Accumulation of hydroxyspermidine in red blood cells, a potential index of tumor proliferation rate.

It has previously been demonstrated that during Lewis Lung carcinoma growth, red blood cell spermidine levels increase concomitantly with tumor volume. If [14C] putrescine or 2-methylputrescine are administered, [14C] spermidine and methylspermidine, respectively, accumulate in red blood cells in proportion with the tumor volume. In the present work the metabolic transformation of 2-hydroxyputrescine, a natural derivative of putrescine, to hydroxyspermidine, was studied in tumor bearing mice. After a single i.p. injection of 2-hydroxyputrescine, higher concentrations of hydroxyspermidine were found in the tumor than in liver. In the red blood cells of Lewis lung carcinoma-bearing mice, hydroxyspermidine was detected between 24 hours and 96 hours after i.p. injection of 2-hydroxyputrescine. The concentration of hydroxyspermidine found in red blood cells was proportional to the tumor volume. Hydroxyspermidine has potential as a marker of malignant cell proliferation in human oncology.