FTIR microscopic studies on normal and H-ras oncogene transfected cultured mouse fibroblasts.

Infrared absorption spectra are well known for their sensitivity to composition and three-dimensional structure of biomolecules. The biochemical changes in the sub-cellular levels developing in abnormal cells, including a majority of cancer forms, manifest themselves in different optical signatures, which can be detected by IR spectroscopy. We measured the IR absorption spectra of monolayers of cultured normal and H-ras transfected mouse fibroblasts, using a microscopic Fourier transform IR (micro-FTIR) technique. The absorption of normal cells was found to be higher than the malignant ones in the spectral range 600-3200 cm(-1). The carbohydrate and phosphate contents were higher in normal cells relative to H-ras transfected cells. An increase in the RNA/DNA ratio was observed for H-ras transfected fibroblasts, which correlates with the increased transcriptional activity expected for the cancerous cells. In part, the variation in absorbance between normal and ras transfected fibroblasts may be due to changes in the cell dimensions.