Effect of recombinant human erythropoietin on hematopoietic and non-hematopoietic malignant cell growth in vitro.

BACKGROUND: Several clinical studies have shown that recombinant human erythropoietin (rHuEpo) can ameliorate the anemia associated with hematologic malignancies and solid tumors. On the other hand, only a few studies have been performed to investigate whether rHuEpo can affect or modulate the growth of malignant cells. MATERIALS AND METHODS: We studied the effects of rHuEpo (0.5 to 10 IU/mL) on clonogenic growth and cell kinetics in ten cell lines derived from both hematologic malignancies and solid tumors. Clonogenic assays were performed by plating 5 x 10(3) cells in agar, while the percentage of cells in S phase was assessed by DNA flow cytometry. RESULTS: rHuEpo did not affect either in vitro colony formation or S phase percentage in the human erythroid cell lines K-562 and HEL expressing erythropoietin receptors (< 40 receptors per cell). No effect of rHuEpo was observed in the remaining hematopoietic cell lines or in five solid tumor cell lines. CONCLUSIONS: These findings indicate that rHuEpo, even at very high concentrations, does not affect either clonogenic growth or DNA synthesis in the cell lines tested. Available evidence suggests that rHuEpo can be safely employed in all malignancies except acute myeloid leukemia.