Characterization of the attenuation of breast cancer bone metastasis in mice by zoledronic acid using (99m)Tc bone scintigraphy.

Metastatic breast cancer often metastasizes to bone. The purposes of the study were (1) to evaluate the use of (99m)Tc-MDP bone scintigraphy for detection of metastatic bone lesions, and (2) to determine the efficacy of zoledronic acid in mice with breast cancer bone metastasis. All tumor-bearing mice were analyzed with radionuclide bone scintigraphy, X-ray, and histological analysis. The metastatic bone tissue was also harvested and analyzed by western blotting and real-time qPCR. Interestingly, zoledronic acid significantly decreased both the tumor burden and the incidence of bone metastasis in mice. In addition, histomorphometric, stereological, and molecular biology analyses demonstrated that zoledronic acid may function to inhibit breast cancer cell growth in the bone microenvironment and regulate the function of osteoblasts and osteoclasts in tumor-bearing mice. Finally, the attenuation of breast cancer bone metastasis using zoledronic acid can be accurately characterized by (99m)Tc bone scintigraphy in mice.