Comparison of the effects of 40% oxygen and two atmospheric absolute air pressure conditions on stress-induced premature senescence of normal human diploid fibroblasts

The pressure during hyperbaric oxygen treatment may increase oxygen toxicity via an augmented oxygen pressure in the gas. Nevertheless, only a few reports have been published on the effect of cells grown under 2 atmospheric absolute (ATA) pressure. To evaluate the effect of pressure on oxygen toxicity and to study effects in addition to oxygen toxicity, we designed an experiment to compare the effects of normobaric mild hyperoxia (NMH, 40% oxygen) and hyperbaric air condition (HA, air with 2 ATA) on human diploid fibroblasts (HDF) in a hyperbaric incubator. HDFs in both the NMH and the HA condition had a similar oxidative stress response and exhibited premature senescence. To investigate differences in gene profiling in cells grown in the NMH and HA conditions, samples from cells exposed to each condition were applied to microarrays. We found no expression difference in genes related to aging and deoxyribonucleic acid damage, but the expression of genes including cell adhesion, stress response, and transcription were significantly increased in fibroblasts that were responsive to pressure. Among 26 statistically reliable genes, the expression of apoptosis related genes such as ADAM22, Bax, BCL2L14, and UBD, as well as tumor suppressor-related genes like Axin2 and ATF, and also mitogen-activated protein kinase-related genes like mitogen-activated protein kinase kinase kinase 1, histamine receptor, and RAB24, were significantly changed in cells responsive to pressureinduced oxidative stress.