Raised polyamines in erythrocytes from melanoma-bearing mice and patients with solid tumours

The levels of polyamines (putrescine, spermidine and spermine) in erythrocytes and plasma were studied using Cloudman S-91 melanoma grown in the lungs of DBA/2 mice. Polyamine levels and the numbers of tumour-cell colonies in the lungs were determined at weekly intervals. Putrescine levels in both erythrocytes and plasma significantly increased 1 week after tumour inoculation. Three weeks after inoculation, however, putrescine levels in the erythrocytes showed a greater increase than those in plasma. Spermidine and spermine levels were initially high at 2 weeks in plasma and at 4 weeks in erythrocytes. However, by 6 weeks the spermidine levels showed a greater increase in erythrocytes than in plasma. These data suggest that erythrocytes may absorb and store polyamines released into the circulation. This finding was subsequently applied to human studies. Fifty-two untreated patients with solid tumours were examined in the preoperative period. All erythrocyte polyamine levels from patients were significantly higher than those from control subjects. Plasma spermidine levels in patients were significantly higher than those in controls, whereas plasma putrescine and spermine levels showed no significant increase. The frequency of raised levels of putrescine, spermidine and spermine in erythrocytes was significantly greater than in plasma. These results suggest that polyamine levels in erythrocytes may provide useful information for the detection of cancer.