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.

Erythropoietin promoted the proliferation of hepatocellular carcinoma through hypoxia induced translocation of its specific receptor

“…What out of our expectation is that the proliferation promotion effect of exogenous rHuEPO could only be exerted under hypoxia but not normoxia. Previously, similar phenomena that HCC cells respond differently to EPO under different conditions was reported in the presence or absence of TGF-beta [ 42 ]. We are quite interested in the mechanism underlying which EPO could behave differently in different oxygen concentration.…”

Investigating the expression, effect and tumorigenic pathway of PADI2 in tumors

“…However, evidence supporting a tumor growth-promoting effect of EPO has been inconclusive. Ehnert et al23 showed that darbepoetin, an EPO derivative, reduces the growth of Huh 7 cells, a hepatocarcinoma cell line, through the upregulation of the tumor-suppressor gene p53. Thus, EPO could delay tumor growth as several preclinical studies have reported.…”

miR-663 overexpression induced by endoplasmic reticulum stress modulates hepatocellular carcinoma cell apoptosis via transforming growth factor beta 1

“…Among the predicted targets, we found TGFB1 as a predicted target with known roles both in HCC proliferation and apoptosis, which made it a good candidate for contributing to apoptosis in HCC. 17 – 19 In this study, we found that TGFB1 expression was decreased following TM incubation ( Figure 6 ), while miR-663 was increased during the same treatment ( Figure 2 ), indicating a reverse correlation between miR-663 and TGFB1. Earlier studies also demonstrated that miR-663 downregulated TGFB1 expression in endothelial cells, papillary thyroid carcinoma cells as well as A549, SW460, and Hela cell lines.…”

“…Lower expression levels of TGFB1 were closely associated with cancer progression, such as cell proliferation and apoptosis. 17 – 19 Based on the results of target prediction, we explored TGFB1 among the genes that were potentially targeted by miR-663. On one hand, as we mentioned before, TGFB1 has known roles in both HCC proliferation and apoptosis.…”