Exposure to hyperbaric oxygen induces cell cycle perturbation in prostate cancer cells

Cell cycle synchronization of tumor cells by exposure to hyperbaric oxygena tion (HBO) may increase the eflicacy of chemotherapy or radiation by placin g cells into a chemosensitive portion of the cycle. The purpose of the curr ent study was to examine oxygen pressure-dependent relationships with respe ct to the cell cycle in prostate tumor cells in vitro. LNCaP cells were gro wn in an incubator at 21% O-2 and then exposed to 100%; oxygen at pressures up to 6 atmospheres (atm) for 1.5 h. Cells were then returned to the incub ator and evaluated for DNA content Lu propidium iodide and new DNA synthesi s with a pulse-chase experiment. Cell cycle effects were evaluated by flow cytometry. Exposure: to HBO increased the percentage of cells synthesizing new DNA in a dose-dependent fashion: 0 atm, 44%; 6 atm, 65%. Cells that syn thesize new DNA accumulate in G(2)/M as a function of partial pressure of o xygen. These results suggest that HBO induces cells to enter the cell cycle and accumulate in G(2)/M. Cell cycle synchronization and entry of senescen t cells into the cell cycle suggest that HBO may be a useful adjuvant to ch emotherapy or radiation in the treatment of prostate cancer. There are two potential mechanisms of action that may make HBO efficacious in the treatme nt of prostate cancel: HBO may potentiate cancer chemotherapeutic agents th at cause damage to DNA during DNA synthesis ol HBO may inhibit cell divisio n causing accumulation in G(2)/M.