Identification of common gene networks responsive to mild hyperthermia in human cancer cells.

Hyperthermia (HT) has been used as a possible treatment modality for various types of malignant tumors. Due to its pleiotropic effects, its combined use with radiotherapy and/or chemotherapy has proven to be beneficial. However, the molecular mechanisms underling the cellular responses to heat stress remain unclear. Therefore, the aim of this study was to identify common gene expression patterns responsive to mild HT (MHT) in human cancer cells. HeLa human cervical squamous cell carcinoma (SCC) and HSC-3 human oral SCC cells were exposed to MHT at 41˚C for 30 min, followed by culture at 37˚C for 0-24 h. MHT did not affect cell viability or the cell cycle. GeneChip microarray analysis clearly revealed that many probe sets were differentially expressed by a factor of ≥1.5 in both cell lines following exposure to MHT. Of the many differentially expressed probe sets, 114 genes were found to be commonly upregulated in both HeLa and HSC‑3 cells, and two significant gene networks were obtained from the commonly upregulated genes. Gene network A included several heat shock proteins, as well as BCL2-associated athanogene 3 (BAG3), and was found to be mainly associated with the biological functions of cellular function and maintenance. Gene network B included several anti-cell death genes, such as early growth response 1 (EGR1) and endothelin 1 (EDN1) and was found to be associated with the biological functions of cell death and survival. Real‑time quantitative polymerase chain reaction demonstrated that the gene expression patterns of the 12 genes selected were consistent with the microarray data in four cancer cell lines. These findings may provide further insight into the detailed molecular mechanisms of the MHT response in cancer cells.