Secretion of erythropoietin-like activity by clones of human renal carcinoma cell line GKA.

Human renal carcinoma cell line GKA was derived from a patient with the paraneoplastic syndrome of erythrocytosis and secretes erythropoietin-like activity into its growth medium (Sytkowski, A. J., Richie, J. P., and Bicknell, K. A. Cancer Res., 43: 1415-1419, 1983). In order to derive homogeneous sublines with higher secretory rates, we cloned line GKA. Over 100 clones were generated, and 21 secreted erythropoietin-like activity, up to 6-fold higher than the uncloned line. This activity stimulated the growth and differentiation of CFU-E derived colonies in plasma clot culture. However, the secreted erythropoietin-like activity did not cross-react in a sensitive radioimmunoassay utilizing highly purified 125I-labeled human urinary erythropoietin and heterologous anti-human urinary erythropoietin antiserum. These results suggest that line GKA secretes an erythropoietic stimulating factor distinct from the hormone erythropoietin.