title: In vitro toxicology evaluation of pharmaceuticals using Raman micro-spectroscopy.
abstract: Raman micro-spectroscopy combined with multivariate analysis was employed to monitor real-time biochemical changes induced in living cells in vitro following exposure to a pharmaceutical. The cancer drug etoposide (topoisomerase II inhibitor) was used to induce double-strand DNA breaks in human type II pneumocyte-like cells (A549 cell-line). Raman spectra of A549 cells exposed to 100 microM etoposide were collected and classical least squares (CLS) analysis used to determine the relative concentrations of the main cellular components. It was found that the concentrations of DNA and RNA significantly (P < 0.05) decreased, whilst the concentration of lipids significantly (P < 0.05) increased with increasing etoposide exposure time as compared to control untreated A549 cells. The concentration of DNA decreased by 27.5 and 87.0% after 24 and 48 h exposure to etoposide respectively. Principal components analysis (PCA) successfully discriminated between treated and untreated cells, with the main variance between treatment groups attributed to changes in DNA and lipid. DNA fragmentation was confirmed by Western blot analysis of apoptosis regulator protein p53 and cell metabolic activity determined by MTT assay. The over-expression of p53 protein in the etoposide treated cells indicated a significant level of DNA fragmentation and apoptosis. MTT tests confirmed that cellular metabolic activity decreased following exposure to etoposide by 29.4 and 61.2% after 24 and 48 h, respectively. Raman micro-spectroscopy may find applications in the toxicology screening of other drugs, chemicals and new biomaterials, with a range of cell types.
authors.affiliation: Department of Materials, Imperial College London, South Kensington Campus, Exhibition Road, London SW7 2AZ, United Kingdom.
authors.forename: Chris A
authors.initials: CA
authors.lastname: Owen
authors.forename: Jamuna
authors.initials: J
authors.lastname: Selvakumaran
authors.forename: Ioan
authors.initials: I
authors.lastname: Notingher
authors.forename: Gavin
authors.initials: G
authors.lastname: Jell
authors.forename: Larry L
authors.initials: LL
authors.lastname: Hench
authors.forename: Molly M
authors.initials: MM
authors.lastname: Stevens
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D002460:Cell Line; D004249:DNA Damage; D053938:DNA Fragmentation / Q000187:drug effects; D005047:Etoposide / Q000633:toxicity; D006801:Humans; D008962:Models, Theoretical; D013059:Spectrum Analysis, Raman / Q000379:methods*; D018675:Toxicity Tests / Q000379:methods*; D016159:Tumor Suppressor Protein p53 / Q000187:drug effects / Q000378:metabolism
chemical_list: D016159:Tumor Suppressor Protein p53; D005047:Etoposide