IR-spectroscopy and IR-microscopy of human breast tumors, xenografted breast tumors, and breast tumor cell lines

Infrared spectra of breast tumor cell Lines and breast tumor tissues have been measured. Infrared measurements of tumor cells revealed that approximately 15 cells are necessary to obtain spectra of good signal-to-noise ratio using an infrared microspectrometer equipped with a conventional infrared thermal source. Comparative studies of human breast tumor cell line suspensions demonstrated that MCF-7 cells and drug-resistant NCI/ADR cells can be differentiated based on their infrared spectra. The most striking differences between MCF-7 and NCI/ADR were found in features assigned to CH2 and CH(3 )stretching vibrations of lipid acyl chains and PO2- stretching vibrations of nucleic acids. To assess the potential of infrared spectroscopy for the diagnosis of breast tumor tissues, thin sections of tissue were mapped by FTIR microspectroscopy. The spectra of these maps were analysed using functional group mapping techniques and cluster analysis, and the output values of the different approaches were then reassembled into infrared images of the tissues. A comparison of the infrared images with the standard light microscopic images of the corresponding areas suggested that: (i) chemical mapping based on single band intensities is (not unexpectedly) an easy way to detect microscopic fat droplets within tissue; (ii) the comparison of infrared images based on band intensities at 1054 and 1339 cm(-1) provides information on tissue areas containing tumor cells; (iii) cluster analysis of the spectra is superior to the single band approach and more appropriate for differentiation between tissue types.