Ultrasound-stimulated microbubbles enhances radiosensitivity in cervical cancer

Background Ultrasound-stimulated microbubble (USMB) therapy has proven efficacy of targeting tumor vasculature and enhancing the effect of radiation in tumor xenografts. In this investigation, we studied whether this treatment enhances the sensitivity of cervical cancer to radiation.Methods Human cervical cancer (ME-180 and SiHa) cells were treated with USMB or exposed to radiation (0, 2, 4, 6 and 8 Gy) or radiation (8 Gy) in combination with USMB. Clone formation assay and CCK-8 assay were used to analyze the proliferation capacity of cells. Apoptosis and DNA double-strand breaks were detected using flow cytometry and immunofluorescence staining of gamma-H2AX (γ-H2AX), respectively. Matrigel tubule formation was performed to evaluate the angiogenesis of human umbilical vein endothelial cells. In xenograft model of SiHa cells, tumor tissue expression of CD31 was detected by immunohistochemistry.Results USMB and radiation synergistically restrained the growth of ME-180 and SiHa cells. USMB promoted radiation-induced apoptosis by enhancing the levels of proapoptotic proteins. Furthermore, USMB enhanced radiation-induced γ-H2AX foci to induce DNA double-strand breaks in cervical cancer cells. USMB in combination with radiation reduced the angiogenic capacity of endothelial cells in vitro. Moreover, USMB strengthened the inhibitory effect of radiation on tumor growth and angiogenesis in xenograft models.Conclusion In conclusion, USMB exposure effectively enhanced the destructive effect of radiation on cervical cancer, suggesting that USMB might be a promising sensitizer of radiotherapy to treat cervical cancer.