Cell experiment:

Cells are plated into 96-well plates and the cells are allowed to attach to the bottom of the plates overnight. Then the cells are treated with different concentrations of different drugs (666-15) for 72 h. The media are removed, and MTT reagent in complete tissue culture media is added to each well and incubated at 37 ℃ for 3 h. The incubation media are removed and 100 μL of DMSO is added to each well. The absorbance of the formed purple formazan solution is read at 570 nm using a plate reader[1].

Animal experiment:

Mice: 666-15 is dissolved in 1% N-methylpyrrolidone (NMP), 5% Tween-80 in water. Each 6- to 8-week old BALB/c nude mouse is inoculated subcutaneously at the right flank with MDA-MB-468 cells. Mice are treated with either vehicle or 666-15 at 10 mg/kg. The mice are treated once a day for 5 consecutive days a week, and the treatment lasted for 5 weeks[1].

• Exp Neurol (2022): 114230. PMID:36162511

666-15 is a potent and selective CREB inhibitor with an IC50 of 81 nM.

666-15 potently inhibits cancer cell growth. In MDA-MB-231 and MDA-MB-468 cells, the GI50 for 666-15 is 73 and 46 nM, respectively. In A549 and MCF-7 cells, it exhibits robust activity as well with GI50 of 0.47 and 0.31 μM. 666-15 is also found to be a rather weak inhibitor of CREB-CBP interaction with IC50 of 18.27 μM. 666-15 inhibits CREB's transcription activity in living cells independent of direct CREB or CBP binding interaction. 666-15 is very potent in inhibiting CREB's transcription activity. 666-15 also inhibits endogenous CREB target gene expression, the transcript level of nuclear receptor related 1 protein (Nurr1/NR4A2)[1].

Preliminary toxicity studies show that intraperitoneal (ip) injection of 10 mg/kg of 666-15 is well tolerated in mice. The tumor growth in the mice treated with 666-15 is efficaciously inhibited with complete tumor stasis. During the same period, the tumor volume in the vehicle-treated group is more than tripled. The body weights of 666-15-treated animals and vehicle-treated ones are indistinguishable from each other during the entire treatment period[1].

[1]. Xie F, et al. Identification of a Potent Inhibitor of CREB-Mediated Gene Transcription with Efficacious in Vivo Anticancer Activity. J Med Chem. 2015 Jun 25;58(12):5075-87.