title: Gene networks involved in apoptosis induced by hyperthermia in human lymphoma U937 cells.
abstract: To define the molecular mechanisms that mediate hyperthermia-induced apoptosis, we performed microarray and computational gene expression analyses. U937 cells, a human myelomonocytic lymphoma cell line, were treated with hyperthermia at 42 degrees C for 90 min and cultured at 37 degrees C. Apoptotic cells ( approximately 15%) were seen 6 h after hyperthermic treatment, and elevated expression of heat shock proteins (HSPs) including Hsp27, Hsp40, and Hsp70 was detected, following the activation of heat shock factor-1. Of the 54,675 probe sets analyzed, 1334 were upregulated and 4214 were downregulated by >2.0-fold in the cells treated with hyperthermia. A non-hierarchical gene clustering algorithm, K-means clustering, demonstrated 10 gene clusters. The gene network U1 or U2 that was obtained from up-regulated genes in cluster I or IX contained HSPA1B, DNAJB1, HSPH1, and TXN or PML, LYN, and DUSP1, and were mainly associated with cellular compromise, and cellular function and maintenance or death, and cancer, respectively. In the decreased gene cluster II, the gene network D1 including CCNE1 and CEBPE was associated with the cell cycle and cellular growth and proliferation. These findings will provide a basis for understanding the detailed molecular mechanisms of apoptosis induced by hyperthermia at 42 degrees C in cells.
authors.affiliation: Department of Radiological Sciences, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama 930-0194, Japan.
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Furusawa
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Tabuchi
authors.forename: Ichiro
authors.initials: I
authors.lastname: Takasaki
authors.forename: Shigehito
authors.initials: S
authors.lastname: Wada
authors.forename: Kenzo
authors.initials: K
authors.lastname: Ohtsuka
authors.forename: Takashi
authors.initials: T
authors.lastname: Kondo
mesh_terms: D017209:Apoptosis / Q000235:genetics*; D016000:Cluster Analysis; D015973:Gene Expression Regulation, Leukemic; D053263:Gene Regulatory Networks / Q000502:physiology*; D006360:Heat-Shock Proteins / Q000235:genetics*; D006358:Hot Temperature; D006801:Humans; D006979:Hyperthermia, Induced; D008223:Lymphoma / Q000235:genetics* / Q000473:pathology / Q000628:therapy; D005810:Multigene Family; D020411:Oligonucleotide Array Sequence Analysis; D016133:Polymerase Chain Reaction; D020298:U937 Cells
chemical_list: D006360:Heat-Shock Proteins