Erasin is a STAT3 inhibitor (IC50 = 9.7 μM) with higher selectivity for inhibiting STAT3 tyrosine phosphorylation than STAT5 and STAT1. It induces apoptosis in various cancer cell lines (e.g., MDA-MB-231, HCC-827) and is effective against Erlotinib-resistant cancer cells.

STAT1:24 μM, STAT3:9.7 μM

Method:
HepG2 and K562 cells were treated with Erasin at concentrations of 0, 5, 10, 25, 50, and 100 μM for 24 hours, with a pre-incubation period of 1–2 hours. Following treatment, cells were stimulated with IL-6 (to activate STAT3) or IFN-γ (to activate STAT1), and tyrosine phosphorylation levels of STAT proteins were assessed.

Result:
Erasin inhibited IL-6-induced phosphorylation of STAT3 at Tyr705 in HepG2 cells in a dose-dependent manner. It also inhibited IFN-γ-induced phosphorylation of STAT1 at Tyr701 to a lesser extent. Tyrosine phosphorylation of STAT5 in K562 cells was not inhibited.[1]