Propagation of a protease-resistant form of prion protein in long-term cultured human glioblastoma cell line T98G

Human prion diseases, such as Creutzfeldt-Jakob disease (CJD), a lethal, neurodegenerative condition, occur in sporadic, genetic and transmitted forms. CJD is associated with the conversion of normal cellular prion protein (PrPC) into a protease-resistant isoform (PrPres). The mechanism of the conversion has not been studied in human cell cultures, due to the lack of a model system. In this study, such a system has been developed by culturing cell lines. Human glioblastoma cell line T98G had no coding-region mutations of the prion protein gene, which was of the 129 M/V genotype, and expressed endogenous PrPC constitutively. T98G cells produced a form of proteinase K (PK)-resistant prion protein fragment following long-term culture and high passage number; its deglycosylated form was approximately 18 kDa. The PK-treated PrPres was detected by immunoblotting with the mAb 6H4, which recognizes residues 144-152, and a polyclonal anti-C-terminal antibody, but not by the mAb 3F4, which recognizes residues 109-112, or the anti-N-terminal mAb HUC2-13. These results suggest that PrPC was converted into a proteinase-resistant form of PrPres in T98G cells.