Stattic, the first nonpeptidic small molecule, potently inhibitsSTAT3activation and nuclear translocation withIC50of 5.1 μM in cell-free assays, highly selectivity over STAT1. Stattic inducesapoptosis. In vitro
Stattic inhibits binding of a phosphotyrosine-containing peptide derived from the gp130 receptor to the STAT3 SH2 domain in a strongly temperature-dependent manner. Stattic only has a very weak effect on binding of a tyrosinephosphorylated peptide to the SH2-domain of the tyrosine kinase Lck. And it doesn’t inhibit dimerization of two other dimeric transcription factors (c-Myc/Max and Jun/Jun). It also inhibits fluorescein-labeled phosphopeptides to the SH2 domains of STAT1 and STAT5b. Stattic selectively inhibits DNA binding of STAT3 homodimers at a concentration of 10 μM. Shown to inhibit cellular phosphorylation of STAT3 at Tyr705 with little effect towards STAT1 phosphorylation at Tyr701 (in HepG2 cells) or the phosphorylation of JAK1, JAK2, and c-Src (in MDA-MB-231 and MDA-MB-235S cells). Stattic increases the apoptotic rate of STAT3-dependent breast cancer cell lines.
