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Abstract: Identification of reliable markers of radiosensitivity and the key molecules that enhance the susceptibility of esophageal cancer cells to anticancer treatments would be highly desirable. To identify molecules that confer radiosensitivity to esophageal squamous carcinoma cells, we assessed the radiosensitivities of the TE-5, TE-9 and TE-12 cloneA1 cell lines. TE-12 cloneA1 cells showed significantly greater susceptibility to radiotherapy at 5 and 10Gy than either TE-5 or TE-9 cells. Consistent with that finding, 24h after irradiation (5Gy), TE-12 cloneA1 cells showed higher levels of caspase 3/7 activity than TE-5 or TE-9 cells. When we used DNA microarrays to compare the gene expression profiles of TE-5 and TE-12 cloneA1 cells, we found that the mRNA and protein expression of insulin-like growth factor binding protein 3 (IGFBP3) and Bcl-2-associated athanogene 1 (BAG1) was five or more times higher in TE-12 cloneA1 cells than TE-5 cells. Conversely, knocking down expression of IGFBP3 and BAG1 mRNA in TE-12 cloneA1 cells using small interfering RNA (siRNA) significantly reduced radiosensitivity. These data suggest that IGFBP3 and BAG1 may be key markers of radiosensitivity that enhance the susceptibility of squamous cell esophageal cancer to radiotherapy. IGFBP3 and BAG1 may thus be useful targets for improved and more individualized treatments for patients with esophageal squamous cell carcinoma. [Copyright &y& Elsevier]

Background. Low-flow hypoxia induces xanthine oxidase-dependent hydrogen peroxide production by hepatocytes in the midzone of blood-perfused rat livers and apoptosis in sinusoidal endothelial cells (SECs). As Bcl-2 is a potent inhibitor of apoptotic cell death and is localized mainly in the inner mitochondrial membrane and crista, the purpose of this study was to determine whether cell-specific changes in mitochondrial Bcl-2 levels could account for the hypoxia-induced apoptosis in SECs.Materials and methods. A low-flow hypoxia model was generated in isolated rat livers by reducing perfusate inflow pressure from 10 to 2.5 cmH2O for 2 h. Apoptosis was then evaluated using the TdT-mediated dUTP-digoxigenin nick end-labeling (TUNEL) method. Mitochondrial Bcl-2 protein levels were determined in hepatocytes and SECs using cryosectioning immunogold labeling electron microscopy.Results. TUNEL-positive nonparenchymal cells, identified as SECs, were observed predominantly in the midzone of low-flow hypoxic rat livers, whereas few parenchymal cells were stained. Mitochondrial Bcl-2 levels were higher in SECs than in hepatocytes under control conditions, but they declined significantly during hypoxia, though no morphological signs of apoptosis were apparent. In hepatocytes, by contrast, Bcl-2 levels were unaffected by hypoxia. Pretreatment with a specific xanthine oxidase inhibitor, sodium (-)-8-(3-methoxy-4-phenylsulfinylphenyl) pyrazolo [1,5-a]-1,3,5-triazine-4-olate monohydrate, which blocks production of hydrogen peroxide, also blocked both the hypoxia-induced apoptosis and the decline in mitochondrial Bcl-2 in SECs.Conclusion. Hydrogen peroxide-dependent declines in Bcl-2 induce apoptosis in SECs in the hypoxic rat liver. [Copyright &y& Elsevier]