TY - JOUR
T1 - Oncogenic KRAS impairs EGFR antibodies' efficiency by C/EBPβ-dependent suppression of EGFR expression
AU - Derer, Stefanie
AU - Berger, Sven
AU - Schlaeth, Martin
AU - Schneider-Merck, Tanja
AU - Klausz, Katja
AU - Lohse, Stefan
AU - Overdijk, Marije B.
AU - Dechant, Michael
AU - Kellner, Christian
AU - Nagelmeier, Iris
AU - Scheel, Andreas H.
AU - van Bueren, Jeroen J.Lammerts
AU - van de Winkel, Jan G.J.
AU - Parren, Paul W.H.I.
AU - Peipp, Matthias
AU - Valerius, Thomas
N1 - Funding Information:
Abbreviations: Ab, antibody; ADCC, antibody-dependent cell-mediated cytotoxicity; CDC, complement-dependent cytotoxicity; C/EBP, CCAAT/enhancer-binding protein; CRC, colorectal cancer; MNC, mononuclear cell; PMN, polymorphonuclear cell; TF, transcription factor Address all correspondence to: Thomas Valerius, MD, Division of Stem Cell Transplantation and Immunotherapy, 2nd Department of Medicine, Christian-Albrechts-University, Kiel, Schittenhelmstraße 12, 24105 Kiel, Germany. E-mail: [email protected] 1This work was supported by grants from the German Research Organization (DFG Va 124/7-1) and Wilhelm Sander-Foundation (2009.098.1). J.J. Lammerts van Bueren, M.B. Overdijk, J.G.J. van de Winkel, and P.W.H.I. Parren are employed by Genmab and own Genmab warrants and/or stock. T. Valerius and M. Dechant received grants from Genmab, Utrecht, The Netherlands. S. Derer, S. Berger, M. Schlaeth, T. Schneider-Merck, K. Klausz, S. Lohse, C. Kellner, I. Nagelmeier, A.H. Scheel, and M. Peipp declare no potential conflict of interest. 2This article refers to supplementary materials, which are designated by Figures W1 and W2 and are available online at www.neoplasia.com. Received 23 November 2011; Revised 17 February 2012; Accepted 20 February 2012 Copyright © 2012 Neoplasia Press, Inc. All rights reserved 1522-8002/12/$25.00 DOI 10.1593/neo.111636
Copyright:
Copyright 2017 Elsevier B.V., All rights reserved.
PY - 2012/3
Y1 - 2012/3
N2 - Oncogenic KRAS mutations in colorectal cancer (CRC) are associated with lack of benefit from epidermal growth factor receptor (EGFR)-directed antibody (Ab) therapy. However, the mechanisms by which constitutively activated KRAS (KRASG12V) impairs effector mechanisms of EGFR-Abs are incompletely understood. Here, we established isogenic cell line models to systematically investigate the impact of KRASG12V on tumor growth in mouse A431 xenograft models as well as on various modes of action triggered by EGFR-Abs in vitro. KRASG12V impaired EGFR-Ab-mediated growth inhibition by stimulating receptor-independent downstream signaling. KRASG12V also rendered tumor cells less responsive to Fc-mediated effector mechanisms of EGFR-Abs-such as complementdependent cytotoxicity (CDC) and Ab-dependent cell-mediated cytotoxicity (ADCC). Impaired CDC and ADCC activities could be linked to reduced EGFR expression in KRAS-mutated versus wild-type (wt) cells, which was restored by small interfering RNA (siRNA)-mediated knockdown of KRAS4b. Immunohistochemistry experiments also revealed lower EGFR expression in KRASmutated versus KRAS-wt harboring CRC samples. Analyses of potential mechanisms by which KRASG12V downregulated EGFR expression demonstrated significantly decreased activity of six distinct transcription factors. Additional experiments suggested the CCAAT/enhancer-binding protein (C/EBP) family to be implicated in the regulation of EGFR promoter activity in KRAS-mutated tumor cells by suppressing EGFR transcription through up-regulation of the inhibitory family member C/EBPβ-LIP. Thus, siRNA-mediated knockdown of C/EBPβ led to enhanced EGFR expression and Ab-mediated cytotoxicity against KRAS-mutated cells. Together, these results demonstrate that KRASG12V signaling induced C/EBPβ-dependent suppression of EGFR expression, thereby impairing Fc-mediated effector mechanisms of EGFR-Abs and rendering KRAS-mutated tumor cells less sensitive to these therapeutic agents.
AB - Oncogenic KRAS mutations in colorectal cancer (CRC) are associated with lack of benefit from epidermal growth factor receptor (EGFR)-directed antibody (Ab) therapy. However, the mechanisms by which constitutively activated KRAS (KRASG12V) impairs effector mechanisms of EGFR-Abs are incompletely understood. Here, we established isogenic cell line models to systematically investigate the impact of KRASG12V on tumor growth in mouse A431 xenograft models as well as on various modes of action triggered by EGFR-Abs in vitro. KRASG12V impaired EGFR-Ab-mediated growth inhibition by stimulating receptor-independent downstream signaling. KRASG12V also rendered tumor cells less responsive to Fc-mediated effector mechanisms of EGFR-Abs-such as complementdependent cytotoxicity (CDC) and Ab-dependent cell-mediated cytotoxicity (ADCC). Impaired CDC and ADCC activities could be linked to reduced EGFR expression in KRAS-mutated versus wild-type (wt) cells, which was restored by small interfering RNA (siRNA)-mediated knockdown of KRAS4b. Immunohistochemistry experiments also revealed lower EGFR expression in KRASmutated versus KRAS-wt harboring CRC samples. Analyses of potential mechanisms by which KRASG12V downregulated EGFR expression demonstrated significantly decreased activity of six distinct transcription factors. Additional experiments suggested the CCAAT/enhancer-binding protein (C/EBP) family to be implicated in the regulation of EGFR promoter activity in KRAS-mutated tumor cells by suppressing EGFR transcription through up-regulation of the inhibitory family member C/EBPβ-LIP. Thus, siRNA-mediated knockdown of C/EBPβ led to enhanced EGFR expression and Ab-mediated cytotoxicity against KRAS-mutated cells. Together, these results demonstrate that KRASG12V signaling induced C/EBPβ-dependent suppression of EGFR expression, thereby impairing Fc-mediated effector mechanisms of EGFR-Abs and rendering KRAS-mutated tumor cells less sensitive to these therapeutic agents.
UR - http://www.scopus.com/inward/record.url?scp=84859168799&partnerID=8YFLogxK
U2 - 10.1593/neo.111636
DO - 10.1593/neo.111636
M3 - Journal articles
AN - SCOPUS:84859168799
SN - 1522-8002
VL - 14
SP - 190
EP - 205
JO - Neoplasia
JF - Neoplasia
IS - 3
ER -
