Synthesis, Biological Evaluation And 3D-QSAR Study Of Novel 4,5-dihydro-1H-pyrazole Thiazole Derivatives As BRAF^V600E Inhibitors

The MAPK protein kinase exert its important action in the transduction of signals for cell, which regulates cell growth, proliferation, differentiation and apoptosis, in response to external stimuli such as growth factors. Phosphorylation of RAF stimulates its serine/threonine activity, activating the downstream MEK and ERK successively. ERK phosphorylates several transcription factors like ELK-1 down to control gene expression, and metabolism, cause cell transformation and contribute to tumor initiation and maintenance. Therefore, inhibition of BRAF for regulating cell signal transduction becomes important in many current human cancer therapeutics approaches.Pyrazole and its derivatives attracts more and more attention over the past decades because of their wide range of pharmacological activities, mainly reflected in antitumor, antibacterial and fungistatic, etc. SB-590885 has the hottest spots, containing the pyrazolyl ring, which inhibits BRAFV600E with a Ki of 0.16 nmol/L.In consequence, the compounds encompassing pyrazole ring as antineoplastic leads is a reasonable attempt for potential inhibitors of BRAFV600E Based on the studies generalized, thiophene and thiazole group manifest a wide range of pharmaceutical of antibacterial, anti-inflammatory and antiviral property when exposed to the native compounds.With the development of scientific research, more reports reveal anticancer activities of the compounds containing thiophene and thiazole group, which inhibits BRAF kinase activity. It uses a common scaffold that comprises a terminal aromatic group (phenyl or pyrazole) that fills the allosteric pocket. The relevant compounds were created by the displacement of the DFG loop and an amide linker which couples an aryl group in the hydrophobic pocket to a hinge-binding heterocycle. Linkage via an amide bond would allow for rapid and efficient screening of several potential hinge-binding groups. As a consequence, the combined substructures (thiophene and thiazole group) without wrecking their original effective characteristics, might exhibit synergistic effects to improve anticancer activities.To explore original therapeutic opportunities, we were designed and synthesized a series of novel 4,5-dihydro-1H-pyrazole derivatives (6a-10d),which contain thiazole and thiophene moiety as potential V600E mutant BRAF kinase (BRAFV600E) inhibitors All the compounds were evaluated in vitro for anticancer activities against WM266.4 (human melanoma cell line) and MCF-7(breast cance cell line). Compound 10d displayed the most potential antiproliferative activity with an IC50 value of 0.12μM against cell line WM266.4 and 0.16/μM against MCF-7 with positive control Sorafenib. Results of the inhibitory activity against BRAFV600E revealed that compound 10d was bearing the best bioactivity with IC50 of 0.05μM as well. On the basis of the result of flow cytometry, with the dose of compound 10d increasing, more and more cancer cell gradually encountered apoptosis or died, which indicated the compound 10d could induce remarkable apoptosis of MCF-7 and WM266.4 cells in a dose dependent manner. Based on the active data, QSAR model was built to examine the interaction of all the compounds with SB-590885 (2FB8.pdb), and to guide the further study.