Shikonin induces apoptosis and G0/G1 phase arrest of gallbladder cancer cells via the JNK signaling pathway

Shikonin, a natural product isolated from the roots of Lithospermum erythrorhizon, is considered to have antitumor effects. Gallbladder cancer (GBC) is a prevalent biliary tract malignancy with few curative therapeutic stragegies and poor prognosis. In the present study, we detected the effects of shikonin on GBC cells as well as the underlying molecular mechanisms. The results demonstrated that GBC cell proliferation was inhibited by shikonin as determined by MTT and colony formation assays. Flow cytometry results demonstrated that shikonin treatment enhanced apoptosis and promoted G0/G1 phase arrest in the GBC cells. Western blot assay showed that shikonin induced mitochondrial-dependent apoptosis via the JNK signaling pathway. Moreover, shikonin suppressed tumor growth in mice bearing GBC-derived xenografts in a dose-dependent manner without side-effects. These results revealed that shikonin exhibits anticancer effects on GBC cells by inducing apoptosis and regulating the cell cycle. Taken together, shikonin may be a novel and safe chemotherapeutic agent for the treatment of GBC.