Identification of genes responsive to the combination of Sonazoid and ultrasound in human leukemia U937 cells

Echo-contrast agents enhance the echogenicity of ultrasound and have been clinically used for diagonosis in current medical fields. Here, the combined effects of Sonazoid, an echo-contrast agent, and ultrasound on the gene expression in human lymphoma U937 cells were investigated using an Affymetrix GeneChip system. The cells were treated with Sonazoid (0.05%; Sonazoid only), ultrasound (0.3 W/cm2 for 1 min; ultrasound only) and the combination of Sonazoid and ultrasound (0.05% Sonazoid plus ultrasound 0.3 W/cm2 for 1 min; Sonazoid + Ultrasound) and followed by incubation for 3 h at 37°C. The percentage of DNA fragmentation 6 h after treatment was 5.8 ± 1.0 (mean ± SD, n = 3), 6.0 ± 0.4, 13.5 ± 1.0, and 18.3 ± 2.3 in cells treated with control, Sonazoid only, ultrasound only and Sonazoid + Ultrasound, respectively. Of approximately 47,000 probe sets analyzed, probe sets that were differentially expressed by a factor 2.0 or greater were 40, 184 and 144 in cells treated with Sonazoid only, ultrasound only and Sonazoid + Ultrasound, respectively. U937 cells, a human lymphoma cell line, were treated with Sonazoid (0.05%), ultrasound (0.3 W/cm2 for 1 min) and the combination of Sonazoid and ultrasound (0.05% Sonazoid plus ultrasound 0.3 W/cm2 for 1 min) and followed by incubation for 3 h at 37°C. Non-treated cells were served as control. Total RNA samples were prepared from the cells. Gene expression was analyzed by an Affymetrix GeneChip® system with a Human Genome U133-plus 2.0 array for analysis of over 47,000 transcripts. Sample preparation for array hybridization was carried out as described in the manufacturer’s instructions.