Naphthol AS-E

Naphthol AS-E is a potent and cell-permeable inhibitor of KIX-KID interaction. Naphthol AS-E directly binds to the KIX domain of CBP (K_d:8.6 μM), blocks the interaction between the KIX domain and the KID domain of CREB with IC₅₀ of 2.26 μM. Naphthol AS-E can be used for cancer research. In Vitro: CREB (cyclic AMP-response element-binding protein) is a downstream transcription factor of a multitude of signaling pathways emanating from receptor tyrosine kinases or G-protein coupled receptors.
CREB can not be activated until it is phosphorylated at Ser133 and its subsequent binding to CREB-binding protein (CBP) through the kinase-inducible domain (KID) in CREB and KID-interacting (KIX) domain in CBP.
In a cell-based CREB Renilla luciferase reporter assay, Naphthol AS-E inhibits CREB-mediated gene transcription with an IC₅₀ of 2.29 μM. In HEK293T-based complementation assay, Naphthol AS-E dose-dependently inhibited Renilla luciferase activity with an IC₅₀ of 2.9 μM by directly binding to CBP's KIX domain (K_d ~8.6 μM using a recombinant KIX).
Naphthol AS-E exhibits low μM activity in inhibiting the proliferation of all these cancer cells, which is consistent with its cellular CREB inhibition potency. The average GI₅₀ values for A549, MCF-7, MDA-MB-231 and MDA-MB-468 are approximately 2.9μM, 2.81μM, 2.35μM and 1.46μM, respectively.
Naphthol AS-E (2.5 μM-10 μM; 48 hours) decreases the expression of anti-apoptotic protein Bcl-2. The expression of VEGF is also decreased.