It is well established that both hematoporphyrin monomethyl ether-sonodynamic therapy (HMME-SDT) and doxorubicin (DOX) can induce cell apoptosis but each alone has its own limitations. To date, the combined effects of HMME-SDT and DOX on inducing cell apoptosis are little known and the mechanism for the combined effects remains poorly understood. In the present study, we reported the synergistic effects of HMME-SDT and DOX on inhibiting the proliferation of human cholangiocarcinoma QBC939 cells and investigated the mechanism of this synergy. The data from MTT assay, flow cytometer, Hoechst staining and cell arrest analysis showed that the combination of HMME-SDT and DOX exhibited higher inhibiting effects on proliferation of QBC939 cells than the sole application of HMME-SDT or DOX. In addition, the synergistic effects were shown to result from the DNA damage as demonstrated by single cell gel electrophoresis and DNA fragmentation. Furthermore, the expression of p53, Fas, Bax and activated caspase-3 protein was significantly upregulated in cells treated with HMME-SDT and DOX, whereas Bcl-2 protein was downregulated. Taken together, our data suggested that the application of HMME-SDT combined with DOX had better inhibiting effects on QBC939 cells and the effects were caused mainly by DNA damage.
Copyright © 2013 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.