BACKGROUND AND PURPOSE: Human tumors are characterized by large variations in oxygen concentration and hypoxic tumors are associated with poor prognosis. In addition, tumors are subjected to periodic changes in oxygenation characterized by hypoxia followed by reoxygenation. Cellular adaptation to hypoxia is well documented, nevertheless little is known about adaptive mechanisms to reoxygenation. Here, we investigate the changes in protein expression during reoxygenation using proteomics. MATERIALS AND METHODS: HeLa cervix carcinoma cells were exposed to 4h of hypoxia (<0.01% O(2)) followed by 1h of reoxygenation. The cellular proteome was examined using 2D gel electrophoresis coupled with mass spectrometry. Validation and investigation of the underlying basis for induced protein expression was investigated using Western blot analysis and quantitative RT-PCR. RESULTS: We identified proteins involved in several cellular processes that are responsible for regulating RNA metabolism, protein synthesis and degradation, including ribosomal protein P0, VCP/p97 and FUSE binding protein 2. CONCLUSIONS: Our results suggest that these newly identified proteins function in pathways that may assist in the recovery of ER stress and protein synthesis during reoxygenation. These proteins may thus be important determinants of the behaviour and survival of tumor cells to transient hypoxic exposures.
BACKGROUND AND PURPOSE:Humantumors are characterized by large variations in oxygen concentration and hypoxic tumors are associated with poor prognosis. In addition, tumors are subjected to periodic changes in oxygenation characterized by hypoxia followed by reoxygenation. Cellular adaptation to hypoxia is well documented, nevertheless little is known about adaptive mechanisms to reoxygenation. Here, we investigate the changes in protein expression during reoxygenation using proteomics. MATERIALS AND METHODS:HeLa cervix carcinoma cells were exposed to 4h of hypoxia (<0.01% O(2)) followed by 1h of reoxygenation. The cellular proteome was examined using 2D gel electrophoresis coupled with mass spectrometry. Validation and investigation of the underlying basis for induced protein expression was investigated using Western blot analysis and quantitative RT-PCR. RESULTS: We identified proteins involved in several cellular processes that are responsible for regulating RNA metabolism, protein synthesis and degradation, including ribosomal protein P0, VCP/p97 and FUSE binding protein 2. CONCLUSIONS: Our results suggest that these newly identified proteins function in pathways that may assist in the recovery of ER stress and protein synthesis during reoxygenation. These proteins may thus be important determinants of the behaviour and survival of tumor cells to transient hypoxic exposures.