Effects of cyclosporin A on erythropoietin production by the human Hep3B
hepatoma cell line
AM Vannucchi, A Grossi, A Bosi, D Rafanelli, M Statello, S Guidi, R Saccardi and P Rossi-Ferrini
Bone Marrow Transplant Unit, Careggi Hospital, Florence, Italy.
There is evidence that the inadequate erythropoietin (Epo) production
observed in patients undergoing allogeneic bone marrow transplantation
(BMT) might be ascribed to an inhibitory effect caused by the
immunosuppressive drug cyclosporin A (CsA). In this in vitro study, we have
evaluated the effects of CsA on the release of Epo in the culture medium by
the human Hep3B hepatoma cell line. In cultures incubated with both CsA and
the nonimmunosuppressive CsA analog MeAla-6, but not with the CsA-unrelated
immunosuppressive agent FK-506, the levels of Epo in the medium were
significantly reduced in comparison with controls, at concentrations (0.01
to 1.6 mumol/L) not affecting total protein synthetic rate nor the
constitutive secretion of alpha- fetoprotein. Hep3B cells were found to
contain a CsA-binding molecule, with an M(r) of 18 Kd, as assessed by high
performance liquid chromatography (HPLC) and ligand-blotting analysis. CsA
did not affect the expression of the Epo gene, as judged by Northern blot
analysis, but caused a significant amount of Epo to remain unsecreted
within the cells; almost all (97% of total) of the intracellular Epo was
associated with the plasma membrane subcellular fraction. We conclude that:
(1) CsA is able to inhibit Epo release in vitro by Hep3B cells, further
supporting the hypothesis that the drug might have a role in the
inappropriately low Epo levels observed in BMT patients; (2) the inhibitory
effect appears to be specific and not caused by a general impairment of
protein synthesis and/or secretion; and (3) the reduced Epo levels found in
the medium of CsA-treated Hep3B cultures are supposed to be the consequence
of an inability of the cells to correctly process Epo molecules for the
secretory pathway.
Volume 82,
Issue 3,
pp. 978-984,
08/01/1993
Copyright © 1993 by The American Society of Hematology
