HuR and Msi1 expression levels correlate positively. (A) MSI1 mRNA and HuR mRNA levels are higher in tumor cells with “stem cells” characteristics. HuR and Msi1 expression was assessed in two primary glioblastoma samples grown as spheroids vs. monolayers. The ACTB mRNA was used for normalization when using the 2−ΔΔCt method for mRNA relative quantification. Data were analyzed with Student’s t-test and were presented as the mean ± standard error of the mean. Experiment was performed in triplicate. (B) HuR and MSI1 mRNA expression positively correlates in GBMs. RT-qPCR was performed on total RNA extracted from the clinical samples and the data was analyzed using the 2−ΔΔCt method. The ACTB mRNA was utilized as an endogenous control and all samples were compared to the U251 glioblastoma cell line. The ΔΔCtMsi1 was plotted on the abscissa, and the ΔΔCtHuR was plotted on the ordinate. A linear regression model was generated with a correlation score of 0.503 and p - value of 0.0201; thus, HuR and Msi1 exhibit statistically significant linear correlation in expression. (C) Representative microscopic images (40X) of immunohistochemistry of Msi1 and HuR in a glioblastoma tissue microarray. (D) Quantifying glioblastoma tissue microarray stainings of HuR and Msi1. Staining scores for HuR and Msi1 in glioblastoma (35 cores) was averaged and compared to the average score for staining in normal brain tissue (5 cores). Both HuR and Msi1 are more expressed in glioblastoma than in normal brain tissue (p – value < 0.0001). Data were analyzed by the Student’s t-test and presented as the mean ± standard error of the mean. (E) Individual scores of each glioblastoma and normal brain tissue samples for HuR and Msi1 are graphed on a vertical scatter plot. In glioblastoma, HuR had an average score of 83.48, SEM = 1.507 with a 95% confidence interval ranging from 80.47 to 86.50 while in normal brain tissue, HuR had an average score of 61.00, SEM = 9.452 with a 95% confidence interval: 39.62 to 82.38. In glioblastoma, Msi1 had an average score of 41.14, SEM = 4.017 with a 95% confidence interval ranging from 33.11 to 49.16 while in normal brain tissue, Msi1 had an average score of 0.0, SEM = 0.0 with a 95% confidence interval ranging from 0.0 to 0.0.