Erythropoietin and G-CSF receptors in human tumor cells: expression and aspects regarding functionality.
OBJECTIVE
Recombinant human erythropoietin (Epo) and granulocyte-colony-stimulating factor (G-CSF) are used to stimulate hematopoiesis in patients with malignant diseases. These cytokines transduce their biological signal via the Epo receptor (EpoR) and G-CSF receptor (G-CSF-R) into the cell. We therefore investigated in human tumor cell lines the expression of these receptors in tumor cells as well as their response to Epo and G-CSF.


METHODS
The expression of EpoR and G-CSF-R mRNA was analyzed with reverse transcription-polymerase chain reaction (RT-PCR). EpoR protein expression was further monitored with Western blot and immunocytochemistry analysis. The cellular response to various concentrations of Epo was evaluated using 3[H]-thymidine uptake, Northern blot of c-fos expression and tyrosine kinase activity assay. The proliferation after G-CSF incubation was analyzed with the MTS assay.


RESULTS
In this study EpoR mRNA and protein were detected in various human tumor cell lines. Treatment with Epo did not influence the proliferation rate of examined EpoR-positive tumor cell lines. Epo did not stimulate the tyrosine kinase activity nor did it affect the c-fos mRNA in these cell lines. G-CSF-R mRNA was only detected in two myeloid cell lines. Treatment with G-CSF did not increase the proliferation of these cells.


CONCLUSIONS
These results demonstrate that Epo and G-CSF did not modulate the growth rate of examined receptor-positive tumor cell lines; the presence of the Epo receptor seems not essential for cell growth of these tumor cells in cell culture.
Westphal
Gabriela
G
Division of Radiobiology in Radiooncology, German Cancer Research Center (DKFZ), Heidelberg. gwestphal@web.de
Niederberger
Ellen
E
Blum
Christoph
C
Wollman
Yoram
Y
Knoch
Tobias A
TA
Rebel
Wolfgang
W
Debus
Jürgen
J
Friedrich
Eckhard
E
D015152:Blotting, Northern; D015153:Blotting, Western; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D009369:Neoplasms / Q000503:physiopathology*; D017467:Receptors, Erythropoietin / Q000096:biosynthesis* / Q000502:physiology; D016188:Receptors, Granulocyte Colony-Stimulating Factor / Q000096:biosynthesis* / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured
D017467:Receptors, Erythropoietin; D016188:Receptors, Granulocyte Colony-Stimulating Factor