A New Approach to the Study of Human Solid Tumor Cells by Means of FT-IR Microspectroscopy

Abstract

Cells coming from normal and neoplastic human lung tissue were analyzed by means of FT-IR microspectroscopy. Among the various methods tested to isolate the cells, mechanical treatment alone was found to yield the best results. Monolayers of cells were homogeneously distributed by cytocentrifuge preparation on BaF2 windows, and several spectra were obtained for different circular micro-areas of the order of one hundred microns in diameter. This procedure made it possible to obtain reliable spectra and to reject those containing additional bands due to impurities arising from the isolation treatment. Spectral differences between normal and neoplastic cells reflect an increase in the intensity of the bands corresponding mainly to PO2− symmetrical and asymmetrical vibrations of DNA in pathological samples with respect to normal ones. The value of the ratio of the integrated areas of the bands at 1080 and 1540 cm−1 due to DNA and proteins, respectively, makes it possible to differentiate between normal and abnormal cells, thus suggesting the use of this parameter as an original approach in the recognition of early neoplastic transformation undetectable by means of traditional procedures.

FT-IR spectromicroscopy of mammalian cell cultures during necrosis and apoptosis induced by drugs

“…The peak area ratio A 1087 /A 1540 is often used to detect change of the DNA/protein content in the cell [35]. Compared to normal cells, we observed an increase of the ratio in Jurkat cells treated with VP-16 (control 0.37 ± 0.03 vs. 0.41 ± 0.04, 0.46 ± 0.04 and 0.47 ± 0.04 in the case of cell treated with VP-16 at 8, 16 and 32 h, respectively), indicating an increase in the DNA content of apoptotic cells [2,36]. These changes were not observed in necrotic cells in fact the A 1087 /A 1540 value was 0.47 ± 0.03; 0.48 ± 0.04 and 0.45 ± 0.04 at 24, 48 and 96 h, respectively.…”

“…Necrosis is characterized by cell swelling, disruption and rapid disintegration of the cell membrane [8] whereas in apoptosis, the cells undergo nuclear and cytoplasmic shrinkage, chromatin condensation and fragmentation, and finally the cells are broken into multiple membrane surrounded bodies (apoptotic bodies) [8]. In this work, we have compared FT-IR features of Jurkat cells during induced apoptosis and necrosis and some information were derived from the analysis of the spectra: (A) In contrast to necrotic cells, the apoptotic cells were characterized by an increase in the CH 2 absorption [32]. (B) The protein distribution in apoptotic cells indicates the presence of more α-helical structures, whereas proteins in necrotic cells become rapidly more and more aggregated [39].…”

“…The bands around 965, 1087 and 1240 cm −1 are considered DNA bands. The 965 cm −1 band corresponds to C-C/C-O stretching of deoxyribose and phosphate of DNA [2]. The band around 1087 cm −1 derives from the symmetric PO 2 − (ν s PO 2 − ) whereas the band around 1240 cm −1 originates from the asymmetric PO 2 − (ν as PO 2 − ) of the phosphate group of DNA [38].…”

“…Many important biological macromolecules, like nucleic acids [35], proteins [34] and lipids [19] have characteristic and well-defined IR-active vibrational modes thus, the analysis of IR spectra can detect, identify and quantify several molecular species within a biological sample. Under this aspects, FT-IR spectroscopy has been use to study variation in the conformation of biological macromolecules occurring between normal cells and cancer cells [1,2,4,11,23,28,31]. In addition, FT-IR spectroscopy represents also an important tool for the comprehension of the interactions between living cells and their surrounding environments [37].…”

Pharmacologic application of Fourier transform IR spectroscopy:In vivo toxicity of carbon tetrachloride on rat liver

“…7 Previous work was conducted on samples from a variety of organs, such as the brain, 8 breast, 9 and lung. 10 This technique, which requires neither reagent nor sample preparation, is nondestructive, quite sensitive, and highly selective because of its ability to be a spectral fingerprint for molecular components. 11 Malins et al applied it to the investigation of pathological conditions such as breast cancers 12 and demonstrated it to be a convenient tool for pharmacotoxicological studies.…”