Inhibition of mitochondrial translation suppresses glioblastoma stem cell growth

Glioblastoma stem cells (GSCs) resist current glioblastoma (GBM) therapies. GSCs rely highly on oxidative phosphorylation (OXPHOS), whose function requires mitochondrial translation. Here we explore the therapeutic potential of targeting mitochondrial translation and report the results of high-content screening with putative blockers of mitochondrial ribosomes. We identify the bacterial antibiotic quinupristin/dalfopristin (Q/D) as an effective suppressor of GSC growth. Q/D also decreases the clonogenicity of GSCs in vitro, consequently dysregulating the cell cycle and inducing apoptosis. Cryoelectron microscopy (cryo-EM) reveals that Q/D binds to the large mitoribosomal subunit, inhibiting mitochondrial protein synthesis and functionally dysregulating OXPHOS complexes. These data suggest that targeting mitochondrial translation could be explored to therapeutically suppress GSC growth in GBM and that Q/D could potentially be repurposed for cancer treatment.

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Screen of putative mitoribosome inhibitors identifies Q/D as effective on GSCs

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Q/D selectively inhibits growth of GSCs

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Treatment with Q/D decreases clonogenicity, blocks cell cycle, and induces apoptosis

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Q/D binds to mitoribosomes and inhibits mitochondrial translation and therefore OXPHOS

Streptogramins for the treatment of infections caused by Gram-positive pathogens

INTRODUCTION

Streptogramins (pristinamycin and quinupristin-dalfopristin) can be interesting options for the treatment of infections due to Gram-positive cocci, especially multidrug-resistant isolates.

AREAS COVERED

This review provides an updated overview of structural and activity characteristics, mechanisms of action and resistance, pharmacokinetic/pharmacodynamic, and clinical use of streptogramins.

EXPERT OPINION

The streptogramin antibiotics act by inhibition of the bacterial protein synthesis. They are composed of two chemically distinct compounds, namely type A and type B streptogramins, which exert a rapid bactericidal activity against a wide range of Gram-positive bacteria (including methicillin-resistant staphylococci and vancomycin-resistant enterococci). Several mechanisms of resistance have been identified in staphylococci and enterococci but the prevalence of streptogramin resistance among clinical isolates remains very low. Even if only a few randomized clinical trials have been conducted, the efficacy of pristinamycin has been largely demonstrated with an extensive use for 50 years in France and some African countries. Despite its effectiveness in the treatment of severe Gram-positive bacterial infections demonstrated in several studies and the low rate of reported resistance, the clinical use of quinupristin-dalfopristin has remained limited, mainly due to its poor tolerance. Altogether, streptogramins (especially pristinamycin) can be considered as potential alternatives for the treatment of Gram-positive infections.

Pharmacokinetics and safety of recently approved drugs used to treat methicillin-resistant Staphylococcus aureus infections in infants, children and adults

Methicillin-resistant Staphylococcus aureus (MRSA) remains a significant cause of morbidity in hospitalized infants. Over the past 15 years, several drugs have been approved for the treatment of S. aureus infections in adults (linezolid, quinupristin/dalfopristin, daptomycin, telavancin, tigecycline and ceftaroline). The use of the majority of these drugs has extended into the treatment of MRSA infections in infants, frequently with minimal safety or dosing information. Only linezolid is approved for use in infants, and pharmacokinetic data in infants are limited to linezolid and daptomycin. Pediatric trials are underway for ceftaroline, telavancin, and daptomycin; however, none of these studies includes infants. Here, we review current pharmacokinetic, safety and efficacy data of these drugs with a specific focus in infants.