Research Progression in the Mechanism of Bone Metastasis and Bone-Targeted Drugs in Prostate Cancer

Prostate cancer is a particularly slow growing cancer, the early stage of the disease is not easy to detect, the some major clinical manifestations include low back pain, urgent and frequent urination, urinary pain, and other urethral symptoms. These symptoms are often experienced after surgical resection or drug castration treatment. Early-stage, prostate cancer is curable, and with disease progression many clinical symptoms become worse with high probability of metastasis. Bone is the most common site of advanced metastasis of prostate cancer. Bone metastasis is a continuous and complex pathological process regulated by tumor cells and bone microenvironment, in which epithelial-mesenchymal transformation, homing and dormancy, reactivation, and proliferation of tumor cells are closely related to its occurrence and development. Several cytokines such as Receptor activator of NF-κB ligand (RANK-L) is overexpressed in bone microenvironment and prostate cancer. RANKL, chemokine family, and integrins are involved in bone metastasis of prostate cancer through complex interaction mechanisms. A variety of bone-targeting drugs such as bisphosphonates, RANKL inhibitors (denosumab) and radiotherapy drugs (radium-223, strontium-89, samarium-153), tyrosine kinase inhibitors, integrin-targeted drugs, etc. are approved for the prevention and treatment of skeletal related events caused by bone metastasis in prostate cancer patients. In this review, the biological mechanism of bone metastasis in prostate cancer and the research progress of bone-targeting drugs are reviewed.