STAT3 Inhibitor XX, APT_STAT3-9R

A cell-permeable STAT3 inhibiting peptide that corresponds to the high affinity STAT3-interacting aptide APT_STAT3 (K_D = 231 nM), originally identified by phage peptide library screening, with the addition of 9 arginines at the C-terminus via a GGGGS linker sequence. Reported to inhibit JAK2-catalyzed STAT3 phosphorylation in cell-free kinase assays and suppress cellular STAT3 phosphorylation as well as DNA-binding activity (by 54% post 6 h 30 µM treatment) in human lung carcinoma A549 cultures, resulting in downregulation of cell cycle progression regulator cyclin D1 and reduced expression of anti-apoptic survivin & Bcl-xL, while exhibiting little effect toward cellular phosphorylation levels of STAT1/5 and Akt. Shown to inhibit A549 proliferation (GI₅₀ = 10 to 20 µM in 12 h by MTT assay; complete inhibition by 30 µM in 2-wk colony formation assay) via apoptosis induction (PI⁺/Annexin V⁺ population = 15% vs. 2.8% with or without 6 h 30 µM drug treatment) in vitro and intratumoral injection is efficacious in suppressing the growth of established tumors derived from B16F1 murine melanoma allograft as well as from human U87MG glioblastoma and A549 (8 mg/kg, q.o.d.) xenografts in mice in vivo. Binding study indicates that the majority of APT_STAT3 affinity is mediated via STAT2 SH2 domain interaction and only moderate affinity is detected toward DNA-binding domain (DBD).

A cell-permeable, 26-mer peptide (APT_STAT3) that binds to STAT3 with high affinity (K_d = 231 nM) and blocks its DNA binding activity.

Cell permeable: yes

Primary Target
STAT3

Supplied as a trifluoroacetate salt.

Following reconstitution, aliquot and freeze (-20°C). Stock solutions are stable for up to 6 months at -20°C.

H-His-Gly-Phe-Gln-Trp-Pro-Gly-(Ser-Trp-Thr-Trp-Glu-Asn-Gly-Lys-Trp-Thr-Trp-Lys)-Gly-Ala-Tyr-Gln-Phe-Leu-Lys-Gly-Gly-Gly-Gly-Ser-Arg-Arg-Arg-Arg-Arg-Arg-Arg-Arg-Arg-OH

Kim, D., et al. 2014. Cancer Res.74, 2144.

CALBIOCHEM is a registered trademark of Merck KGaA, Darmstadt, Germany

Toxicity: Standard Handling (A)