Nicaraven reduces cancer metastasis to irradiated lungs by decreasing CCL8 and macrophage recruitment

Radiotherapy for cancer patients damages normal tissues, thereby inducing an inflammatory response and promoting cancer metastasis. We investigated whether nicaraven, a compound with radioprotective and anti-inflammatory properties, could attenuate radiation-induced cancer metastasis to the lungs of mice. Nicaraven and amifostine, another commercial radioprotective agent, had limited effects on both the radiosensitivity of Lewis lung carcinoma cells in vitro and radiation-induced tumor growth inhibition in vivo. Using experimental and spontaneous metastasis models, we confirmed that thorax irradiation with 5 Gy X-rays dramatically increased the number of tumors in the lungs. Interestingly, the number of tumors in the lungs was significantly reduced by administering nicaraven but not by administering amifostine daily after radiation exposure. Furthermore, nicaraven administration effectively inhibited CCL8 expression and macrophage recruitment in the lungs 1 day after thorax irradiation. Our data suggest that nicaraven attenuates radiation-induced lung metastasis, likely by regulating the inflammatory response after radiation exposure.