title: Label-Free Raman Spectroscopic Imaging Monitors the Integral Physiologically Relevant Drug Responses in Cancer Cells.
abstract: Predictions about the cellular efficacy of drugs tested in vitro are usually based on the measured responses of a few proteins or signal transduction pathways. However, cellular proteins are highly coupled in networks, and observations of single proteins may not adequately reflect the in vivo cellular response to drugs. This might explain some large discrepancies between in vitro drug studies and drug responses observed in patients. We present a novel in vitro marker-free approach that enables detection of cellular responses to a drug. We use Raman spectral imaging to measure the effect of the epidermal growth factor receptor (EGFR) inhibitor panitumumab on cell lines expressing wild-type Kirsten-Ras (K-Ras) and oncogenic K-Ras mutations. Oncogenic K-Ras mutation blocks the response to anti-EGFR therapy in patients, but this effect is not readily observed in vitro. The Raman studies detect large panitumumab-induced differences in vitro in cells harboring wild-type K-Ras as seen in A in red but not in cells with K-Ras mutations as seen in B; these studies reflect the observed patient outcomes. However, the effect is not observed when extracellular-signal-regulated kinase phosphorylation is monitored. The Raman spectra show for cells with wild-type K-Ras alterations based on the responses to panitumumab. The subcellular component with the largest spectral response to panitumumab was lipid droplets, but this effect was not observed when cells harbored K-Ras mutations. This study develops a noninvasive, label-free, in vitro vibrational spectroscopic test to determine the integral physiologically relevant drug response in cell lines. This approach opens a new field of patient-centered drug testing that could deliver superior patient therapies.
authors.affiliation: †Department of Biophysics and ‡Department of Molecular GI-Oncology, Clinical Research Center, Ruhr-University Bochum, 44780 Bochum, Germany.
authors.forename: Samir F
authors.initials: SF
authors.lastname: El-Mashtoly
authors.affiliation: †Department of Biophysics and ‡Department of Molecular GI-Oncology, Clinical Research Center, Ruhr-University Bochum, 44780 Bochum, Germany.
authors.forename: Hesham K
authors.initials: HK
authors.lastname: Yosef
authors.affiliation: †Department of Biophysics and ‡Department of Molecular GI-Oncology, Clinical Research Center, Ruhr-University Bochum, 44780 Bochum, Germany.
authors.forename: Dennis
authors.initials: D
authors.lastname: Petersen
authors.affiliation: †Department of Biophysics and ‡Department of Molecular GI-Oncology, Clinical Research Center, Ruhr-University Bochum, 44780 Bochum, Germany.
authors.forename: Laven
authors.initials: L
authors.lastname: Mavarani
authors.affiliation: †Department of Biophysics and ‡Department of Molecular GI-Oncology, Clinical Research Center, Ruhr-University Bochum, 44780 Bochum, Germany.
authors.forename: Abdelouahid
authors.initials: A
authors.lastname: Maghnouj
authors.affiliation: †Department of Biophysics and ‡Department of Molecular GI-Oncology, Clinical Research Center, Ruhr-University Bochum, 44780 Bochum, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Hahn
authors.affiliation: †Department of Biophysics and ‡Department of Molecular GI-Oncology, Clinical Research Center, Ruhr-University Bochum, 44780 Bochum, Germany.
authors.forename: Carsten
authors.initials: C
authors.lastname: Kötting
authors.affiliation: †Department of Biophysics and ‡Department of Molecular GI-Oncology, Clinical Research Center, Ruhr-University Bochum, 44780 Bochum, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Gerwert
mesh_terms: D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000494:pharmacology*; D000970:Antineoplastic Agents / Q000737:chemistry / Q000494:pharmacology*; D066246:ErbB Receptors / Q000037:antagonists & inhibitors* / Q000737:chemistry; D006801:Humans; D015999:Multivariate Analysis; D009154:Mutation; D000077544:Panitumumab; D013059:Spectrum Analysis, Raman; D013329:Structure-Activity Relationship; D014407:Tumor Cells, Cultured; D018631:ras Proteins / Q000235:genetics
chemical_list: D000911:Antibodies, Monoclonal; D000970:Antineoplastic Agents; D000077544:Panitumumab; D066246:ErbB Receptors; D018631:ras Proteins