Design, synthesis and anti-osteosarcoma activity study of novel pyrido [2,3-d]pyrimidine derivatives by inhibiting DKK1-Wnt/β-catenin pathway

Osteosarcoma is a common primary malignant bone tumor in adolescents. Wnt/beta-catenin has been proved to play a pro-oncogenic role and was overactivated in osteosarcoma. Therefore, this pathway has become an interesting therapeutic target for osteosarcoma. Herein we report the design, synthesis and biological activities of a series of novel pyrido[2,3-d]pyrimidine derivatives based on our previous work. Among these, the representative compound 2-{[1,3-dimethyl-7-(4-methyl-piperazin-1-yl)-2,4-dioxo-1,2,3,4-tetrahydropyrido[2,3-d]pyrimidin-5-yl]amino}-N-[4-(trifluoromethoxy)phenyl]acetamide (7m) has exhibited good anti-proliferative activity towards 143B and MG63 cells with good selectivity over non-cancerous HSF cells. In the assay of Ca2+ concentration, the compound 7m increased the intracellular Ca2+ concentration in 143B cells. In addition, the expression of DKK1 increased, and that of p-beta-catenin decreased by 7m treatment. Finally, the Hoechst 33,342 staining, Annexin-FITC/PI staining and mitochondrial fluorescence staining have clearly demonstrated that compound 7m induced apoptosis in 143B cells.