Erythropoietin receptor expression in human melanoma cells

Erythropoietin is well known for its role in the control of erythropoiesis, where it acts by binding to its cognate receptor (EpoR) on the surface of erythroid progenitor cells. Here we present the novel finding that the EpoR is also expressed in cells of the melanocytic lineage. It is expressed in transformed cell lines established from normal melanocytes and also in esta blished human melanoma cell lines derived from melanoma metastases, but not in normal primary human melanocytes. The analysis of individual subclones isolated from spontaneously transformed melanocytes revealed that approxima tely 50% of all the clones examined expressed the EpoR. Further analysis of the individual growth characteristics of EpoR-positive and EpoR-negative c lones indicated that, under standard cell culture conditions, expression of the receptor did not affect cell growth. Expression of this receptor is co nsequently most likely driven by an event that is associated with, but not absolutely required for, the transformed phenotype. While the definite func tion of this receptor in melanoma cells is still unknown and additional stu dies are required, our findings support the hypothesis that the EpoR may se rve as a progression marker for human melanoma. This observation might be u seful in the early diagnosis of melanoma. (C) 2000 Lippincott Williams & Wi lkins.