Fredrik Jerhammar1, Ann-Charlotte Johansson2, Rebecca Ceder3, Jenny Welander4, Agneta Jansson5, Roland C Grafström6, Peter Söderkvist4, Karin Roberg7. 1. Division of Oto-Rhino-Laryngology and Head and Neck Surgery, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, Linköping, Sweden. 2. Division of Oto-Rhino-Laryngology and Head and Neck Surgery, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, Linköping, Sweden. Electronic address: ann-charlotte.johansson@liu.se. 3. Division of Molecular Toxicology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden. 4. Division of Cell Biology, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, Linköping, Sweden. 5. Division of Oncology, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, Linköping, Sweden. 6. Division of Molecular Toxicology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden; Medical Biotechnology, VTT Technical Research Centre of Finland, Turku, Finland. 7. Division of Oto-Rhino-Laryngology and Head and Neck Surgery, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, Linköping, Sweden; Department of ENT-Head and Neck Surgery UHL, County Council of Östergötland, Linköping, Sweden.
Abstract
OBJECTIVES: Targeted therapy against the epidermal growth factor receptor (EGFR) only variably represents a therapeutic advance in head and neck squamous cell carcinoma (HNSCC). This study addresses the need of biomarkers of treatment response to the EGFR-targeting antibody cetuximab (Erbitux®). MATERIALS AND METHODS: The intrinsic cetuximab sensitivity of HNSCC cell lines was assessed by a crystal violet assay. Gene copy number analysis of five resistant and five sensitive cell lines was performed using the Affymetrix SNP 6.0 platform. Quantitative real-time PCR was used for verification of selected copy number alterations and assessment of mRNA expression. The functional importance of the findings on the gene and mRNA level was investigated employing siRNA technology. The data was statistically evaluated using Mann-Whitney U-test and Spearman's correlation test. RESULTS: Analysis of the intrinsic cetuximab sensitivity of 32 HNSCC cell lines characterized five and nine lines as cetuximab sensitive or resistant, respectively. Gene copy number analysis of five resistant versus five sensitive cell lines identified 39 amplified protein-coding genes, including YAP1, in the genomic regions 11q22.1 or 5p13-15. Assessment using qPCR verified that YAP1 amplification associated with cetuximab resistance. Amplification of YAP1 correlated to higher mRNA levels, and RNA knockdown resulted in increased cetuximab sensitivity. Assessment of several independent clinical data sets in the public domain confirmed YAP1 amplifications in multiple tumor types including HNSCC, along with highly differential expression in a subset of HNSCC patients. CONCLUSION: Taken together, we provide evidence that YAP1 could represent a novel biomarker gene of cetuximab resistance in HNSCC cell lines.
OBJECTIVES: Targeted therapy against the epidermal growth factor receptor (EGFR) only variably represents a therapeutic advance in head and neck squamous cell carcinoma (HNSCC). This study addresses the need of biomarkers of treatment response to the EGFR-targeting antibody cetuximab (Erbitux®). MATERIALS AND METHODS: The intrinsic cetuximab sensitivity of HNSCC cell lines was assessed by a crystal violet assay. Gene copy number analysis of five resistant and five sensitive cell lines was performed using the Affymetrix SNP 6.0 platform. Quantitative real-time PCR was used for verification of selected copy number alterations and assessment of mRNA expression. The functional importance of the findings on the gene and mRNA level was investigated employing siRNA technology. The data was statistically evaluated using Mann-Whitney U-test and Spearman's correlation test. RESULTS: Analysis of the intrinsic cetuximab sensitivity of 32 HNSCC cell lines characterized five and nine lines as cetuximab sensitive or resistant, respectively. Gene copy number analysis of five resistant versus five sensitive cell lines identified 39 amplified protein-coding genes, including YAP1, in the genomic regions 11q22.1 or 5p13-15. Assessment using qPCR verified that YAP1 amplification associated with cetuximab resistance. Amplification of YAP1 correlated to higher mRNA levels, and RNA knockdown resulted in increased cetuximab sensitivity. Assessment of several independent clinical data sets in the public domain confirmed YAP1 amplifications in multiple tumor types including HNSCC, along with highly differential expression in a subset of HNSCC patients. CONCLUSION: Taken together, we provide evidence that YAP1 could represent a novel biomarker gene of cetuximab resistance in HNSCC cell lines.
Authors: Maximilian Krüger; Andreas Max Pabst; Bilal Al-Nawas; Sven Horke; Maximilian Moergel Journal: J Cancer Res Clin Oncol Date: 2015-02-24 Impact factor: 4.553
Authors: Samantha E Hiemer; Liye Zhang; Vinay K Kartha; Trevor S Packer; Munirah Almershed; Vikki Noonan; Maria Kukuruzinska; Manish V Bais; Stefano Monti; Xaralabos Varelas Journal: Mol Cancer Res Date: 2015-03-20 Impact factor: 5.852