FTIR microscopic studies on normal and H-Ras oncogene transfected culturedmouse fibroblasts

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