Synthesis and preliminary structure-activity relationship study of 2-aryl-2H-pyrazolo[4,3-c]quinolin-3-ones as potential checkpoint kinase 1 (Chk1) inhibitors

Design, synthesis and evaluation of novel thienopyridazine derivatives as Chk1/2 inhibitors

In order to search for novel checkpoint kinase 1/2 (Chk1) inhibitors, we have designed and synthesized a series of new compounds incorporating thienopyridazine core. Bioevaluation showed that compounds 10j, 10i, 13e and 10o exhibited relatively good inhibitory activity. Notably, compound 10o displayed high selectivity against a panel of kinases and inhibited Chk1/2 signaling pathway stimulated by DNA damage drugs in cellular level. Molecular docking of 10o to the ATP-binding site of Chk1 kinase domain indicated the existence of polar interactions between 10o and the ATP-ribose-binding residues of Chk1. In mouse HT-29 xenografts, a synergistic effect was observed. Co-treatment by CPT-11 and 10o significantly diminished the tumor volume, indicating the great potential of 10o as a candidate of Chk1/2 inhibitor.

CHK1 monitors spindle assembly checkpoint and DNA damage repair during the first cleavage of mouse early embryos

OBJECTIVES

DNA damage and errors of accurate chromosome segregation lead to aneuploidy and foetal defects. DNA repair and the spindle assembly checkpoint (SAC) are the mechanisms developed to protect from these defects. Checkpoint kinase 1 (CHK1) is reported to be an important DNA damage response protein in multiple models, but its functions remain unclear in early mouse embryos.

MATERIALS AND METHODS

Immunofluorescence staining, immunoblotting and real-time reverse transcription polymerase chain reaction were used to perform the analyses. Reactive oxygen species levels and Annexin-V were also detected.

RESULTS

Loss of CHK1 activity accelerated progress of the cell cycle at the first cleavage; however, it disturbed the development of early embryos to the morula/blastocyst stages. Further analysis indicated that CHK1 participated in spindle assembly and chromosome alignment, possibly due to its regulation of kinetochore-microtubule attachment and recruitment of BubR1 and p-Aurora B to the kinetochores, indicating its role in SAC activity. Loss of CHK1 activity led to embryonic DNA damage and oxidative stress, which further induced early apoptosis and autophagy, indicating that CHK1 is responsible for interphase DNA damage repair.

CONCLUSIONS

Our results indicate that CHK1 is a key regulator of the SAC and DNA damage repair during early embryonic development in mice.

Selected arylsulphonyl pyrazole derivatives as potential Chk1 kinase ligands-computational investigations

Protein kinases control diversity of biochemical processes in human organism. Checkpoint 1 kinase (Chk1) is an important element of the checkpoint signalling pathways and is responsible for DNA damage repair. Hence, this kinase plays an essential role in cancer cells survival and has become an important target for anticancer agents. Our previous investigations showed that some arylsulphonyl indazole derivatives displayed anticancer effect in vitro. In the present study, in order to verify possibility of interactions of pyrazole and indazole derivatives with Chk1, we focused on the docking of selected tosyl derivatives of indazole and condensed pyrazole 1-7 to the Chk1 pocket, analysis of interactions involving optimized ligand-protein system using DFT formalism, and estimation of the interaction enthalpy of the ligand-protein complex by applying the PM7 method. The estimation of binding affinity seems to indicate that the indazole 5-substituted with 3,5-dimethylpyrazole 4 and condensed pyrazoloquinoline derivative 7 fit the best to the Chk1-binding pocket. The values of the energy of interaction, i.e. the enthalpy change (ΔHint), were between - 85.06 and - 124.04 kcal mol-1 for the optimized ligand-Chk1 complexes. The relaxation of the ligands within the complexes azole-protein as well as the distribution of hydrogen contacts between the ligands and kinase pocket amino acids was also analysed using molecular dynamics as a supporting method. Graphical Abstract Presentation of methods used to describe the interactions between arylsulphonyl pyrazole derivatives and Chk1 kinase.