Cholangiocarcinoma (CCA), the common primary malignant tumor of bile duct epithelial cells, is unresponsive to most chemotherapeutic drugs. Diagnosis with CCA has a poor prognosis, and therefore urgently requires effective therapeutic agents. In the present study we investigated anti-cancer effects of andrographolide analogue 3A.1 (19-tert-butyldiphenylsilyl-8, 17-epoxy andrographolide) and its mechanism in human CCA cell line KKU-M213 derived from a Thai CCA patient. By 24h after exposure, the analogue 3A.1 exhibited a potent cytotoxic effect on KKU-M213 cells with an inhibition concentration 50 (IC50) of approximately 8.0µM. Analogue 3A.1 suppressed DNA topoisomerase II α (Topo II α) protein expression, arrested the cell cycle at sub G0/G1 phase, induced cleavage of DNA repair protein poly (ADP-ribose) polymerases-1 (PARP-1), and enhanced expression of tumor suppressor protein p53 and pro-apoptotic protein Bax. In addition, analogue 3A.1 induced caspase 3 activity and inhibited cyclin D1, CDK6, and COX-2 protein expression. These results suggest that andrographolide analogue 3A.1, a novel topo II inhibitor, has significant potential to be developed as a new anticancer agent for the treatment of CCA.
Keywords: Andrographolide analogue; Apoptosis; Cholangiocarcinoma; KKU-M213 cell line; Topoisomerase II α.
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