title: Stem cell property epithelial-to-mesenchymal transition is a core transcriptional network for predicting cetuximab (Erbitux™) efficacy in KRAS wild-type tumor cells.
abstract: Beyond a well-recognized effect of KRAS mutations in determining de novo inefficacy of cetuximab (CTX) in metastatic colorectal cancer, we urgently need a biomarker signature for predicting CTX efficacy in KRAS wild-type (WT) tumors. CTX-adapted EGFR gene-amplified KRAS WT tumor cell populations were induced by stepwise-chronic exposure of A431 epidermoid cancer cells to CTX. Genome-wide analyses of 44K Agilent's whole human arrays were bioinformatically evaluated by Gene Set Enrichment Analysis (GSEA)-based screening of the KEGG pathway database. Molecular functioning of CTX was found to depend on: (i) The occurrence of a positive feedback loop on Epidermal Growth Factor Receptor (EGFR) activation driven by genes coding for EGFR ligands (e.g., amphiregulin); (ii) the lack of a negative feedback on mitogen-activated protein kinase (MAPK) activation regulated by dual-specificity phosphatases (e.g., DUSP6) and; (iii) the transcriptional status of gene pathways controlling the epithelial-to-mesenchymal transition (EMT) and its reversal (MET) program (actin cytoskeleton and cell-cell communication-e.g., keratins-focal adhesion signaling-e.g., integrins-and EMT-inducing cytokines - e.g., transforming growth factor-β). Quantitative real-time PCR, high-content immunostaining, and flow-cytometry analyses confirmed that CTX efficacy depends on its ability to promote: (i) Stronger cell-cell contacts by up-regulating the expression of the epithelial markers E-cadherin and occludin; (ii) down-regulation of the epithelial transcriptional repressors Zeb, Snail, and Slug accompanied by restoration of cortical F-actin; and (iii) complete prevention of the CD44(pos)/CD24(neg/low) mesenchymal immunophenotype. The impact of EGFR ligands/MAPK phosphatases gene transcripts in predicting CTX efficacy in KRAS WT tumors may be tightly linked with the ability of CTX to concurrently reverse the EMT status, a pivotal property of migrating cancer stem cells.
authors.affiliation: Unit of Translational Research, Catalan Institute of Oncology, Girona, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Oliveras-Ferraros
authors.forename: Alejandro
authors.initials: A
authors.lastname: Vazquez-Martin
authors.forename: Sílvia
authors.initials: S
authors.lastname: Cufí
authors.forename: Bernardo
authors.initials: B
authors.lastname: Queralt
authors.forename: Luciana
authors.initials: L
authors.lastname: Báez
authors.forename: Raquel
authors.initials: R
authors.lastname: Guardeño
authors.forename: Xavier
authors.initials: X
authors.lastname: Hernández-Yagüe
authors.forename: Begoña
authors.initials: B
authors.lastname: Martin-Castillo
authors.forename: Joan
authors.initials: J
authors.lastname: Brunet
authors.forename: Javier A
authors.initials: JA
authors.lastname: Menendez
mesh_terms: D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents / Q000494:pharmacology*; D051927:CD24 Antigen / Q000378:metabolism; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy / Q000378:metabolism; D045744:Cell Line, Tumor; D000068818:Cetuximab; D015536:Down-Regulation; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects*; D066246:ErbB Receptors / Q000378:metabolism; D005260:Female; D053263:Gene Regulatory Networks; D006801:Humans; D018960:Hyaluronan Receptors / Q000378:metabolism; D018307:Neoplasms, Squamous Cell / Q000188:drug therapy / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000378:metabolism; D016283:Proto-Oncogene Proteins p21(ras); D014846:Vulvar Neoplasms / Q000188:drug therapy / Q000378:metabolism; D018631:ras Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D051927:CD24 Antigen; C497889:CD24 protein, human; C497483:CD44 protein, human; D018960:Hyaluronan Receptors; C117307:KRAS protein, human; D011518:Proto-Oncogene Proteins; D066246:ErbB Receptors; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins; D000068818:Cetuximab