ATN-224 (Bis(choline)tetrathiomolybdate) inhibits SOD1 activity in endothelial cells, an effect that is dose dependent with an IC50 of 17.5±3.7 nM. ATN-224 is an oral Cu2+/Zn2+-superoxide dismutase 1 (SOD1) inhibitor.

SOD1 (endothelial cells):17.5±3.7 nM

ATN-224 is an orally-available inorganic small molecule that inhibits the copper/zinc-dependent enzyme, superoxide dismutase 1 (Cu/Zn-SOD1), in endothelial and tumor cells[2] amd it is able to inhibit SOD1 activity in endothelial cells, an effect that is dose dependent with an IC50 of 17.5±3.7 nM. ATN-224 inhibits FGF-2-induced ERK1/2 phosphorylation in a dose-dependent and time-dependent manner with an IC50 between 1.25 and 2.5 μM, consistent with the IC50 for the inhibition of proliferation[1], and it inhibits the proliferation of both HUVEC (IC50=1.4±0.3 μM; n=5) and it is also able to inhibit the activity of purified bovine SOD1 with an IC50 of 0.33±0.03 μM after 24 hours of incubation. ATN-224 has a specific and high affinity for copper ions (108 mol/L-1) and shows no binding to calcium, iron, magnesium, zinc, or manganese ions at concentrations up to 1 mM as determined by isothermal titration calorimetry. The SOD1 inhibition by ATN-224 is time dependent, reaching maximal inhibition at ~16 hours. ATN-224 seems to inhibit SOD1 by depleting the enzyme of copper.

Oral administration of ATN-224 leads to the inhibition of angiogenesis before any measurable reduction in copper levels in either plasma or the Matrigel plug is observed. Moreover, ATN-224 significantly (P<0.05) suppresses angiogenesis in the Matrigel plug model in mice, regardless of whether it is directly added to the plug or administered orally. These findings indicate that ATN-224's anti-angiogenic effects are not dependent on the depletion of copper[1].