Ultrasound and contrast agents enhance VEGF siRNA-mediated anti-cancer effect on human nasopharyngeal carcinoma / 中华超声影像学杂志

ABSTRACT

Objective To study the enhancing effect of ultrasound plus microbubble on small interference RNA(siRNA)transfection in vitro and in vivo.Methods Human vascular epithelial growth factor(VEGF)siRNA with 2'deoxy modification(VEGF 2'-eoxy siRNA,VdsR)was used.The human CNE cells(fromnasopharyngeal carcinoma)line was used for in vitro cell-based experiments and in vivo mouse xenograft model.Two different microbubble agents.BR14 and Levovist.were used together with the RNA transfection reagent RNA-mate.ELISA and RT-PCR assays were used to assess VEGF gene expression.Immunohistochemical staining (IHC)was performed to assess CD31 expression in xenograft tumors.Results VdsR transfection in CNE cells abolished VEGF expression as determined by ELISA experiments.In the first mouse xenograft experiment,ultrasound exposure dramatically enhanced VdsR-mediated tumor inhibition.In the second mouse xenograft experiment,when VdsR was mixed with the microbubble reagents and then injected into xenografts,ultrasoundexposure significantly reduced tumor growth in BR14-mixed VdsR group but not in the Levovist-mixed VdsR group compared to the control.RT-PCR experiments demonstrated that VEGF expression in ultrasound-exposed tumors was significantly lower than that in the control.Meanwhile,VEGF expression in the tumor tissue treated by BRl4-mixed VdsR declined as compared with the controls.Tumor vascular density as measured by CD31 immunostaining was significantly decreased in ultrasound-exposed tumors compared to the control.Conclusions Ultrasound exposure and/or microbubble can significantly enhance delivery and the efficiency of VdsR-mediated anti-tumor effects,and should be a location-specific enhancement approach for siRNA-based anti-cancer therapy.