IMMORTALIZATION AND TRANSFORMATION ARE ASSOCIATED WITH SPECIFIC ALTERATIONS IN CHOLINE METABOLISM

Analysis of transformed, immortalized, and primary rat Schwann cells b y high-resolution proton nuclear magnetic resonance spectroscopy revea ls that immortalization of Schwann cells (by SV40 large T antigen) ind uced a decrease in sn-glycero-3-phosphocholine (GPCho), whereas H-ras alone, which is known to cause growth arrest in these cells, induced a marked increase in GPCho and a decrease in phosphocholine (PCho). An increase of PCho was found only in cells fully transformed by both onc ogenes together. Moreover, we examined 11 human tumor cell lines, all of which expressed a PCho:GPCho ratio similar to that of filly transfo rmed rat Schwann cells. Importantly, neither the absolute levels of PC ho nor the ratio of PCho:GPCho were correlated with the rate of cell d ivision across a range of normal (primary cultures) and transformed ce lls. Thus, raised PCho:GPCho ratios may serve as an indicator of multi ple oncogenic lesions and malignancy in noninvasive tumor investigatio ns.