To examine the cytotoxic activity of congeners of 3-amino-isoquinoline, we performed the phenotypic screening using panel of 60 cell lines and found that (N-(6,7-dimethoxy-1-methyl-isoquinolin-3-yl)-4-{[(1-ethyl-4-methyl-1H-pyrazol-3-yl)methyl]amino}benzamide (4d)) exhibited the significant effect against different tumor cell lines while showing the high activity toward human colorectal cancer HCT-116 cells (IC50 = 18 μm) and human breast cancer T-47D cells (GI50 = 1.9 μm). Virtual screening indicated that these compounds target protein kinases and phosphodiesterases (PDE). However, wet screening among panel of protein kinases did not show any significant activity. By contrast, 50 μm of 4c and 4d inhibited the growth of HKe3-mtKRAS spheroids in the 3D floating (3DF) culture suggesting that 4c and 4d target PDE4B which is selectively upregulated by mtKRAS in 3DF culture.
Chem Biol Drug Des. 2016 Apr;87(4):575-82. doi: 10.1111/cbdd.12691. Epub 2015 Dec 29.