title: In vitro prediction of the efficacy of molecularly targeted cancer therapy by Raman spectral imaging.
abstract: Mutational acquired resistance is a major challenge in cancer therapy. Somatic tumours harbouring some oncogenic mutations are characterised by a high mortality rate. Surprisingly, preclinical evaluation methods do not show clearly resistance of mutated cancers to some drugs. Here, we implemented Raman spectral imaging to investigate the oncogenic mutation resistance to epidermal growth factor receptor targeting therapy. Colon cancer cells with and without oncogenic mutations such as KRAS and BRAF mutations were treated with erlotinib, an inhibitor of epidermal growth factor receptor, in order to detect the impact of these mutations on Raman spectra of the cells. Clinical studies suggested that oncogenic KRAS and BRAF mutations inhibit the response to erlotinib therapy in patients, but this effect is not observed in vitro. The Raman results indicate that erlotinib induces large spectral changes in SW-48 cells that harbour wild-type KRAS and BRAF. These spectral changes can be used as a marker of response to therapy. HT-29 cells (BRAF mutated) and SW-480 cells (KRAS mutated) display a smaller and no significant response, respectively. However, the erlotinib effect on these cells is not observed when phosphorylation of extracellular-signal-regulated kinase and AKT is monitored by Western blot, where this phosphorylation is the conventional in vitro test. Lipid droplets show a large response to erlotinib only in the case of cells harbouring wild-type KRAS and BRAF, as indicated by Raman difference spectra. This study shows the great potential of Raman spectral imaging as an in vitro tool for detecting mutational drug resistance.
authors.affiliation: Department of Biophysics, Ruhr University Bochum, Universitätsstr. 150, 44780, Bochum, Germany.
authors.forename: Hesham K
authors.initials: HK
authors.lastname: Yosef
authors.affiliation: Department of Biophysics, Ruhr University Bochum, Universitätsstr. 150, 44780, Bochum, Germany.
authors.forename: Laven
authors.initials: L
authors.lastname: Mavarani
authors.affiliation: Department of Molecular GI-Oncology, Clinical Research Center, Ruhr University Bochum, Universitätsstr. 150, 44780, Bochum, Germany.
authors.forename: Abdelouahid
authors.initials: A
authors.lastname: Maghnouj
authors.affiliation: Department of Molecular GI-Oncology, Clinical Research Center, Ruhr University Bochum, Universitätsstr. 150, 44780, Bochum, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Hahn
authors.affiliation: Department of Biophysics, Ruhr University Bochum, Universitätsstr. 150, 44780, Bochum, Germany.
authors.forename: Samir F
authors.initials: SF
authors.lastname: El-Mashtoly
authors.affiliation: Department of Biophysics, Ruhr University Bochum, Universitätsstr. 150, 44780, Bochum, Germany. gerwert@bph.rub.de.
authors.forename: Klaus
authors.initials: K
authors.lastname: Gerwert
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology* / Q000627:therapeutic use; D045744:Cell Line, Tumor; D003106:Colon / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D003110:Colonic Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D019008:Drug Resistance, Neoplasm; D066246:ErbB Receptors / Q000037:antagonists & inhibitors*; D000069347:Erlotinib Hydrochloride / Q000494:pharmacology* / Q000627:therapeutic use; D019073:HT29 Cells; D006801:Humans; D018613:Microscopy, Confocal / Q000379:methods; D058990:Molecular Targeted Therapy; D009154:Mutation; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics; D013059:Spectrum Analysis, Raman / Q000379:methods*
chemical_list: D000970:Antineoplastic Agents; C117307:KRAS protein, human; D000069347:Erlotinib Hydrochloride; C512478:EGFR protein, human; D066246:ErbB Receptors; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf; D016283:Proto-Oncogene Proteins p21(ras)
keywords: BRAF; Colon cancer; Erlotinib; KRAS; Oncogenic mutation; Raman imaging