Susceptibility to exogenously added interferon-β protein depends on intracellular interferon-β mRNA level in human glioma cells

In this study, we used seven human glioma cell lines (SK-MG-1, SK-MG-4, SK-AO2, U87MG, U251SP, U251MG and T98) and one human melanoma cell line (MMAN). At first, we examined the relationship between spontaneous expression of HuIFN-β mRNA and susceptibility to exogenously added HuIFN-β protein (50 IU/ml) in human glioma cells and then confirmed a significant correlation between them. Next, we confirmed that administration of 0-100 IU/ml exogenously added HuIFN-β protein upregulated the HuIFN-β mRNA in a dose-dependent manner using the RT-PCR technique and that the HuIFN-β mRNA was suppressed by siRNA for HuIFN-β in SK-MG-1 and MMAN cells. Furthermore, we confirmed that the siRNA for HuIFN-β significantly suppressed the antiproliferative effect of SK-MG-1 cells treated with 10-100 IU/ml HuIFN-β protein and MMAN cells with 25 and 50 IU/ml HuIFN-β protein. We found this phenomenon in another human glioma cell line, U87MG cells, as well. This finding would suggest that susceptibility to exogenously added HuIFN-β protein is related to the amount of intracellular HuIFN-β mRNA in human glioma and melanoma cells.