title: Darbepoetin inhibits proliferation of hepatic cancer cells in the presence of TGF-β.
abstract: Darbepoetin (DPO), an erythropoietin (EPO) derivative, was licensed in 2002 to treat patients with solid tumors suffering from chemotherapy-dependent anemia, although various tumors express EPO to improve vascularization, thus favoring tumor growth and spreading. Therefore, we wanted to investigate direct effects of DPO on the liver tumor cell lines HepG2, SkHep1, Huh-7, AKN1, HCC-T and HCC-M, as well as on primary human hepatocytes (hHeps). DPO (0-40 ng/ml) did not affect viability of hHeps, HepG2, SkHep1, AKN1, HCC-T and HCC-M cells, as determined by Resazurin conversion. However, Huh-7 cells' viability dose-dependently decreased from 5 ng/ml DPO on. Lack of LDH release into culture medium and negative DNA laddering excluded apoptosis or necrosis as the cause for the reduced Resazurin conversion. In Huh-7 cells, DPO increased the expression of p53. Interestingly, Huh-7 cells showed the highest basal TGF-β1 expression as compared to the other cell lines. Upon inhibition of TGF-β1 signaling, DPO no longer reduced viability in Huh-7 cells. On the contrary, co-incubation with TGF-β1 made the other cell lines responsive to DPO. Summarizing our data, we show that DPO reduces the growth of Huh-7 cells by up-regulation of the tumor-suppressor gene p53. This mechanism seems to be dependent on a strong TGF-β expression and corresponding signaling in these cells, as other cell lines became responsive to DPO with TGF-β1 supplementation. The knowledge of this mechanism offers great perspectives for the understanding and treatment of solid liver tumors.
authors.affiliation: BG Trauma Center, Eberhard Karls Universität Tübingen, Schnarrenbergstraße 95, 72076, Tübingen, Germany.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Ehnert
authors.forename: Thomas
authors.initials: T
authors.lastname: Freude
authors.forename: Carmen
authors.initials: C
authors.lastname: Eicher
authors.forename: Britta
authors.initials: B
authors.lastname: Burkhardt
authors.forename: Juan J
authors.initials: JJ
authors.lastname: Martínez Sánchez
authors.forename: Jan
authors.initials: J
authors.lastname: Neumann
authors.forename: Ruben
authors.initials: R
authors.lastname: Mühl-Benninghaus
authors.forename: Steven
authors.initials: S
authors.lastname: Dooley
authors.forename: Stefan
authors.initials: S
authors.lastname: Pscherer
authors.forename: Andreas K
authors.initials: AK
authors.lastname: Nussler
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D000068256:Darbepoetin alfa; D004305:Dose-Response Relationship, Drug; D004921:Erythropoietin / Q000031:analogs & derivatives* / Q000494:pharmacology; D022781:Hepatocytes / Q000187:drug effects; D006801:Humans; D008113:Liver Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D010766:Phosphorylation / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects; D016212:Transforming Growth Factor beta / Q000378:metabolism*; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects
chemical_list: C495901:TP53 protein, human; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D016159:Tumor Suppressor Protein p53; D004921:Erythropoietin; D000068256:Darbepoetin alfa