Raman imaging of single living cells: probing effects of non-cytotoxic doses of an anti-cancer drugThis paper was submitted as part of an Analystthemed issue on Optical Diagnosis. The issue includes work which was presented at SPEC 2010 Shedding Light on Disease: Optical Diagnosis for the New Millennium, which was held in Manchester, UK June 26th–July 1st 2010. Other papers on this topic can be found in issue 12 of vol. 135 (2010). This issue can be found from the Analysthomepage (http://www.rsc.org/analyst).

Identifying cell response to a chemotherapy drug treatment, in particular at the single cell level, is an important issue in patient management. This study aims at evaluating the effect of gemcitabine on single living cells using micro-Raman imaging. We used as a model the non-small lung cancer cell line, Calu-1, exposed to cytostatic doses (1 nM to 1 μM for 24 h and 48 h) of gemcitabine, an antitumor drug currently used in the treatment of lung cancer. Following drug treatment as a function of doses and incubation times, the Raman maps of single living cells were acquired. Cell biomolecules (DNA, RNA, and proteins) were chemically extracted and their spectral signatures used to evaluate their respective distribution in the cellular spectral information of control and treated cells. The quantification of these distributions reveals a significant effect of 100 nM gemcitabine at 48 h incubation (concomitant decrease of nucleic acids and increase of proteins). PCA analyses performed both on nuclear and extracted biomolecules spectra show a time-dependent effect of the drug. These promising results reveal that effects of subtoxic doses can be monitored at the single cell level highlighting the importance of such studies for clinical applications. [ABSTRACT FROM AUTHOR]