A new homogeneous high-throughput screening assay for profiling compound activity on the human ether-a-go-go-related gene channel.
Long QT syndrome, either inherited or acquired from drug treatments, can result in ventricular arrhythmia (torsade de pointes) and sudden death. Human ether-a-go-go-related gene (hERG) channel inhibition by drugs is now recognized as a common reason for the acquired form of long QT syndrome. It has been reported that more than 100 known drugs inhibit the activity of the hERG channel. Since 1997, several drugs have been withdrawn from the market due to the long QT syndrome caused by hERG inhibition. Food and Drug Administration regulations now require safety data on hERG channels for investigative new drug (IND) applications. The assessment of compound activity on the hERG channel has now become an important part of the safety evaluation in the process of drug discovery. During the past decade, several in vitro assay methods have been developed and significant resources have been used to characterize hERG channel activities. However, evaluation of compound activities on hERG have not been performed for large compound collections due to technical difficulty, lack of throughput, and/or lack of biological relevance to function. Here we report a modified form of the FluxOR thallium flux assay, capable of measuring hERG activity in a homogeneous 1536-well plate format. To validate the assay, we screened a 7-point dilution series of the LOPAC 1280 library collection and reported rank order potencies of ten common hERG inhibitors. A correlation was also observed for the hERG channel activities of 10 known hERG inhibitors determined in this thallium flux assay and in the patch clamp experiment. Our findings indicate that this thallium flux assay can be used as an alternative method to profile large-volume compound libraries for compound activity on the hERG channel.
Titus
Steven A
SA
NIH Chemical Genomics Center, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA.
Beacham
Daniel
D
Shahane
Sampada A
SA
Southall
Noel
N
Xia
Menghang
M
Huang
Ruili
R
Hooten
Elizabeth
E
Zhao
Yong
Y
Shou
Louie
L
Austin
Christopher P
CP
Zheng
Wei
W
D000818:Animals; D002452:Cell Count; D002460:Cell Line; D004396:Coloring Agents / Q000378:metabolism; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D004353:Drug Evaluation, Preclinical / Q000379:methods*; D051638:Ether-A-Go-Go Potassium Channels / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D005110:Extracellular Space / Q000378:metabolism; D006801:Humans; D018408:Patch-Clamp Techniques; D026902:Potassium Channel Blockers / Q000494:pharmacology*; D015203:Reproducibility of Results; D013793:Thallium / Q000378:metabolism
D004396:Coloring Agents; D051638:Ether-A-Go-Go Potassium Channels; D026902:Potassium Channel Blockers; D013793:Thallium; D004121:Dimethyl Sulfoxide