Identification of genes responsive to low intensity pulsed ultrasound in a human leukemia cell line Molt-4

We examined the gene expression of human leukemia Molt-4 cells treated with non-thermal low intensity pulsed ultrasound. Six hours after 0.3 W/cm(2) pulsed ultrasound treatment, apoptosis (24 +/- 3.3%, mean +/- SD) with minimal cell lysis was observed. Of approximately 16,600 genes analyzed, BCL2-associated athanogene 3 (BAG3), Dual (Hsp40) homolog, subfamily B, member I (DNAJB1), heat shock 70 kDa protein 113 (HSPA1B), and heat shock 70 kDa protein 6 (HSPA6) showed increased levels of expression while isopentenyl-diphosphate delta isomerase (IDII) and 3-hydroxy-3-methylglutaryl-coenzyme A synthase I (HMGCS1) showed decreased levels in the cells 3 h after the ultrasound treatment. The expression levels of these six genes were confirmed by a real-time quantitative polymerase chain reaction. To our knowledge, this is the first report of DNA microarray analysis of genes that are differentially expressed in response to apoptosis induced by non-thermal low intensity pulsed ultrasound in human leukemia cells. The present results will provide a basis for further understanding of the molecular mechanisms of effects of not only low intensity pulsed ultrasound but also that of mechanical shear stress in the cells. (c) 2006 Elsevier Ireland Ltd. All rights reserved.