Description
Hyperthermia is widely used to treat patients with various cancers. 42.5C is well known as the inflection point of hyperthermia and generally up to 42C of hyperthermia is used in clinical cases combined with other therapies. Here, the effects of heat stress at 42 or 44C for 15 min on the gene expression in human lymphoma U937 cells were investigated using an Affymetrix GeneChip system. The cells were treated with heat stress (42 or 44C for 15 min), followed by incubation for 0, 1, 3 or 6 h at 37C. The percentage of DNA fragmentation was 8.4 2.2 (mean SD) at 42C for 6 h and 21.0 2.0 at 44C for 6 h. Of approximately 47,000 probe sets analyzed, many genes that were differentially expressed by a factor 2.0 or greater were identified in the cells treated with heat stress at 42 and 44C.