SH5-07 is a hydroxamic acid-based Stat3 inhibitor (IC50: 3.9 μM).

STAT3:3.9 μM (cell free)

SH5-07, a hydroxamic acid analog of BP-1-102, selectively inhibits Stat3 activity in a dose-dependent manner (IC50: 3.9±0.6 μM in vitro), specifically targeting Stat3:Stat3 DNA-binding over Stat1:Stat3, with minimal impact on Stat1:Stat1. By binding to Stat3, it disrupts its interaction with growth factor receptors, thus inhibiting Stat3 phosphorylation. This inhibition leads to reduced expression of Stat3-regulated genes, including Bcl-xL, Bcl-2, c-Myc, Survivin, Cyclin D1, and Mcl-1, following a 24-hour exposure to 5 μM SH5-07, ultimately exerting antitumor effects against cells with constitutively active Stat3.

Tail vein injection or oral gavage delivery of SH5-07 inhibits the growth of 90-150 mm^3 established subcutaneous mouse xenografts of human glioma (U251MG) and breast (MDA-MB-231) tumors with aberrantly-active Stat3, associated with decreased Mcl-1, c-Myc, and Cyclin D1 expression. No significant changes in body weights, blood cell counts, organ gross anatomy, or signs of toxicity are observed.

Cells are treated with 0-8 μM agent for 24-48 h. For cell cycle profile analysis, cells are harvested and fixed with 70% ice-cold ethanol and stained with propidium iodide (PI). For apoptosis analysis, cells are collected and stained with FITC-Annexin V using the Apoptosis Detection Kit. Both the DNA content of cells and the Annexin V-positive cells are analyzed by the flow cytometer. Cell cycle phase distribution is analyzed using the Cell-Fit program. Data acquisition is gated to exclude cell doublets.

Mice are injected subcutaneously in the left flank area with U251MG cells in 200 μL of PBS/Matrigel matrix, or MDA-MB-231 cells in 100 μL of PBS. Mice with tumors of 90-150 mm^3 (MDA-MB-231) or 150 mm^3 (U251MG) are grouped for identical mean tumor sizes, administered 3, 5 or 6 mg/kg SH5-07 via oral gavage daily or tail vein injection every 2 or 3 days, and monitored every 3-7 days. Tumor sizes are measured with calipers and converted to tumor volume.