Hyperbaric Oxygen Inhibits Benign and Malignant Human Mammary Epithelial Cell Proliferation

Background: Hyperbaric oxygenation (HBO) therapy is the administration of 100%-inhaled oxygen to patients at increased atmospheric pressure. Materials and Methods: We used an in vitro model to examine the effects of HBO on mammary cell proliferation. Normal mammary epithelia, primary tumor and metastatic tumor cells derived from the same patient and immortalized by transfection with the human papilloma virus E6 oncogene, as well as the MCF7 human mammary adenocarcinoma cell line, were studied. Results: HBO (97.9% O 2 , 2.1% CO 2 , 2.4 atmospheres absolute) inhibited the proliferation of all 4 cell types as measured by light microscopy, [ 3 H]thymidine uptake, a tetrazolium-based colorimetric assay and a clonogenicity assay. The anti-proliferative effect of HBO was time-dependent (p