Background:

1A-116 is a specific Rac1 inhibitor.

1A-116 shows lesser effect on MCF7::pcDNA.3 cells than on MCF7::C1199 cells. 1A-116 treatment decreases phospho-PAK1 levels in a time-dependent manner. The presence of 1A-116 reverts the PAK1 phosphorylation induced by 4-hydroxytamoxifen (Tam). The presence of 1A-116 also effectively reverts Rac1-PAK1-mediated estrogen receptor (ER) phosphorylation at Ser305[1]. 1A-116 shows a significant increase in antiproliferative activity on F3II cells, showing an IC50 value of 4 µM. A-116 also dramatically impairs Rac1 activation at low micromolar range (1 µM)[2].

Daily treatment of mice with compound 1A-116 at 3mg/kg body weight/day reduces about 60% the formation of total metastatic lung colonies. A significant antitumor activity is obtained for macronodules (more than 1 mm in diameter) by treatment with 1A-116 in this highly aggressive breast cancer model. The treatment with 1A-116 reduces the total lung weight compare to the control group, leading to a total weight similar to the average pulmonary weight of Balb/c mice[2].

[1]. Gonzalez N, et al. Pharmacological inhibition of Rac1-PAK1 axis restores tamoxifen sensitivity in human resistant breast cancer cells. Cell Signal. 2017 Jan;30:154-161. [2]. Cardama GA, et al. Preclinical development of novel Rac1-GEF signaling inhibitors using a rational design approach in highly aggressive breast cancer cell lines. Anticancer Agents Med Chem. 2014;14(6):840-51.