Ochromycinone (STA 21) is a selective STAT3 inhibitor.

In cells, STA-21 inhibits Stat3 DNA binding activity, Stat3 dimerization, and Stat3-dependent luciferase activity. STA-21 remarkably inhibits the growth and the survival of the breast carcinoma cells MDA-MB-231, MDA-MB-435s, and MDA-MB-468 that express persistently activated Stat3. [1] In RH30 and RD2 cells, STA-21 also inhibits cell viability and growth and induced apoptosis through caspases 3, 8 and 9 pathways. [2]

In IL-1Ra–KO mice, STA-21 (0.5 mg/kg, i.p.) reduces the arthritis score and the incidence of arthritis by decreasing the proportion of Th17 cells and increasing the proportion of Treg cells expressing FoxP3. [3]

Human breast cancer cell lines MDA-MB-231, MDA-MB-435s, MDA-MB-453, MDA-MB-468, and MCF7, human ovarian carcinoma cell line Caov-3, and human skin fibroblasts were cultured in DMEM containing 10% FBS and appropriate antibiotics in a 5% CO2 incubator at 37°C. For testing different compounds, the cells were exposed to the compounds for 48 h at a final concentration of 20 or 30 μM, respectively. Then, the cells were harvested and subjected to flow-cytometry analysis.(Only for Reference)