Dihydroartemisinin (DHA), a semisynthetic derivative of artemisinin, has been shown to exhibit anti-angiogenic and anti-tumor effects apart from its antimalarial activity. In this study, we demonstrate that the combined treatment of cisplatin (CDDP) and DHA exerts a strong, synergistic anti-proliferative effect in human lung carcinoma cells, including A549 and A549/DDP cells, with an average combination index below 0.7. Moreover, the in vivo anti-tumor efficacy of CDDP treatment was increased by DHA. The enhanced anti-cancer activities were also accompanied by reduced tumor microvessel density, increased CDDP concentration within A549 and A549/DDP xenograft BALB/c athymic mice models and suppressed expression of the vascularization-related proteins HIF-1α and VEGF both in vivo and in vitro. Furthermore, the level of apoptosis in the tumor cells increased with the combined treatment of DHA and CDDP. Taken together, our results indicate that a combination of DHA and CDDP treatments synergistically affects tumor angiogenesis, and these results provide a clear rationale for the investigation of these drugs in future clinical trials.
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