Losartan potassium (DuP-753 potassium), an Angiotensin II Receptor Blocker, selectively and competitively inhibits the binding of angiotensin II to the angiotensin I (AT1) receptor.

AT1 receptor:20 nM

Losartan competes with the binding of angiotensin II to AT1 receptors, with an IC50 of 20 nM[1]. At 40 μM, losartan affects ISC and prevents the effect of ANGII on ISC[2]. It significantly reduces Ang II-mediated cell proliferation in endometrial cancer cells, and in combination with anti-miR-155, it exhibits a significantly greater antiproliferative effect compared to each drug alone[3].

An MTT assay is used to measure cell proliferation and viability. For the assay, 5000 cells in 200?μL media per well are seeded in a 96 well plate. After overnight incubation to allow for cell attachment, the medium is removed by suction. MTT at 1?mg/mL concentration in serum-free medium is added and then incubated for 4?h at 37°C. After removal of MTT solution, 100?μL of DMSO is added to dissolve formazan crystals. Absorbance at 570?nm and at 600?nm as a reference is then measured using a microplate reader. The difference in absorbance is thus relative to the extent of cell survival.