Continuous Quinacrine Treatment Results in the Formation of Drug-Resistant Prions

PLoS Pathogens

Giuseppe Legname¹  Misol Ahn¹  Stanley B. Prusiner¹  Pierre Lessard²  Stephen J. DeArmond³  Sina Ghaemmaghami³  Kurt Giles³ 

[1] Department of Neurology, University of California, San Francisco, California, United States of America;Department of Pathology, University of California, San Francisco, California, United States of America;Institute for Neurodegenerative Diseases, University of California, San Francisco, California, United States of America

关键词: Prions;    Animal prion diseases;    Enzyme-linked immunoassays;    Prion diseases;    Mouse models;    Cell cultures;    Drug administration;    Drug therapy;   

DOI  :  10.1371/journal.ppat.1000673

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

Quinacrine is a potent antiprion compound in cell culture models of prion disease but has failed to show efficacy in animal bioassays and human clinical trials. Previous studies demonstrated that quinacrine inefficiently penetrates the blood-brain barrier (BBB), which could contribute to its lack of efficacy in vivo. As quinacrine is known to be a substrate for P-glycoprotein multi-drug resistance (MDR) transporters, we circumvented its poor BBB permeability by utilizing MDR0/0 mice that are deficient in mdr1a and mdr1b genes. Mice treated with 40 mg/kg/day of quinacrine accumulated up to 100 µM of quinacrine in their brains without acute toxicity. PrPSc levels in the brains of prion-inoculated MDR0/0 mice diminished upon the initiation of quinacrine treatment. However, this reduction was transient and PrPSc levels recovered despite the continuous administration of quinacrine. Treatment with quinacrine did not prolong the survival times of prion-inoculated, wild-type or MDR0/0 mice compared to untreated mice. A similar phenomenon was observed in cultured differentiated prion-infected neuroblastoma cells: PrPSc levels initially decreased after quinacrine treatment then rapidly recovered after 3 d of continuous treatment. Biochemical characterization of PrPSc that persisted in the brains of quinacrine-treated mice had a lower conformational stability and different immunoaffinities compared to that found in the brains of untreated controls. These physical properties were not maintained upon passage in MDR0/0 mice. From these data, we propose that quinacrine eliminates a specific subset of PrPSc conformers, resulting in the survival of drug-resistant prion conformations. Transient accumulation of this drug-resistant prion population provides a possible explanation for the lack of in vivo efficacy of quinacrine and other antiprion drugs.

【 授权许可】

CC BY