Study of gemcitabine‐sensitive/resistant cancer cells by cell cloning and synchrotron FTIR microspectroscopy

Abstract

Over the last few years, significant scientific insight on the effects of chemotherapy drugs at cellular level using synchrotron-based FTIR (S-FTIR) microspectroscopy has been obtained. The work carried out so far has identified spectral differences in cancer cells before and after the addition of drugs. However, this had to account for the following issues. First, chemotherapy agents cause both chemical and morphological changes in cells, the latter being responsible for changes in the spectral profile not correlated with biochemical characteristics. Second, as the work has been carried out in mixed populations of cells (resistant and sensitive), it is important to distinguish the spectral differences which are due to sensitivity/resistance to those due to cell morphology and/or cell mixture. Here, we successfully cloned resistant and sensitive lung cancer cells to a chemotherapy drug. This allowed us to study a more uniform population and, more important, allowed us to study sensitive and resistant cells prior to the addition of the drug with S-FTIR microscopy. Principal component analysis (PCA) did not detect major differences in resistant cells prior to and after adding the drug. However, PCA separated sensitive cells prior to and after the addition of the drug. This would indicate that the spectral differences between cells prior to and after adding a drug might reside on those more or less sensitive cells that have been able to remain alive when they were collected to be studied with S-FTIR microspectroscopy. This is a proof of concept and a feasibility study showing a methodology that opens a new way to identify the effects of drugs on more homogeneous cell populations using vibrational spectroscopy. V C 2014 International Society for Advancement of Cytometry

In situ Fourier transform infrared analysis of live cells' response to doxorubicin

“…Subtle differences in cell spectra have been used to distinguish cells in different stages in the cell cycle [2], apoptotic cells [3] or cell lines [4,5], to identify cancer cells [6], and to predict the aggressiveness of cancer cells [7]. Several studies have shown a relationship between the mode of action of chemotherapy drugs and changes in FTIR spectra of dried cells [8][9][10], as well as differences in FTIR spectra of drug-resistant and drug-sensitive cells [11][12][13]. In these studies cells were treated with a mildly cytotoxic or cytostatic concentration of drug, generally the IC 50 value for the drug toxicity, and were then collected and dried prior FTIR analysis, as water causes a strong interference in FTIR analysis.…”

In vitro label‐free screening of chemotherapeutic drugs using Raman microspectroscopy: Towards a new paradigm of spectralomics

“…Cellular resistance pathways were specifically targeted by Yosef et al who used Raman spectral imaging to investigate the oncogenic mutation resistance to epidermal growth factor receptor targeting therapy and 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 as markers of cell resistance. Rutter et al utilised a cell cloning technique to specifically isolate sensitive and resistant cells from a mixed cell population, and investigated the difference in response of gemcitabine‐sensitive and gemcitabine‐resistant Calu‐1 epidermoid lung cancer cells to the commercial drug, using IR spectroscopy. Furthermore, Siddique et al showed that it was also possible to identify differences of nilotinib‐sensitive and nilotinib‐resistant K562 (a chronic myelogenous leukaemia cell line) cloned cells, using both FTIR and Raman microspectroscopies.…”

Vibrational spectroscopy as a tool for studying drug-cell interaction: Could high throughput vibrational spectroscopic screening improve drug development?

“…Rutter et al [69] investigated the difference in response of gemcitabinesensitive and gemcitabine-resistant CALU-1 epidermoid lung cancer cells to gemcitabine. By cloning sensitive and resistant cell populations, from a mixed population, they showed that PCA did not discriminate treated from untreated resistant cells, but did for sensitive cells.…”