum and that high Msi1 expression is associated with a poor prognosis. Using a nude mouse xenograft model, we demonstrate that Msi1 is important for tumor growth. We then used RIP-chip (ribonucleoprotein immunoprecipitation followed by microarray analysis) to identify mRNA targets of Msi1 in medulloblastoma. In conclusion, our results suggest that Msi1 functions as a regulator of multiple processes in medulloblastoma formation and could become an important therapeutic target. RIP-Chip analysis to identify mRNA preferentially associated with Msi1 protein. RIP-Chip experiments were performed on two biologically replicated samples. A total of 8 microarrays were carried on using technical replicates of Msi1 antibody vs. prebleed serum for each dye orientation. We prepared two biological replicates for two different arrays. Each array consisted of 4 microarrays with 2 replicates for each dye orientation.