Synergistic effect of docetaxel and gambogic acid on bone metastasis of lung cancer

Gambogic acid (GA) as an active compound isolated from Gamboge, have been investigated for many years and proved to be a promising natural anticancer agent for clinical treatment. This study aimed to investigate the inhibitory effect of docetaxel (DTX) combined with gambogic acid on bone metastasis of lung cancer. The anti-proliferation effect of the combination of DTX and GA on Lewis lung cancer (LLC) cells was determined by MTT assays. The anticancer effect of the combination of DTX and GA on bone metastasis of lung cancer in vivo was explored. Evaluation of the efficacy of drug therapy was performed by comparing the degree of bone destruction and the pathological section of bone tissue of the treated mice with that of the control mice. In vitro cytotoxicity, cell migration, and osteoclast-induced formation assay showed that GA enhanced the therapeutic effect of DTX in Lewis lung cancer cell with a synergistic effect. In an orthotopic mouse model of bone metastasis, the average survival of the DTX + GA combination group (32.61d ± 1.06 d) was significantly increased compared with that of the DTX group (25.75 d ± 0.67 d) or GA group (23.99 d ± 0.58 d), *P < 0.01. The combination of DTX and GA has synergistic effect and resulted in more effective inhibition of tumor metastasis, providing a strong preclinical rationale for the clinical development of the DTX + GA combination for treating bone metastasis of lung cancer.