LAUSR

Abstract Background/Aim: This study evaluated the effect of haematogenous administration of acridine orange (AO) alone and in combination with zoledronate (ZOL) on bone metastases. Materials and Methods: E0771 cells (1.0×105 cells/10 μl) were injected directly into the right femur of female mice. The mice were divided into five groups according to treatment (drugs and irradiation) and were reared and sacrificed after 6 weeks. Micro-computed tomography (μCT) was performed to calculate the destruction rate of the femur bone. We measured tumour weight and volume at sacrifice and performed terminal deoxynucleotidyl transferase dUTP Nick-End Labelling staining of tumours. Results: At 4 weeks, the bone destruction rate was lower in the AO+ZOL group than in the radiation group. At 6 weeks, the AO+ZOL group had a lower bone destruction rate than the control and radiation groups; the ZOL group had a lower rate than the radiation group. The AO and AO+ZOL groups had suppressed tumour weight and volume compared to the control and radiation groups. The number of extraosseous apoptotic cells was higher in the AO+ZOL group than in all other groups except the AO group. Conclusion: In a model of local bone metastasis of breast cancer, haematogenous administration of AO reduced tumour size and more so when combined with ZOL.