Glutathione protects metastatic melanoma cells against oxidative stress in the murine hepatic microvasculature

Calcein‐labeled B16 melanoma (B16M) cells were injected intraportally, and in vivo video microscopy was used to study the distribution and damage of cancer cells arrested in the liver microvasculature over a period of 4 hours. The contribution of glutathione (GSH)‐dependent antioxidant machinery to the possible oxidative stress–resistance mechanism of B16M cell was determined by in vitro incubation with the selective inhibitor of GSH synthesis l‐buthionine (S,R)‐sulphoximine (BSO) before B16M cell injection in untreated and 0.5‐mg/kg lipopolysaccharide (LPS)‐treated mice. In addition, untreated and LPS‐treated isolated syngeneic hepatic sinusoidal endothelial cells (HSE) were used to determine in vitro their specific contribution to B16M cell damage. Trauma inherent to intrasinusoidal lodgement damaged 35% of B16M cells in both normal and LPS‐treated mouse liver. The rest of the arrested B16M cells remained intact in normal liver for at least 4 hours, although their damaged cell percentage significantly (P < .05) increased since the second hour in normal mice injected with BSO‐treated cells and since the first hour in LPS‐treated mice given untreated cells. Recombinant human interleukin‐1 receptor antagonist (rHuIL‐1‐Ra) given to mice 15 minutes before LPS significantly (P < .05) abrogated B16M cell damage. On the other hand, 40% of the B16M cells co‐cultured with unstimulated HSE and 70% of the co‐cultured with LPS‐treated HSE became sensitive to endothelial cell–mediated damage after BSO treatment. These results demonstrate that a high intracellular level of GSH protects B16M cells from possible in vivo and in vitro sinusoidal cell–mediated oxidative stress, contributing to the mechanism of metastatic cell survival within the hepatic microvasculature.