Human colon adenocarcinoma cell lines display infrared spectroscopic features of malignant colon tissues

Seven human colon cell lines were studied by infrared spectroscopy including study of several spectral parameters under high pressure (pressure tuning spectroscopy). The results were compared to those obtained from the study of normal and malignant colon tissues (B. Rigas et al., Proc. Natl. Acad. Sci. USA, 87: 8140-8144, 1990; P. T. T. Wong and B. Rigas., Appl. Spectrosc., 44: 1715, 1990). The seven adenocarcinoma cell lines displayed almost all of the important spectroscopic features of colon cancer tissues: (a) increased hydrogen-bonding of the phosphodiester groups of nucleic acids; (b) decreased hydrogen-bonding of the C--OH groups of carbohydrates and proteins; (c) a prominent band at 972 cm-1; and (d) a shift of the band normally appearing at 1082 cm-1 to 1086 cm-1. These cell lines differed spectroscopically from the colon cancer tissues in that: (a) they displayed a band at 991 cm-1, which is weak in colon tissues; and (b) the packing and degree of disorder of membrane lipids were close to those observed in normal colonic tissues. These findings (i) establish IR spectroscopy, used in combination with pressure tuning, as a useful method to address problems of tumor biology in cell culture systems, (ii) indicate that these cell lines offer a useful experimental model to explore the origin of the spectroscopic changes that we observed in colon cancer tissues, and (iii) support the idea that the malignant colonocyte is the likely source of all or most spectroscopic abnormalities of human colon cancer.