Effects of mechanical trauma and free-radical exposure on the membrane-integrity of Ehrlich ascites tumor cells.

During hematogenous metastasis, the majority of cancer cells entering the microcirculation are rapidly killed as a consequence of loss of membrane integrity. This is partially due to mechanical trauma associated with intramicrovascular cancer cell deformation, and possibly to the action of free radicals released by endothelial and other cells. In an in vitro analysis of these two modalities, we have studied the effects of mechanical (filtration) trauma and exposure to hydrogen peroxide on the surface membrane integrity of Ehrlich ascites tumor cells. It was shown that final concentrations of H2O2 down to 0.001%, and filtration through 10 microns Nuclepore each produced significant loss in surface membrane integrity. An additive effect was demonstrated between exposure to 0.001% H2O2 and filtration, but the additive effect was not detectable at 0.01%. Overall, the results indicate the feasibility of trauma due to mechanical deformation and exposure to free radicals, contributing to the inefficiency of the metastatic process.