Accelerated heme synthesis and degradation in transformed fibroblasts

Various parameters of the heme biosynthetic pathway were studied in two cell lines, one nontransformed and the other malignantly transformed ( MLV MS), both replicating at the same rate. Using the above system enabled us to distinguish between phenomena characteristic of the malignant transformation per se and those due to accelerated growth rate. Heme synthesis and degradation as well as the activities of ALAS, ALAD, PBGD, and FC were found to be increased in the transformed cells. However, the concentration of intracellular heme was markedly reduced from 30.4 ± 4.4 pmole/mg protein in nontransformed cells to 10.5 ± 2.6 pmole/mg protein in transformed cells. These observations show that malignant transformation leads to changes in heme metabolism unrelated to growth rate in this cell line.