Background:

IC50: 0.36 μM for KIX-KID interaction

NSC228155 is a potent inhibitor of KIX-KID interaction.

Cyclic-AMP response-element binding protein (CREB) is identified as a stimulus-activated transcription factor. Its transcription activity needs its binding with CREB-binding protein (CBP) after CREB is phosphorylated at Ser133. The domains involved for CREB-CBP interaction are kinase-inducible domain (KID) from CREB and KID-interacting domain (KIX) from CBP.

In vitro: Previous study found that NSC228155 could dose-dependently inhibit KIX–KID interaction as measured by the split RLuc assay. In living HEK 293T cells, NSC228155 could inhibit CREB-mediated gene transcription with an IC50 of 2.09 μM. NSC228155 also inhibited VP16-CREB-mediated gene transcription with an IC50 of 6.14 μM. Though this was around 3-fold higher than the IC50 of CREB-mediated gene transcription, such results indicated that NSC228155 was not particularly selective in inhibiting KIX–KID interaction inside these living cells. Therefore, although NSC228155 was a potent inhibitor of KIX-KID interaction, it was not selective against CREB-mediated gene transcription, and further SAR studies identified a 4-aniline substituted analog displaying a higher selectivity index [1].

In vivo: So far, there is no animal in vivo data reported.

Clinical trial: Up to now, NSC228155 is still in the preclinical development stage.

Reference:
[1] Xie F, Li BX, Broussard C, Xiao X.  Identification, synthesis and evaluation of substituted benzofurazans as inhibitors of CREB-mediated gene transcription. Bioorg Med Chem Lett. 2013 Oct 1;23(19):5371-5.