Design, synthesis and pharmacological evaluation of novel 2-chloro-3-(1H-benzo[d]imidazol-2-yl)quinoline derivatives as antitumor agents: in vitro and in vivo antitumor activity, cell cycle arrest and apoptotic response

A series of novel 2-chloro-3-(1H-benzo[d]imidazol-2-yl)quinoline derivatives (3a(1)−3d(6)) were designed and synthesized as antitumor agents. In vitro antitumor assay results showed that some compounds exhibited moderate to high inhibitory activities against HepG2, SK-OV-3, NCI-H460 and BEL-7404 tumor cell lines, and most compounds exhibited much lower cytotoxicities against HL-7702 normal cell line compared to 5-FU and cisplatin. In vivo antitumor assay results showed that the representative compound 3a(1) exhibited effective inhibition on tumor growth in the HepG2 xenograft mouse model. Mechanistic studies suggested that 3a(1) may exert antitumor activity by the up-regulation of Bax, intracellular Ca(2+) release, ROS generation, p21, p27 and p53, downregulation of Bcl-2, activation of caspase-9 and caspase-3 and subsequent cleavage of PARP, and inhibition of CDK activity.