[Micro-Raman spectra for lipids in colorectal tissue]

Confocal Raman microscopy system was used to investigate the etiology of colorectal cancer at the molecular level. A total of two hundred and thirty four micro-Raman spectra were measured from thirty nine patients for surgically resected colorectal cancer specimens and adjacent normal tissues in the region 900-2 100 cm(-1). Two bands at 1 064 and 1 134 cm(-1) which are attributed to the all-trans bond stretching vibrations of the C-C lipid skeleton decreased in colorectal cancer tissue samples. The ratio of the Raman band intensity at 1 299 cm(-1) assigned to in-phase CH2 twisting vibrations of lipids to that at 1 264 cm(-1) from CH in-plane deformation was different for colorectal cancerous and normal tissues. The mean values of the (I1 299/I1 264) were 3.17 for normal tissues and 1.33 for cancer tissues using the software function of "Compare Means". Further, the scatter plots were used for grouping the ratio of Raman intensity at 1 299 to 1 264 cm(-1) according to tissue pathologic types by graph of the SPSS16.00 software. The decision lines (I1 299 /I1 264 = 1.96) separates between cancer and normal tissue with a coincidence rate of 94% (188/200) according to the histological results by graph. The results show that the differences between cancer and normal tissue spectra appear to arise from a decrease in the degree of the longitudinal order and an increase in the degree of unsaturation of lipid, which causes the fluidity of lipid to increases when normal cells are transformed into cancerous cells.