The celecoxib derivatives AR-12 and AR-14 induce autophagy and clear prion-infected cells from prions

Basant A Abdulrahman,Simrika Thapa,Hermann M Schatzl,Stefan Proniuk,Li Lu,Sabine Gilch,Alexander Zukiwski,Shubha Jain,Dalia Abdelaziz

doi:10.1038/s41598-017-17770-8

Abstract

Prion diseases are fatal infectious neurodegenerative disorders that affect both humans and animals. The autocatalytic conversion of the cellular prion protein (PrPC) into the pathologic isoform PrPSc is a key feature in prion pathogenesis. AR-12 is an IND-approved derivative of celecoxib that demonstrated preclinical activity against several microbial diseases. Recently, AR-12 has been shown to facilitate clearance of misfolded proteins. The latter proposes AR-12 to be a potential therapeutic agent for neurodegenerative disorders. In this study, we investigated the role of AR-12 and its derivatives in controlling prion infection. We tested AR-12 in prion infected neuronal and non-neuronal cell lines. Immunoblotting and confocal microscopy results showed that AR-12 and its analogue AR-14 reduced PrPSc levels after only 72 hours of treatment. Furthermore, infected cells were cured of PrPSc after exposure of AR-12 or AR-14 for only two weeks. We partially attribute the influence of the AR compounds on prion propagation to autophagy stimulation, in line with our previous findings that drug-induced stimulation of autophagy has anti-prion effects in vitro and in vivo. Taken together, this study demonstrates that AR-12 and the AR-14 analogue are potential new therapeutic agents for prion diseases and possibly protein misfolding disorders involving prion-like mechanisms.

Highlights

The highly conserved PRNP/Prnp gene encodes the cellular prion protein (PrPC), a protein highly expressed in the central nervous system in neurons and glial cells, and present in non-brain cells
Our findings were confirmed by PrPSc-specific immunofluorescence analysis and real-time quaking-induced conversion (RT-QuIC), where application of AR-12 and its analogue AR-14 to infected cells resulted in a robust decrease in prion conversion activity
In order to analyze whether AR-12 is affecting the level of PrPSc in ScN2a cells, we treated cells for 72 h with increasing concentrations of AR-12, from 0.5 to 3 μM, in a single application

Summary

Introduction

The highly conserved PRNP/Prnp gene encodes the cellular prion protein (PrPC), a protein highly expressed in the central nervous system in neurons and glial cells, and present in non-brain cells. In the last two decades, great efforts have been made to establish treatment options for prion diseases These included testing existing drugs for anti-prion activity in experimental models[14,15,16,17,18,19,20,21] with only a few agents progressing to human studies of patients with prion diseases[22,23,24,25]. Our findings were confirmed by PrPSc-specific immunofluorescence analysis and real-time quaking-induced conversion (RT-QuIC), where application of AR-12 and its analogue AR-14 to infected cells resulted in a robust decrease in prion conversion activity. This very efficient anti-prion effect upon short-term treatment suggests that the compound may have multiple effects on prion propagation and/or acts on PrPSc clearance. Our data show that AR-12 and its derivatives could be promising therapeutic tools for the treatment of prion diseases and protein misfolding diseases

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Results

Conclusion