POM-1 is a Non-Specific ATPase Inhibitor that Competitively Inhibits Luciferase

Introduction/Methods: Sodium polyoxotungstate (POM-1) is often either a drug of interest or suggested as a potential exonuclease ATPase inhibitor to aid ATP measurements using assays, and genetically encoded reporters. POM-1 is also currently being clinically investigated as a cancer therapy due to its inhibition of NTPDases 1, 2, 3 which hydrolyze ATP and its related purines. There are concerns that POM-1 may non-specifically affect kinases, phosphatases and ATPases which presents a significant source of error when using ATP assays, reporters, and investigating the efficacy and safety of POM-1 as a therapeutic. We hypothesized that POM-1 would provide an inexpensive ecto-ATPase inhibitor to replace ARL67156 in the measurement of ATP by luciferase assay. Results: While POM-1 was significantly less expensive ($0.07/experiment) than ARL67156 ($68/experiment), POM-1 competitively inhibits luciferase (oxidoreductase) activity. The addition of POM-1 significantly reduced firefly luciferase activity (luminescence) in a dose-dependent manner, and increasing ATP concentrations recovered enzyme activity. POM-1 half-maximal inhibitory concentration (IC 50 ) for luciferase ranged from 1.3 µM in the presence of 10 nM ATP, to 36.3 µM in the presence of 100 µM ATP. Conclusions: Reports of POM-1 Ki range from 0.8 μM to 2.58 μM for NTPDase 1, 3.29 μM to 28.8 μM NTPDase 2, and 663 nM to 3.26 μM for NTPDase 3. Our tested ranges of POM-1 IC 50 supports growing concerns on POM-1’s non-specific actions, and should be noted when investigating its use as a therapeutic. These non-specific effects may also prevent its use with current measurement and diagnostic tools that investigate ATP release. This work was supported by grant RGPIN-2019-04925 from the Natural Sciences and Engineering Research Council (NSERC) of Canada. This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.