Identification of genes responsive to hyperthermia in human leukemia U937 cells

Hyperthermia (41˚C <) is widely used to treat patients with various cancers. Here, the effects of hyperthermia (42˚C for 90 min) on the gene expression in human lymphoma U937 cells were investigated using an Affymetrix GeneChip system. The cells were treated with hyperthermia (42°C for 90 min) and followed by incubation for 0, 1, 3 or 6 h at 37°C. The percentage of DNA fragmentation was 7.5 ± 0.9 (mean ± SD), 10.1 ± 0.2, and 17.3 ± 2.3 at the incubation periods of 1, 3, and 6 h, respectively. Of approximately 47,000 probe sets analyzed, the hyperthermia down-regulated 4,214 probe sets and up-regulated 1,334 by a factor 2.0 or greater. U937 cells, a human lymphoma cell line, were treated with hyperthermia (42°C for 90 min) and followed by incubation for 0, 1, 3 or 6 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.