Effect of ultrasound sonication on clonogenic survival and mitochondria of ovarian cancer cells in the presence of methylene blue.

ABSTRACT

OBJECTIVES: This study aimed to investigate the effect of ultrasound sonication in the presence of methylene blue on clonogenic survival and mitochondria of ovarian cancer cells. METHODS: Human ovarian cancer HO-8910 cells, which were incubated with different concentrations of methylene blue for 1 hour, were exposed to an ultrasonic wave for 5 seconds with intensity of 0.46 W/cm(2). Clonogenic survival of HO-8910 cells after ultrasound sonication was measured by a colony-forming unit assay. Mitochondrial structural changes were observed on transmission electron microscopy, and the mitochondrial membrane potential was evaluated by confocal laser-scanning microscopy with rhodamine 123 staining. RESULTS: The colony-forming units of HO-8910 cells decreased considerably after ultrasound sonication in the presence of methylene blue. Transmission electron microscopy showed slightly enlarged mitochondria in the ultrasound-treated cells in the absence of methylene blue; however, seriously damaged mitochondria, even with almost complete disappearance of cristae, were found in the cells treated by ultrasound sonication in the presence of methylene blue. The mitochondrial membrane potential collapsed significantly when HO-8910 cells were treated by ultrasound sonication in the presence of methylene blue (P < .05). CONCLUSIONS: Ultrasound sonication in the presence of methylene blue markedly damaged mitochondrial structure and function and decreased clonogenic survival of HO-8910 cells.