Journal: The Journal of Biological Chemistry
Article Title: Inhibition of the Na + /K + -ATPase by cardiac glycosides suppresses expression of the IDO1 immune checkpoint in cancer cells by reducing STAT1 activation
doi: 10.1016/j.jbc.2022.101707
Figure Lengend Snippet: ATP1A1 knockdown and cardiac glycoside treatment result in synergistic inhibition of IDO1 expression and activity in MDA-MB-231 cells. A , SBFI intracellular Na + measurements in NTC versus ATP1A1 siRNA transfected cells, n = 3. ∗ p < 0.05, unpaired, two-tailed t test. Inset , representative Western blot of ATP1A1 and GAPDH protein expression in samples transfected with NTC or ATP1A1 siRNA. B , kynurenine assay of untransfected, NTC siRNA, or ATP1A1 siRNA-transfected TNF/IFN-ɣ (24 h) stimulated MDA-MB-231 cells treated with 0.05% DMSO or increasing concentrations of ouabain (50, 100, 200 nM), n = 3. Inset , normalized viability (inhibitor/DMSO control) versus normalized IDO activity (inhibitor/DMSO control) from each of three wells of one kynurenine assay. C , kynurenine assay of untransfected, NTC siRNA, or ATP1A1 siRNA transfected TNF/IFN-ɣ (24 h) stimulated MDA-MB-231 cells treated with 0.05% DMSO or increasing concentrations of digoxin (75, 150, 300 nM), n = 3. Inset , normalized viability (inhibitor/DMSO control) versus normalized IDO activity (inhibitor/DMSO control) from each of three wells of one kynurenine assay. D , representative Western blot of ATP1A1, PD-L1, IDO1, and GAPDH protein expression for experiments in ( B ). The same samples were run and blotted simultaneously on two separate membranes. GAPDH loading control for each blot is noted. E , representative Western blot of ATP1A1, PD-L1, IDO1, and GAPDH protein expression for experiments in ( C ). The same samples were run and blotted simultaneously on two separate membranes. GAPDH loading control for each blot is noted. F , IDO1 mRNA expression for NTC or ATP1A1 siRNA transfected, TNF/IFN-ɣ (24 h) stimulated MDA-MB-231 cells treated with increasing concentrations of ouabain, n = 3. G , IDO1 mRNA expression for NTC or ATP1A1 siRNA transfected, TNF/IFN-ɣ (24 h) stimulated MDA-MB-231 cells treated with increasing concentrations of digoxin, n = 3. IDO1, indoleamine-pyrrole 2′,3′-dioxygenase 1; SBFI, sodium-binding benzofuran isophthalate.
Article Snippet: A pCMV3-C-Flag-IDO1 (NM_002164.4) (SinoBiological, HG11650-CF) and a pCMV3-C-Flag empty vector (CV012) were purchased from SinoBiological.
Techniques: Inhibition, Expressing, Activity Assay, Transfection, Two Tailed Test, Western Blot, Binding Assay