Repurposing of Loperamide as a New Drug With Anticancer Activity for Human Osteosarcoma

Background/Aim: Osteosarcoma is an aggressive malignant bone tumor, with unfavorable outcomes in patients with metastatic and recurrent disease. To improve patient survival new treatment options are needed. By using the drug repurposing approach, which takes advantage of already approved drugs with non-oncology primary use, we investigated the activity of loperamide, a peripheral opiate receptor agonist, a drug widely used in clinical practice to treat acute non-specific and chronic diarrhea, on human osteosarcoma. Materials and Methods: Human osteosarcoma cell lines (143B, Saos-2, HOS and MG-63) and multidrug-resistant MG-63DXR30 cells were treated with loperamide. Proliferation and cell viability were determined by viable cell count and acid phosphatase assay. Loperamide activity on cell cycle and apoptosis induction were evaluated by flow cytometry and a luminescence assay testing caspase 3/7 activity, respectively. Results: Loperamide significantly inhibited cell proliferation, through alteration of cell cycle profile at G0/G1 phase and apoptotic death in human osteosarcoma cells. Furthermore, loperamide significantly inhibited the growth of multidrug-resistant osteosarcoma cells. Conclusion: Our findings provide new perspectives for loperamide and its therapeutic repositioning for the treatment of osteosarcoma.