Osteosarcoma (OS) is the most common primary malignant
tumor of bone with a high propensity for lung
metastasis. Despite significant advances in surgical techniques and chemotherapeutic regimens over the past few decades, there has been minimal improvement in OS patient survival. There is an urgent need to identify novel
antitumor agents to treat human OS. Repurposing the clinically-used drugs represents a rapid and effective approach to the development of new
anticancer agents. The
anthelmintic drug niclosamide has recently been identified as a potential
anticancer agent in human
cancers. Here, we investigate if
niclosamide can be developed as an anti-OS
drug. We find that
niclosamide can effectively inhibit OS cell proliferation and survival at low micromolar concentrations. Cell migration and wounding closure are significantly inhibited by
niclosamide.
Niclosamide induces cell apoptosis and inhibits cell cycle progression in OS cells. Analysis of
niclosamide's effect on 11
cancer-related signal pathway reporters reveals that three of them, the E2F1, AP1, and c-Myc-responsive reporters, are significantly inhibited. To a lesser extent, the HIF1α, TCF/LEF, CREB, NFκB, Smad/TGFβ, and Rbpj/Notch pathway reporters are also inhibited, while the NFAT and Wnt/β-
catenin reporters are not significantly affected by
niclosamide treatment. We demonstrate that the expression of c-Fos, c-Jun. E2F1, and c-Myc in OS cells is effectively inhibited by
niclosamide. Furthermore,
niclosamide is shown to effectively inhibit
tumor growth in a mouse xenograft
tumor model of human
osteosarcoma cells. Taken together, these results strongly suggest that
niclosamide may exert its anticancer activity in OS cells by targeting multiple signaling pathways. Future investigations should be directed to exploring the antitumor activity in clinically relevant OS models and ultimately in clinical trials.