Title
Inhibition of the EGF receptor blocks autocrine growth and increases the cytotoxic effects of doxorubicin in rat hepatoma cells. Role of reactive oxygen species production and glutathione depletion
Date Issued
15 May 2008
Access level
metadata only access
Resource Type
journal article
Author(s)
Caja L.
Sancho P.
Bertran E.
Fabregat I.
Fundació Institut d'Investigació Biomèdica de Bellvitge
Abstract
FaO rat hepatoma cells show increased levels of the epidermal growth factor receptor (EGFR) ligands, when compared with adult normal hepatocytes, and higher activity of the TNF-alpha converting enzyme (TACE/ADAM17), which is required for EGFR ligand proteolysis and activation. In this work we have analysed the consequences of inhibiting the EGFR in FaO rat hepatoma cells, focusing the attention on autocrine growth and protection from apoptosis. Results have indicated that FaO cells show overactivation of the EGFR pathway, which induces basal growth (in the absence of serum) and protection from pro-apoptotic agents, such as doxorubicin, generating drug resistance. Treatment of cells with the combination of doxorubicin and the tyrphostin 4-(3-chloroanilino)-6,7-dimethoxyquinazoline (AG1478, a potent and specific inhibitor of EGFR tyrosine kinase) potently inhibits autocrine growth and induces apoptosis. The apoptotic effect correlates with high expression and activation of the pro-apoptotic Bax and decreased transcript and protein levels of the anti-apoptotic Mcl-1 and Bcl-xL. Furthermore, the combination of AG1478 and doxorubicin induces reactive oxygen species (ROS) production and glutathione depletion in FaO cells, coincident with up-regulation of the NADPH oxidase NOX4 and down-regulation of the gamma-glutamylcysteine synthetase (γ-GCS), a key regulatory enzyme of the glutathione synthesis. Incubation of cells with glutathione ethyl ester attenuates the apoptosis induced by the combination of doxorubicin and AG1478, which indicates that glutathione depletion is required for an efficient cell death. In conclusion, targeting EGFR combined with other conventional pro-apoptotic drugs should potentially be effective in antineoplastic therapy towards liver cancer. © 2008 Elsevier Inc. All rights reserved.
Start page
1935
End page
1945
Volume
75
Issue
10
Language
English
Scopus EID
2-s2.0-42649140547
PubMed ID
Source
Biochemical Pharmacology
ISSN of the container
00062952
Sponsor(s)
This work was supported by grants from the Ministerio de Educación y Ciencia, Spain (BFU2006-01036), Ministerio de Sanidad y Consumo, Spain (ISCIII-RETIC RD06/0020) and AGAUR-Generalitat de Catalunya (2005SGR-00549). CO is recipient of a pre-doctoral fellowship from the IDIBELL, Catalunya, Spain. LC and PS are recipients of a pre-doctoral fellowship and a postdoctoral contract, respectively, from the Instituto de Salud Carlos III/Ministerio de Sanidad y Consumo, Spain. Authors are very grateful to Marina Noriega (IDIBELL) and Ester Castaño (Serveis Cientificotècnics, UB) for their technical assistance. We are very grateful to Serono Laboratories (Madrid, Spain) for supplying epidermal growth factor.
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