Inhibition of lung metastasis of osteosarcoma cell line POS-1 transplanted into mice by thigh ligation

Using a model with external ligation of the thigh, the effect of ischemia-reperfusion injury on tumor growth and the activity of lung metastasis was investigated in mice inoculated a spontaneous murine osteosarcoma cell line (POS-1) in vivo. POS-1 cell suspension was inoculated into the right hind footpad of 70 mice. Four weeks after inoculation, the ipsilateral thigh was ligated for 3 h in 15 mice and the contralateral thigh in 15 mice. Another ten mice were inoculated with POS-1 without ligating the thigh. The number of metastatic foci on the lung surface 6 weeks after inoculation was 2.29 +/- 0.98 (mean SE) foci/lungs in mice with ipsilateral ligation and 6.25 +/- 2.41 in mice with contralateral ligation, which were significantly lower than control (13.40 +/- 1.42 in mice no ligation) (P < 0.01). The number of metastatic foci on the lung surface in mice with intraperitoneal injection of superoxide dismutase (SOD) and catalase was 3.25 +/- 0.65 (mean +/- SE) foci/lungs in mice with ligation which was significantly greater than that in mice without SOD and catalase injection 1.29 +/- 0.97 (P = 0.04). Cell viability was 9.12 +/- 4.07% with 100 muM H2O2 in 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay. It revealed that at concentrations of 100 muM H2O2 or higher was cytotoxic to POS-1. In cell invasion assay, the number of invading cells with 10 muM H2O2 was 2.80 +/- 0.53 cells/field, which was significantly lower than control (5.93 +/- 0.18) (mean +/- SE), indicating that low-dose H2O2 suppressed invasion of POS-1. These results suggested that reperfusion injury had selective cytotoxicity to POS-1 through producing reactive oxygen species. Activated oxygen was considered to inhibit the regional growth and the ability of lung metastasis of POS-1 cells. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.