Design, synthesis and anti leukemia cells proliferation activities of pyrimidylaminoquinoline derivatives as DOT1L inhibitors.

A series of novel pyrimidylaminoquinoline derivatives 8(a-i) and 9(a-i) containing amino side chain, and the bisaminoquinoline analogs 3(b-e) have been designed and synthesized by structural modifications on a lead DOT1L inhibitor, 3a. All the compounds have been evaluated for their DOT1L inhibitory activities. The results showed that most of the compounds have strong anti DOT1L activities. Compounds 3e, 8h and 9e are the most potential ones from each category with the IC values of 1.06 ± 0.35 μM, 5.72 ± 1.56 μM and 3.55 ± 1.28 μM, respectively. Such inhibitors expressed significant binding interactions with DOT1L by surface plasmon resonance (SPR)-based binding assay. The results of molecular docking experiments suggested that they could occupy the SAM binding pocket of DOT1L. Compounds 8h and 9e exhibited better inhibitory activities but poor selectivities against the both MLL-rearranged MV4-11 cells and the non MLL-rearranged Kasumi-1 cells than those of 3a and 3e, which suggested that the introduction of the amino side chain would be beneficial for their anti leukemia cells proliferation activities, possibly due to the improvement of the fat solubility. Additionally, the direct cellular inhibition activities were found that compound 9e could effectively down-regulate both the level of H3k79 methylation and MLL-rearranged leukemia gene expression of Hoxa9 and Meis1 in MV4-11 in the qRT-PCR and western blot studies. These observations suggested DOT1L was one of the potential targets but perhaps not the most pivotal one for these compounds, which made their poor selectivities against leukemia cells proliferation.