Abstract
The inhibition of phosphofructokinase (PFK) by sera from patients with malignant tumors was measured to study its clinical effectiveness in tumor genesis. The inhibitory activity of the serum was measured by its reduction of PFK activity after adding it to a PFK standard. The reduction ratio was expressed as inhibition index. Sera from 100 malignant tumor patients and 59 benign disease patients were compared with sera from 100 healthy individuals. The PFK inhibition index from healthy individuals was 1.276±0.155 (mean ± SD), and the cutoff value for the normal upper limit was set at 1.586, the mean +2 SD. The PFK inhibition index of sera from malignant tumor patients, 1.503±0.232, was significantly higher (p<0.001) than that of healthy individuals, and the positive rate was 32 % (32/100) . In patients with gastric or colorectal cancer, the PFK inhibition index did not correlate with the degree of pathohistological advance. The PFK inhibition index of sera from benign diseases, 1.327±0.219, was not significantly higher (p<0.01) than that of healthy individuals, and the positive rate was 13.6 % (8/59) . The results indicate that the PFK inhibition index is applicable as an effective tumor marker. The mechanism of PFK inhibition by serum from cancer patients was not clarified, but our chemical study suggested that PFK was inhibited by heat-stable and SH modification substance in the serum.
